2004 GT3- getting camber at rear - how?

[JBW]

I am looking for some adjustable LHS rear wheel control arms for my Porsche 996 2004 GT3 CS

I am starting circuit racing & we need to get morecamber into the slick tyres to make them work - ie get hot!

Apparently - the standard arms on a road 996 GT3 just won't give enough camber adjustment.

will 996 GT3 Cup (or RS?) arms do the job?

Appreciate any insights/parts available

thanks :)

Edited August 18, 2011 by JBW

[Loren]

Yes, Cup rear trailing arms are likely the way to go.

[ericinboca]

More visual aids. These are installed on a 986S, but the arms are the same. The arrow shows were the shims are installed. And I placed a bunch of shims in the shot so you can see you have a lot of choices in shim width.

[clord]

Hi JWB.... In addition to the above info, adjustable/split lower control arms came stock on the 04-05 GT3RS as well as the Cup car of that period. Interestingly, when I checked a few years ago, the RS lower control are part numbers were the same as the stock, adjustable/split lower control arms on the front of the 04 GT3.

[JBW]

Yes, Cup rear trailing arms are likely the way to go.

fantastic - thanks!

[JBW]

More visual aids. These are installed on a 986S, but the arms are the same. The arrow shows were the shims are installed. And I placed a bunch of shims in the shot so you can see you have a lot of choices in shim width.

awesome advice- thanks

[JBW]

Hi JWB.... In addition to the above info, adjustable/split lower control arms came stock on the 04-05 GT3RS as well as the Cup car of that period. Interestingly, when I checked a few years ago, the RS lower control are part numbers were the same as the stock, adjustable/split lower control arms on the front of the 04 GT3.

Thanks- bit confused - my car is '04 996 CS

so do I upgrade to RS/Cup arms?

think these are correct: ??

996 331 053 90 leftwishbone assembly

996 331 054 90 Right

cheers

[clord]

Hi JWB.... Sorry if I confused the issue. The answer is yes, the 996 GT3RS or 996 GT3 Cup lower rear control arms (not really wishbone shaped) have a bolted split at the inboard end into which you can insert various thicknesses of spacers in order to effectively lengthen the lower arms, thereby getting additional negative camber. I don't have access to PET right now, so I can't confirm the part numbers you list. The spacers are an available Porsche part...at a price. In my own case, I got a machinist to make me a handful of various thicknesses out of aluminum stock. I found (for the front end of my GT3) that the 3/8ths inch just right for the camber I want for the track. These days, there are also other vendors that make split lower control arms that will work. I see then advertised in Pano and Excellence magazines.

[bobsan]

it's not camber that generates tyre heat, it's toe in or toe out.

[JBW]

Yes, Cup rear trailing arms are likely the way to go.

Thanks Loren

so the Cup rear trailing arm includes parts 1-8-9 in the diagram?

cheers

[JBW]

Hi JWB.... Sorry if I confused the issue. The answer is yes, the 996 GT3RS or 996 GT3 Cup lower rear control arms (not really wishbone shaped) have a bolted split at the inboard end into which you can insert various thicknesses of spacers in order to effectively lengthen the lower arms, thereby getting additional negative camber. I don't have access to PET right now, so I can't confirm the part numbers you list. The spacers are an available Porsche part...at a price. In my own case, I got a machinist to make me a handful of various thicknesses out of aluminum stock. I found (for the front end of my GT3) that the 3/8ths inch just right for the camber I want for the track. These days, there are also other vendors that make split lower control arms that will work. I see then advertised in Pano and Excellence magazines.

thanks Craig - I'm getting there - all clear now! cheers :)

[JBW]

it's not camber that generates tyre heat, it's toe in or toe out.

I'm only going off what the Workshop says to me - we need camber to get heat & push the rears to grip better under load ....especially thru high speed corners

is there a simpler way to do it then? - ie with toe?

many thanks

[clord]

JBW..... Sounds as if the workshop knows what it is doing.

[david_yorkshire]

suspension set up is complex;

no one single change will sort all evils !

simply adding more neg camber will not necessarily get more heat in the tyres

it will allow you to lean on the car harder in corners, which in turn will generate more heat; (I run -5 deg on the race car, and -2.5 on the road/track car)

toe effect on heat is minimal; I run toe in on my road/track GT3 and toe out on my 997 cup car when racing !

don't forget ride height - possibly one of the most overlooked items

our cars sag at the rear (heavy bottom!)

get the ride height back to stock and you will be amazed how much better the car handles, especially at high speed.

I'd get friendly with a well respected geometry workshop to get the best out of your car - these things are very sensitive to setup

here in the UK Centre Gravity are one of the recognized experts