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

[DougW]

Anybody ever tried a LSD diff instead of the torsen ? When I use to race IMSA IS I tried a torsen and never got the exit to work just wondered if that isn't part of the issues here?
DougW

[fatoni]

Originally Posted by DougW

Anybody ever tried a LSD diff instead of the torsen ? When I use to race IMSA IS I tried a torsen and never got the exit to work just wondered if that isn't part of the issues here?
DougW

a torsen is an lsd. you mean a clutch type? no i havent. im pretty sure torsens only work when both wheels are loaded though.

[Racecomp Engineering]

Originally Posted by Calum

Whiteline has a new bushings that works with the factory lower control arm. With that in mind, would you still prefer an aftermarket arm?

Thanks

To be honest I haven't seen or used that piece, but I'm interested.

- Andy

[DougW]

I always considered a torsen an open diff since unloaded it will spin the tires at a different rate, but yes I'm wondering about a clutch type since under torque it would stabilize the chassis. Just thinking out loud again.
DougW

[koevasi]

Originally Posted by Racecomp Engineering

That's a little more toe than I'd like, front and rear. Toe out in the front can make it feel darty and maybe move the weight around too fast in your case.

I would do 0 toe in front, a little less toe-in for the rear. Then maybe add a front swaybar. OR raise the front slightly.

Seeing some in-car video would help too....gotta be smoooooooth with a car like this!

- Andy

Thanks Andy.

The rear is slightly higher to keep in line with the recommended ride height per the instructions.

The car IS very darty lol and I love the quick transitions but I am thinking the rears just can't keep up? The set up worked quite well for me with the smaller 205 section tires. Could it be that proper tires are highlighting the 'deficiencies' in my alignment settings?

Also, the steering has gotten very light (I'd go as far as to say it's a bit vague) with AD08 despite the greater contact patch. Is this something I could dial back once the toe is again at zero?

I love this thread. It's like having my own pit crew! Thanks for all your help guys.

Steven

[YDNA]

i totally forgot that my kwv3's might've been installed wrong in the front. do you guys have any input on where the helper spring should be? on top of the spring or on the bottom? or does it not matter?

[ZDan]

Seeing some weird ideas in here... Higher spring rates do not "load the tires more". Tire load is strictly a function of cornering G's, c.g. height, and track width (and front/rear roll stiffness distribution). Higher spring rates (up to a point) should be easier on tires at the track as you don't get nearly as much camber change relative to the ground between hard braking and hard cornering.

The difference between good street rubber and serious R-comps is something like 0.9g and 1.2g lateral grip, relatively. If a given set of spring rates are about right for Rcomps, then .9/1.2 or 75% those rates should be about right for street tires.

For a street/track compromise, you're going to be limited by what's tolerable on the street. The stock rates are very low for track work (appropriate for a production street car). You're going to go WAY stiffer than that before you have higher spring rates than ideal for street tires at the track.

[7thgear]

helper springs seem to go on everywhere.. haha

[CSG Mike]

Originally Posted by Calum

Yes please. It's a lot easier to learn something when I have a specific goal that's reasonable. Learning everything about suspension dynamics is a little daunting, but learning a few definitions in order to understand a small snippet of suspension dynamics is much easier. I've learned a lot from this thread, thank you for that, and hope to learn more.

Also, could you give and few examples like, for RS3's I would run such and such springs rates with proper damping. But with V12's I'd run ______ spring rates.

The simplest way I can explain, is that the higher spring rates result in faster weight transfers, which mean a higher impulse.

This impulse puts a larger shock load on the tread and sidewalls, resulting in more heat generation, which R-comps, with more heat tolerance, less tread pattern (siping), and stiffer sidewalls, handle better.

Beyond this, is a TON of variables that all interact with each other, regarding the net effect. Hoosier has some great documentation on this, as do a lot of university FSAE teams.

[Clipdat]

I got my RCE Yellow springs installed along with 17x9 +45 (3mm front spacer) wheels and 245/40 tires, then had an alignment immediately afterwards (no miles on the springs). Can you give me any thoughts about the alignment specs and where I should go from here?

[ZDan]

Originally Posted by CSG Mike

The simplest way I can explain, is that the higher spring rates result in faster weight transfers, which mean a higher impulse.

You can't turn in as aggressively on street tires vs. R-comps, that's kind of a given. It may be easier to overdrive street tires on corner entry with stiffer springs, but it doesn't mean you *have* to do it...

[solidONE]

Originally Posted by Clipdat

I got my RCE Yellow springs installed along with 17x9 +45 (3mm front spacer) wheels and 245/40 tires, then had an alignment immediately afterwards (no miles on the springs). Can you give me any thoughts about the alignment specs and where I should go from here?

Without any addition of camber adjusting components people are just paying for toe adjustments when they take their 86's in for alignment. I'd feel ripped off... not getting my money's worth.

Judging from your alignment specs and my own experience with lowering springs on this car, you will likely get quite a bit of understeer around corners. You'd want to add some neg camber out front and/or take out some neg camber out of the rear wheels to get it closer to neutral. Although, Racecomp Andy can probably give advice on what adjustments you need seeing that this is their product.

Just as reference, I'm running 3.8k/4.5k springs with -2.6* of camber added to the front wheels and -2.3* camber in the back wheels after lowering. With 245/40/17 Eagle F1 Assym tires, and the car understeers a bit. Ran the same setup with only about *1.5* of camber out front at the track and it understeered a lot.

[solidONE]

Originally Posted by ZDan

Seeing some weird ideas in here... Higher spring rates do not "load the tires more". Tire load is strictly a function of cornering G's, c.g. height, and track width (and front/rear roll stiffness distribution). Higher spring rates (up to a point) should be easier on tires at the track as you don't get nearly as much camber change relative to the ground between hard braking and hard cornering.

The difference between good street rubber and serious R-comps is something like 0.9g and 1.2g lateral grip, relatively. If a given set of spring rates are about right for Rcomps, then .9/1.2 or 75% those rates should be about right for street tires.

For a street/track compromise, you're going to be limited by what's tolerable on the street. The stock rates are very low for track work (appropriate for a production street car). You're going to go WAY stiffer than that before you have higher spring rates than ideal for street tires at the track.

I think both @Calum and I were looking for some numbers. A range of spring rates to work within for some different tires. Since nobody seems to want to do this we have to make our own "guestimations."

Having seen some test results done on some of the RS-3/AD08/Rival/RE11 level tires they are capable of holding around 1.1g on the skidpad, more or less. The V12/PS2/ContiSC2 level tires provide plus minus .95g of sticky. So .95/1.1 is about 85%. 85% of CSG's 10k/12K rates on their SRC's running 1.1g tires come out to be 8.5K/10.2K with V12/PS2 level tires.

[raul]

Originally Posted by Clipdat

I got my RCE Yellow springs installed along with 17x9 +45 (3mm front spacer) wheels and 245/40 tires, then had an alignment immediately afterwards (no miles on the springs). Can you give me any thoughts about the alignment specs and where I should go from here?

Straight from RCE's website. They also packed it in my box when I got my Yellows.