Comprehensive Sra Suspension Tuning Guide

[swan song]

I noticed the front spring rate is bigger than the rear when you order custom but stock the rear is stiffer. Why is this? And does anyone have a good suggested spring rate for street performance but not gonna get old after a two hour drive?

Front spring rate is stiffer so you don’t have too much dive under hard braking. The rear is softer so you get squat from acceleration. This effectively “absorbs” some weight transfer, helping the rear tires to not break loose so soon. That’s all springs are folks. What gets old after two hours? That depends on what you are DOING for two hours. Two hour race stint? Run em high. Two hour freeway ride? Run em low. Two hour city driving? Doesn’t matter. It’ll suck either way.

[corax]

That's mildly surprising, what are the stock spring rates?

stock = front 96 lbs/inch, rear 107 lbs/inch
I roughly doubled that, 200 lbs/inch front & 225 lbs/inch rear, and am happy with it.  It's stiff, but not very bouncy.

[Bodey73]

Stock spring rates are Front 96 and the rear is 132 based on the images below of a thread on this forum

[Bodey73]

Front spring rate is stiffer so you don’t have too much dive under hard braking. The rear is softer so you get squat from acceleration. This effectively “absorbs” some weight transfer, helping the rear tires to not break loose so soon. That’s all springs are folks. What gets old after two hours? That depends on what you are DOING for two hours. Two hour race stint? Run em high. Two hour freeway ride? Run em low. Two hour city driving? Doesn’t matter. It’ll suck either way.

This is my daily driver is what I mean, but I have KYB AGX shocks so I could get like a reasonable spring rate and just change the shocks settings if I wanted to go to a track? Thanks though your info was useful but I’m still confused why the factory springs are stiffer in the rear. However it does make sense that with the springs in the rear being less stiff than the front that will allow the rear to get more grip

[Teranfirbt]

Dampers (shocks) don't change much about the balance on the car, that's all in the springs. Going too stiff on your dampers will result in less control of your car because the springs won't be able to do their job, resulting in loss of tire contact patch force.
The job of dampers in a car is to control wheel motion that comes from resonance in the springs. Springs are what control body roll and ultimately the balance of the car.
Sway bars also control body roll, but because of the realities of cars, sway bar motion is generally less damped than the springs, so it's desirable to control your body motion with springs and use sways bars as a final tuning tool.

At the end of the day, you can put a set of decent lowering springs on your car with a set of KYB Excel G dampers and learn a lot about your car. I had no trouble keeping up with Miatas and Caymans in my MR2 with a set of Eibachs and Excel G's (and good tires). Good tires are what really change a car into a track car. I've got Falken RE615K+'s on my MR2, although I've heard Direzza Star Spec II or RE71R are better tires and have more grip.

[corax]

Stock spring rates are Front 96 and the rear is 132 based on the images below of a thread on this forum

First image shows the spring rate for an IRS Celica is 132, SRA rear spring rate is 107.

[Bodey73]

I have an ‘85 GTS

[Bodey73]

Would you recommend the medium or the large t3 strut spacer for the SW20s? It says the mediums are for the rears (which is out front) but I believe someone said they still needed it to be longer

[swan song]

Would you recommend the medium or the large t3 strut spacer for the SW20s? It says the mediums are for the rears (which is out front) but I believe someone said they still needed it to be longer

Ask Gabe at T3

[Bodey73]

Front spring rate is stiffer so you don’t have too much dive under hard braking. The rear is softer so you get squat from acceleration. This effectively “absorbs” some weight transfer, helping the rear tires to not break loose so soon. That’s all springs are folks. What gets old after two hours? That depends on what you are DOING for two hours. Two hour race stint? Run em high. Two hour freeway ride? Run em low. Two hour city driving? Doesn’t matter. It’ll suck either way.

https://www.youtube.com/watch?v=cJZjnb_sp9o
^ This guy at 3 minutes says otherwise? But wouldn’t harder spring rates actually adjust quicker?

[Sigma Projects]

https://www.youtube.com/watch?v=cJZjnb_sp9o
^ This guy at 3 minutes says otherwise? But wouldn’t harder spring rates actually adjust quicker?

I know old post, but just saw the post. They're talking about a drift car, so they're setup more for over steer, more so than a track car is and they want more stability in the front wheels than they do in the rear.

For a track/autocross car it's a bit different. You want to have a roll stiffness bias that allows your drive wheels to make the most grip without creating understeer. So in our cars since they're RWD you want the roll stiffness to be less in the back than it is in the front. It's the opposite for FWD cars who dive hard into a corner and rely on the front wheels for grip.

[2jra65]

A good drift car is setup the same as a good autocross/ race car. There is no difference besides steering angle most of the time.

[Sigma Projects]

A good drift car is setup the same as a good autocross/ race car. There is no difference besides steering angle most of the time.

I've always seen more oversteer setup into the car for drifting. Am I mistaken? I know in more competitive drift series they work on improving grip because of the speeds they're trying to achieve, but in general I was always under the impression setting up the car to be loose was more advantages for drifting and setting up a car to be more neutral for the track was ideal.

[swan song]

You are supposed to set up a drift car for understeer so when you lose the ass end (intentionally), your throttle down pushes the front tires while the back is also out. This is a “4 wheel drift”, and is the best way to make tire smoke since all four tires are smoking, and that’s what American drift judges look at. It’s an entirely different reason in Japan.

 

A good drift car is setup the same as a good autocross/ race car. There is no difference besides steering angle most of the time.

And Ackerman. Ackerman is pretty much eliminated on a dedicated drift machine.

[twotone_ra64]

Let us leave the explanation to the professionals:

https://www.youtube.com/watch?v=mATgvmMYl-M