NotTwinTurboYet

Hi guys,

I'm searching informations on that special model, the 964 RS/RSR 3.8L. You know, it's that normally aspirated version on the RS with the Turbo Look and a 3.8L engine.
In fact, I need a very specific info about the rear wheels. When you look at pictures of that car, you see that obviously the ET for the rear wheels has nothing to see with the turbo version. I want to know what does that mean. Do that RS 3.8 has C2 or C4 rear arms, or do they have the turbo ones (I guess no simply looking at pictures).
Moreover, I have an information on the wheels I need to confirm with you. They seem to be 9x18 ET 48 front and 11x18 ET 5 (five!) rear. Is that correct?

If yes, it probably means that the RS/RSR 3.8L has a turbolook with standard rear arms. That's what I want to know

If anyone knows more, you are welcome!

A+

Glenn from Denver

I can only comment on the RSR (the one I have!).

The RSR is not a street legal vehicle. The wheels are BBS 3-piece centerlock units. There are no markings on the wheels that indicate offsets. The wheels are 9x18 and 11x18. These are the same wheels/offsets that are mounted on the 993 GT2 (I think).

I can't really comment on the control arms as I don't have a C2 or Turbo for comparison.

The picture of the car above is the RS. This is a street legal vehicle with regular 5-lug wheels.

NotTwinTurboYet

Hi Glenn,
Lucky guy you are to own such a car!
I think the picture shows the street legal version yes, but I can't be 100% sure

Could I ask you, next time you go under the car (and I'm sure you go under your car very often!) to take some pictures of the rear control arm?
No no, I'm not crazy , just wondering what's "behind".

A+

NineMeister

We are currently building an accurate replica of the 3.8RS from a genuine 964 RSL, and I can confirm that the genuine 3.8RS rear wheels are more or less nil offset and are designed to fit the stock C2/C4 trailing arms. Since we have the car and a new set of genuine wheels in the shop, if I get a chance tomorrow I will post up the front/rear sizes and offsets.

Should anyone be interested, the 3.8RS that we are building will be LHD and Amethyst colour, powered by a stock 3.6 engine on Motec that should have around 315-325 bhp when finished.

NotTwinTurboYet

Thanks for the info NineMeister!
And keep us updated on your project, pictures, pictures!!!
This is a very important information for me. I heard so many times that we should not go for a Turbo Look on a C2/C4 whithout carrying out all other turbo modifications (including turbo rear control arms). Finally that's not true, Porsche itself made the RS 3.8 like this! BTW, I think we are speaking of the RS control arms, there are not so different, but I remember that the mounting parts are not the same, therefore they have to be changed on a C2/C4, but it's less expensive than to go for wider turbo arms!
If you can have the offset, I'm also interested!
A+

NineMeister

The wheels we have are 9x18 ET63 and 11x18 ET5. It is possible that the RSR runs the turbo track set up at the front with std C2RS kit on the rear, I'll have to update you once the car is out of the bodyshop and being built.

NotTwinTurboYet

Cool, thanks for the update NineMeister!
And keep me updated about that car, I'm very interested in what your doing!

A+

jrotsaert

about 50 road legal 3.8 RS' (wide body) were made. They look indentical to the race 3.8 RSRs but have a VERY different engine. The offset is indeed 5 at the rear.
JM

Geoffrey

Are you speaking of the racing version RSR 3.8 or street version RS 3.8? The racing version has wheels in 9.5x18 and 11.4x18 with 245/645/18 and 305/645/18 slicks. The parts manual list 2 wheel choices, one from BBS and another from Speedline, although I've only seen them with BBS wheels. All 964 based race cars use N/A trailing arms. The 964 has 2 sets of bolt holes for the front control arm, one set for narrow body, and one set for turbo body. To change them, you bolt the suspension to the appropriate bolt hole. The RSR uses the turbo body mounting points for the front suspension, with the 964RS rear control arms.

I'm in the process of putting one together out of 964 and 993RSR parts.

Cupcar

The difference in the 964 RS / 3.8 RSR control arms is in the design of the rubber mount. The normal cars rubber mount allows axial motion that generates rear toe in under load, the RS/RSR mount is stiffer and does not have this axial motion.

Geoffrey

Yes, the control arm casting is the same, only the bushing is different.

Miles965uk

Hey im looking into converting my turbo to NA arms and going on the same principle as the 3.8 - i.e 11J wheels with a narrow offset. if you do some searched on my recent posts you should find some stuff there.
Im looking into swapping my turbo hubs over - these have a lower offset thus you can use turbo rotors and calipers.

Ag02M5

Ever take any pics of the wheels and rear suspension setup?

I'd like to know what the dims were of the inner and outer rear wheel lips.

RT

GG Allin

Here's an okay pic of the rear wheel of a 3.8 RSR.

Geoffrey

The dimensions of the wheel halves will depend on the brand and model of the wheel used. For instance, on my RSR, I'm running a BBS 8039 center with a 3.5" outer and 8.5" inner. If I used a BBS 8051, then the outer would be a 4" outer and 8" inner. The correct BBS wheels used on the RSR were 8041 and 8040 (I can't remember which is front and which is rear) and the offsets are different than mine.

The rear suspension arms are the narrow body arms, so they are the same arms as an RS street car bushing aside. The inner spring plate on the factory supported 94 version was a special plate that allowed for the selection of 2 camber choices with the twist of a nut. It was different from the 93 model which was essentially like the RS street model. The 94s factory cars also had fender extensions similar to the 993RSRs that bolted to the bodywork in the latter part of the year.