ACSGP

Continuing the conversation on weight reduction, assuming I've reduced weight the simple way via brakes, discs and rims, how else can I bring the weight down?

Is there an easy way by changing the wheel carriers/tie-rods to aluminium versions? Does the 964 RS use such lightweight parts, and can they be installed on my C2?

Bill Verburg

964RS used steel wheel carriers, though w/ a different design wrt the brake mounts as compared to normal 964.

Yes, you can adapt 993 or even better 993RS wheel carriers to a 964 front end.

The difference between steel 964 and aluminum 993RS is 4.5#/side

964speed

What about carbon fiber hood, fenders and bumpers? That weight has to be signiffcant

Bill Verburg

yes, but it's not unsprung or rotating weight

aj986s

Weight reduction anywhere (sprung or unsprung) will improve power-to-weight ration, which can improve acceleration and/or top speed.

But reducing unsprung weight also results in better suspension response/improved handling. On a drag strip, either reduction will likely result in the same 1/4 mile time. But on a road circuit, the belief is that 1 lb removed from unsprung weight will yield a faster laptime than 1 lb removed from sprung weight.

Here's a weblink with a bit more elaborate explanation:
http://victorylibrary.com/mopar/sprung-c.htm

Tom W

Responding to the original question: Bill provided your answer. Other than that, there are no meaningful alternative parts that drop much more weight that you can easily buy.

The unasked question is should you worry about this and spend the money to do it simply to reduce weight or unsprung weight. My $0.02 from observations of going from a normal C2 (call it 3200 lbs) to 2800 lbs to 2400 lbs and now to 2150 lbs ...

Dropping the weight helps. Dropping 1000 lbs makes a big difference in acceleration and cornering. A 997 GT3 is a lot faster than a 964 on the track. Drop 1000 lbs from that 964 and you can be faster than a '7 GT3.

I don't think anyone less than a pro level driver will be able to feel a handling difference or see a reduced lap time by simply dropping 10 or 20 lbs of unsprung weight. Most intermediate drivers I instruct don't even see a difference in lap time with a 190 lb (sprung) difference.

I've seen a number of intermediate to advanced level drivers (me included) drop 200-400 lbs of weight and not have any difference in lap time initially. After 3-4 events of getting used to the 'new' car, times start to drop. It's simply a matter of driving the car at the limit of what the car is capable of instead of driving at the limits imposed by the skills of the driver. Most pro's drive to the cars limits while most of us weekend warriors drive to our limits.

Think long and hard about spending money on weight reduction simply for the purpose of weight reduction and the desire to go faster. Increased seat time and a data system are more likely to provide a greater reduction in lap time at less cost.

joey bagadonuts

Well said, Tom.

We actually had a pair of local 993 racers who switched from PCA GT class (stripped cars) to stock class over the Winter, i.e. they needed to add 300-400 lbs of sprung weight to their cars. At every race this year, they notched times which were within a second +/- than those produced in GT trim. And this was true at, both, the short and long circuits.

ACSGP

Thanks guys for your response. I'm a bit OCD on unsprung weight, and now that I have the time and the 964, I'll be trying to improve the car as much as I can.

Bill - I loved your comparison of the 964 RS and 993 RS on Pelican Parts. What about reducing the weight at the rear?

BTW - haven't tracked the car and no real intention to do so. The pleasure is to have a well sorted car in the handling stakes.

LA964RS

Manthey had a great quote about rotating weight...every 1 lb of reduced rotating weight was equal to 7 lbs of sprung weight. There's some incentive to use the lightest brake rotors, wheels and tires.

ACSGP

Totally agree, that's why I went with the Conti CSC3s as they were 1 lb lighter than the equivalent Michelin PS2s on my Audi.

junkart

Choosing the right wheel design is also as important as the weight itself. For example, wheel A and wheel B have the exact same weight, but wheel A is a mesh design and wheel B is a 5 spoke design. Wheel A will give you less unsprung weight because most of the weight is at the center hub area and lighter on the outer rim area compared to the B wheel. 5 Spoke design wheels generally need more even material mass distribution for structural integrity.

It's like swinging a baseball bat by grabbing it on the skinny handle vs grabbing it on the fat-end.

Weight distribution My $0.02.

Bill Verburg

On a 964 there aren't any significant things that can be done to the rear axles to make them lighter. Another advantage of the 993 up is the rear suspension, you wouldn't believe how light the suspension arms are

Bill Verburg

light rotors are truely wonderful, until they don't work because they are too hot, it's all a compromise

ACSGP

So Biil, 2 things:

1. Has anyone installed a 993 rear suspension on a 964 yet; and

2. On the light rotors, the larger, floating rotors are supposed to shed more heat than the solid one piece ones, so not so sure about your comments abt compromise.

LA964RS

You run the lightweight hats not the rotors.....that's what was meant. Makes the whole rotor assembly lighter