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

[solidONE]

Science!

[Racecomp Engineering]

Originally Posted by iketeru

I've been thinking about replacing the bushings in the rear subframe and diff mounts, but I'm reluctant to charge ahead without knowing the reason for doing so, even though it's a relatively cheap upgrade. whenever I see underbody videos of the movement in these locations, it seems to me that they exist to eliminate smaller vibrations which cause NVH.

my question is, is making these locations more stiff by replacing with poly equivalent to slightly increasing the damping in the coilovers, or do you think the dampers were designed to work with the bushings to start with? that is, if you put in poly, are you feeling the damping as it was meant to be, or not going to get enough damping?

thanks for the great thread, let me know if i'm in over my head.

You'll feel some interesting things when you replace soft bushings with poly or solid bushings...enough that you may adjust your damping. Not "equivalent" to increasing damping but some of the things you thought were one thing actually were the bushings deflecting.

- Andy

[Gixxersixxerman]

I have a question... I installed RSR sporti coilovers, had my alignment done today.. One of the guys that is a good autoX driver, race track driver, and instructor, did my alignment.. After talking and everything.. We decided to 0 the toe front and rear.. The same way he drives his.. I've looked and looked and it looks as if this is a common setting.. But most articles I read suggest a 1/8" toe in, for the rear.. 0 Toe, in the rear seems to be recommended for real aggressive street driving, trackday.. So my question is, what am I looking at when I get to the track, what should I expect.. It seemed more.... Responsive, maybe is the word.. I wouldn't say twitchy, but maybe that could be a descriptive word for it.. I didn't feel nervous or anything just a lot more.. The car deffiently went where the steering wheel moved.. Instantly..

So is this going to be a lot more tail happy, Mike, you rode with me, is this something that should be ok to run with how you feel my experience lvl is?? I just don't want to dive into turn one or two at streets and go ass end into the dirt

[7thgear]

Hey guys, have a question for you

i'm trying to create a simple and effective explanation why R-Comp tires would prefer stiffer suspensions, and that their use on OEM sprung cars doesn't quite bring out the best in them (ie, autocross being a BIG compromise), and likewise that Street Tires lose their optimum effect if put on an overly sprung car.

i'm a little fuzzy on the details though.

[Captain Snooze]

Andy@Racecomp
Off topic but sort of handling related.
Could you please tell me how the Recaro CS compares to stock? Would a person describe the CS as being more or less snug than stock?

(I am asking about the CS because it is the only after market seat I am aware of that has the option of an air bag which is required to keep it legal here.)

[wootwoot]

Hey guys,

What is the best solution to adjusting rear camber? I know the upper arm is the best location, but all reports I have seen say that the whiteline adjustable bushings are junk. They are difficult to adjust, hard to install, and apparently the hardware corrodes quickly causing other interesting issues.

On the other hand there seem to be many lower arms for sale that are quality units. Easy to install and adjust. But I know this isn't the best location to change camber from. Also, being mostly a street car, I do not want bearings in my suspension which most of the lower arms have.

Head spinning....

[solidONE]

Originally Posted by wootwoot

Hey guys,

What is the best solution to adjusting rear camber? I know the upper arm is the best location, but all reports I have seen say that the whiteline adjustable bushings are junk. They are difficult to adjust, hard to install, and apparently the hardware corrodes quickly causing other interesting issues.

On the other hand there seem to be many lower arms for sale that are quality units. Easy to install and adjust. But I know this isn't the best location to change camber from. Also, being mostly a street car, I do not want bearings in my suspension which most of the lower arms have.

Head spinning....

I have heard some people running modified eccentric bolts on the rear lca pick ups for camber adjustment. Not sure if it's a good idea, but it will be very easy to adjust and also very cheap.

[wootwoot]

Originally Posted by solidONE

I have heard some people running modified eccentric bolts on the rear lca pick ups for camber adjustment. Not sure if it's a good idea, but it will be very easy to adjust and also very cheap.

I don't think you can torque those bolts down very much.... That is why most people suggest OEM crash bolts for the front of the car over aftermarket camber bolts....

[solidONE]

For the sake of discussion I want to ask about tires and spring rates. What are the limits or recommendations for spring rates for various different levels of tire grip?

For instance, It seems CSG have been getting good results with relatively high spring rates on RS3/AD08 level tires. 10K/12K springs.

Another expample is my Swift BRZ spec springs with stock tires. The tires will lose traction rather prematurely with the 3.8K/4.5K combo. I would say the spring rates are at the upper limit if not over the limit of the factory Michelins.

What would be the upper limits for spring rates for say... Hankook V12 or other grippier summer tires 240-300TW range on this chassis? Assuming you will also provide decent damping for the suggested spring rates. What about R-comps "street-tires" such as the NT-01?

[solidONE]

Originally Posted by wootwoot

I don't think you can torque those bolts down very much.... That is why most people suggest OEM crash bolts for the front of the car over aftermarket camber bolts....

The lower SPC bolt that replaces the 14mm bolt is rated at 76 ft-lb, while the 16mm upper camber bolt is rated at 106 ft-lb.

[wootwoot]

Originally Posted by solidONE

The lower SPC bolt that replaces the 14mm bolt is rated at 76 ft-lb, while the 16mm upper camber bolt is rated at 106 ft-lb.

Really?! What is the stock 14mm rated for?

[solidONE]

Originally Posted by wootwoot

Really?! What is the stock 14mm rated for?

Not sure... My guess is about 80 ft lb of torque

[koevasi]

Originally Posted by solidONE

For the sake of discussion I want to ask about tires and spring rates. What are the limits or recommendations for spring rates for various different levels of tire grip?

For instance, It seems CSG have been getting good results with relatively high spring rates on RS3/AD08 level tires. 10K/12K springs.

Another expample is my Swift BRZ spec springs with stock tires. The tires will lose traction rather prematurely with the 3.8K/4.5K combo. I would say the spring rates are at the upper limit if not over the limit of the factory Michelins.

What would be the upper limits for spring rates for say... Hankook V12 or other grippier summer tires 240-300TW range on this chassis? Assuming you will also provide decent damping for the suggested spring rates. What about R-comps "street-tires" such as the NT-01?

Also very interested.

I recently changed from 205/55/16 PS3s to 215/45/17 AD08s (not the 'monster' 245/255 section tires). Granted, with 7kg/mm spring rates I felt that 205s just weren't taking the increased load all that well and the car felt overly stiff all the time, and very harsh most of the time. However, it had a nice low speed handling balance (on smoother surfaces) of just the right amount of predictable understeer and oversteer. I do mountain runs mostly and I don't want or need a massively tail happy car.

With AD08, the springs don't seem to be bothered at all. For some reason there is also a lot more oversteer in low to mid speed corners and playing around with rear dampening settings don't seem to do much. Steering also feels a lot more vague than before. Am I just over-tired? Been thinking about sway bar options but I need to understand what's going on with my car.

Sorry if this question is a little beneath everyone else!

Cheers, Steven

[solidONE]

Originally Posted by koevasi

Also very interested.

I recently changed from 205/55/16 PS3s to 215/45/17 AD08s (not the 'monster' 245/255 section tires). Granted, with 7kg/mm spring rates I felt that 205s just weren't taking the increased load all that well and the car felt overly stiff all the time, and very harsh most of the time. However, it had a nice low speed handling balance (on smoother surfaces) of just the right amount of predictable understeer and oversteer. I do mountain runs mostly and I don't want or need a massively tail happy car.

With AD08, the springs don't seem to be bothered at all. For some reason there is also a lot more oversteer in low to mid speed corners and playing around with rear dampening settings don't seem to do much. Steering also feels a lot more vague than before. Am I just over-tired? Been thinking about sway bar options but I need to understand what's going on with my car.

Sorry if this question is a little beneath everyone else!

Cheers, Steven

I believe the oversteer you are experiencing is partly caused by the increased grip out front from the upgraded tires. Before you purchase anything else, you can try unhooking the rear sway bar from the end links and tie it away against the subframe with zipties.

I did this and was pleasantly surprised at how it behaved. This was with factory suspension on RS3 hankook tires. Though with the factory springs it would wallow on long turns, I'm assuming the rear suspension was bouncing off the bumstops. With your spring rates you probably wont experience this. The rear end gripped really well with the rear sway bar unhooked.

What is your set up? What dampers and alignment?