Would like to start a list. Anyone know what factory TL springs are? I did find a formula for calculating spring rate if no on ehas stock #'s.

Tein coilovers are 671 / 336
S Tech are 307 / 196
H Tech are 296 / 184
Swift springs are 353/140-202
Tanabe springs are 325/134


where;
F is the force the spring exerts
k is the spring rate of the spring.
x is the displacement from equilibrium length i.e. the length at which the spring is neither compressed or stretched
The spring rate of a coil spring may be calculated by a simple algebraic equation or it may be measured in a spring testing machine. The spring constant k can be calculated as follows:
where;
d is the wire diameter,
G is the spring's shear modulus (e.g., about 12,000,000 lbf/in² or 80 GPa for steel), and N is the number of wraps
D is the diameter of the coil.

 

I think we could calculate the spring rate of the factory TL springs by measuring the amount of change in length of the the springs after we put a known amount of weight on it. Such as, measure the lenth of 1 spring, then put 500 pounds on the spring and then re-measure the length. The spring rate would be 500 divided by "3 inches" = 166

Spring rate is a ratio used to measure how resistant a spring is to being compressed or expanded during the spring's deflection. The magnitude of the spring force increases as deflection increases according to Hooke's Law. Briefly, this can be stated as
where
F is the force the spring exertsk is the spring rate of the spring.x is the displacement from equilibrium length i.e. the length at which the spring is neither compressed or stretched.

 

This reminds me of physics class. This method should work; however finding the proper tools to be able to load exactly 500lb+ safely is the difficulty. Determining the rates for a linear spring should be pretty straight forward. To do a progressive spring, there are extra factors that must be accounted for as you'd have to separate the linear portion from the softer progressive portion when measuring. This would be similar to a question I had on a physics final in college except they usually give you the length x and make you solve for an unknown like k along with some other curve ball. ; )

 

Very good info. Those Tein coilovers while stiff are going to have a ton of understeer, pretty much what I expected from the aftermarket.

We're about to get the numbers for a-spec, hopefully.

I've having this done right now for my car. I added a spacer to effectively take out a coil on my rear a-spec springs. These don't alter the height at all, they just make it about 30% stiffer. I did it till I got the handling balance where I want it. I'm having the rate measured and custom springs made because spacers are not a permanent fix.

 

This should work for variable springs too. So, where in the formula does it account for variable rate springs? By the number of windings. And the softness, as you mentioned, is measured by the amount the spring compresses under a given load. But I agree about measuring 500 pounds and doing it safely.. But it doesn't have to be 500. I just used a large number to present the real world a bit more accurately. But according to the formula, it can be 300 or 200, as long as there is some compression to measure. But its possible on the variable rate springs, you will need to test it with more weight, to get it to collapse more. Or measure it with a low weight, and then measure with a high weight. So you can get the ange

 

You'll just have two numbers instead of one like most progressive springs do. The first represents how it feels under normal driving. The second is large bumps and at the limit cornering. I personaly don't like progressives but some people love them.

 

ange = range. And I agree, I dont like the progressive rate springs either. They take away from the sporty feel during normal driving. (because it makes is soft) I still have never felt any springs as nice as my 96 WS6 Formula. Even the 2000+ didnt feel as mean as that car. I shoulda kept it. haha.. But at the time I didnt know as much about cars and how to fix them nor the means to do it. And those LT1's, require heavy maintenance after 90k. anywho.. off the subject again. haha

 

let me / us know when you get the spring rate on the regular TL's. please. And who is "we"?

 

[quote=I hate cars;

We're about to get the numbers for a-spec, hopefully.

[/quote]

Did you get the results from the a-spec springs yet?

 

For 04 - 08 TL

Tein S Tech
Spring Rate Front: 5.5 kg/mm = 307 lb/in
Spring Rate Rear: 3.5 kg/mm = 196 lb/in
Ride Height Lowering Front: 30.5 mm = 1.2 in
Ride Height Lowering Rear : 32 mm = 1.3 in


Tanabe:
Springs Rate Front 5.8 kg/mm
spring rate Rear: 2.6 kg/mm
Lowers Front: -0.9 in
Lowers Rear: -1.0 in

 

Very nice! Another reminder for me to follow up on the other rates.

 

uh huh I'm about an inch from the trigger. I'm also about to order one of them JL amps. I'm so tired of this sound system. And by the way, my shocks are so bad, that when I got my car like 2 years ago, I noticed the back end was bouncy. And days like today when I got a load of groceries, my car handles so nicely!! ahh pure ecxtasy. I cant wait to do springs and shocks. I'm lowering it a little. Bt I would liek to know what the Aspec spring rates are. I plan on Nuespeed Koni's, and either apsec springs, or H-tech or S-tech. The S-tech may be too harsh from what I hear, but their spring rates dont seem to be to extreme. So thts sorta confusing me. But I want the koni's to add some flexibility in the height as well as the dampening. You have to remember I came directly from a 97 SS Camaro that I lowered, with 35/25mm antisway bars and fat z rated tires. That car did not lean. So, I'm in pain here. And the reason I dont go back to a car like that, is because I am not going to work on another Camaro or Trans Am, again unless its an 85, 87, 88 or 89 model. And the corvettes are harder to work on than my Camaro, and even more of a high price tag with the same Mr. Goodwrench quality. So, Good ridence to GM for a while. haha Oh and I have not forgotton about when they srewed me on my bad paint job on my old Iroc. Dang clear coat peeled off the base coat.

 

And I have 3 other instances over the years where GM dealers lied to me and treated me improperly. But I just have to remember my breathing right now... *Inhale.. exhale**... Inhale.. exhale..

 

I'll keep pushing on the a-spec rates but I can tell you for sure that it rides very close, maybe a little softer than a stock SS of those years.

 

what years? but either way, for me these days, its more about "leaning" than how firm the ride is. But I would like to firm up "some". So I'll be looking for the fatest front and rear anti sway bars I can find. Like around January. I'm only at 56k miles on my car.. So I got lots of life left.

 

Chad, maybe try to do the sway bars in a step by step process, just to see the differences or changes.? I did the progress rear first, and then the type-s front sway bar(months later), and then the Koni's with H&R sports(almost a year later). The sway bars make quite a change in body roll while still on stock suspension(springs/shocks) while still allowing some travel. I am interested to see more spring rates, do you have any for the H&R sports?

 

right.. a step by step process will determine. But the spring I put on will be in the 300 pounds/in range. I am not going with the 600 pounds/in range springs. Plus I want it lower, so i'm going with springs when I do the shocks. Plus, it has to do with "already being in there". Like, if I replace shocks, then thats the time to do springs too. I dont want to duplicate my work. Anywho.. I don't have the spring rate for HR at the present. But feel free to post if you get it. Try to make it clear though, without having to read your whole post.