So I am seriously contemplating this conversion to run some deeper rear wheels.

I had a couple notes with Adrian Streather who generally thought it was a bad idea (and I respect his Porsche knowledge)...in part due to reinforced suspension on the RSR among other things. He actually said a similar car was "undriveable" but did not elaborate.

What are your thoughts? I don't think everything Porsche engineering is always perfection, though in this case there may be some good reason. Also, it may have been to partly to accomodate the same wheels on both cars.

Personally, I don't see how it could have that significant of an effect. Suspension mounts the same and will have same travel. I can use brake calipers with same size pistons and same diameter rotor. I can source different sway bars. I have read the narrow body gear isn't as strong but there are some pretty serious narrow bodys running around.

I have read that deeper wheels cause more wear on the bearings and what not...probably due to the fact that you are providing a longer torque arm. But outside some additional stresses (which may be good enough reason not to do it alone) what handling characteristics would change by narrowing the suspension and moving the wheels outward. The tires still hit the ground in the same place and the suspension still compresses the same.

Appreciate your thoughts.

RT

 

Also note, the car is 90% street and some driving events. Not intended to be a hard core track car.

 

I am not aware of the reasoning behing Porsche's decision to use different arms on the turbo. Porsche does things for different reasons and it might be an engineereing decisions, or it might simply be cosmetic ie wheel.

Here are some facts: All 964 based race cars use 964 narrow body suspension. This means Turbo LM, RSR 3.8, and RS 3.8 street car. The track is the same since you change the overall width of the rear via wheel offset. Only the scrub radius is changed, and I'm not sure how much that really affects a trailing arm car.

There are a number of racing cars here in the US built from narrow body rear suspension, some of them running 13" wide slicks. Yes, wider wheels put more of a strain on the wheel bearings, however, I doubt that your street turbo can put the same load on the wheel bearing as say a factory 964Cup with slicks.

My experience suggests that it is fine. I have the conversion on my widebody, acutally it was a narrowbody with turbo bodywork applied. You will need wheels with different offsets, and rear brake rotors/calipers (I think).

I say go for it, you'll be happy.

 

Thanks for the response.

Any opinions on the NA, RSA, euro RS parts...trailing arms and drive shafts? I believe the differences in the trailing arms are all in the bushing. I have no idea though on the drive shafts. What do you run?

Cheers.

RT

 

Just curious if there has been any update on this I'd be curious to see how it turns out

 

Just collecting parts now. Have narrow body rear trailing arms, 993 brakes.

Need brake rotors, ebrake cable and axles, then build wheels to suit. Then a new sway bar.

This is a LONG term project so unfortunately no update. I am trying to see what axle/cv's I can use. It sounds like I am not really limited to c2 964.

Cheers.

RT

In the end, it is going to be killer.

 

I have to side with Geoff on this.
I've never heard that RSR's were "undriveable", in fact, I've heard the opposite. How many race cars has Adrian Streather built? Honestly I don't understand where he comes up with some of this stuff.....

 

Sounds like an awesome project you cannot beat the look of a nice stepped lip in the rear! Please keep us updated!

 

Robert right? I think its a great conversion ,not sure why anyone would want to poo
poo the idea..likely the only real effect will be the one desired ,the narrowed track to
accomodate the wheel offset you'd like.
I've considered doing this as well on my 965 project but a little ways from the suspension mods at this point..although I did just come upon a set of 3.75 inch outer
kinesis rimhalfs that have this project written all over them..
Keep us posted please,thanks Bert

 

Stock calipers work fine. You just need NA rotors. I did this on my 1991 model.

 

I've also considered this mod as I'm convinced the car can use more rear tire as compared to the front (for me that is). With that said I've realized with the right wheels and work 305's can fit with the stock setup (I've seen it done....and now have the wheels to do it). Which means that's a whole lotta change to run 315's.

I've seen a 94 with this update (or is that a back date) running 335's and must admit....the look from the rear was outstanding.

 

Jeff ,sorry to point it out but your in a whole different washington now!Bert
(avatar change coming?)

 

Hey Bert...thanks for keeping me honest!

Yes...I'm most certianly in a different Washington!!