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

[koevasi]

Originally Posted by solidONE

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?

What's surprising about it is that the front is nowhere near its limits when the rear lets go - in fact it feels like I could easily add another 5-10mph on turn in before seeing any signs of understeer. When the rear does let go, it does so quite quickly - think AP1 S2000? - and I am losing a lot of time 'drifting' which is definitely not the type of driving I enjoy.

Ideally I don't want to numb down the front end just so I can bring the rears into play but if I have to, I guess I have to.

As for my set up, I am on tein flex (before being phased out with mono and street options) with 7kg/mm front and rear.

F: 2.3 camber, 0.25 degree toe out,
R: 2.15 camber (with lowering, no LCA used to correct atm), 0.25 toe in
Lowered 30mm front and 28mm rear

[Racecomp Engineering]

Originally Posted by 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.)

You are definitely more snug than stock with the Recaros. Much more sitting "in" the seat rather than "on" (not that OEM is that bad in this car). A tiny bit lower if you like too. It's amazing what these differences mean in terms of feel while driving...it's pretty nice.

- Andy

[Racecomp Engineering]

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....

If it were me right now, I would use the fixed non-adjustable Whiteline upper bushings and an adjustable lower arm. I believe the WL lower arm will use poly bushings.

- Andy

[Racecomp Engineering]

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?

Depends on application a bit and also driver. Do you want one super fast lap on a circuit or auto-x course? Or do you want 20 slightly slower but consistent laps? OR a stable car you can trust in the canyons?

Generally though I'd say CSG is in the upper range of where I'd be for a car on sticky street tires. Going stiffer or adding big swaybars to that you start overloading the tires prematurely or overheating with multiple laps.

- Andy

[Calum]

Originally Posted by koevasi

What's surprising about it is that the front is nowhere near its limits when the rear lets go - in fact it feels like I could easily add another 5-10mph on turn in before seeing any signs of understeer. When the rear does let go, it does so quite quickly - think AP1 S2000? - and I am losing a lot of time 'drifting' which is definitely not the type of driving I enjoy.

Ideally I don't want to numb down the front end just so I can bring the rears into play but if I have to, I guess I have to.

As for my set up, I am on tein flex (before being phased out with mono and street options) with 7kg/mm front and rear.

F: 2.3 camber, 0.25 degree toe out,
R: 2.15 camber (with lowering, no LCA used to correct atm), 0.25 toe in
Lowered 30mm front and 28mm rear

I'm certainly not an expert here so please feel free to tell me I'm wrong.

By lowering more in the front you've shifted the weight forward without moving mass. That means the front will have more force on the tires creating more grip and conversly, less grip from the rear tires. Adding to things though, is that you still have the same mass and thus moment of inertia pulling the back out in a corner. If you can adjust it so that your level again, I think you might find what your looking for.

What was the motivation for the lowering more in the front?

[Racecomp Engineering]

Originally Posted by koevasi

What's surprising about it is that the front is nowhere near its limits when the rear lets go - in fact it feels like I could easily add another 5-10mph on turn in before seeing any signs of understeer. When the rear does let go, it does so quite quickly - think AP1 S2000? - and I am losing a lot of time 'drifting' which is definitely not the type of driving I enjoy.

Ideally I don't want to numb down the front end just so I can bring the rears into play but if I have to, I guess I have to.

As for my set up, I am on tein flex (before being phased out with mono and street options) with 7kg/mm front and rear.

F: 2.3 camber, 0.25 degree toe out,
R: 2.15 camber (with lowering, no LCA used to correct atm), 0.25 toe in
Lowered 30mm front and 28mm rear

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

[Racecomp Engineering]

Originally Posted by Calum

I'm certainly not an expert here so please feel free to tell me I'm wrong.

By lowering more in the front you've shifted the weight forward without moving mass. That means the front will have more force on the tires creating more grip and conversly, less grip from the rear tires. Adding to things though, is that you still have the same mass and thus moment of inertia pulling the back out in a corner. If you can adjust it so that your level again, I think you might find what your looking for.

What was the motivation for the lowering more in the front?

Remember you can't shift the weight balance much at all front to back with a height adjustable coilover...

But yes, raising the front might help slightly in this case by changing the roll center height.

- Andy

[Calum]

Originally Posted by Racecomp Engineering

If it were me right now, I would use the fixed non-adjustable Whiteline upper bushings and an adjustable lower arm. I believe the WL lower arm will use poly bushings.

- Andy

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

[solidONE]

Originally Posted by Racecomp Engineering

Depends on application a bit and also driver. Do you want one super fast lap on a circuit or auto-x course? Or do you want 20 slightly slower but consistent laps? OR a stable car you can trust in the canyons?

Generally though I'd say CSG is in the upper range of where I'd be for a car on sticky street tires. Going stiffer or adding big swaybars to that you start overloading the tires prematurely or overheating with multiple laps.

- Andy

All of the above?

Consistency is probably the top priority in most instances. Also adaptability to all scenarios, circuit, autocross, and canyons with minor adjustments. A streetable car that is capable of throwing down some fast runs on circuit and autocross is was most people *points to self* are after.

[7thgear]

Originally Posted by solidONE

All of the above?

Consistency is probably the top priority in most instances. Also adaptability to all scenarios, circuit, autocross, and canyons with minor adjustments. A streetable car that is capable of throwing down some fast runs on circuit and autocross is was most people *points to self* are after.

First, define fast.

If fast is “top contender in your class,” then you’redelusional to think that you could build a jack-of-all trades car and becompetitive at every type of venue.

Especially when you start factoring in modification rulesfor whatever series you’re participating in.

If fast is “turn some heads,” then a trained right footand a completely stock car can do that for you. No need to spend a cent. (okaymaybe tires and brakes, but that’s only so you can stay out longer)

If fast is “kill some porsches at my local HPDAs” thenyou just need to add another 100hp or so and train your right foot very veryvery well. Batteling rich folk who can’t drive on large tracks is all aboutpower, cuz they’ll make it really difficult for you to pass during corners, soif you can match their corner acceleration they’ll fold like a house of cards.

[solidONE]

Originally Posted by 7thgear

First, define fast.

If fast is “top contender in your class,” then you’redelusional to think that you could build a jack-of-all trades car and becompetitive at every type of venue.

Especially when you start factoring in modification rulesfor whatever series you’re participating in.

If fast is “turn some heads,” then a trained right footand a completely stock car can do that for you. No need to spend a cent. (okaymaybe tires and brakes, but that’s only so you can stay out longer)

If fast is “kill some porsches at my local HPDAs” thenyou just need to add another 100hp or so and train your right foot very veryvery well. Batteling rich folk who can’t drive on large tracks is all aboutpower, cuz they’ll make it really difficult for you to pass during corners, soif you can match their corner acceleration they’ll fold like a house of cards.

It only took some rs3 and some stoptec street pads for me to "kill" some more powerful cars, including a Porsche, my first track day on buttonwillow, and I was going at a decently slow pace....

"Fast" is a relative word. For the sake of this discussion what I mean by "fast" is faster than a similarly equipped car that doesn't not have the spring rates dailed in to a given tire. This is not taking driver ability into account. I mean having the spring rates dialed to match the tires so that the car is balanced and controllable, predictable at speed in each of the different scenarios with only adjustments to alignment and tire pressures to suit. Again, only talking about springs and tires. I don't think there has to be a huge compromise to acheive this.

[CSG Mike]

Yay this thread is back.

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?

Higher spring rates will load the tire more, causing the tires to heat up faster. RCE is correct; we're at the upper limit of what a 225 street tire will handle. If we were running R-comps or slicks, then we'd be able to go even higher.

As it sits, if I'm going for an all-out DGAF time attack lap where I'm holding nothing back (overdriving the car), I can get 2-3 laps before the tires start to overheat. (2:01-ish pace at BW)

If I'm going at a brisk 95% pace with very clean driving (e.g. for the purpose of a video or a ride-along), then I can get 5-8 laps before the tires start to overheat. (2:03-ish pace at BW)

Originally Posted by 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.

Sidewall flex, tread squirm, and loading impulse. Let me know if you want me to go into detail.

[Calum]

Originally Posted by CSG Mike

Yay this thread is back.



Higher spring rates will load the tire more, causing the tires to heat up faster. RCE is correct; we're at the upper limit of what a 225 street tire will handle. If we were running R-comps or slicks, then we'd be able to go even higher.

As it sits, if I'm going for an all-out DGAF time attack lap where I'm holding nothing back (overdriving the car), I can get 2-3 laps before the tires start to overheat. (2:01-ish pace at BW)

If I'm going at a brisk 95% pace with very clean driving (e.g. for the purpose of a video or a ride-along), then I can get 5-8 laps before the tires start to overheat. (2:03-ish pace at BW)




Sidewall flex, tread squirm, and loading impulse. Let me know if you want me to go into detail.

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.

[solidONE]

Originally Posted by Calum

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.

Yeah the shorter version of my question. I'd also like to know how the "east coast shops" like to set up their tire/springs for circuit auto cross and dual duty 86's.