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

[Keenercarguy]

Thanks! I had intended to shoot for -1.8 to -2.0 in the back and just absolutely as much as I can in the front. So I'm glad I was on the right track, and I'm glad I asked. Thanks again. Someday hopefully I'll have the money for Tarmac II's and Raceseng camber plates haha... Someday.

[cueball89]

2016 brz that is completely stock running factory 35psi tire pressures. I'm noticing over certain bumps/ heaves the rear end of the car becomes unstable. In a turn the rear end will start to slide and in a straight line it feels like the rear of the car is slamming down on the backside of the bump. I feel like there is too much rebound on the stock rear shocks or not enough rear spring rate? The front end seems ok over the bumps.

My gd wrx wagon with konis, sti springs and many poly bushings doesn't have this problem over the same bump. When the roads get rough with undgelating bumps the wrx is "glued" to the road and I can can carry speed and take corners with no issues. The brz seems to get "thrown" around a bit.

I've read a few threads talking about the same issue but no one was able to pin point what was causing the issue. I did read that aftermarket shocks fixed the issue, so I assume it's related to the shock valving?

[bhmax]

I felt like mine was acting similarly. I found myself trying lower psi in the rear tires, cutting the largest part out of the rear bumpstops, and removing the rear sway bar. Currently I'm reasonably happy with how it acts.

Originally Posted by cueball89

2016 brz that is completely stock running factory 35psi tire pressures. I'm noticing over certain bumps/ heaves the rear end of the car becomes unstable. In a turn the rear end will start to slide and in a straight line it feels like the rear of the car is slamming down on the backside of the bump. I feel like there is too much rebound on the stock rear shocks or not enough rear spring rate? The front end seems ok over the bumps.

My gd wrx wagon with konis, sti springs and many poly bushings doesn't have this problem over the same bump. When the roads get rough with undgelating bumps the wrx is "glued" to the road and I can can carry speed and take corners with no issues. The brz seems to get "thrown" around a bit.

I've read a few threads talking about the same issue but no one was able to pin point what was causing the issue. I did read that aftermarket shocks fixed the issue, so I assume it's related to the shock valving?

[cjd]

So I had an interesting discussion at an AutoX yesterday and it got me curious.

At what point (if any) would there be a benefit running a wider rear tire? Assuming body roll is controlled and I can run less front bar to address at least some of the understeer that is typically touted as a reason to avoid stagger, is it still power dependent?

Specifically I'd be considering 245/255 on 17x9. Close to full STX prep (stock diff and seats being the big changes I haven't done)

C

[churchx]

typically reason to avoid stagger is that many car subsystems are designed with car specific grip bias in mind. Brakes, electronic nannies, suspension, etc. There is also slight savings advantage of getting more out of tire set by keeping ability to rotate them. Yes, you can "fix"/"workaround"/"compensate" grip bias change by staggered setup by different suspension upgrades/readjusting and such .. but why do mistake in first place and rise such need at all?
If you need wider tire for more grip within class spec or if you install forced induction .. why not go for square 245 or square 255? Can you name any practical reason you must run staggered?
To me it looks, that 90% reasoning for those that chose staggered setup, is 'because it is cool', because some more expensive cars <insert porsche/ferrari/lambo/F1 and alikes here> has such, so it must be better and they haven't seen or decidedly ignore advises to not do that, as car with all it's subsystems is designed around square setup.
Funny, that friend of mine, that has car with staggered setup by design/from factory (few MR2-s), described it as annoyance he would be glad to rid off, and liked that mine luckily has good/normal square setup. He keeps factory staggered setup for same reasons we should keep square though.

[Hostile_Kittens]

So I bought Tarmac 2's with the Whiteline value-pak a while a go and it came with the KCA326 rear upper camber adjustment bushings. I'm looking to install them soon and wanted some advice.

I've got adjustable lower control and toe arms already an have been running around -2.5 in the back.

Should I put neutral camber on the uppers and then adjust the bottoms as required to keep the -2.5? Would neutral be the 12 or 6 o'clock position?

Should I put max positive camber on the upper and adjust the bottoms out to maintain -2.5 for a slightly wider track? Would that screw up my hub bearings?

I've got the STi trailing arms, which aren't adjustable, will these screw up the caster angle?

I haven't really found any threads or anything about these, I'm assuming because they're a tremendous pain in the ass to install. Luckily I've access to a full shop on base w/ a press and an alignment rack I can use.

[cjd]

Originally Posted by churchx

If you need wider tire for more grip within class spec or if you install forced induction .. why not go for square 245 or square 255? Can you name any practical reason you must run staggered?

I run square 255 now and will probably try 245 square, but wanted a little more thought on the subject. Bias re: brakes makes sense, though I admit I'm curious how a bit more rear bias would work. I'm also curious if the reported improvement in responsiveness from the 245 is just from the front, or both - I suspect both but in unequal measure. I don't know if launches gain anything to speak of from a wider tire. I still hear conventional wisdom mostly. In this discussion I don't care about cost and rotation benefits, just specifics on how and what changes with handling.

C

[Racecomp Engineering]

Originally Posted by Hostile_Kittens

So I bought Tarmac 2's with the Whiteline value-pak a while a go and it came with the KCA326 rear upper camber adjustment bushings. I'm looking to install them soon and wanted some advice.

I've got adjustable lower control and toe arms already an have been running around -2.5 in the back.

Should I put neutral camber on the uppers and then adjust the bottoms as required to keep the -2.5? Would neutral be the 12 or 6 o'clock position?

Should I put max positive camber on the upper and adjust the bottoms out to maintain -2.5 for a slightly wider track? Would that screw up my hub bearings?

I've got the STi trailing arms, which aren't adjustable, will these screw up the caster angle?

I haven't really found any threads or anything about these, I'm assuming because they're a tremendous pain in the ass to install. Luckily I've access to a full shop on base w/ a press and an alignment rack I can use.

Neat trick from MotoIQ on those bushings:
http://www.motoiq.com/MagazineArticl...Whiteline.aspx

You can see how the Whiteline upper control arm eccentric bushing allows adjustability. We set the bushings to reduce negative camber and also to raise the upper control arm inner pivot as high as possible to raise the rear roll center. When the car is lowered the rear roll center drops. Too low of a roll center can make the car twitchy at the limit. When you correct the front roll center like we did in the last installment of Project -FR-S the roll axis starts to get flatter. We feel that the roll axis needs to slope forward for the most natural feel to the car. By raising the rear roll center we can maintain this relationship.

I would do this if you have both the rear camber bushings and rear adjustable LCAs. Don't worry about your STI trailing arms.

We also got some of the tilt out of the upper control arm to reduce anti squat which will help corner exit traction some.

As in they have the front bushing adjusted slightly differently then the rear. Not 100% necessary, but a neat trick.

- Andrew

[Racecomp Engineering]

Originally Posted by cjd

So I had an interesting discussion at an AutoX yesterday and it got me curious.

At what point (if any) would there be a benefit running a wider rear tire? Assuming body roll is controlled and I can run less front bar to address at least some of the understeer that is typically touted as a reason to avoid stagger, is it still power dependent?

Specifically I'd be considering 245/255 on 17x9. Close to full STX prep (stock diff and seats being the big changes I haven't done)

C

I'm not sure it would be an overall gain over a square set-up in STX.

[cueball89]

Originally Posted by bhmax

I felt like mine was acting similarly. I found myself trying lower psi in the rear tires, cutting the largest part out of the rear bumpstops, and removing the rear sway bar. Currently I'm reasonably happy with how it acts.

Interesting. I'm going to wind up changing the shocks on the car most likely. Just need to figure out which route I want to go, koni's, bilstein's or cusco's.


At around the 15 minute mark the rear brz shocks are discussed. Seems to support what we are experiencing / feeling.
[ame="https://www.youtube.com/watch?v=MHyVoiP0o_8"]Scion FR-S / Subaru BRZ | Comparing OE vs Bilstein vs FCM dampers, v2.38 - YouTube[/ame]

[DoomsdayJesus]

What's your opinion on stock dimension rotors good for street/occasional track use? Is there any consensus on durable rotors for use with both track and street pads? I'm not looking to go nuts, just functional, durable, good value rotors, but I could be talked into spending a little more if it's seriously worth it for longevity.

Asking because my OEM rotors need lathing in the front after throwing on/bedding and running Hawk HP+ pads, which I don't plan on using on the street.

[ScionOfHorus]

OEM blanks work fine for dual-purpose use.

Sent from my Nexus 5X using Tapatalk

[DoomsdayJesus]

Originally Posted by ScionOfHorus

OEM blanks work fine for dual-purpose use.

Sent from my Nexus 5X using Tapatalk

I've had the HP+ pads on since Saturday and it's pretty obvious the stock rotors are taking a beating in the front. I'm worried about warping with the heat, too.

[strat61caster]

Originally Posted by DoomsdayJesus

I've had the HP+ pads on since Saturday and it's pretty obvious the stock rotors are taking a beating in the front. I'm worried about warping with the heat, too.

From everything I've read, warped rotors haven't happened since the 60's, uneven pad deposits is likely what's being felt and why turning them down helps.

I also haven't seen anyone but a vendor recommend anything other than OE replacement blank rotors. Centric gets a bunch of love and is cheap available on Amazon.

https://www.amazon.com/Centric-Parts...centric+rotors