CSG and RCE tag-team suspension Q&A thread! Ask us anything!

[Spuds]

Originally Posted by RotARy15

I've been needing to re-toe the front end so this would be a good time to install an anti-dive kit, if they are worth anything.

I've installed the rear Traction Mod and been very happy with it. However, I am less convinced about anti-dive. I've had my eyes on the Jackson kit but don't really understand what it will actually do for me.

There is very little in the way of reviews online. I've found a single youtube video where there was no discernable change to physical dive/compression under braking, but the review mentioned the front end was "more gooder on corner entry, fr fr no cap" or something to that effect. I'll take anything that makes the car pointier but if I don't fully understand it, then I'm worried about making some other aspect worse.

Traction mod: Recommend checking this thread out soon. https://www.ft86club.com/forums/showthread.php?t=155702

I'll give it a shot from a theoretical perspective...
Easy description of antidive is to imagine your suspension is on a very long longitudinal swing arm. The distance between the pivot point of that swing arm and axis of braking force (front contact patch to center of gravity) determines how much torque about the pivot point the spring has to counteract. More torque, more dive.

By changing the angle of the front LCA, you change where that swing arm pivot point is. The Cusco kit moves the front attachment point lower, moving the longitudinal swing arm pivot higher, increasing the "antidive geometry". This means the nose of the car will dive less under braking.

Why is this good?
-If you have aero this can be helpful to keep the wings and things at the appropriate angles.
-It lets you run lower ride heights with softer springs before you start bottoming out and hitting bump stops.
-Less camber gain under braking, which is good for straight line braking.
-Generally smaller body motions result in more consistent grip profiles for the tires, for better or for worse.

Great, what's the catch?
-The suspension with more antidive/antilift is not as compliant with mixed inputs, meaning any bumps or hills during trail braking are going to result in a greater understeer tendency.
-The driver has a smaller window of sensory input regarding how much braking is being applied.
-Less camber gain under braking, which is generally worse for mixed inputs.

[RotARy15]

Not so sure they fit my purpose then. Seems like something I would need to actually try, but for the price, probably not worth it on an OEM+ build.

[Scargod]

My second gen BRZ has fully adjustable suspension components on TSS Fab subframes. I'm the Guinea Pig for his new subframes. In the fall I was running the front subframe with no issues. Car handled fine. While the rear was being finished I ran the stock subframe with GKTech solid subframe and diff bushings.
I typically run at 4-1/2" inches front and 5" rear (at the pinch welds).
Part of 2025 I ran Ohlins Road & Track SUS MP21S2. Front Stroke: 120 mm/4.72” / Rear Stroke looks to be about 75mm or 3".
My JRZ RS Pro3 Motorsport shocks date back to 2017-2018 and came from CSG! I'm their second owner. The JRZ's are around 5-1/2 to 6" stroke in the front, depending on the bump-stops. Rear stroke is 4"+.
I've been setting the car up so that I have a 60/40 shock travel in the front. This required me having to turn special spacers on my lathe and move my caster/camber plates to the top of the shock towers, where alone I recouped about an inch of compression travel. I gained another 3/8" by using all of the threaded portion of the shaft that I could. I made special nuts for this so that threads extended down into the spherical bearing. I'm very happy with the front geometry and its very nearly a 60/40 stroke though not a 75/25 I've read about. BTW I have full aero.
It's the rear of the car that's killing me and what I don't understand.
The new subframe is supposed to yield a 5/8" drop. When I try to go to full compression (with the springs and bump-stop removed) I can only get to 1-1/2" of travel before the upper control arm hits the monocoque metal frame. I tried a Cusco UCA and it was negligibly better. Best looking of all (for the most travel) was the stock arm... I did not bother fitting it on the subframe.
I can't get full travel from the JRZ's. Droop yields no positive camber. At the interference point I'm at -3° which is okay. At issue is that I'm an inch or so away from contacting the bump-stop. I'm hitting the body frame before I've used half of my shock's travel.
I don't know what to do but to move the structural sheet metal in at the interference point or grind on the side of the arm. Before I do that I thought I'd check my sanity and see if anyone else has had a similar experience and/or what a different solution would be. The last thing I want to do is move the subframe down to gain UCA clearance. I like where the diff sits and all the rest of the geometry, as is.
BTW, I really like the toe links and the long trailing arms that came with the TSS Fab subframe. Great welding and construction. William has been great to work with.

[J95]

Question here, I did adjust my ride height (KW v3) to:

335 mm F/ 340 mm R (fender to hub center)
Which is a drop of ~31 mm

I take my car to the shop for a new alignment, camber values are:
before: -2.8 F / -2.0 R
after: -3.5 / -3.2

Then I measure ride height after shop alignment:
323 mm / 325 mm
Which is a drop of ~45 mm

This is a huge change in ride height, isn't?

I understand that I have to redo my ride height, which means changes in static toe/camber again, which means I will need another alignment. Looks like an endless loop, what's the best way to proceed here?

Btw I tracked my car with this setup, it did not feel right, probably the car is sitting on bumpstops way too much

My goal now is 340 mm / 340 mm and -4° / -2.8°.

[Ohio Enthusiast]

Originally Posted by J95

Then I measure ride height after shop alignment:
323 mm / 325 mm
Which is a drop of ~45 mm

This is a huge change in ride height, isn't?

Did you ask them to change the ride height? If you only asked for alignment (i.e. camber and toe adjustment) the ride height shouldn't have been changed at all.

Personally I would either find a good race shop that you can work with to set your suspension and will respect your exact specifications for ride height, camber and toe, and can do corner balance as well. Or do the alignment myself - camber is quite easy to do with a digital angle gauge; toe is harder, but toe plates will get you close if you only need to correct toe from camber change and most alignment shops could manage to correct toe if needed.

[J95]

Originally Posted by Ohio Enthusiast

Did you ask them to change the ride height? If you only asked for alignment (i.e. camber and toe adjustment) the ride height shouldn't have been changed at all.

Personally I would either find a good race shop that you can work with to set your suspension and will respect your exact specifications for ride height, camber and toe, and can do corner balance as well. Or do the alignment myself - camber is quite easy to do with a digital angle gauge; toe is harder, but toe plates will get you close if you only need to correct toe from camber change and most alignment shops could manage to correct toe if needed.

Nope, they only changed camber and toe. But ride height is a side effect of chamber change. At least the fender to hub distance

At least I experimented it myself when I adjusted my camber bolts. The ride height decreased a bit when I maxed out the camber bolts. Now the shop adjusted my camber plates, and decreased ride height again...

[Ohio Enthusiast]

Originally Posted by J95

Nope, they only changed camber and toe. But ride height is a side effect of chamber change. At least the fender to hub distance

Yes, it would change a bit, but I really doubt adding around 1 degree of negative camber will shift the ride height by 15mm, especially in the rear.
What's your rear camber adjustment? LCA or UCA (although neither should affect height much when adjusted)?

[J95]

Originally Posted by Ohio Enthusiast

Yes, it would change a bit, but I really doubt adding around 1 degree of negative camber will shift the ride height by 15mm, especially in the rear.
What's your rear camber adjustment? LCA or UCA (although neither should affect height much when adjusted)?

I have rear LCA. I don't know why the height shifts so much... but it does, checked with LCA, camber bolts and top mounts

So I will raise the coilovers until 340 mm, and will get a camber tool because you are right, it looks easy to DIY. Then the shop just need to zero out the toe

Does -4° F / -2.8° R look ok for very little street use? I read that camber does not affect wear that much

[Ohio Enthusiast]

Originally Posted by J95

I have rear LCA. I don't know why the height shifts so much... but it does, checked with LCA, camber bolts and top mounts

So I will raise the coilovers until 340 mm

I'd be interested to see if this turns out to actually be the case. I don't suppose you have the coilover height measurement from before the shop's alignment?

Originally Posted by J95

Does -4° F / -2.8° R look ok for very little street use? I read that camber does not affect wear that much

I'd probably aim for more negative camber in the rear, as much as -3.5. There're no good references for heavily tracked cars (every thread devolves into "it depends" without people actually sharing hard numbers). 949 racing's specs are probably the most easily accessible, and they recommend -3.5 to -5 in the front and -3.5 in the rear.

I have even wear with -3 front camber on a mostly street car. I bumped it to -3.5 now and will see how evenly it wears.

[J95]

Originally Posted by Ohio Enthusiast

I'd be interested to see if this turns out to actually be the case. I don't suppose you have the coilover height measurement from before the shop's alignment?

Yes I do, it was something like:
PRE alignment:

fender to hub (mm):
334 | 337 Front
342 | 340 Rear

distance (mm) from coilover collard to last thread (the more, the higher ride height)
14.5 | 11
78 | 89

POST alignment (added ~1° negative camber):
324 | 322 Front
324 | 326 Rear

[Ohio Enthusiast]

Originally Posted by J95

distance (mm) from coilover collard to last thread (the more, the higher ride height)
14.5 | 11
78 | 89

Nice. Compare these measurements to what's on the car now. If they haven't moved, then the camber is the only thing that changed. Fascinating stuff.

[Racecomp Engineering]

What I do:

1. get ride heights close
2. roughly align camber settings
3. reset ride height and/or corner balance
4. final alignment

Sounds like a lot, but 1 and 2 are basically a standard coilover installation plus a little extra thought.

- Andrew