Brake question

[speedman]

What is the thickest brake rotor that can be mounted on a SC spindle. I want toput bigger calipers on my SC, but without thicker disc is isn't worth much. I want to use the stock spindles

[Steve@Rennsport]

Hi,

Your spindles will support almost any rotor you want up to 380mm,....

The limit is dependent on wheel diameter and what calipers you will use. Rotor thickness is determined by caliper throat width,....

As an example, your stock SC calipers limit you to 20mm thick rotors. Anything wider requires Carrera calipers (24mm), 930 calipers (32mm & 28mm), S4 calipers (32mm & 28mm), or 993TT calipers (32mm & 28mm).

[speedman]

Do I need to do anything with wheel bearings? I am looking into 964 black brakes. So I can get any rotor to fit. I have 16" fuchs so what am I looking in thickness

[Walt Fricke]

RT

How you spend your $ is, of course, up to you. Bigger brakes don't make a car less safe, which is all us busybodies can really care about. But unless you track your SC, you don't need more braking power.

If you track the car, you can still make do with stock brakes with the right pads, high temp fluid, and a good cooling air ducting system. And maybe an insulating thin backing plate - stainless or titanium. Lots of stock class SCs are raced with the required stock brakes and these allowed modifications. They make it through 1.5 hour enduros just fine if properly set up. You will never see that kind of stress on the street.

Boiling the fluid is the limiter. One advantage of bigger brakes is larger pad area, which spreads the heat out, if you are having an overheating problem. Interestingly, pad area is nowhere to be found in the engineering formula for braking power! So you don't brake better, you just can brake as well for a longer time.

The 3.2s got the thicker rotors because they have more thermal mass. Which is good for an overheating problem, but but not so good for acceleration (more rotating mass).

Larger diameter rotors (which your 16" rims would allow up to a point, your brakes having been designed to fit the stock 15" rims, and even the optional "luxury" 14" rims) do increase the mechanical/geometric braking capacity (all, of course, limited by the tire grip) which is part of the formula (as is tire diameter: larger means pushing harder on the brake pedal for the same force).

But Steve gave you all there is to know about how thick a rotor you can use with that menu of calipers. All you have to do is figure out what will fit on your hub, and is its diameter compatible with the caliper you get, and will the new rotor be centered in that caliper. You can space the calipers inward with shims, and a bit outward with some machining. And do a lot more with custom work and adapters.

Oh - I think you might be able to use Carrera rotors with the early aluminum S calipers. Those were wider calipers in order to use a thicker brake pad, but you might be able to use the stock A caliper pad in them and a wider rotor.

Big reds look cool, but you ought to lift one and compare its weight with a 930 or S4 caliper.

Or does your SC sport a 4L twin turbo?

Walt

[Steve@Rennsport]

Originally Posted by speedman

Do I need to do anything with wheel bearings? I am looking into 964 black brakes. So I can get any rotor to fit. I have 16" fuchs so what am I looking in thickness

Your wheel bearings will be just fine as long as they are in good condition. This is the time to remove & clean the inner and outer bearings, check the outer races in the hubs, and pack them with a good grease such as Swepco #101 or Neo.

964 brakes can work with Carrera rotors or another 28mm thick rotor, but if you do track days, you will need a front cooling kit and really good brake fluid.

[H-viken]

QUOTE
If you track the car, you can still make do with stock brakes with the right pads, high temp fluid, and a good cooling air ducting system. And maybe an insulating thin backing plate - stainless or titanium. Lots of stock class SCs are raced with the required stock brakes and these allowed modifications. They make it through 1.5 hour enduros just fine if properly set up. You will never see that kind of stress on the street.
UNQUOTE

There are a lot of things Porsche owners can "make do with", but where's the fun in that? Once behind the wheel we all like to think we are Schumacher.

In my mind a big part of the fun of owning a Porsche is the "slippery slope". What project can I come up with next? (the wife's reaction)

[Bill Verburg]

Originally Posted by speedman

Do I need to do anything with wheel bearings? I am looking into 964 black brakes. So I can get any rotor to fit. I have 16" fuchs so what am I looking in thickness

I used 964 calipers on 304x32mm 930 rotors in front and 309x28mm 930 rotors in back.

For the front you bolt a flat rotor adapter to you stock hubs so there are no bearing issues




The front caliper ears are machined off and a caliper adapter is used


in back the 930 rotor is a bolt on once the splash plate is removed, the calipers need to have the stock mounting holes filled, then redrilled for the 3" 911 trailing arm mounts and the throats need to be ground a bit to accept the wide 28mm rotors, depend on the pad brand but usually the pads have to be ground down a tad too.




The thing that adds stress to wheel bearings is wheels w/ the wrong o/s

[JeremyD]

After almost going down this road, I think you will find that the 993 brake option is a little easier to stomach. Look at Steve Weiner's rotor option - the 993 rears on 930 rotors work well. Without a PPV the balance is good.

VCI has some options
Vehicle Craft Specialty Services for Porsche cars

Probraking is reasonable
ProBraking

Mr. Weiner
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