Actual Spring difference BRZ vs FRS

[Dimman]

Wonder if they got JDM spec setup?

[Z86]

Originally Posted by Dave-ROR

Prokit is 1" front and rear, part # 82105.140

Sportline is 1.4" front and rear, part # 4.10582

I don't have the rates for either.

They are also working on some other stuff as well, but I'll let Tony post that info once it's available.

So will the Prokit be ok with the standard shocks? Really just looking to lower the car by about an inch.

[Dave-ROR]

Originally Posted by Z86

So will the Prokit be ok with the standard shocks? Really just looking to lower the car by about an inch.

Yes. Both are designed to work with reasonable new stock shocks.

The Pro-kit rates are lower and it has less drop obviously. Alignment should be within spec with the pro-kits at least, not 100% sure about the Sportlines but I'd guess so, but maybe the rear camber might be out of spec.

[Sam Strano]

Since I've lowered my car already... I can tell you that the camber gain from lowering is huge. I'm down 1", and have -1.7 and -2.1 camber in the rear. So you better think hard about that when you are getting ready to drop the car.

As for dampers with springs. It's smart if you make springs to tell the world that the stock dampers work with them, easier to sell $200 than have folks feel the need to spend more. That said, I never recommend it. Stock dampers are usually not that great. They are built to a price, and built to make the most folks buying the car happy enough. They are not premium stuff, not meant to last a long time, and most notably valved to work with (irony of irony) the stock springs, which are taller and softer.... Stiffer springs require more rebound damping to deal with the higher spring rate and greater amount of stored energy. Then add that the damper has to damp that higher rate/energy in a now shorter amount of travel.

I have KW's on my car, with a bit of tweaking to the springs (still more than double teh stock rates). And you know what? The car not only tracks better, but while very firm, it's much less harsh than it was in stock trim too.

[Dave-ROR]

The camber gains have been all over the place so far. Agree on the rest. For me lowering springs would likely be temporary until I switched out to a threaded body setup.

However, the springs will work on stock dampers but of course the buyer should expect reduced lifespan on the dampers and depending on the spring rates the dampers may not be a great match for the dampers as well.

On a new car it's still a workable (if not the most ideal) solution for those who want something now without spending the cash for the good stuff

I suspect most of your front cable is from the lower strut mount, KW's are notched like usual. The rear camber of this car appears to be *very* sensitive to lowering though.

[Jackson]

Originally Posted by Wepeel

What are the Eibach spring specs (rate, drop)?

Pro-Kit (82105.140)
Front: lowers 1" | rate 148-200lbs/in
Rear: lowers 1" | rate 103-274lbs/in

Sportline (4.10582)
Front: lowers 1.4" | rate 120-211lbs/in
Rear: lowers 1.4" | rate 86-296lbs/in

Both kits are progressive in design but that initial rate doesn't mean much. Even at static height the spring will already be into the upper end of the progessive rate.

Originally Posted by Dimman

Did you chuck your originals? Can you retest?

I'm curious about maybe different rates for different countries.

Did Eibach USA test their own or was this info passed down from Germany?

We do all of our own testing in Corona, CA. We did test the BRZ and FR-S shocks and they are both very similar. There wasn't enough difference to convince that they changed valving from the FR-S to BRZ. Our engineers think the shocks are most likely the same but just tested slightly different from one another. Most OE shocks will have a slight variance in shock dyno numbers from car to car.

[Dimman]

Originally Posted by Jackson

Pro-Kit (82105.140)
Front: lowers 1" | rate 148-200lbs/in
Rear: lowers 1" | rate 103-274lbs/in

Sportline (4.10582)
Front: lowers 1.4" | rate 120-211lbs/in
Rear: lowers 1.4" | rate 86-296lbs/in

Both kits are progressive in design but that initial rate doesn't mean much. Even at static height the spring will already be into the upper end of the progessive rate.




We do all of our own testing in Corona, CA. We did test the BRZ and FR-S shocks and they are both very similar. There wasn't enough difference to convince that they changed valving from the FR-S to BRZ. Our engineers think the shocks are most likely the same but just tested slightly different from one another. Most OE shocks will have a slight variance in shock dyno numbers from car to car.

Would you expect a rate difference between here, Japan and Europe?

[Jackson]

Originally Posted by Dimman

Would you expect a rate difference between here, Japan and Europe?

I would but we don't have any of that data yet.

[7thgear]

these OEM rates are shocking

with an equal weight split i was expecting equal spring rates, but this is pretty baller.

[Sam Strano]

I can't see how the gains have been all over the place. I can see numbers being all over based off where the car started life, but that's not a measure of the rate of gain, it's a measure of how much range there is between cars. My car might have had -1 to start in the rear, I really don't know. But assuming it was close to spec, it gained a good 1 degree (maybe more) in 1" of drop. Easy enough to find out, all some has to do is run a gain test on a car with the spring and shock removed. I wish I had time I'd do it today, but I'm leaving for Washington state in a few hours.

Point being, even lowering springs will gain you a lot of negative camber in the rear. If you don't want it there just for tire wear, or for balance of the car assuming you don't want to run a lot of negative front, then something will need done. I have Whiteline compensation kits because I know this will be an issue, I'm sure Eibach and others will have them soon too. Now, I want the camber because I autox and track day my stuff, and so for now I'm ok with the numbers I have.

[sdiver68]

Originally Posted by Sam Strano

I think the thinking was the Subaru has stiffer front springs to promote more understeer at the limit which is more in keeping with what is typical of a Subaru car. Scion wanted the car more free, hence the softer front springs. But to counter that the Scion has front struts that are valved differently (stiffer). I suspect they are stiffer on compression a bit, not sure how much more, if any more, rebound they possess.

I think this "promoting understeer" at the the limit thing is a pre-release myth perpetuated by Toyota engineers who wanted to establish some sort of superiority from their tuning. Randy Probst found the FR-S to oversteer a bit too much on track and the BRZ faster around the track due to being more neutral.

To be nice about it, the Toyota tuning might be a little more aggressive at lower speeds such as for Auto-X

[Calum]

Originally Posted by Jackson

Pro-Kit (82105.140)
Front: lowers 1" | rate 148-200lbs/in
Rear: lowers 1" | rate 103-274lbs/in

Sportline (4.10582)
Front: lowers 1.4" | rate 120-211lbs/in
Rear: lowers 1.4" | rate 86-296lbs/in

Both kits are progressive in design but that initial rate doesn't mean much. Even at static height the spring will already be into the upper end of the progessive rate.


We do all of our own testing in Corona, CA. We did test the BRZ and FR-S shocks and they are both very similar. There wasn't enough difference to convince that they changed valving from the FR-S to BRZ. Our engineers think the shocks are most likely the same but just tested slightly different from one another. Most OE shocks will have a slight variance in shock dyno numbers from car to car.

I'm really curious about the shock dynos and the differences front to rear. Any chance you could post the results?

Oh, and a big thumbs up for the transparency.

[Jackson]

Originally Posted by Calum

I'm really curious about the shock dynos and the differences front to rear. Any chance you could post the results?

Oh, and a big thumbs up for the transparency.

I'll see if I can dig something up. We're outta here until Thursday. Have a good 4th of July, everyone!

[Sam Strano]

Originally Posted by sdiver68

I think this "promoting understeer" at the the limit thing is a pre-release myth perpetuated by Toyota engineers who wanted to establish some sort of superiority from their tuning. Randy Probst found the FR-S to oversteer a bit too much on track and the BRZ faster around the track due to being more neutral.

To be nice about it, the Toyota tuning might be a little more aggressive at lower speeds such as for Auto-X

Well, I didn't find my FR-S to be too loose in stock trim. The alignment wasn't great though and it's very possible and in fact I suspect likely that the fact teh FR-S was too free might well have been that (and maybe the BRZ was setup tighter just as luck of the draw).

Considering the cars are pretty much the same, there is some reason they did different springs and dampers.

As for more neutral, well, that can also mean "have more understeer" vs. a car that is more free (which doesn't mean it's a oversteering mess either).