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

[Racecomp Engineering]

Originally Posted by SomeoneWhoIsntMe

I'm building a drift car right now, and I'm looking at going with Bilstein HD's with coil sleeves on them, because I'd like something that handles well but is flexible in terms of valving and spring rates. I'll have extra weight up front because of an engine swap, and standard coilovers won't fit anyway because I'll be running nissan spindles to get the steering geometry I'd like.

I read in a motoiq article that on Ryan Tuerck's 2JZ-powered FRS, they're running KW's with 10k rates front and 7k rear. Doesn't the motion ratio of the rear coilover location mean that the 7k spring rate out back is effectively even softer, compared to a car with the rear shock mounted to the upright? It also mentions that they're using some sort of a custom rear bar, with the stock bar up front.

Does it sound reasonable to assume that they're using relatively soft springs out back to allow the car to squat more and transfer weight to the back for more forward bite, while using a lot of rear bar to give it the transitional oversteer characteristics they want?

With that in mind, would the rear bilstein B8's for this car be in the ballpark of being able to damp 400lb/in springs if I tried to duplicate such a setup? I was going to go with 550 lb/in springs up front, and the 3000GT bilstein strut inserts I'll be running are supposed to be able to handle rates like that.

edit: also, what are my options for spherical bearing rear shock mounts? since the GR / ZC6 has multilink rear and the shock mounts don't adjust camber, it seems like there's not a ton of options for this. it'd be nice if there's such a product available at a reasonable price, I'd like to avoid having to design and fabricate something I can just buy.

The Bilstein B14 coilovers may be a better starting point. Shorter shock and already a coilover. Just replace the standard progressive springs with your choice. Still cheap.

Yes due to the motion ratio in the rear that 7k rear is closer to 4.3 kg/mm wheel rate. With a boosted 2JZ making 6000 hp (whatever) it doesn't totally surprise me that they are that soft back there and then using swaybar tuning to balance the car.

Raceseng makes rear top mounts with a raised mounting point so they add bump travel. Worth a look.

- Andy

[SomeoneWhoIsntMe]

The B8's look to be around 1" shorter stroke already give or take (please correct me if I'm wrong), and if I'm using parts shop max RLCA's, I get to choose between 25-40mm of drop, and then with raceseng shock tops I can get either 1" or 2" of extra bump travel (and correspondingly less droop)... surely the potential for around 4.5-5" lower ride height in the rear will be enough, especially since you can't do much about the roll center back there without custom uprights or a subframe.

On a lower-powered (350-400whp instead of 800+), less torquey car with similar weight distribution, would it then make sense to run more spring and less bar in the back? 550f/500r with a slighly larger bar than stock, and go from there?

[Racecomp Engineering]

B8's have shorter total stroke but don't gain you any bump travel IIRC except from a shorter internal bumpstop (probably). I just think you'd have a little more flexibility and an easier time with the B14s with minimal price difference.

We generally run even spring rates on our cars but occasionally recommend stiffer in the rear. For a drift focused car I would probably go with firmer rates in the rear and a damn good rear diff.

- Andy

[Malt]

Originally Posted by Racecomp Engineering

You would definitely benefit from more camber but it's a compromise (with convenience or tire wear).

We ran larger sways with T2s on 245 MPSS and it was such a good set-up.

- Andy

Just got back from my alignment/tire install.



Oh man these tires are amazing. Such a night and day difference front the stock primacy's. Going to give it a few days for me to fully feel the difference but I think all I needed was these tires and to finally get my alignment adjusted properly. I'll still probably get the sways in the future but I feel pretty good about where my suspension is setup atm.

[Racecomp Engineering]

Originally Posted by Malt

Just got back from my alignment/tire install.



Oh man these tires are amazing. Such a night and day difference front the stock primacy's. Going to give it a few days for me to fully feel the difference but I think all I needed was these tires and to finally get my alignment adjusted properly. I'll still probably get the sways in the future but I feel pretty good about where my suspension is setup atm.

Looks great!

- Andy

[Malt]

Originally Posted by Racecomp Engineering

Looks great!

- Andy

Part of me wants more caster so I don't have to worry so much about static camber. MMMMMMM caster

[Racecomp Engineering]

Originally Posted by Malt

Part of me wants more caster so I don't have to worry so much about static camber. MMMMMMM caster

7 degrees is pretty damn solid. Feels good man.

- Andy

[Malt]

Originally Posted by Racecomp Engineering

7 degrees is pretty damn solid. Feels good man.

- Andy

Chalk it up to the awesomeness that is @Raceseng cascam! I'll admit they are expensive but my god are they worth it!.

[NissanGuy]

Originally Posted by Racecomp Engineering

It is very bumpstop active...from memory I think the fronts are 0.5 inches from touching the bumpstops. So you're well into them on every corner.

Holy balls, that's scary. It would explain a few things, though... Does anyone actually sell shorter bump stops, or should I just chop up the OEMs, like with some lowering springs?

[7thgear]

Originally Posted by NissanGuy

Holy balls, that's scary. It would explain a few things, though... Does anyone actually sell shorter bump stops, or should I just chop up the OEMs, like with some lowering springs?

you are misunderstanding the function of the bumpstop, it is an integral part of the suspension system.


It's end effect is that of a progressive spring, a ridiculously cheap solution that compliments the typical coil spring design.




as for hard landings, bumpstops should never protect you from that... proper spring and damper compression settings are there to protect you from landings.. the bumpstops are just there to ensure that the strut/damper doesn't snap or shatter so that you can at least drive your ass to a shop.

[Racecomp Engineering]

Originally Posted by NissanGuy

Holy balls, that's scary. It would explain a few things, though... Does anyone actually sell shorter bump stops, or should I just chop up the OEMs, like with some lowering springs?

Like 7thgear said it's designed that way and a lot of modern cars do similar. I have a few theories as to why but have never confirmed with an engineer.

Either way, I'm not a huge fan of it for performance driving. It does the job but it's very progressive and the spring rate ramps up fairly quick.

With our 20mm drop lowering springs, we include replacement bumpstops front and rear. I don't think I would recommend running those bumpstops or cut OEMs on the stock springs since the stock spring rates are so soft up front (our springs are quite a bit stiffer).

- Andy

[gramicci101]

Originally Posted by Marchy

.

Going to be in the same position shortly, so I'm definitely curious about the answer.

[Racecomp Engineering]

Originally Posted by Marchy

So i have a question about alignment, my only "real" experience is playing around on forza so i have a basic understanding but not enough to go in and tell my alignment shop what i want.

I recently lowered my car on RCE yellow springs (still on stock shocks) and i'm picking up some Whiteline Camber bolts and spc rear LCA's to put on before my alignment. I was curious what would be best for a mostly DD set up with some auto-x use. Wheel/tires are 17x9 with 245/40 PSS.

i was thinking up front around -1 degree of camber and between -.02 to -0.06 toe

for the rear around -1.5 degree camber and not really sure on toe for this one.

and i figure weight will play into this, i'm around 195lbs (give or take 5 lbs)

-1.5 camber up front if you can get it with just the bolts and -1.75 or so in the rear.

0 toe front, and a tiny bit of toe in for the rear. Very little.

- Andy

[Racecomp Engineering]

Originally Posted by Marchy

Thanks Andy! and by a little bit of toe, are we talking positive? (like 0.01 or 0.02)

Toe in (positive).

- Andy