Cupcar

The USA Cup cars arrived here with the European RS suspension and this was re-installed for their sale for street use with the exceptions listed to follow below. This suspension is composed of:

• Monoball metal to metal bearing upper spring mounts front and rear
• 247 pound Front /440 pound Rear spring rates
• Bilstein monotube shocks rear
• Bilstein dual tube struts front
• Stiffer rubber in the front suspension pivots
• Elimination of the Weissach axel in the rear trailing arm to allow easier throttle steer
• Adjustable 24 mm front and 18 mm rear stabilizer bars with metal to metal bearings in front drop links
• Extended adjustment in the rear trailing arm plates
• Stiffer rubber steering coupling from the C4
• Aluminum front hubs
• 50 mm (~2") lower than USA normal ride height.

The RS suspension is quite aggressive and is much stiffer than an RS America for example which only has 169 pound front and 263 pound rear spring rates, rubber shock mounts, softer suspension rubber and smaller stabilizer bars.

The Euro RS suspension cars are great on the track right out of the box.

For the Racing Carrera Cup conversion the only modifications were to exchange the following parts to:

• Stiffer rubber front stabilizer bar bushings
• Stiffer rubber Cup/RSR specific front steering arm rubber couplings rather than RS' C4 units
• Front and rear monotube Bilstein shocks
• 200-600 pound progressive rate front springs and 240-800 pound progressive rear springs.
• Rear trailing arm plates inverted for more negative camber
• Modified monoball upper spring mounts. These are of the older, unsealed Carrera Cup design rather than the later sealed RSR type used on the RS. Also, the front racing mount moves the strut into a position of more negative camber than the RS mount does.

In the re-conversion I understand that, to save time and money, the cars did not have the stiffer stabilizer bar bushings or the stiffer steering couplings removed from them. So this is something that the 25 converted cars have that the 20 unconverted cars don't. I have not been able to absolutely establish this fact.

As for the front hubs, my unconverted car has aluminum hubs, I do no know if they were changed by Andial to steel hubs for the racing series, and left on the converted street cars; this is something that would be interesting to me to know.

Note that the conversion back to street trim was facilitated by the fact that each team who bought a car was to get all the street parts, thus each car had a forklift pallet set aside with these parts neatly packed for shipment. All Andial had to do was re-install the parts off these pallets to back-convert the cars to street specification. I visited Andial during both the "race conversion" and the "back to street conversion" cycles to see this.

dave morris

Thanks for sharing Cupcar. That's great history ... I'm always impressed with your knowledge of these great cars.

JBH

Wow - this thread just keeps getting better...maybe for archive purposes the title should be changed.

analogmike

very interesting!!

Amazing what changes have occurred since then....

They made a batch of race cars, and created a series, but nobody came.
PCA club racing was in it's infancy, there were not that many "real race cars" around, most
PCA racers had modified DE/street cars.

Fifteen years later, huge waiting lists for new factory race cars, at twice the price. You can't get one, sorry! IMSA GT3 cup is most successful series in a very short time.

Think about what it would take to make a GT3 cup car street legal (!) Could never happen.

No telling what the future will bring but always interesting to think about it.

Thanks for the info!

Cupcar

I think the most interesting change that has occurred over the years is the effect of the internet and world wide web.

In times past Porsche could build a Carrera RS or GT3 and sell it in Europe with nobody knowing in the USA.

I remember when the Carrera RS 2.7 was available in Europe and we only got the 911 S over here, when I talked of the RS, nobody really understood or I think even believed such a car existed at first.

In 1992 the European 964 RS was a mystery to people in the USA and usually confused with the RS America when they are radically different cars.

Even the first generation GT3 was sold in Europe with pretty much nobody knowing about it here in the USA.

Porsche stated that they would never sell a car in only one market in the future but still tried to get away with the GT3 RS which made people question them.

Now it is all in the open on the internet and Porsche can't hide this type of stuff and we get the RS, even if it is diluted in form.

Rob 97 993c2

cupcar,
firstly thanks for the detail on the 964 usa cup.
Just curious, what exactly did andial to transform the cars for the racing series? i assume they would no longer be street legal?

Cupcar

As you can see from my post above, the cars were imported in street legal form as a car very similar to a European Carrera RS and ready to be converted to a racing car.

To complete the conversion to a Carrera Cup racing car, in addition to the changes in my suspension post listed above, the cars had the following done:

• Intallation of a welded in Matter roll cage (same as MOO3 option or M001 Carrera Cup cage in Europe)
• Recaro SPG seat installation
• Intsallation of wooden floorboard on drivers side
• Installation of 6 point harness to mounts already in car
• Complete removal of interior carpeting,lower dash padding, airbag system and alarm system.
• Removal of front bumper beam
• Removal of oil cooler fan and installation of duct plate
• Replacement of fog-lights with red painted alloy plates
• Installation of 9.5 inch rear wheels, 8" rear wheels moved to front
• Removal of the engine belly pan
• ABS brain moved to alternate location already in car higher in trunk
• Hood Pins installed on hood
• Fitting of cables to the battery switch already in car so switch activated from inside and outside of car.
• Furthur lowering of car to a point where it cleared a 10 cm test block
• Intallation of MOMO steering wheel
• Intallation of Toyo racing tires 235/45 front 255/40 rear
• Installation of open exhaust
• Removal of heater blower on engine with replacement by duct
• Installation of racing clutch disc
• Installation of window net
• Tow hook installation using bracing for this already in car
• Dyno test of engine to make sure they were identical
• Mounting of DME brain behind driver's seat using special plate mounted to pre-drilled holes in the chassis.
• Installation of Pagid racing brake pads
• Removal of brake backing plates with installation of ABS wiring insulation and heat shields
• Installation of a wiring harness to make the ABS switchable on and off with switch on dash (harness also allows the battery switch to function as kill switch)
• Removal of the brake proportioning valve.
• Installation high pressure off switch for ABS

As you can see this would make the car illegal to drive in most states.

All the above plus the suspension modifications listed in post above was reversed in the re-conversion to street specification.

Cupcar

Note I edited in more things to my list of racing car conversion steps in my post above.

Cupcar

As shipped from Porsche and after Andial's re-conversion to street specification they looked like this:



After Andial's race conversion they looked like this: