Lower Links 101

[NorCal_Prerunner]

It would be sweet if every month or so, there could be some kind of technical thread on building a piece or part of a desert truck from start to finish. I was hoping to cover building lower links for a 3 or 4 link setup. I always see plenty of great parts completely finished, Bent, Boxed, TIG welded, Dimple Died, ect, but never get to see the full make-up of a part from start to finish.

1. You determine you actually need or want a 4-link setup on your truck.
2. You have the tools, fabrication skills, and aren't a complete dumb ass.
3. You don't have access to a mechanical engineering program such as Solid Works to design it.
4. Where do you start?

A: What materials are you going to use? Tubing type, diameter, thicknes? Plate type, thickness? Heim size, threaded insert? Bushing type for front pivot? Cool, all that crap out of the way.

B: How to determine the lenght of the lower link?

C: Things to consider when designing the lower link?

D: Some images of expoded views of different lower link designs. (Kris loves to post, so let's see an exploded view of one of the lower links he has designed)

There is so much more that goes into a 3 or 4 link setup than building lower links. Everything could not be covered in an organized fashion in one post. I hope this post provides educational info for some of us.

Looking for posts from people have successfully designed and built a 3 or 4link setup that worked well.

What do you think. And no, 1,2, and 3 are NOT describing me, I just thought it would be an interesting and informative post. Later, J_





It's never too late to be what you might have been....

[Kritter]

No lower links my man..sorry. Havent had the want (read, money) to take the time and design one...yet. V8Ranger might have some of his SW drawings or I know John Richer has some.

Kris
"Buy American before it's too late..."

[1992f150]

no one in the bussiness wants to give away their secrets.

Azusa: shame of the foothills

[Curtis Guise]

I think that is a good idea. And starting with a 3 or 4 link setup sounds good to me since I plan to start building one soon. I have some ideas from looking at other trucks but to know how to get the correct geometry and materials to use would be great. (from people that know what they are talking about)

If enough people would contribute to this idea then maybe Klaus could start a new topic on the board called "projects" or something like that.

[ntsqd]

Some of the things that need consideration in a rear linkage design:

Roll Center Progression (where it is relative to the axle at any point in the travel)

Roll Axis Inclination (To avoid or minimize 'Rear Steer' when the axle is twisted relative to the chassis)

Instant Center Location (Anti-Squat/Anti-Rise Properties)

Pinion Angle Delta (How much and in what direction the pinion angle changes from bump to droop)

Wheelbase Delta (How much the wheelbase changes from full bump to full droop)

Those are just off the bottom of my head. Everyone will assign their own priorities to these, and what ever others I missed. Where's Bob ?

Perhaps we ought to start a new thread ?



TS

I used swerve around my halucinations, now I drive right thru them.

[NorCal_Prerunner]

Looks like TS has most of the things to consider when building a lower link covered. So now let's some basics covered such as A, B, and D. I don't want this post to get hyjacked with buckets of super tech info yet. Let's just get the basics covered first. Remember this post is NOT how to completely build a 4-link, just a part of it. All of TS's comments are very important. In due time though. Although this is a complex task, we are not talking about a designing and building a new type of micro-processor for a main logic board, so I don't understand the trade secret comment. We're talking about a fawking lower link. Good information for everyone.

It's never too late to be what you might have been....

[CRAIGHALL]

One thing I tend to see alot even on some fairly nice trucks is the coilover & bypass mounts being above the centerline of the front and rear pivots. This makes the arm rely on the front, which is usually a bushing to keep it straight,prematurely wearing out the bushing. the mounts should be below the centerline allowing the arm to stay vertical and not wear your shock heims or your expensive delrin bushing or that 95.00 rear heim, usually I see 1-1/4" heims. Tube arms are simpler than sheet metal ones but you need the vertical strength at the shock mounts so I seem to favor a sheet metal arm possibly out of .090 chromolly if the sides are tall and vertical or maybe 1/8" if you make a triangle and taper the sides up . Try not to leave an open pocket at the shock mounts so that water and dirt collect and rust away your arm. I have some arms drawn but, there on auto cad at work (sheet metal shop) Just some things I've seen on other arms I've only made tube ones Craig

[Curtis Guise]

The only problem is that if you try and answer B (lower link length) then almost everything that Thom brought up will be a factor. Because the length of that one piece has something to do with the rest of the setup. So in my opinion it would make sense to figure out the geometry of the entire setup.

I guess what I am trying to say is that it might be hard to answer B without the thread getting alot of "super tech info". But that's ok with me.

[NorCal_Prerunner]

I'll all for super tech, but let's get the basics out of the way first. I agree with you that B is too hard to answer without addressing a lot of other things. I wish there was a orderly way the board could sort the posts. Thanks for the reply JDfab.

It's never too late to be what you might have been....

[ntsqd]

Somebody measure their truck. It needs to be a representitive truck.
Best way to measure is to use a flat piece of level concrete, a plumb-bob, and some chalk. We need to know:

Center of Gravity: Let's use the common assumption - the crank centerline at the flywheel surface. We need to know how far back it is fron the front axle centerline and we need to know how high off the ground it is.

Wheelbase. Measure it, don't quote what is considered 'common knowledge.'

Eventually we'll need to know where the frame rail is, but those two numbers will get this going.



TS

I used swerve around my halucinations, now I drive right thru them.

[FABRICATOR]

Has the first part of question #1 been answered? What is the need or application? This should determine priorities.

<font color=orange>The best ideas are the ones that look obvious to the casual observer.</font color=orange>

[NorCal_Prerunner]

TS,

I'll take measurements of my truck and post them tomorrow, Not a problem. It is a Toyota standard cab.


It's never too late to be what you might have been....

[NorCal_Prerunner]

I guess #1 hasn't really been answered, so here it is.

Need: Prerun, chase, low budget race truck, let's say 4 MDR races per year.
Application: Class 7/1450 Toyota standard cab.

It's never too late to be what you might have been....

[ntsqd]

You bring up a point that I see often overlooked. I call it "wobbly arms", arms that are designed so that the damper and/or coil-over loads are working to twist the arm over sideways. My only problem with putting the damper mount(s) below the Line of Action ("LOA", the straightline btwn the front & rear pivot points) is that I've yet to see one that didn't make me wonder what would happen if just exactly the right sized rock came along......
Others have pondered this b4 me and one result is the bent arms you sometimes see. Those have a deliberate bend in them so that the damper mount(s) are on the top of the arm structure, but are still below the LOA of the arm. I see those as a broken arm looking for a place to happen, or they are overbuilt and cause excessive unsprung weight.

If the loads could be known or predicted, then determining the arm's needed section modulus at any given point along it's length would be a rather simple exercise. Translating the section modulus into actual metal would be the hardest part.

TS

I used swerve around my halucinations, now I drive right thru them.

[ntsqd]

You bring up a point that I see often overlooked. I think of them as "wobbly arms", arms that are designed so that the damper and/or coil-over loads are working to twist the arm over sideways. My only problem with putting the damper mount(s) below the Line of Action ("LOA", the straightline btwn the front & rear pivot points) is that I've yet to see one that didn't make me wonder what would happen if just exactly the right sized rock came along......
Others have pondered this b4 me and one result is the bent arms you sometimes see. Those have a deliberate bend in them so that the damper mount(s) are on the top of the arm structure, but are still below the LOA of the arm. I see those as a broken arm looking for a place to happen, or they are overbuilt and cause excessive unsprung weight.

If the loads could be known or predicted, then determining the arm's needed section modulus at any given point along it's length would be a rather simple exercise. Translating the section modulus into actual metal would be the hardest part.

TS

I used swerve around my halucinations, now I drive right thru them.

[rdc]

Remember, what you accomplish by placing the load below the center line only reduces what you call "wobbly arms", on compression. On rebound your gona get the "wobbles." Its one or the other, unless you control the arm with a tight bushing at one end or at the point where the load is connected, as in this example.

http://race-dezert.com/skunkz/newhan/27.jpg

Sorry the picture is sooooo big.

[ntsqd]

True, but the whole load of the truck's rear axle weight + any transfered off the front + any dynamic loading during a landing is acting on it in compression, while only the unsprung weight's inertia + any energy still stored in the springs is acting on it in extension. I'll compromise in the direction of the greater loading.
Doesn't negate the need for a bushing with anti-twist properties, just reduces the loads trying to twist the arm.

TS

I used swerve around my halucinations, now I drive right thru them.

[billymanfroy]

Looks like we've established that a front bushing is the smart way to go. I've talked to several people - ones who would know - and they all recommend bushings at the front for the reasons you discussed. Theoretically, you could get away with running heims on both ends, but only if the shock mounts were on the C/L of the two ends. But why? Bushings are cheaper, safer, and are probably lighter. The consensus was to run silica bronze for the actual bushing. Bolt thru hole size is up to you, but you gotta think bigger is better.

We are in the process right now of drawing up arms, mounts, links, etc. in Autocad 2000. As John Richer says on his site, that really is the only way to get your brain around what actually happens when the thing cycles, and also how long the UPPER links are, and especially where they are mounted in relation to all the rest. We're doing exactly as they did using 3/16" plate for the lower links (no tubing). I have always thought that the bow or kink in most lower trailing arms was a risk, but I've never seen one fail or heard of one failing. Baldwin tore his rear end out at Laughlin (and Baja 500 too, right?) but they appear to just use tubes to locate their rear end and don't use a traditional arm. Don’t know how to accurately compare the two, but you have to believe they use pretty beefy heims (~1 ¼”) like everyone else. I have a friend who runs an ex-corr pro2 truck, and I swear his lower links drag not only on the ground at times, but literally under ground sometimes. I always thought there must be a better way, but he's never had to do anything to them but repaint them (often). I know, I know, short course and desert is apples to oranges.

I think it’s important to think about, along with the questions already raised, how much travel do you really need? 35” in the rear with stock beams (or a-arms) in the front is silly, and will probably hurt more than it will help. I’ll keep you posted on this, because we are going to have 28” in the rear, and 16” in the front. Most people (whether racing or prerunning) probably think they are eventually going to go full-tilt and go 6-9” wider front and rear, coilovers & bypasses. (Don’t forget the added 200+ lbs for the “biggest-junk-yard-V6-I-can-get” swap) Why? Because everyone else does? According to some of the experts I’ve been talking with, you shouldn’t really need more than one 2.5” per corner on a 7-type truck. Of course, set up is more critical and less forgiving, but done right, you’ll be happy for years to come.

Here are some basics:
Sheet metal boxed trailing arms. Silica bronze bushing in the front (3/4” bolt, 1.75x.120” tubing) 1 ¼” heim on axle.

Upper links: Not sure, 1”x.120” 4130 tubing with 7/8” heims. or 1 ¼” x.120” 4130 tubing with 1” heims.

Shocks: King 2.5” x16 coilovers w/ reservoirs (dual rate)

1” speedway sway bar

70” track width (until we extend the front)


I will post some pics as we go, and hopefully so will other people. We’ll eventually have to pare this long rambling thing down to the bare facts so it’s useful, too.

Billy

[FABRICATOR]

Both ends of each trailing arm must be able to swivel in all directions.

<font color=orange>The best ideas are the ones that look obvious to the casual observer.</font color=orange>

[billymanfroy]

OK, Chuck... I'll bite.

Would you please elaborate as to why you need heims at both ends? How do you set that up?

Thanks.

Billy

http://home.off-road.com/~jricher/images/white ranger/susprear/4linkmount5.JPG

http://home.off-road.com/~jricher/images/white ranger/susprear/fulllean.JPG

[Curtis Guise]

"Both ends of each trailing arm must be able to swivel in all directions."

When I think about it that makes sense, but then why do all the TT's and nice prerunners have a standard bushing in the front instead of a heim? And all of those trucks are built by excellent fabricators. For examples allot of the trucks on the skunkz page are like that.

[crashesalot2003]

i was thinking, would it make sense to use some sort of uerithane bushing up front, to help eliminate most wobble, but still allow good articulation? just a thought


no brain, no pain

[RacerX]

billymanfroy- When baldwin ripped those links off, he hit a rock the size of a microwave. That will tear anything up. A single link with a bushing and a hiem or two hiems will crumble the same.

[FABRICATOR]

Most, if not all, Trophy Trucks use swivel rod ends ("Heims") at both ends of the lower control arms (LCA's). Pre-runners, depending on application, use either swivel rod ends or rubber/urethane bushings at the forward end. There will be lateral movement of the LCA's. Any connection that does not allow for this will either wear rapidly, force something to flex, or both. Resilient bushings (rubber/urethane) are good for keeping the arm from flopping, but don't live long when subjected to a lot of movement.

<font color=orange>The best ideas are the ones that look obvious to the casual observer.</font color=orange>

[CRAIGHALL]

What about the upper link or links? I've got a 9" yet to be installed but I've already welded on my upper and lower mounts. On top I'm gonna use two 7/8" high misalign heims (the ones with the shoulders) and not space them smaller ,but use 3/4" bolts. I felt two 3/4" bolts holding two heims would be stronger and last longer (load spread twice) than a single 1-1/4" heim that you have to misalign to 7/8" I think thats the size bolt. With a 7/8" bung (1.25 o.d.) you can run two 1.5 x. 120 wall tubes for links,plus you get minor side to side adjustment. I think you can get of these for the price of a single 1-1/4" and you can get 20 deg. with the 7/8". Hope it works I already welded the mounts!!

On the lower I'm gonna use a large uniball 2.125 o.d. 1" bore misaligned down to 3/4" I think. Do you really need the heim adjustment for length? arms would be jigged identical in length with the mounting brackets being located off of existing holes in my carrier bearing crossmember (97-ext.cab ranger).Lower arm lenght to be about 60 5/8". Uupper yet to be figured, around 53" I think. I'm going to use two set screws in the uniball cup to keep out any slight misfit. Unaballs are still cheaper than a big heim on the bottom.

[partybarge_pilot]

Bushings up front will bind to some degree on articulation depending on how much wheel travel you have and how long your arms are. I have yet to see a TT with bronze bushings. All that I have seen are delrin or urithane. Both will give a little flex when needed. This also helps isolate some vibration from the frame.

[Curtis Guise]

Before putting much thought into it I was considering turning out some Delrin bushings for the front pivot like I used on the inner pivots on my lower a-arms on my race truck. But I didn't think about the flex they would need to allow for the lower arms on a 4 link. Delrin will allow almost no flex compared to a urethane bushing. So it sounds like Urethane or a heim is the way to go?

[NorCal_Prerunner]

Some measurements for Thom. I didn't quite know how to get the exact measurement for the bottom of the flywheel, so I measured the distance from the back/bottom edge of the block down to the ground.This is just for reference. It is the process of determining the link length and the geometry that we're after.
http://home.earthlink.net/~joshuanie/4link.gif

It's never too late to be what you might have been....

[ntsqd]

Sorry I didn't get back to you on that, busy at work with some testing of a new caliper. It did several months worth of racing on the dyno today.

What we need is the elevation of the center of the flywheel/crankshaft at the clutch surface. This is the commonly accepted rough approximation for the Center of Gravity of vehicles not highly modified.
To get exact, you need to first get corner weights (or at least front/rear percentages) with the vehicle sitting level. Then do it again with the vehicle tilted at a large angle. You can apply the percentages gleened from the first weighing to the wheelbase to find where the CG is front to rear. With the second measurement in hand apply a little Trig to find the elevation of the CG.

My thot was to put the Instant Center on the commonly approximated CG. We could have a whole discussion about where it really should go, but I lack the background in dez rigs to debate it and that's not our point anyway. Putting it on the CG makes getting the basics down easier.
So draw your upper & lower arm LOA's from that point to where they will mount on the axle housing. As one post said, do this in something like AutoCAD. Then you can easily cycle the suspension a quiery the program for what the various angles change to. You can model it in graph paper & construction cardboard. With enough time you can derive the same information.

TS

I used swerve around my halucinations, now I drive right thru them.

[ntsqd]

My take on the front bushing vs. rod end/spherical bearing debate is that a properly done bushing will stabilize the arm from trying to twist. Which will cost you some articulation due to binding. It does build in an un-tunable swaybar. I'm willing to live with that since it gives me control over what the arm is doing otherwise.
If the arms are designed with the kind of twisting that articulation will put into them such that the strain is spread out over a long area of the arm, then the induced stress won't be high enough to rapidly fail the arm at any one point. Make no mistake though that you have just created something with a limited life expectancy. If you want the arm to last the natural life of the vehicle, then a spheric in some fashion is called for.

TS

I used swerve around my halucinations, now I drive right thru them.

[NorCal_Prerunner]

For progression of the post, can we estimate where it is based on my quick drawing? Like I said, it is more about the process at this point rather than the exact measurements.

It's never too late to be what you might have been....

[CRAIGHALL]

here's mine

[ntsqd]

As I recall you said your measurement is from the lower most surface of the block at it's rear-most edge. I'd estimate that the crank centerline is ~2" above that, and that the flywheel's friction surface is ~2" to the rear of that. I would say that we should adjust the dimensions so that we're closer to a real truck's dimensions.

Where the pivot points on the housing are going to be would be my next chore. I fully expect that they might get moved around some, but need to start with something. From observing various rear linkages it appears that the lower link axle pivots are always very close to the axle centerline. This makes the travel path easy to predict since it's dominated by the lower link. The axle will travel in a partial circular path of a radius very close to the length of the lower arm and centered about where the lower arm's frame pivot is.
When I worked out my friend's linkage (hasn't been built yet, no idea how it works) I started with the lower arm pivots 3" forward of the axle centerline and 3" down from the centerline. The upper pivots I put 9" above the centerline and on the fore/aft centerline.

The next chore is to draw a line btwn the IC and each of the pivot points. Wouldn't hurt to break out your Herb Adam's book at this point either. There are some good drawings in it on this topic.

TS

I used swerve around my halucinations, now I drive right thru them.

[Curtis Guise]

This is just something that I thought of when looking at CRAIGHALL's drawing. What happens if you take both the upper and lower links front pivots and align them? I don't have a CAD program to try it.

Also I see alot of trucks with the rear lower pivot directly in front of the axle housing instead of below the housing. Wouldn't that be better because it would keep the arm higher off the ground?

[billymanfroy]

<blockquote><font size=1>In reply to:</font><hr>

I see alot of trucks with the rear lower pivot directly in front of the axle housing instead of below the housing. Wouldn't that be better because it would keep the arm higher off the ground?

<hr></blockquote>


Curtis,

Here's the way I understand it. Ideally, you would want the force directly under the axle as CRAIGHALL has it. This is the direction you want the force acting on the axle to keep it from trying to twist. Straight out in front would be better for clearance, but ALL of the forces would be then trying to twist the axle forward on compression and back on rebound.

John Richer explains it a lot better here:
<A target="_blank" HREF=http://home.off-road.com/~jricher/newrearsusp.htm>http://home.off-road.com/~jricher/newrearsusp.htm</A>

Here's their Autocad drawing, too.
http://home.off-road.com/~jricher/images/white ranger/SUSPENSION.jpg


Thom,

I didn't see anywhere on Richer's build up where they considered the C of G, and I can't do it now because my truck is all torn apart. I can measure my crank from the ground and from the front wheels, but what do I do with that info? How do I use that to determine where my front pivots end up or how long my LCA's are going to be? Thanks

Billy

[RacerX]

Enough of Bob Vilas's (sp?) "This old truck", how about we ask the builders of race winning vehicle's how it is done.

[NorCal_Prerunner]

Hey Anthony,
How about you give Donahoe, H&M, and Camburg a call and tell them about the post. Otherwise, stop wasting everyones time with useless posts like that. This thread has more good info in it thus far than most. And if you feel like putting in your 0 cents again, why don't you just email me directly.

Here's some pics of some lower links for an F150 extended cab in progress, built by H&M. Anyone have an idea as to what diameter the tube looks like + possible thickness as well as the thickness of the plate? TIG welded Cromoly no doubt.
http://home.earthlink.net/~joshuanie/hnmlinks/vesay1_big.jpg
http://home.earthlink.net/~joshuanie/hnmlinks/vesay2_big.jpg
http://home.earthlink.net/~joshuanie/hnmlinks/vesay3_big.jpg
http://home.earthlink.net/~joshuanie/hnmlinks/vesay4_big.jpg
http://home.earthlink.net/~joshuanie/hnmlinks/vesay5_big.jpg

It's never too late to be what you might have been....

[Kritter]

I am sure John has well thought out his design...he is a mechanical engineer and working in the design field by trade.

Kris
"Buy American before it's too late..."

[ntsqd]

Have at it. See what they'll tell you. I know what I'd tell you where I in that possition: diddly squat. Why would I give up for free some hard earned knowlege that might be my competitive edge ?

TS

I used swerve around my halucinations, now I drive right thru them.

[ntsqd]

Putting the LA's pivot directly forward of the axle CL makes that pivot point the center of torque reaction rotation and means that the UA has to resist all of the torque reaction. Moving the pivot down allows the LA to help a little. Does reduce clearence a little.

Rather than endlessly debating where to put the IC, I thot to put it right on the CG at static ride height. That avoids debating where it might better be put while still being demonstrative of the process of laying out the rear suspension. We're at the point where reading the rear suspension chapter in Herb Adam's chassis book will be really helpful. All we've done so far is duplicate his approach as applied to semi-real world truck.

Looking at the Richer dwgs it's odd, I'd started a layout and arbitrarily chosen a 50" long LA. From the measurements & my rough guess that puts the frame pivot of the LA just about equal to the front U-J which will minimize driveshaft plunge.

Those pockets under the damper mounts on the arm pictured are what I was worrying about catching just the right sized rock. I personally feel that such pockets should be open to the bottom. That creates some strength of design issues that need to be resolved.

TS

I used swerve around my halucinations, now I drive right thru them.

[FABRICATOR]

Billy, (sorry to go back and answer an old question on this progressive post)
Re: "Would you please elaborate as to why you need Heims at both ends? How do you set that up?

Rubber(?) bushings at the front are fine for most pre-runners. Heims on both ends are necessary for long travel and long races. A total Heim setup is just about the same as the system in your pictures. With Heims, and preferrably with bushings, an effort must be made to minimize flopping of the LCA (lower control arm). Prevention of flooping under compression must have priority. The lower shock pivot point should be located slightly below the centerline of the LCA pivot points. On most applications, a coil over shock will maintain positive pressure against the LCA at all times (bounce and rebound). The preferred method is a staggered arrangement with the by-pass just below center and the coil-over just below that.



<font color=orange>The best ideas are the ones that look obvious to the casual observer.</font color=orange>

[billymanfroy]

Chuck,

Thanks for covering that. We do have our LCA set up with the shock mount 1" under the C/L of the ends. I really did consider running heims at both ends (I even bought four 1 1/4" heims & bungs). We're committed to bushings now that our sheet metal is being laser cut.

I went with mild, since the 4130 was $400 more per 4' x 8' sheet. I hated to do it, but I just reached the $3,000 mark, and not one thing has been put on the truck yet... I'm running out of money in a hurry.

I was given a flyer from Chad McNeil's outfit that advertises a 30"-35" travel kit. This is what it comes with:
(1) 9 inch Rear Differential (With stock parts)
(2) Trailing Arms - lower links
(1) Wishbone Arm - upper link
(3) 1"1/4 Chromolloy Hyme Joints
(8) Nylotron Graphite Bushings
(2) Trailing Arm Pivot Brackets
(1) Wishbone Pivot Chassis Crossmember
(1) Installation Hardware Kit
(1) Installation Instructions
$2500.00
This is a link to it: <A target="_blank" HREF=http://www.mcneiloff-road.com/3-link.html>http://www.mcneiloff-road.com/3-link.html</A>

I never dreamed that doing it myself would cost more than that, but then again my $3k includes King 2.5" Coilovers, and two 9" center sections and 1 new gear set. I don't know anything about these guys, what their stuff looks like or works like, but that seems pretty hard to beat. PLEASE! I'm not posting this stuff to invite people to bash them, so please don't. I just thought it was an interesting alternative for those who don't want to go through what I've been going through for the last 2-3 weeks. I've never priced any other vendors' kits, but maybe somebody should!

On a funnier note, I've got a call into Herb Adams to pick his brain on this subject. He's supposed to call me back in late December. Think he'll call back?!? I'll be sure to let you all know if he does, and what he says. We will already be testing by then hopefully.

Billy


<P ID="edit"><FONT SIZE=-1>Edited by billymanfroy on 12/06/02 04:05 PM (server time).</FONT></P>

[ntsqd]

This is a drawing I put together for reference. In this drawing I used the dimensions from way above for a basis and used 50" for the lower arm and 40" for the upper arm. The upper arm housing pivot is 9" above centerline and the lower arm pivot on the housing is 3" down and 3" forward of the centerline. The heavy line is the Anti-Squat - Anti-Rise border. It is plotted with 8" on bump travel and 8" of droop travel.

I make no claim that this will work well, it's just something to work from. Notice that the Instant center remains above the Anti-Squat border.

TS

I used swerve around my halucinations, now I drive right thru them.

[ntsqd]

Just did a qwik calc on this drawing, the driveshaft's total plunge is slightly less than 7/16" Some rock crawlers need 16".........

TS

I used swerve around my halucinations, now I drive right thru them.

[FABRICATOR]

Previous input was to help keep things usable and explain a few things, not to interfere with design. Drawing looks realistic. CG may be a bit farther back than that presumed. Pre-runners often have rear mounted fuel tanks, spares, battery, rear cage, heavier than stock bumper, jack, etc. Anti-dive and squat depend on how much street use there will be. They generally do not help during fast forward. Moving the pivot points forward of the axle would either shorten the arms, move the arm's front pivots forward, or both, and does not seem advantageous.

<font color=orange>The best ideas are the ones that look obvious to the casual observer.</font color=orange>

[ntsqd]

I figured that, but others may not have.
My thot all along has been to get something representitive up on the board and not be mired down in debating exactly where certain key features (like CG) really are. Take Fabricator's points home and chew on them if you're going to do this mod. They're good points and they come from someone with a lot more dezert race experience than I. Only reason I can see for designing in a lot of Anti-Rise would be if you intend to wheelie the front over the rough stuff as one certain Chevy in Dezert People does (name of current team is escaping me at the moment).

On the front heim vs. bushed end topic, you've made me think about what really happens during use. I'm inclined to stay on the bushing side of the issue, BUT I also know that for that config to work well two things need consideration. The first is that the arm in question has to be sufficiently non rigid in the lateral direction to allow for some deflection (over it's whole length or it will break) so that the bushings are not loaded to premature failurewhen the housing is crossed up. The second is that the bushings will have a set life span and trying to exceed that would be folly.

If a person were determined to use a bushing and have an arm rigid in all directions, then you would need to use a second bushing directly behind the first. The second bushing would have it's pivot axis in the verticle plane. That would yield the anti-wobble properties of a single bushing w/o causing a bushing wear or linkage binding problem when crossed up. That, unfortunately, yields greater complexity and two more failure points.

TS

I used swerve around my halucinations, now I drive right thru them.

[FABRICATOR]

You brought up 2 important points. Although it won't happen in this application, wheelying(sp) over the rough stuff is the ultimate goal. The farther you are from being able to do this, the more it is slowing you down. Another item is that the LCA is a very rigid piece with a lot of leverage. A well designed arm will tear off just about any forward mount if it is allowed to. Flexing of the arms should not be expected. A rod end, or a rubber or urethane bushing should be doing all the twisting. To use rigid bushings would require one surrounding or behind the other 90* apart. This in turn would require the rear joint to take up the entire range of axle twist. If properly setup, it is not undesirable for the LCA to be able to twist in place.

<font color=orange>The best ideas are the ones that look obvious to the casual observer.</font color=orange>

[AZmiik]

So is what your saying is that the Ideal bushing would end up looking like a u-joint or that hybrid joint in the uni-ball replacement thread a couple of weeks ago?

If you are going to use rod ends on both end is all that is keeping the LCA from flopping side to side on the shock rod ends the downward force acting below the CL of the LCA?

Mike

[ntsqd]

That's what I described, sort of an offset axis UJ. I didn't see the hybrid part mentioned so I've no idea how it would work.

If introducing some compliance is deemed necessary, and some sort of single axis of rotation bushing is not to be considered, then I would make a sub-frame to mount one or both forward LCA Spherical Rod Ends (SRE ?), which is then mounted to the frame via some sort of urethane or rubber bushes. How's that for a run-on sentence ?

Yes, in the case of SRE's at both ends then only thing that would keep the LCA from trying to flop on it's side would be the below CL mounting of the damper(s). That is some considerable force so the distance below CL should not have to be great.

TS

I used swerve around my halucinations, now I drive right thru them.

[FABRICATOR]

Question #1: No, the ideal bushing is a swivel rod end.
Question #2: Yes, as long as things are setup properly. The coil over must be attached as low or lower than any other shock. If the by-pass shock is set up for heavy damping just before full extension (or top out), it can cause flopping if it is mounted too far below the CL of the LCA. The final few inches of spring rate can also affect flopping. There must be some spring pressure all the way out. If things are just right, rod ends are best. If things are in the ball park, a rubber bushing will work for light to medium duty use. If things are way off, nothing will last very long.

<font color=orange>The best ideas are the ones that look obvious to the casual observer.</font color=orange>

[AZmiik]

The hybrid part I was refering to was used as a upper pivot on the uprights on the Fly N Hi truck someone posted awhile back.

[billymanfroy]

Look what santa just brought me! We got the rest of the scrap, too. Time to fire up the welder...

[evan_clanin]

that looks nice bill, does anybody know if there are kits like this around for toyotas

i wana be like austin when i grow up, he gets all the chicks

[jwfab1]

That looks like Richer Racing's setup.

[ntsqd]

Did the loan of the fixture to build those on come with ?

TS

I used swerve around my halucinations, now I drive right thru them.

[billymanfroy]

RE: "does anybody know if there are kits like this around for toyotas "

Not yet, but it's very possible will have one drawn up shortly for Curt & Patty Hayos. I don't know the year, but they have a standard cab. We'll be taking the measurements off their truck. We are also doing 2 more for ranger extra cabs. BTW, say hi to the keys for me.


RE: "That looks like Richer Racing's setup."

I'd be outright lying if I said we didn't base nearly everything on their deal. We have longer arms and upper links, though, because they have a shortbed and we have a longbed. We are also using 1.5" 4130 upper links with 7/8" heims spaced down to 5/8" bolts. Their stuff looked smaller than that to me.


RE: "Did the loan of the fixture to build those on come with ?"

I wish. We are going to build a jig for them if they become too difficult to manage with a s**tload of clamps. You can't tell from the pic, but they have little tabs so they fit together like puzzle pieces (Again, ala Richer). Should have it all welded up and on the truck by the end of the weekend. My shocks don't arrive until tomorrow, but I have everything else including hardware in hand. We'll post pics and let you know how it goes...

[ntsqd]

I would make the fixture for them first. That way they all are much, much closer to being the same. Make it as burley as you can.
I noticed the tab/slot features. Figured that was for self indexing of the parts.

We haven't looked at Roll Center (& it's progression) or Roll Axis (& how that generates rear-steer). Since both of those are the result of how the UCA and the LCA interact it may not be on topic here. Roll Steer of a 3 or 4 link is something that I see very little about in the chassis design books. In a Dez application I feel you can't afford to ignore it.

TS

I used swerve around my halucinations, now I drive right thru them.

[motoxscott]

Billy,

What did you use for material 3/16" cold rolled steel ??? Are you gonna build any internal structure to them ?

Just curious

[billymanfroy]

Man, am I glad you said that! Mostly because we didn't even consider any of the "proper" things like roll center and anti-dive/anti-squat ahead of time. We don't know for sure even where our c of g is. We did discuss it, and figured that this upgrade would hopefully solve so many of our wheel hop and lack of droop problems that we wouldn't even notice if those other things end up being out of whack slightly.

To be honest, you're still largely limited by the shape of the frame as to where you can mount the forward links, so hopefully it's close enough. Once it's back together, we can get the correct measurements and compare that to what we actually did. (Cart before the horse much?)

[billymanfroy]

on the second day of Christmas
the brown truck brought to me:

2 King Shocks
http://www.hepcoblue.com/billy/shocks1.jpg

...and a pile of laser cut steeeeeeeel!
http://www.hepcoblue.com/billy/cutpieces2.jpg

Merry Christmas, y'all.

[partybarge_pilot]

You must have been alot better than Me this year!!

[evan_clanin]

i tried to say hi to the keys but all they could say back was u need another round captian. hell if i know im a lil hosed right now i think im gona go to bed.

i wana be like austin when i grow up, he gets all the chicks

[crashesalot2003]

i think we are going to get shafted this because santa spent all of his time on you

no brain, no pain

[ntsqd]

Engine still in the truck ? If so, then you can approximate the CG. Based on Chuck's comment I'd move it back some from the flywheel face, but I'd leave it, for the time being, at crankshaft centerline. 'Erase' in a cad program is a lot less work than the smoke wrench/sawzall combo.

You'll want the LCA's LOAs to converge somewhere forward of the truck and the UCA's LOAs to converge behind the axle CL. You can't change the side view angles of the CA's, but you can change the top view angles of the CA's. The more horizontal you can make the line btwn those two points, the less Roll Steer you will have. Just remember that the UCA's have to have enough angle to properly locate the rear axle laterally.

TS

I used swerve around my halucinations, now I drive right thru them.

[billymanfroy]

More progress... We're having someone who can weld really good finish them today so we don't ugly them up.

http://www.hepcoblue.com/billy/tackedarms.jpg

[V8Ranger]

Why not just make the lower links parallel? What are the benefitsof having the LCA's LOA converging in front of the truck vs. being parallel. It seems like you don't have any other choice if you were to run a bushing.
Thanks

[ntsqd]

You can do that. Most don't. I won't pretend to know why. I'll speculate that it's done this way for a couple of reasons.
1) with Convergence you have a defined forward point in space to locate the Roll Center
2) It may help with axle lateral location.
I could be way off though.

TS

I used swerve around my halucinations, now I drive right thru them.

[partybarge_pilot]

It helps get your mounts on the axle farther out when your frames in the way. The farther out you get the mounts the less likely it will be to lean and less sway bar needed. Plus the added bounus of helping out with location.

[NorCal_Prerunner]

Are we done? Is that it?

It's never too late to be what you might have been....

[ACID_RAIN28]

I think the keg is dust, with 2837 views and 68 posts wait 69!

IF ALL ELSE FAILS.......DROP THE "HAMMER"!

[billymanfroy]

Josh,

We are ALMOST done. Still waiting for some finish work and the last test fit before coating. We sent the rearend to rockstar trux for the upper link mounts on the housing. We also need to mount the top of the shocks and limit straps.

I slapped together this page with some pics.

<A target="_blank" HREF=http://www.hepcoblue.com/suspension.htm>http://www.hepcoblue.com/suspension.htm</A>

As far as we can tell, we have 26" of travel, 1 degree of rotation, <.5" of plunge. Of course we'll have to make taller stands to find out for sure, since it we have another 1-2" of shock stroke left with the rear end sitting on the ground.

WOO HOO

Billy

[JrSyko]

The page has no thumbnails on it.

See ya in the dirt!

[Prater]

It's working for me, try again.

-Prater

[motoxscott]

Billy, I'm curious why you didn't setup the lower arms for bypasses..........any specific reason? Are you planning to only ever run a coilover?

Looks good, keep up the good work.

[billymanfroy]

We are only running a coilover. We originally did the drawings with two shock mounts, but I was promised by someone who would know that a coilover would be all we need. (He's someone we all know and trust, but I don't want to drop names)

We can always make new arms rather cheaply. The hardest part was fitting the forward bushing correctly, and then welding it all together.

We are a little worried about the ride height, but we'll haveto put it together first before we panic.

Billy

[V8Ranger]

About how much does would it cost to get all of that material laser cut. Also who would you recommend?

[NorCal_Prerunner]

Billy,

Any pics of the finished 4Link?

How did testing go?

It's never too late to be what you might have been....

[billymanfroy]

We were right. The ride height was way off. It was quite tricky getting the frame high enough off the ground to let the suspension sag all the way out. I think we'll use the forklift at work to make it easier. We had to run the spring nuts all the way up to the top of the shock to get it close, and it still took 2-3 heavy dudes on the back to get the rear down close to the front. The farther up you go with the collar, the more down travel you lose because you have to limit the shock from opening far enough to let the springs come loose. That's very important if you want your springs to stay on the shock. We ordered softer springs last Friday and they still haven't showed. I'm hoping to get them tonight and put it all back together and set it on the ground again to see the difference. With this 3rd set of springs, we'll have 3 different spring combinations we can try out.

I've taken some shots of the unbelievable bracing on top of the diff that Rockstar Trucks did for us. (The only NorCal offroad fab place I know of). <A target="_blank" HREF=http://www.rockstartrux.com>http://www.rockstartrux.com</A> It looks totally awsome, so I'll post those along with pics of it all put together soon. If it works half as good as it looks, we should be very happy. I'm also going to calculate out the Instant Center using the method above (I got Herb Adams' book finally) and see what we've got for anti squat. I do wish we had paid more attention to that ahead of time, but it looks just from eyeballing it that we are not that far off, if at all. Plus, it's all subjective anyway, right?

If we get it done, we're doing the Oakland USHRA Pro Arena Truck race on 1/3-1/5 for a test. I'll give you all the reviews of the ride after that.

Billy

[fathead1]

Billy,
looking good!! How much has this project cost you so far?
This has been a great thread!! I know I have learned alot, and I'm sure others have as well.
Be sure to let us know how it works, and I agree, if it works 1/2 as good as it looks, you should be happy as hell..



" I can weld way better than my wife "

[rdc]

Hmmmmmm?

JoJo

[rdc]

Hmmmm?

JoJo

[rdc]

Lwr Arm photo #1

JoJo

[TRDshaunTRD]

none of those attachments worked

"Those who risk nothing, are nothing."

[RicherRacing]

Billy,
Your suspension is looking good. Glad my dxf file worked for you to get the steel cut.
Did you play with the geometry to fit your truck? It looks like your upper arms attach to your diff higher than mine. Which shock hole did you keep, the front or the rear? Will you be running a sway bar? What spring rates are you going with to lower the ride height? Keep up the good work and hope to get to meet you someday.
John

[rdc]

Billet Arms

JoJo

[rdc]

Billet Arms 2

JoJo

[jarreptolson]

I'll take a set

[crashesalot2003]

those billet arms look really trick, but they look like they would be heavier than a boxed arm. or is it just me?

no brain, no pain

[RicherRacing]

Aluminum weighs 0.1 # per cubic inch, steel 0.283# per cubic inch.
Aluminum arms should weigh less than half of a steel boxed arm, probably around 15# each.
Did you machine these yourself or have a machine shop make them?
It is hard to tell from the photos but I assume you left a center web and machined the pockets from both sides.
How much would they sell for?
How are you attaching the rear heim?

John

[ACID_RAIN28]

What aluminum did you make them out of? Is that a haas that they were milled in? Stupid question but they appear to be lower links, correct?

IF ALL ELSE FAILS.......DROP THE "HAMMER"!

[leftwing55]

And are they going to be as strong as the steel units? I would be interested if the strength is there.. Also, what's going to happen the first time a rock dings them? Strength seems to be the biggest question there.

Rob

KEEP THE RUBBER SIDE DOWN

[Kritter]

7075 would have been a good choice. They look too expensive to be practical...might be good for a show truck though.

Kris
"Buy American before it's too late"

[sirhk100]

Those look a lot like the ones CST had on their truck at SEMA. I swear if I remember right they had billet lower links in the rear and billet control arms up front. He said they were strictly for show...

Khris

'92 Ford Exploder (AKA Dezert Limo cause it's loaded)

[ntsqd]

The strength up front may be on par with a fab'd steel, but after a year's worth of fatigue I suspect they won't be. As others have posted a lot depends on the alloy used. If what ever their service life happens to be is acceptable and the $$$ to make more is there I'd say go with it.

TS

I used swerve around my halucinations, now I drive right thru them.

[billymanfroy]

Well, THEY WORK!!!! WOO HOO!!! The truck rides like a dream, even though we had to limit it to 14" to run the Pro Arena truck races this weekend in Oakland. Our "new" posi does not work even a little, and we still smoked some V8 4WD trucks and jeeps around a very small course. I actually made the final round on Saturday, and got faster and faster every day. I'd swear it made our mostly stock front end work better as well, not worse like we feared.

You would not beleive the difference in the way the truck handles and sucks up the bumps (they were actually pretty small). All I can say is, good riddance leaf springs!

The arms drag pretty hard, but it was gooey clay, so I didn't notice. We are going to trim these arms which won't make them as pretty or as strong, but they should have more ground clearance.

USHRA paid me $600 for 4 shows, so that might just tempt me to head for Anaheim if we can get the posi fixed and replace a bent spindle before then. I'll post some pics ASAP. If you've ever considered doing a 4-link, I am telling you from years of leaf spring experience, it is a night and day difference, and it's tunable. Well worth the money and effort.

Billy

[motoxscott]

Yes I would have to agree......leaf springs are over-rated. Glad to hear it worked out well for you.

[NorCal_Prerunner]

Billy,

Where's the pix of the finished 4-link? Let's see the pix from the USHRA tough truck comp......

It's never too late to be what you might have been....

[billymanfroy]

I'm working on it, really! I have some pics on the way from two different photographers, ans lots from inside the garage on my crappy digital camera that I can't get the pics out of now. We put in our old posi unit and fixed the front end (it was just the lower ball joint), so we're heading to Anaheim for Saturday's 7:30 show. I guess I'll find out how good these V8 dudes are then, because it's supposedly a long track (well, not long the baja, but you know what I mean)

BTW, I'm only bringing 2 crew guys, so we should have 2-4 tickets left over if anyone's interested. I MIGHT be able to get you in the pits, too. I heard they had TT racing in the parking lot last year at the same time. (Motards, etc.)

Email me at bill@hepcoblue.com if you're interested, and I will post ASAP I promise.

Billy

http://www.hepcoblue.com/Images/rear_susp.jpg

http://www.hepcoblue.com/Images/rear_susp_side.jpg
<P ID="edit"><FONT SIZE=-1>Edited by billymanfroy on 01/10/03 10:31 AM (server time).</FONT></P>

[WorkInProgress]

Billy are you talking about the Monster Jam on Saturday night at Edison. I will be there. I got like 16 of my friends going. We got third row from the bottom. Its gonna be tight. Cant wait to see your truck in action.

[klaus]

In regards to those Aluminum Lower links posted above....

They are made out of 7050 Aluminum and cost under $2000.00 pair.
For more info contact: jmr5@pacbell.net

http://www.race-dezert.com/wwwthreads/files/6-40479-LWR1.jpg

http://www.race-dezert.com/wwwthreads/files/6-40480-LWR3.jpg

[NorCal_Prerunner]

I wanted to print the entire thread as one print and couldn't think of a way to get the whole thread together using the search function. So I replied to the last post.

It's never too late to be what you might have been....

[geoff]

almost time for an upper links 101?

we figured out how to stich weld the lowers i made in this post...

http://www.race-dezert.com/cgi-bin/wwwthreads/showthreaded.pl?Cat=&Board=shop&Number=48209&page=1&view=collapsed&sb=5&o=7&part=

ill post a pic of the weld later.

"We are the music makers, and we are the dreamers of the dreams." -- Willy Wonka

[jeff]

NorCal...

Go to the Control Panel and click on your display properties. Change the number of posts you want to view in each thread. I have mine of 50 because I like having it one continuous page. I suppose it would also work well if you wanted to print everything out.

Aloha

[bROk]

As far as the LCA turning in or having the "wobbles" how much would these help if anyone has used them. Pic is from HnM 7 truck...

A smart-ass is better than a dumb-ass

[SpareChangeRacng]

That's a sway bar. They work similarly to the stock sway bars found on cars. The Herbst have a SWEET disconnect setup to where they can dis-engage their sway bars through the big stuff, but have it re-engage over the leveler, softer, or street sections. Steve

[bROk]

So are they reccomended? Who does and does not use them? Also cost?

A smart-ass is better than a dumb-ass

[SpareChangeRacng]

I'm defiantely putting one on my truck, but then again I plan on driving it on the street - somewhat. I believe it is all personal preference on whether you run them in the dirt, but as far as I can tell, many people run um in dirt only trucks too. I'd like to hear other opinions on this also though. Steve

[billymanfroy]

Well, it is a matter of preference - if you think driving like this around town will impress the cops, then don't buy a sway bar. I can say for racing, the single most important piece I added for settling the truck down was a Speedway Engineering 1" solid sway bar. It came with everything for $300. All we had to do was make mounts and vertical links. Even before we went to coilovers, it felt like training wheels in the corners and gave me WAY more confidence in tight turns. You're going to love the thing...

Rock Crawlers would probably disagree with me though...

http://www.mcneiloff-road.com/newhome_r2_c2.gif

[Kritter]

He was hittin the 3 wheel for Klaus' offroad rap video!

Kris
<A target="_blank" HREF=http://www.barneysprecision.com/fabproducts.htm> Fab Parts</A>

[bROk]

sweet, thanks for the advice... in case anyones interested I googled it...

http://www.1speedway.com/



A smart-ass is better than a dumb-ass

[SpareChangeRacng]

Stock Car Products also has a bunch of different optios for sawy bar setups. Steve

[ntsqd]

Actually most pro crawlers run some sort of very soft sway bar on one or both axles. By adding some roll stiffness to the vehicle they prevent inertia induced flop-overs.
Quite a few of last weekend's competitors were using Currie's "Anti-Rock" swaybar kit. Those that didn't were using Speedway parts for the most part.

The axle that has the greatest swaybar rate will actually have the least traction in a corner. Witness those dez race vehicles with only a rear bar and how easy they are to kick out with the throttle. So if Rally style is how you want your set-up to be, go with more rear swaybar rate.

TS

I used swerve around my halucinations, now I drive right thru them.

[ACID_RAIN28]

There is nothing really fancy about the disconnecting sway bar, sprint cars use it as well as many other applications, all it is, is a locking mech on one of the arms, I have seen it in many catalogs, if i remember which one I let you know, they were actually not that expense when compared to the regular bar, and I plan on putting on on my truck just for the adj factor.

"Everything you do is triggered by an emotion of either desire or fear."

[geoff]

My Lower links

Made from a 1.75x.120 DOM lower tube bent with a 2"x5" box section cut to fit and welded.

http://www.full-race.com/toyota_4_link/lower_link_3.jpg
picture of the box cut and tacked

http://www.full-race.com/toyota_4_link/lower_link_5.jpg
same thing

http://www.full-race.com/toyota_4_link/lower_link_7.jpg
the box section top portion was kept extra long to wrap around


http://www.full-race.com/toyota_4_link/lower_link_8.jpg



http://www.full-race.com/toyota_4_link/mild_steel_TIG.jpg
heres the normal tig welds

when we were at sema, i noticed on almost all of the trophy trucks, a stitch weld, so we tried it out

http://www.full-race.com/toyota_4_link/mild_steel_TIG_cross_stich.jpg


http://www.full-race.com/toyota_4_link/mild_steel_TIG_cross_stich_1.jpg



now lets get upper links 101 !!!!

"We are the music makers, and we are the dreamers of the dreams." -- Willy Wonka

[bROk]

Geoff, I like those LCAs - the box steel seems to be a simple yet effective idea, I actually have some box steel left over (I used i to truss my 9") - maybe Ill try using it for my LCAs when I get to that point - please post pics of the inside of the arms where the shocks bolt on if you have any pics or when you have it finished.

Thanks



A smart-ass is better than a dumb-ass

[WorkInProgress]

Earlier on this thread people were talking about using a bushing for the front mount and a rod end for the rear mount but check out this pic. it is one of the gieser bros trucks. it looks like that is the rear mount made for a bushing. would you be able to do that. both bushings, or bushing rear and rod end front?

You gots to pay da cost to be da boss. - Snoop

[DougM]

Why are so many TIG welds on race car suspension/cages undercut? The beads appear that no one even uses filler rod?

just my observance or?

[hoeker]

looks like it's setup for a spherical bearing to me.


Some are born great, some achieve greatness,
and some have greatness thrust upon them.

[properprerunner]

They use spherical bearings instead of heims for the rearend mount.

[Kritter]

uniball type mount is what that arm is using.

Kris
<A target="_blank" HREF=http://www.barneysprecision.com/fabproducts.htm> Fab Parts</A>

[WorkInProgress]

Ok i got it. What do you think they are using for the front.

You gots to pay da cost to be da boss. - Snoop

[geoff]

Doug -- not sure if you are referring to our welds, but there is a TON of 70S2 rod in there, it was a 3/16" plate welded to a flat surface, definatley no undercutting...

"We are the music makers, and we are the dreamers of the dreams." -- Willy Wonka

[bROk]

so reason being that bearing will result in less wobble in the LCAs???

A smart-ass is better than a dumb-ass

[ntsqd]

Geoff, by "stitch weld" do you mean a deliberate weaving of the torch as opposed to moving it in a straight line down the seam or ? The 'stitch weld' pic looks like classic figure 8 torch motion.
Mild critique of the warp-around, would have been less of a stress riser if it could have extended out onto the tube a ways and not had a square end to it.

DougM, those weld beads look to me like a stepped or laminated weld join. If the bead has a concave surface it can look undercut w/o actually being undercut. Would be nice if the beads had a flat surface as that would be the most gradual cross section change, but it's too hard to tell for sure if that is the case in most pics.

TS

I used swerve around my halucinations, now I drive right thru them.

[tsm1mt]

On top I'm gonna use two 7/8" high misalign heims (the ones with the shoulders) and not space them smaller ,but use 3/4" bolts. I felt two 3/4" bolts holding two heims would be stronger and last longer (load spread twice) than a single 1-1/4" heim that you have to misalign to 7/8" I think thats the size bolt. With a 7/8" bung (1.25 o.d.) you can run two 1.5 x. 120 wall tubes for links,plus you get minor side to side adjustment. I think you can get of these for the price of a single 1-1/4" and you can get 20 deg. with the 7/8". Hope it works I already welded the mounts!!



After searching a bit and reading a few threads.. I know I've seen the "1-1/4 Heim" comment from various places n' such, but I'm curious what kind of "rating" a guy should look for when building a rear 4-link.

Knowing that it "depends" I'll throw out a "typical" V8 Class 8 for my question.. or a ProTruck. Something in that neighborhood.

I've seen 1-1/4" heims rated in the 40,000lbs range.. but I've also seen 3/4x3/4 heims rated similar in a smaller, lighter package (though maybe not cheaper).

Wouldn't the "strength" be more critical than the physical size and the kind of packaging that strength comes in?

I realize that at some point you run into other problems - like the strength of 3/4" Grade 8 bolt vs a 1" or 1.25" Gr8 bolt, but again, those are just numbers to be plugged in.

What kind of NUMBERS should a guy shoot for when shopping for Heims for linking the rear of a Class 8 (which might be on the slight overkill side for a Class 7).

Trophy truck power and abuse isn't in my budget.

[partybarge_pilot]

While the 3/4 is strong enough you will get a much longer life span from the 1-1/4.

[tsm1mt]

While the 3/4 is strong enough you will get a much longer life span from the 1-1/4.

I take it the argument is the 1-1/4 has a larger surface area to distribute the load/wear, thus it should take longer to wear.

Am I still looking for the "40,000lbs tensile rating" range or something else? I'm assuming the 1.25 heims come in various flavors and strengths, too.

I don't want to cut corners and undersize things, but at the same time, I'm not a fan of throwing more money at a part than I need to. ;)

[the frog]

why am i unable to see any of the pics on this thread?

anyone can help here?

[ntsqd]

It's an old thread, pics may not have made the transition to the new bbs system.

As to what size to use, it seems to me that if you can get a 3/4" and a 1-1/4" SRE in the same load rating that there are probably a 1" & possibly a 1-1/8" SRE's with the same load ratings. Comes down to Fatigue Life. How long do you want it to live?

[elqdeasu]

And the thread lives on.............

I'm working on my 4-Link design in Solidworks and I want to make sure that I'm in the ball park with the lower link design. I've tried searching everywhere but can't find the typical weight of a lower link on a class 7, class 8, or trophy truck. I'm thinking that the typical weight is around 50-70 pounds. Am I in the ball park or way off in the parking lot somewhere?

My design is at approximately 55 pounds and it still doesn't seem strong enough.

Thanks in advance

[ACID_RAIN28]

55 pounds is "A" link or all of the links?

[McClintock]

Mine are no where near that weight.

[elqdeasu]

55 pounds is "A" link or all of the links?

55 lbs is the weight of one lower link! It's 60" eye-to-eye and Chromoly. I thought that 55 lbs was getting a bit too heavy. It's sounding like I need to redesign and ease up on the forces I'm using for the calcs. Thanks for the quick responses.

[CRAIGHALL]

How thick of plate you using?

[billymanfroy]

Ours are a couple inches shorter, but only weigh ~40 lbs. We used 3/16" regular steel, and it's only doubled up right where the shocks mount. Bronze bushings on front, 1.25" heims on the back. Made our own end to weld the bung into. It was 3-4 lbs. alone.

I had a mount fail and speared the front of the link into the ground at about 30 mph at Parker. It buried itself almost 2 feet into the ground. Nothing's ever bent or tweaked on them, and they get used alot.

[thanks jason]http://www.highrevphoto.com/paypal.php?gal=score72706/s7&pic=708_SCORE_bb0303.jpg[/thanks jason]

[elqdeasu]

After messing around with the design for hours, I converted the whole thing to 3/16" plate everywhere. That brought the links a lot closer to being strong enough for the forces that I'm applying. I can save some weight by reducing the wall thickness around areas where the stresses are not as high. I still have to thicken up the areas that still look a bit weak or re-evaluate the forces that I'm appliying. I was just worried about the weight getting out of control and it seems now that I am a bit on the heavier side.

I'll try to post a picture when I am done with the design.

I still beleive that a 5,500+ lb trophy truck's lower link must way at least 50 lbs. but then again I'm only building a Tacoma.

What do you guys think? Keep those weight numbers coming. Thanks

Good info and good looking truck Billy, Thanks.

[McClintock]

Taller the better and you can lighten the materials up a bit.

[ACID_RAIN28]

Why 3/16? For such a small truck you should have not problem using combos of .080, .090, and .120 for construction, but that is my opinion. Also do you plan on heat treating the parts??

[McClintock]

Best thing about 3/16 is bash resistance especially if your links hang lower then axle/ have a bend in them.

[ntsqd]

What kind of FS's are you using? That might be where all of the weight is right there.

[elqdeasu]

What kind of FS's are you using? That might be where all of the weight is right there.

On a 4,000 lb Tacoma, I'm figuring that one worst case scenario would be a six foot jump (Laughlin Leap?) landing on the rear two wheels only, full compression. I calculated a force of ~60,000 lbs total. I divided that by four assuming two coilovers and two bumpstops (no bypasses yet anyways). That leaves 15,000 lbs. per lower link applied at the shock with the two ends of the link hinged.

The second worst case would be landing at a 45 degree angle off the same jump introducing a horizontal force of 1/2 of the 60,000 lbs. That would be 30,000 lbs horizontal but I figure that one lower link would only see 40% of that (wild guess) because the other lower link and top links would absorb the rest. So that leaves about 12,000 lbs horizontal force on the diff side of the link and the mount side contrained (using bushing).

[elqdeasu]

What kind of FS's are you using? That might be where all of the weight is right there.

Sorry ntsqd, I thought you were asking about the forces. I am trying to get a Factor of Safety of at least 1.5. It's getting there.

[ACID_RAIN28]

I had a little extra time yester day and wieght our TT link and it was 50 lbs. dry (no spherical or rod end) On this part there is not one piece that is 3/16" It uses a 1 1/4 thick wall tube for the bottom edges and 1/8 plate everywhere else. Hope that helps your quest.

[therail]

It uses a 1 1/4 thick wall tube for the bottom edges and 1/8 plate everywhere else.

could you elaborate a little please? i cant tell if its one .250" wall tube or a 1.250" tube with a generally thick wall.

[ACID_RAIN28]

Sorry, it is a tube that is 1.250 OD and .188 wall

[FABRICATOR]

.188" = 3/16"

[TigTech]

Why are so many TIG welds on race car suspension/cages undercut? The beads appear that no one even uses filler rod?

just my observance or?
A pretty weld is not neccesarily a quality weld.. but a quality weld can be pretty...
You right in your obsevance.. it is harder to keep the weld shape as consistant in apearance when feeding larger amounts of filler per dip with smaller wire. So some welders tend to run in a comfort zone pushing just a dab per step. More amps and larger wire perhaps is the answer if you dont sacrafice the root penatration by over cooling the weld with the added mass of the wire and rolling over the front of the weld pool.. Second cover pass...maybe if you are not concerned about your heat affected zone as in 4130. Curious if you are meaning true undercut ..as in the edge of the weld or just underfill. Sometimes it is just a poorly groomed tungtsen forced to linger for penatration that will suck along the edge from arc wonder. But that is different I think from what you refer.

[TigTech]

Pardon the typos

[down4glamis]

you didn't need to bring up an old post to critize or an old post just to elaborate on the proper technique of welding...

[151fab]

I think we should welcome someone who has what sounds like some real knowledge about the subject of welding. TigTech, you could have posted that response on at least a dozen different threads here at RDC and it would have been relevant. However, alot of people think the subject of welding, and especially welding 4130, has been well worn. Anyways, welcome to RDC.

On the subject of lower rear links: Has anyone else seen the super trick setup Kartek is selling for the front mounts? Its a uniball cup that has two plates that bolt to the sides. These plates limit the articulation of the link to two dimensions by the use of a aluminum (I think) misalignment spacer that registers within a oblong hole through the plates. This eliminates the wobble without limiting the needed articulation.:D :D :D

[151fab]

Oh ya, and considering the batch of really horrable threads that have passed through this site lately (Crapping on toilets found abandoned in the middle of the desert and Who would win in a fight between Chuck Norris and the 24 dude); I, for one, am glad to see a real tech subject get bumped!

[down4glamis]

those things are really expensive, and asking for 1 thing to go wrong and toast the whole setup. Blitzkrieg Offroad has made a "gnarticulator" that allows for a uniball to be placed on the front pivot of an upper link, and get rid of the "wobble" it is much simpler than the Kartek one, and far less expensive. it could be used for a variety of things, and could be a great way to get rid of the baja bushings in leafsprings!

this thread is just REALLY old, and is about links, not welding. not to bring him/you down, just pointing it out. i get bad rep points for bringing up something, and asking a tottally relevant question to a thread that pertains EXACTL Y to what i was talking about. but ehhh... Welcome to RDC

[151fab]

No worries, I'll give you a good rep point.

[151fab]

Oh, never mind it seems I've already given you a rep point and the RDC gods will not allow me to give you another just yet.

[down4glamis]

lol me too, i gave you one just a lil while ago.

[ACID_RAIN28]

On our old Truck and pre-runner we use the kartek uni-ball parts and have never had a failure. They work just fine.

[baja619]

Who Has The Best Looking Lower Links. Give Me A Rating Level Of 1-10

[JESSE_at_TLT]

I'm trying to figure out what type of pivot to put at the chassis end of the lower links in an application where the lower shock mounts have to be at least slightly above the centerline. Since neither Kartek or Blitzkrieg has any information about their respective wobble-stopping devices on their websites, I asked them to send me some information by email. This is what I got:

[JESSE_at_TLT]

Kartek

http://www.trailslesstraveled.com/media/forums/kartek_wobble_stopper.jpg

the OD of the cup housing is 2.741
the width from spacer to spacer is 3.043
surface area to weld to would be 1.982

[JESSE_at_TLT]

Blitzkrieg

http://www.trailslesstraveled.com/media/forums/blitz_01.jpg

http://www.trailslesstraveled.com/media/forums/blitz_02.jpg

http://www.trailslesstraveled.com/media/forums/blitz_03.jpg

[JESSE_at_TLT]

I think Drew at Poly Performance used with some type of mechanical linkage to keep the lower links on the rear end of his CJ7 straight. I searched all over the pirate forum and can't seem to find them though. Drew? How about it?

[JESSE_at_TLT]

Drew just posted this picture for me over on the Pirate forum. Those little stabilizer links seem like a pretty good idea to me.

http://pirate4x4.com/forum/attachment.php?attachmentid=324214&stc=1&d=1189281153

[McClintock]

Look at some of Huseman's builds, he has a similar link between the lower links and the axle, keeping the trailing arm in a harmless position.

Blitzkrieg makes something to combat the arms rolling over

http://www.blitzkriegoffroad.com/?actn=viewproduct&id=16&pid=62

http://www.blitzkriegoffroad.com/admin/_images/products/16/62/large/FJSectionView.jpg
http://www.blitzkriegoffroad.com/admin/_images/products/16/62/large/FJ1.jpg
http://www.blitzkriegoffroad.com/admin/_images/products/16/62/large/FJ2.jpg

[JESSE_at_TLT]

Anyone have any pictures of the linkage on Huseman's trucks?

[charlie_brown]

i have seen the little links on a ford ranger and it looks just like the one pict. above but on the rear end not the frame. the rear end is the place to do that at. it sure would save on bushings.

[McClintock]

I remember the photos from a prerunners.com / ROR event. The owner or the truck is Ryan Rose, maybe hell see it and post up.

[CRAIGHALL]

Ideally (at least to me) you would want your trailing arm to not twist at all since it doesn't need to. It obviously needs to swing in an arc but it also needs to pivot from side to side slightly as the rear axle articulates. The blitz ones look like they allow a slight bit of motion in all angles. The Kartek ones (once you weld them on properly) allow no twist but do allow the side to side. Just be sure to loctite or safety wire the cover/cap bolts.