Palting

OK. I've been enjoying the C4S a lot on the track (DE only). I've adapted to driving the car well in stock form, several instructors I had actually said the car is very neutral and nicely balanced (?). But, I keep wearing out the outside of the tires so quick I could cry. Fiddling with tire pressures don't help, and you can only flip the tires so often before it gets tiresome and expensive. I need more negative camber all around. Don't want to mess with the C4S suspension too much, so I thought I'd use the 987S for more track duty. Would'nt you know it, or I guess I should have known it, the same thing is happening !!

So now, what do I do? I still want to drive both cars on the street, still have warranty, so some kind of a compromise is needed and not just rip the stock suspension out. It's something simillar to jeeva's problems and I've been following thihose threads closely, but I'm limiting mine to simply getting more negative camber. More negative camber is the goal. What would I need on a 996 C4S? On the 987S, I got it with PASM, so is there even an option on a 987S with PASM?

Thanks in advance.

DJF1

Not an expert here and I'm not sure if it can be done with the stock suspension ( i know it can be done on a 993) as I have no clue how it looks on a 996, but the first thing that jumped into my mind is monoball perches with camber plates like the ones used by TRG. On their site they have them and I have the same ones for my 993's. I have not noticed on the street any significant ride degredation and this should be your ticket if you wanna keep everything stock:
http://www.theracersgroup.com/parts/...ber_plates.htm

bruinbro

How much $$$ do you want to spend? $2-3K will get you coilovers with monoballs that will get you -3 deg on your 987. The monoball mounts are a good alternate but your camber change is going to be limited by the ride height.

Bruinbro

Sanjeevan

Copied from my thread, as this is a related issue...

O.K, the reason I am going through this exercise is similar to Paltings,....even my instructors have mentioned how well balanced my car is, Walter Rohrl said the same thing when he was testing the C4S. So, I really don't want to change the suspension. When using R-compounds the front outside heats up more, which tells me there is inadequate camber (with the corsas it's livable, but i'd like to change it, if one it's cheap and two does'nt affect any other part of the car's handling).

Camber plates are an option,..but it's more expensive, some say not an ideal way to approach camber change, and does nothing for the oversteer problem or body roll issues.

The alternate route which I am pondering at this stage is the roll bar. I NEED SOME HELP FROM YOU GUY'S ON THIS ISSUE.

Again from Don Alexanders book, " Camber gain is caused by suspension geometry changes caused by body roll,........most suspension gain positive camber during bump (compression) travel, and the outside tire goes into compression....stiffer front springs and antiroll bar reduce body roll, which reduce bump travel and camber gain. This reduces the amount of static negative camber needed.....

So, it appears to me by stiffening the front antiroll bar one can reduce the need for more negative camber in the front, but this will worsen the understeer (which is certainly livable at this point). I was hoping it would not worsen understeer, and thus the reason for my initial quote from the book, but it seems like it will worsen it for my C4S.

So, what are the options,...the springs will stiffen pitch and roll, and the car is quite stable in acceleration and braking, so it's the roll that's the issue and not pitch. So, could tuning front and rear antiroll bars solve both issues ( camber and understeer).

How about front and rear gt3 adjustable sway bars ,....stiffer bars stiffen all ends, so going to stiffer bars all around with the same ratio of stiffeness for each wheel will keep the weight distribution the same but will minimize body roll, which will cure the camber issue (not the understeer, as the weight distribution is still the same). After which I will adjust the rear for higher stiffness which will transfer more weight to the rear and cure the understeer problem. So, in theory this should solve bothe issues,...do I have this right, or am I wrong with my thought process.
Thanks
Jeeva

RXDOC

[QUOTE=jeeva]Copied from my thread, as this is a related issue...

O.K, the reason I am going through this exercise is similar to Paltings,....even my instructors have mentioned how well balanced my car is, Walter Rohrl said the same thing when he was testing the C4S.


I just can't see how you guys can rave about the C4S Suspension? When I bought my 2002 TT and took it to the track, I was very unhappy with the ride. (and the C4S & TT share the same suspension). My care rode like a Buick, pitching and dipping at every turn. Our cars are set up like "luxury cruisers" for the 90% of owners that never track.
Unless I am wrong about the C4S, the single best (must DO) upgrade you can make is aftermarket adjustable coilovers (PSS9, Motons, JRZ). I did the PSS9's, had the dial in the negative camber, and the car performs 100% better. The difference is like night and day! I have now done 8 DE days w/PSS9's (and 1 without).
Just my $0.05 worth (inflation).

Sanjeevan

RXDOC, I am certain that JRZ and Motons will be much better than the stock setup, But i still would'nt characterize it as "buick like" . I can for sure say that pitching is very minimal with the setup, probably the weight difference between the turbo and C4S may expalin why?, bodyroll is an issue, is sort of managable, for instance both on turn 2 and thundervalley at mid-ohio, getting on the brakes actually settles the car, so I really don't wait for the car to settle totally before braking, I get on the brakes to stabilize the car and brake further to slow down at those spots. So, It's livable till I can get a better setup.
I would'nt say the suspension is a must do for C4S like the C2,(Walter Rohl called it the best balanced NA 996, only other comparision at that time was the C2 and C4)...C4S suspension is a far better setup than that. IMO, a good seat/harness/bar is the only must do mod. for the C4S. Actaully with the stock setup every expansion joint rattles through my head, it's funny if you read this in the archives, some who track there C4S think like me, and others have explained it the way you do. But, it's true that like Palting, instructors have told me how well balanced the car is.

John H

Balance to me means no excessive understeer or oversteer. I don't think the nosediving under braking or leaning when turning equals balance. At least, not in my mind. I think your instructors and Mr Rohl were referring to the understeer/oversteer issue. My 993 was well balanced with Eibach sport springs. It nose dived and body rolled like crazy. I have a picture taken while hard on the brakes. The front aftermarket spoiler almost scraped the ground. Now that we have coilovers and adjustable sways, the car is still well balanced but also flat thru the corners and under braking.

It is the body roll that is wearing out your tires. I was getting one weekend per set of Hoosiers before the upgrade and alignment. Now we have 3 weekends on a set and they are still going strong, i.e. no abnormal wear on the outer edge. I think that in a year or two the upgrade will pay for itself in tire savings.

Palting

Thanks for the input, all.

Believe it or not, you can rotate the C4S and make it understeer, oversteer or 4 wheel drift as you see fit for the corner you're in. And again, believe it or not, PSM doesn't intervene until you're way out of sorts. Anyway, this isn't about how great or not the C4S is. It's about solving the rapid outside tire wear.

I know that getting aftermarket suspension or the X73/74 is an improvement in many ways over stock. But will it result in even tire wear and solve the rapid outside tread wear problem? I'd hate to have improvements in areas I don't really care about, and STILL wear out the outside of my tires.

John H, I have no doubt the proper upgrade will pay for itself with tire savings. Are you all saying that just controlling the body roll with coilovers and adjustable sways will do the trick? Are we talking PSS9 and GT3 sways, like RXDOC says?

RXDOC, I didn't realize you could dial in more negative camber than the stock range with the coilovers. I thought you would still be limited with the standard suspension geometry despite changing to coilovers, and would still have to do camber plates.

Bruinbro, which coilovers and monoballs for the 987? Are they PASM compatible? $2-3K would be in the budget if it helps save on tires down the road.

Would simply using camber plates be such a bad idea?

TD in DC

Palting,

Try asking Gert Carnewal these questions -- www.carnewal.com. He has always been a very good source of technical information about potential upgrades to 996s of all types. I know that the C2 and C4S suspensions are very different so I don't know if it matters at all, but I had -2.5 rear camber dialed in with my PSS9s. I wore the insides of the tires a bit much so I backed it off to -2.0. Now, my tires wear very evenly. Send Gert and e-mail with your questions.

TD

RXDOC

Jeeva:
Sorry, I stand corrected. My only experience is with the TT. It drove like a Buick before the upgrade. It also sat up like a 4X4 before I lowered it to GT2 specs.
Back in Feb., I was tracking my TT at RoadAtlanta with 2 (two) other friends that had a C4 and C4S. We were running together most times, the body roll with their cars was very noticeable. It was even obvious in the track pictures one of the professional Photogs took of us. We were all commenting on how much the C4's were dipping and rolling in the pictures.
If you guys have found a way to be fast and smooth on the track, that is wonderful.

RXDOC

[QUOTE=John H]Balance to me means no excessive understeer or oversteer. I don't think the nosediving under braking or leaning when turning equals balance. At least, not in my mind. I think your instructors and Mr Rohl were referring to the understeer/oversteer issue. My 993 was well balanced with Eibach sport springs. It nose dived and body rolled like crazy. I have a picture taken while hard on the brakes. The front aftermarket spoiler almost scraped the ground. Now that we have coilovers and adjustable sways, the car is still well balanced but also flat thru the corners and under braking.

John:
This is exactly what I was trying to convey in my post, but couldn't say it correctly. That is exactly how my car was on the track with the standard suspension.
Thanks

adrial

Lowering the car in and of itself will get you more negative camber, how much? That, I dont know. I would guess it is somewhere around 1 degree/inch.

In bump, your suspension gains negative camber. This is to compensate for the positive camber that roll produces.

Sanjeevan

Palting, as you may know JIC cross allows for aggressive front camber setup.
Jeeva