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

[Racecomp Engineering]

Originally Posted by normancw

@Racecomp Engineering @CSG Mike

I'm planning to get RCE Tarmac 2, camber/caster plates and AP Sprint brakes this year. I track about 10 times (20 hours).

Without increasing NVH over stock, would you recommend bushings? If yes, which ones? How about away bars?

I have 17x9 ET35 rims with 245/40R17 RS3s and will be getting a SC as well.

Thanks!

I almost always recommend bushings. There are a few key ones that make a big difference with minimal to zero NVH change. Steering rack bushings isn't a must do, but it's pretty nice and there's zero NVH change. Front control arm bushing, rear upper camber bushing (get the non-adjustable WL one), and the rear subframe bushing are good ones to get with very minor NVH increase.

They help on all cars, but even more so when you are firming up the chassis with coilovers. Soft squishy OEM bushings become weak points.

I usually say yes on swaybars too, you get a little more roll resistance and the ability to make quick/easy changes to the balance of the car. Better to tune steady state balance with swaybars than dampers. They aren't 100% necessary for every case though and it may be worth trying the car without them (easy to add later).

- Andy

[Racecomp Engineering]

Originally Posted by FRS Johnny

For entry coils. Whats the difference between Stance, BC, Fortune, etc?
I'm looking to daily mostly, but still canyon run occasionally. Yet I still want to be lowered. I'm looking into Fortune, but I hear stories that they don't go low enough. Do the Fortune have as much adjustability as BC? I would greatly appreciate help!

Not much if a difference from my point of view. I have the most experience with BC and I'll just say they aren't for me. Fortune look like they have a little more attention paid to function.

No clue on how low any of them go. Sorry!

- Andy

[Racecomp Engineering]

Originally Posted by ultra

Just want:
- More grip (higher cornering speeds)
- Lower lap times
- Less steady state understeer at the limit (more front grip)
- Less lift off oversteer (no trouble catching & balancing it but it slows me down a bit)

aaand local time attack doesn't allow aero mods in the class I'm targeting (go figure) so not going there.

I'm going to try out the more aggressive alignment and some tire pressure tweaks next time out. Will see how that it works. Then worry about tires ($$) then different suspension ($$$). No big rush, just trying to think ahead a bit.

But yes, you are most probably right. Those last few tenths are always the most expensive; it may or may not be worth chasing after them.

You'll get 1 and 2 with just the tires for what it's worth.

- Andy

[Racecomp Engineering]

Originally Posted by 8686

@Racecomp Engineering @CSG Mike

I have SWIFT brz spec springs and I blow my shocks. The road condition in area is very bad. Now I need new shocks. I am thinking of Bilstein B6 but they are double the price of koni yellows. Appreciate your kind advice on what to chose.

Both are good but I'd be tempted to try the Bilsteins personally. The extra cost is due to the fact that it's a full unit and not an insert like Koni.

- Andy

[Racecomp Engineering]

Originally Posted by u/Josh

It is my understanding that damper settings have no effect on steady state performance because the damper only provides force when the wheel is moving in bump or compression and not once it has settled into its steady state position. Is practice different than theory in this case?

IMO if you try to make significant changes to steady state balance with your dampers you're going to chase your tail (figuratively) and waste your time.

- Andy

[Racecomp Engineering]

Originally Posted by solma

@Racecomp Engineering @CSG Mike

Question about rear suspension geometry, last summer after adding KW V3, rear upper arm whiteline camber kit(bushing) and running staggered setup 235/255 I have found that I am not able to rotate de rear when turning, instead I get understeer all the time(I am a smooth driver that do not like upsetting the car entering a curve).

So I decide to map out the dynamic toe in the rear suspension as I think it is where the solution is, my finding seem to go along with what I am feeling on the track.

I find that toe, at oem height, is toe-ing out on compression and toe-ing in in decompression.(logical by the fact that rear suspension can take more load during a turn) up to a certain point, close to max compression, the toe start to come in(must be for stability/security)

But there was a twist in the geometry and upper arm bushing(one is more compliant compare to the other). When torque is applied to the wheel, the hub start turning clockwise(due to weaker bushing), by doing so the toe is toe-ing out(without mesuring it, it seem quite a lot, possibly 2-3deg). This happen only when suspension is compress and torque is apply.

So here my question, because of the lowering(I am at maximum height for daily driving, so i just lower the car 3/4inch), but spring are stiffer then oem(less compression in cornering)=less toe out , plus because I have replace the upper arm bushing with poly it meen I have lost the toe-ing out feature on power, and last because I have larger tire in the rear(so need to transfert more working load at the rear), the solution I have found is to modify the pivot point(on the subframe) of the toe link, I did try it, its working, I can play with the decompression and compression toe-ing, so do you think its a good idea?

The max toe out I can get, under full compression is around 2 deg out with 1 deg in in full decompression. The oem value are around 0.6deg out (compress) and 0.5 deg in(decompress)

IMO the biggest cause of your understeer is the staggered tire set-up. There's no real need for it IMO. You are on the right track with the toe curve in the rear but it is not as big an issue. Set your static toe numbers accordingly and enjoy.

- Andy

[Racecomp Engineering]

Originally Posted by u/Josh

And that is where theory differs from reality. Thanks.

Is this also a situation where the driver feels like the car is handling better but his lap times (or cornering speed in that particular corner) aren't improving? The way I see it is if you are front grip limited to begin with, more compression damping in the rear isn't going to get you more front grip in "steady state" cornering, just less rear grip. Thus the car feels like it's rotating better but you're still limited by the same amount of front grip you always had.

More compression damping in the rear won't really do anything in steady state.

- Andy

[TouchMyHonda]

Are kw clubsports / rce t2 twin tube or mono tube?

[Racecomp Engineering]

Originally Posted by TouchMyHonda

Are kw clubsports / rce t2 twin tube or mono tube?

Twin tube.

- Andy

[solma]

Originally Posted by CSG Mike

If it works for you, it's always a good idea.

Have you considered using square tires or changing your spring rates to try to balance the car instead?

When I say it works, I mean I can play with the value, as it is winter, I will not be able to try it out before at least 3 month. That why I was asking an opinion on the subject before going ahead with drilling a new mounting holes in the subframe bracket.

As for spring rates, no , wanted to see before what all modification on suspension had changed compare to oem setup, and try regain oem setup.

[Calum]

Originally Posted by normancw

[MENTION=5622]
I don't see the non-adjustable WL rear upper camber bushing on your website. I only see:

Whiteline Rear Camber Adjuster Kit, $149.90
http://www.racecompengineering.com/i...-sti-2008.html

I'm pretty sure this is what he's talking about.
http://www.whiteline.com.au/product_..._number=W63225

[Racecomp Engineering]

Originally Posted by normancw

@Racecomp Engineering
Thanks! Are you referring to these bushings?

Whiteline Steering Rack Mount Bushings, $45.90
http://www.racecompengineering.com/i...-bushings.html

Yes the WL or the TIC version, which we can get but it's not on our site.

Originally Posted by normancw

Whiteline Front Control Arm - lower inner rear bushing, $54.90
http://www.racecompengineering.com/i...r-bushing.html

Yes, and the ALK, part number KCA434

Originally Posted by normancw

Whiteline Crossmember Mount Bushing Set, $44.90
http://www.racecompengineering.com/i...shing-set.html

I was thinking the rear diff inserts, KDT922. Cheaper and less NVH. KDT922 is the 45 buck one and the other is 150 bucks.

Originally Posted by Calum

I'm pretty sure this is what he's talking about.
http://www.whiteline.com.au/product_..._number=W63225

That would be the one! It's the non-adjustable version of their rear camber bushing. Still need to press it in but it's not nearly as much of a headache.

I need to have that added to our site.


- Andy

[Malt]

I recently had an alignment done since I had my coilovers installed (amazing RCE T2's ) and I knew going in that I couldn't get perfect rear alignment because I didn't install any means of rear camber adjustment. I was surprised at how different the left and rear specs were so I went ahead and purchased the upper adjustable bushings at Myles suggestion. Got a call back from the alignment shop this morning in reference to their concerns to how difficult it would be align them. I sent over the install PDF from whitelines site and their concerns were eased some but noted that it would take longer than normal to adjust with these instead of a lower control arm. Regardless of their concerns, I do agree with Myles that these are the superior option because of the replacement of the soft rubber bushings with a poly bushing and the fact that adjusting the camber will not affect the toe like the lower control arms will.

Anyway, my question is since the car is going to be on stands again while I get these installed I might as well replace other things at the same time since I'm going to need another alignment. I've been looking at the offset bushings from perrin for the front control arm to add caster. I've got the raceseng caster/camber top hats and I noted that on my alignment the caster was different on the left and right. I guess my goal is to get more caster with these bushing and then using the top hats to make them equal left and right. Is there a need to have them equal or is a couple of tenths off from one another ok?

So, is there such a thing as to much caster on the front? Also, is there any other bushings that I should replace while I have the suspension apart again that will require an alignment if replaced that will be beneficial for a mostly street driven BRZ that will see a couple HPDE events a year?

[CSG Mike]

Originally Posted by Malt

I recently had an alignment done since I had my coilovers installed (amazing RCE T2's ) and I knew going in that I couldn't get perfect rear alignment because I didn't install any means of rear camber adjustment. I was surprised at how different the left and rear specs were so I went ahead and purchased the upper adjustable bushings at Myles suggestion. Got a call back from the alignment shop this morning in reference to their concerns to how difficult it would be align them. I sent over the install PDF from whitelines site and their concerns were eased some but noted that it would take longer than normal to adjust with these instead of a lower control arm. Regardless of their concerns, I do agree with Myles that these are the superior option because of the replacement of the soft rubber bushings with a poly bushing and the fact that adjusting the camber will not affect the toe like the lower control arms will.

Anyway, my question is since the car is going to be on stands again while I get these installed I might as well replace other things at the same time since I'm going to need another alignment. I've been looking at the offset bushings from perrin for the front control arm to add caster. I've got the raceseng caster/camber top hats and I noted that on my alignment the caster was different on the left and right. I guess my goal is to get more caster with these bushing and then using the top hats to make them equal left and right. Is there a need to have them equal or is a couple of tenths off from one another ok?

So, is there such a thing as to much caster on the front? Also, is there any other bushings that I should replace while I have the suspension apart again that will require an alignment if replaced that will be beneficial for a mostly street driven BRZ that will see a couple HPDE events a year?

A good alignment shop will know how to even the left/right camber, by playing with tolerance in the mounting points of the suspension and subframe; that's how our car was aligned before we had coilovers.

Too much caster? No, but make sure your wheels clear your fenders!