Sportsman Buggy Suspension

[67BAJA]

My girlfriend and I are about to redesign our rear suspension. We are on a budget, which is partly why I am posting on RDC before I buy everything. Our philosophy is "Best bang for the buck", no cheap crap but also nothing frivolous (although both of those are in the eye of the beholder). We race sportsman buggy in MDR and need some more travel in the rear and some work with shock fade. So here is our current set up:

Wheelbase 103in, 2x3 rear arms, type II C.V's, 2.5 dia. 12in stroke SAW c/o's. Currently we get about 12in of travel with the CV angle at about 19 degrees.
(FYI: Front 1.25 in. over arms, 2.0 SAW coilovers 10 in stroke, about 10-11 in of travel, front does fine though.)

Things we know we are getting:
1. 3in dia. 3-tube 14in. stroke SAW bypasses (already bought those off RDC)
2. 930 C.V's (polished and race cages?)
3. Longer arms???? This is what we are not sure about. Should we buy 3x3's or widen our torsion housing and put on something else? What about dual pivot vs. our current spring plate etc…
Want to do it right the first time, so we don't have to set up the mounts, valving etc more than once.

I have talked to a couple of people and received differing opinions, thought I would see what other people have done and what to think about or stay away from, especially anybody with experience building 5 open cars, since we want to stay within the 5 open rules, just in case

Thanks for the help
Sorry about the dirty pictures, haven't cleaned the car from the last race, and went driving in Ocotillo mud!

[67BAJA]

Here's one of the car in action.

[phorensic]

Well here are a few pics of the rear suspension on our 5 unlimited buggy. The owner/fabricator said he pretty much copied it off a class one. If you see major geometry differences between your setup and ours, I would say try to shoot for our setup style more.

This doesn't show much besides shock angle/placement.
http://www.digital-addiction.net/albums/524spyphotos/PB270006.sized.jpg

http://www.digital-addiction.net/albums/524_testing/P9050008.sized.jpg

http://www.digital-addiction.net/albums/524_testing/P9050009.sized.jpg

Sorry I don't have better pics, but I hope those help. If you have any questions, just ask. I've asked a lot about the car and have hung around it a lot, so I know a think or two about it's design/setup. If I can't answer the question I might be able to ask the fabricator.

[WannaB-class5]

I don't race yet but I can give you a few numbers. I run 3X3's with a single 2.5 SAW 12" shock and 930's. I get 14.5" of travel no problem and I know I am not near max angle. The bump and strap I used were just kinda there for me. If I needed to I can get more (but like I said I dont race so its not important to me.) Let me know if you want pictures....but I was just throwing some numbers out for ya!

[desertspeed]

Phorensic-
That is a nice looking car- I have a 4 seat baja that I am upgrading to better components. Can you give some specifics on the rear suspension setup. I am mainly interested in the type of arms, hubs, CVs, axles, etc.

By the way, I was checking out the first pic and something caught my eye- the grey 4Runner in the background used to be mine!

[67BAJA]

Yeah I am sure if I run 3x3's I can get a decent amount of travel, my question is if class 5 guys usually widen the torsion housing and run different size arms, and in that case do they go alot wider but not longer to fall within the 105 in wheel base requirment. Also, what about dual pivot arms, do you guys run costum arms or do people run arms from Mckenzies, Kartek etc... Heat treated, not heat treated etc....

[Ryan_P]

Well, I was planning on running Tatum Motorsports Outboard hub trailing arms around a 5x5 or so, give or take, but now I plan on having Baja Shop just build my arms when they build the chassis.

If you wanna buy midboard hubs I can give you a killer deal! haha

Also, dual pivot is ideal to keep the tire scrub and camber change to an absolute minimum or 0 at that. Heated treated, yes and no, some do it, some don't, i guess it's just personal preference.

-Ryan

[MikeLeung]

If your running coil overs in the rear...ditch the spring plate and go with dual pivot rear arms. The easiest way is to buy a set...but you can also make a set ( if you know how) It all depends on your budget...cause once you go with dual pivot rear trailing arms, you might as well go with mid board hubs and disc brakes. But you could just stick with the aluminum hubs and stub axles. In regards to 930 CV's ....with out question, polished and race cages.

[67BAJA]

Mike,
Yeah we don't have the cash to run the mid board hubs and disc brakes, yet. The problem with that is that if and when we upgrade to those, we will need to get new rear arms again.

[phorensic]

Phorensic-
That is a nice looking car- I have a 4 seat baja that I am upgrading to better components. Can you give some specifics on the rear suspension setup. I am mainly interested in the type of arms, hubs, CVs, axles, etc.

By the way, I was checking out the first pic and something caught my eye- the grey 4Runner in the background used to be mine!


The arms are custom tubular arms he made himself. I'll try to get info on the hubs, CVs, axles, etc. What I do know is that it is capable of 24" of tavel, but is strapped and bumped a few inches less than that.

I hang out with the owner of that 4runner all the time. His name is Ryan. He has done quite a few upgrades since he bought it from you... it's starting to take serious shape. He posts on this forum, I'm just at a loss for what his posting name is.

[Ryan_P]

If they are capable of 24'' of travel, more than likely they are using 934 race prepped cv's and looks like on a mendeola tranny.

By the look of the hubs and brakes, I am guessing CNC hubs and brakes. Fill us in phorensic.

-Ryan

[ntsqd]

By the way, I was checking out the first pic and something caught my eye- the grey 4Runner in the background used to be mine!

I wondered that when I saw it. Was that a 5M or a 7M?

[phorensic]

It is a 7MGE. Don't know why he didn't swap in the 7MGTE.

[Class5]

Matt thanks for the heads up on the thread, I am the owner and builder of the 524 car that is on the site. It sounds lke you all have alot of questions and I will start with the stats of my car and go from there. We are running Fortin Rear hubs with 934.5 ..."935"cvs with race cages in them. The rear arms are 30" long from center of hub to piviot. We have a 2.5 14 "c/o and a 3 tube 2.5 bypass that is a 16. We have swayaways on the rear but are looking for a shock sponser at this time so that may be changing. We currently are limited to 20" of rear wheel travel due to axle plunge. and car ground clearnce. We can get something like 28+ out of the back but dont need it, we would have to change shock mounts, alxes, and misc hub parts...The cvs angles are at 25 to 27 right noww but we can get 29 out of them if we want. The five car is aprox 88 inches wide.. I hope this helps

Class 10 cars run the hubs with 28-32 degrees down angle
Class 1 cars currently run the hubs with 25-26 degrees down angle with over 300 Hp
I have bben told 930s you can run 21-23 degrees down angle

[FullsizeFun]

You should run the 3x3s with the Pro-Am sportsman 930 microstub hubs (Kartek). The sportsman hubs are cheaper than the full race hubs and are still really strong. Race prep polished and lightend 930s with 300M cages. If you keep it torsion bar, then run the 300M bars 26-9/16 long and SAW springplates. And use the caps for the torsion housing that have the wider bolt pattern for increased springplate angle. Otherwise go to coilover. You should be able to get 18+ inches with this setup for about $3-4K.
Then once you do all this to the rear you are going to want more in the front. hahaha.
Dave

[67BAJA]

Does anybody know if my inner trailing arm mounts (picture 2 of first post) are stock? Also, are they still sufficent if I decide to run a longer dual pivot arm?

[uncledirty]

No thats not the factory pivot, your car was a swing axle (it's a 67 right?) You can get heavier duty pivots from Mckenzies or Kartek or add gussets to yours. Those look like the old Chenowth pivots.

[gwm]

Ok, this is probabably a dumb question, but remember I'm a truck guy who just bought a partnership interest in a Class 5 car so I need to learn this stuff. Why is the inner pivot angled toward the outside of the car rather than parrallel to the tube.

George

[ntsqd]

If it were parallel to the tube you would have two pivots in different fore/aft locations. That would bind up. With an angle the centerline of the inner pivot is pointing towards where the outer pivot is. That gives you one pivot axis instead of two, but it does cause some camber change thru the range of motion.
Cars laid out from the beginning to have coil-overs (1's, 10's, some sand rails) have the pivots perpendicular to the chassis centerline.

[Ryan_P]

Here you go Erik, this is what is recommended above and is a VERY good buy IMO, I would've ran these if I didn't get a deal on the Summer Bros. hubs and brakes.

http://www.kartek.com/prod-windows/play/brakes/prm-ms1000e.htm

-Ryan

[gwm]

Ok, that makes perfect sense. I think I was thrown off because our car has coilovers and has the angled inner pivot. Looking at it now, it was pretty clearly a torsion beam car in an earlier iteration and was converted to coilovers when the new chassis was built. In doing this they used the existing beams, cut off the torsion plate mount, and made a new outer pivot with a rod end. More questions will come I'm sure. Thanks.

[67BAJA]

What is the pros of moving my engine and tranny back? I know that the CV angles will be improved with long arms, but I can't think of another pro. I know that more of my weight will be towards the rear, is that good or bad.

[FullsizeFun]

You dont really need to move the motor and tranny back for 3x3 arms. keep your springplates how you have it and run 3x3s with microstub hubs and 930 cvs. done.