Questions on Coilovers on Yota

[fishd00d]

Ok well I got my coilovers today. I got some 2.5 12" SAW's. I got dual rate. But I have a few questions.

1. Is it best to run Dual Rate with a 12" shock that will be getting 14" travel or did I just need single rate?

2. Anyone reccomend a spring size? Baja Concepts reccomended 500 over 500 so thats what I went with. Does this sound right for a Toyota Ext. Cab 4WD?

Its gona be a tight fit with the V6 but I think I can do it. I start making the hoops tomorrow and hopefully I can have the front end done by tomorrow because I am suppost to goto the desert Thursday afternoon!

Also I ordered some Downey springs for the back since mine are just about to break! Anyone have any thoughts on the Downey springs? I figured they cant be that bad for $135 for the pair!

Go Big Or Go Home

[rdc]

i have an 88 toyota with a full coil-over front end. it has 12 inch king 2.5s, with duel rate coils, 600 on bottom, 500 on top.i use a 12 inch shock and have 17 inches travel, and the duel rate works great. 500 over 500 seams sort of strange, you might as well just run a single rate coil. because duel rate coils are supposed to have a main spring (bottom, longer, higher rate), and a tender spring, (top, shorter, lower rate). that is the hole purpose of using duel rate coils. anyway, as for the downy leafs, i had a pair on my truck a while back. They worked a lot better than stock, but they arent nationals thats for sure. but you cant beat the price. i heard Baja Concepts is offering some toyota 62 inch leafs for like 325 dollors, which is like half price. and they are the best leafs you can get for a yota. just something to look into. hope this helped.

BUILD IT YOURSELF, BREAK IT YOURSELF, THEN BUILD IT YOURSELF AGAIN - PTD Off-Road Motorsports

[rdc]

P.S. A buddy of mine builds front ends for yotas at his fab shop, when hes doing it on a v6, he usually uses 2.0 shocks, because of the less room in the engine compartment. but his kits are pretty involved, so maybe you wont have a problem. hope it works out for ya.

BUILD IT YOURSELF, BREAK IT YOURSELF, THEN BUILD IT YOURSELF AGAIN - PTD Off-Road Motorsports

[drtdevil93]

toyota class 7:

dual rates still have 2 different rates. if you have two 500 lb/in coils, the effective rate is 250 lb/in. once the slider hits the stop nut, then it goes to the 500 lb/in rate, giving it 2 rates.

erik

[rdc]

Well I sure like to know how that is? I mean if the primary and secondary are the same spring then why would it be any different than having one big spring? I understand that effective rate comes into play when you have two different rate springs. Maybe Dylan can spread some light on this..

Tony

[sirhk100]

It's a physics problem basically. If you take one 18" spring and compress it 8" the spring has obviously compressed 8". DUH!! If you take 2 9" springs that are the same rate as the single spring stack them so that they are 18" and compress them the same 8" each spring has only compressed a total of 4". This is a start of the explination and I'm sure that someone can explain it better. Basically though it has to do with the center part where they are stacked being able to move and that each spring is compressed only half the distance. Correct me if I'm wrong but if you're using a dual rate coilovers with say a 600lb and a 300lb spring and tested it on a machine that measured the resistance wouldn't you actually get a shock with three levels of resistance through the compression cycle. one at 300lb, another at 450lb, and then the final 600lb rate?

'99YZ400,
'92 Ford Exploder lifted work in progress,
lifted golf cart

[BradM]

That only works if the springs are different lengths or if there is a mechanical limit set on the shock body to limit the travel of one spring. If the springs are the same size (diameter, wire diameter, number of coils, and free length) then the deflection in both springs will be equal.

There are other reasons for dual springs than a variable rate. On a shock with 12" of travel, there will be 26-28" of spring (a rough guess). Springs that long will likely be custom made or very hard to find in stock if they are available. Also, shorter springs have a reduced tendency to bow and rub on the shock body.



"The only source of knowledge is experience." - Albert Einstein

[BradM]

Khris, you are wrong on that one. If you stack a 300 lb/in spring and a 600 lb/in spring in series, the equivalent spring rate of the series combination is 200 lb/in. That applies until the softer spring reaches a mechanical limit stop or until it reaches a solid state (coil bind). Most coil springs have a rated maximum deflection which is about 80-85% of the total deflection because spring rates become non-linear in the initial 15% and final 15% of deflection. That also reduces the maximum stresses in the coils.

If you take the spring rate of the softer spring by itself (300 lb/in) and multiply if by the recommended maximum deflection of that spring, that will give you the location of the mechanical limit stop (don't forget to account for preload). At that point, if the 300 lb/in spring reaches a mechanical limit stop, all remaining load will be applied to the 600 lb/in spring. Therefore your spring rate will change from 200 lb/in to 600 lb/in at that point.

Effective spring rates for springs in series can be calculated the same as resistors in parallel. For two springs: (S1 * S2) / (S1 S2) will work. For more than two springs: 1/Se = 1/S1 1/S2 1/Sn where Se is the effective spring rate for all springs and n is the total number of springs.



"The only source of knowledge is experience." - Albert Einstein<P ID="edit"><FONT SIZE=-1>Edited by BradM on 10/31/01 08:27 AM (server time).</FONT></P>

[sirhk100]

Thanks for the info, I wasn't quite sure I was right and I guess this time I wasn't. Thanks for the info!!

'99YZ400,
'92 Ford Exploder lifted work in progress,
lifted golf cart

[rdc]

BradM is right, but I think his equation was missing a sign (S1*S2)/(S1+S2), You can go to Sway-A-Way web site and they have a couple of pages that give some spring rate selection info and the dual rate spring equations.

[BradM]

Actually, I had the plus signs in the equations and when I edited my post, they were dropped. Why is the John? For what ever reason, in the editing mode the symbols won't carry through.

The alternate series spring calculation is 1/(effective rate) equals 1/(rate of spring 1) plus 1/(rate of spring 2) plus 1/(every other spring rate).

Brad
<P ID="edit"><FONT SIZE=-1>Edited by BradM on 10/31/01 10:01 AM (server time).</FONT></P>

[fishd00d]

Hmm, well I got an F in algebra heh. But I will take what you guys said into account if I can understand it :) I'm going to pickup the springs here in a second.

Man this is such a tight fit. I am talking about centimeters of clearence heh. Anyone know if anyone elce has put coilovers on a V6 Yota? If so anyone got any pics?

Go Big Or Go Home

[rdc]

If anyone is interested I have a spread sheet that gives the dual rate equivalent rates that reads like a multiplication table, it easier than getting out your calculator.

[Ryno]

Fish-

How big are the hoops? I am assuming you are bailing the t-bars? I know your yota weighs about 300 pounds less than my chevy, so I'm looking for spring rates here folks. I wanna do the same coilover conversion, and have a nice set of arms and stub axles built, ot the axles built off the stock axles. Anyone seen this or done it?

Ryno

PS-How much room would going to 2.0 shocks give you?

Build it like a Rhino, and Leave it be.

[fishd00d]

WHOOO! I got the drivers side (hard side) hoop done! Its all bent and ready to weld in. I am not sure how big the hoops are. They are as high as I could go without hitting the airbox on the drivers side. Yes I am ditching the tortion bars. I know nothing about spring rates so I am just going by what Baja Concepts recommended. 500 over 500. I know its not dual rate and if it dosent work good they said they will exchange them for different rates. HOPEFULLY I can have the truck finished and back on the road tomorrow for the desert this weekend!

Go Big Or Go Home

[fishd00d]

Yay! Drivers side is welded in place!

http://www.pencilart.com/hoop.jpg

Go Big Or Go Home

[John_Bitting]

Fish get off the internet and finish that thing so we can see it sitting on the ground. I want to see the shocks bolted in place... :-)

[fishd00d]

Wel I have one problem. The welder just broke! The wheel that feeds the wire wont turn anymore!!! FIGURES! So I have to run to home depot and buy the best one they have and then return it tomorrow :) Any suggestions? :) I am thinking the most expensive one.

Go Big Or Go Home

[rdc]

Yeah fish get to work! And stop calling me about the welder being broken. Just get your butt to Home Depot and buy a new one! LOL!!!!

Tony

[fishd00d]

Here ya go John!

http://www.pencilart.com/hoop2.jpg

I need a fricking car to get to Home Depot! Arrr. I'm thinking about riding my bike then taking the shopping cart home cause there is no way I am carring a welder home on my bike!

Go Big Or Go Home

[sirhk100]

Now that's desperation!!!! :)

'99YZ400,
'92 Ford Exploder lifted work in progress,
lifted golf cart

[Waldo]

GO FISH!
GO FISH!
GO FISH!


Get it?

BRAAAAAAAAP!

[Dylan]

It’s really important to know the motion ratio of the A-arm before you start figuring out spring rates.
You can get dual rate out of any combination of spring even if they are the same top and bottom. To get dual rate you must stop one of the springs from compressing at some point in the travel. This can happen because one of the springs goes to coil bind or because you are stopping it with your dual rate stop nuts coming into contact with the floater. If you have the same rate upper and lower you will get 100% rate increase when you hit dual rate, if the spring that is being stopped is the softer of the two you will get more than 100% rate increase. When setting dual rate make sure that the main spring that is still active after your second rate has uncured still has enough travel left to use the remaining shock travel. Check out swayaway.com’s spring rate calc. page for diagrams and an explanation of motion ratio.

[rdc]

Dylan, I know that you know what you are talking about so I am in no way saying you are wrong. I just want to understand how if you put two 500lbs springs together you get a effective rate of 250? Does it have something to do with the increase in length? I personally disagree that you get any effective rate lower than the lowest spring. I am just looking at it from a logical side.

The way I look at it is like this. If I run a single spring with a rate of say 275lbs then thats the rate I have, correct? So why if I put a 450lbs spring below it would it now have a rate of 171lbs ??? The way I see it is the 450lbs spring remains a soild until the 275lbs spring is stopped.

With the theory of effective rate that has been stated it would be true that you could take any rate spring and stack a certain number together and end up with almost no rate. I know it would always have some rate. Example put 500, 500lbs spring in a stack. By what you are saying you would end up with a 1lb spring rate. Is this true??? I mean hey I will beleive anything I see, heck I have seen water run up hill. But this effective spring rate sounds all wrong.. Just my 2 cents...

Tony

[sirhk100]

Find 2 springs if you can that are fairly soft and stack them to see if they are softer on top of each other.

'99YZ400,
'92 Ford Exploder lifted work in progress,
lifted golf cart

[fishd00d]

WHOO!!! Got one side done!!

http://www.pencilart.com/leftdone.jpg


Time to do the other side!

Go Big Or Go Home

[rdc]

Austin,

Looking good. Looks like your going to make it to the dez.. How is that Home Depot welder doing??? Did you end up riding your bike to get it?

And on the spring rate discusion. I just thought about the fact that I have a force guage at work. I will get two small springs and run a test next week. Then we will know. I will video it so everyone can see it in living color!



Tony

[fishd00d]

Well actually Home Depot only had WeldPack 100. Those arent even close to strong enough so I just bought a Millermatic 135 from Airgas. I think I am just going to keep it. I just got the new leafs in on the left side. So now the whole left side is done! I will get the right side done tomorrow and be on the way to the desert! My friends already are out there :(

Oh I got different springs afterall. I got 450 over 500. So now it really is "dual rate" :)

Heres some pics:

http://www.pencilart.com/leftdone2.jpg

http://www.pencilart.com/leftdone3.jpg

Go Big Or Go Home

[drtdevil93]

ok, lets try it this way.

put your hand on the floor, put a 500lb rate spring on your hand, and then put 500 lbs of weight on to the spring. what happens? the coil sags 1 inch. how much weight is still on your hand? 500 lbs.
now think instead of your hand you put another coil spring. the second coil gets 500 lbs on it, and sags an inch as well. so, from the 500 lbs you place on it, it sags a total of 2 inches. 500/2=250lb/inches.
i know its confusing til you get it, and then you feel like a jackass for not getting it sooner.

wait til you get into calculating spring rates on a leaf spring. that is when the math gets real fun. (hint: infinite progression?)

erik

[Flea]

Great Example!

GOD BLESS AMERICA! and hopefully my poor truck too.

[BradM]

Hey Tony,

You claim to be an electronics engineer so I'll try another idea that maybe you can understand. Spring in series are the same as resistors in parallel. If you are still not convinced, test it yourself.



"The only source of knowledge is experience." - Albert Einstein

[Chris_Wilson]

And springs in series have the same math as capacitors in series - and the analogy works.
Resistors are the dampers as capacitors are the springs. (And diodes are bypass valves
and inductors are the mass of the oil...)

[Flea]

WOW! up untill that last one i was with it but this is getting outa hand!

GOD BLESS AMERICA! and hopefully my poor truck too.

[Quick_Prerunner]

Hey I can't really see that well from the pics, but it looks like you only have 2 points going to the frame. If this is the case you are most likely gonna need atleast another bar going down to the frame. Probably in the center of the hoop. Also, If i were you, I'd get some plating and make some gussets for where the tubes go to the frame. I've seen shocks hoops separate from the frame before and the end result isn't real pretty. Basically I'm advising you to spread out the load a bit. Just my 2 cents.

Mike

[fishd00d]

Yea its only half done. Tomorrow I am adding the engine cage and also am going to plate a lot of it. Just wait a few days and I think it will be ready!

Go Big Or Go Home

[rdc]

Okay I ran the test... I took two springs that were almost identical and yes when you put them both in seires (stacked) they compress the same amount as they did alone per the load. So yes the effective rate was halr of each springs rate. But why??? That is what no one has answered. I am thinking that it is more like each indavidual coil moves "X" under a given load. The more coils you have in a spring the more it will move per given load. Wouldn't it half the rate if you took a spring and of a certain rate and doubled its length without changing anything else, ie wire dia... Also by that theory if you cut a spring in half you will double the rate? Hmmmmm something to think about. Could you then effectively make some minor rate increases to a spring by trimming off a few coils?

I don't have time right now to post the picks of my test but anyone wants me to I will get them up by next week.

Tony

[BradM]

Well Tony, at least you believe it even if you don't understand it. And your theories are not exactly right either. Actually, the length of the spring does not have any direct effect on the rate. The factors that are used to determine the rate are: wire diameter (d), shear modulus of the material (G), mean spring diameter (D = OD - d), and the number of active coils (N = total number of coils - 2 for a spring with both ends closed and ground). The equation is:

k = (G * d^4) / (8 * D^3 * N)

So you can see that the wire diameter and the mean diameter have the largest effect. The number of active coils has an inverse effect such that if you add more coils, the spring becomes softer without regard to the length. Therefore, if you cut coils off one end of a spring it does not change the rate because of the change in length but rather because of the reduced number of coils and the change in end condition. Play with it and you can see the effects. I'll even send you an excel spread sheet with all the formulas if it will help make a believe out of you. Send me a PM or and email with your address if you want it.

BTW, G is approximately equal to 11.4 x 10^6 psi for oil tempered spring wire



"The only source of knowledge is experience." - Albert Einstein

[rdc]

Sorry I guss I should have been more clear. I was basing the length theory on "X" number of coils per set length.. Say like 1 coil per every 2". So I was right earlier in my postings when I said it had something to do with length. I wasn't refering to streching the spring! I was still talking about having the same # of coils per inch or what ever... So what I am getting at is that it has nothing to do with a dual coil. The reason for using dual coils has more to do with cost and other factors of making a long spring.



Tony

[ntsqd]

An intuitive way to look at coil springs is to consider them to be the bizarrely shaped torsion bars that they are. If you unwind a coil spring you have a torsion bar. If you paint a stripe down the wire, when you put a load on the spring you will see the line rotate around the wire because as the spring compress' the wire twists.
So inceasing the number of active coils makes the wire longer. Longer torsion bars for a given wire diameter are softer. I know this has been covered b4, I'm just hoping to make it easier to grasp.

Now for a confuser.
If you really dive into Brad's formula you can find out that a certain diameter in the core of the wire is doing basically nothing. So, if you want a lighter spring, you need to convince the spring maker to make it out of a tubular wire. Good luck.

TS

"Teach you all I know and you're still stupid"
-- Howdy Lee

[fishd00d]

Hmmm...Ok...Yea...Sure heh

Go Big Or Go Home

[The_Hulk]

If you have two springs with different rates which spring should go on the top, the stronger or the weaker one? Or does it matter?

[Flea]

the stiffer spring goes on the bottom that way you can set top coil spring to hit the coil stop and then you will get 100% of the stiffer coils rate, so if the coil divider hits the coil stop then the softer spring on top can no longer be compressed leaving you with a much stiffer rate to help aid in bottoming out and possibly aid rebound but im no expert so please add to this guys...

GOD BLESS AMERICA! and hopefully my poor truck too.

[geoff]

anyone have this spreadsheet?

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

[partybarge_pilot]

try these.

<A target="_blank" HREF=http://www.proshocks.com/calcs/index.htm>http://www.proshocks.com/calcs/index.htm</A>

[fishd00d]

Man this was an old post. Thats some old school pics of the piece and a guy named Fish that knew nothing about trucks lol.

Go Big Or Go Home

[ntsqd]

I just finished reading "Unfair Advantage", Mark Donohue's biography. Early on those Porsche 917's he raced in Can-Am had tapered wire, taper coil diameter coil springs made of titainium. Who wants to calculate those spring's rates ?

TS

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

[John_Bitting]

Yeah Fish you were the man welding the bump cans upside down and then posting it for us to check out.. :-)

[fishd00d]

Hey that was high tech. You know you were jelous! But they did work with a little modification lol.

Go Big Or Go Home

[shower]

Combining springs in series:
1/Kt=1/Ka+1/Kb+1/Kc..........
Where Kt is the total rate. And Ka, Kb, Kc, etc. the the individual rates of each spring in the series.