f4 plt

Looking for information on upgrading th brakes in my '83 SC running 16" Wheels. I understand the turbo brakes will fit, but will the early Boxster brakes fit with 16" wheels? Thanks

Bill Verburg

The issue w/ SC brakes is related to the heat generated
Solutiions
1) reduce the weight of the car, those brakes are fine up to ~ 2200#
2) increase cooling, many add the 996/993 cooling scoops and or active ducting from the front valance
3) use modern track pads w/ built in thermal breaks and higher temp operating range also use better brake fluid, Castrol SRF is the best and most SC's w/ stock brakes need it.
3) if all else fails bigger rotors

To get bigger rotors you need matching calipers
in order of effectiveness
swap in 3.2 Carrera front rotors and calipers, no other changes required

swap in 3.2 Carrera f/r rotors and calipers and 23.8mm m/c this moves some heat to the back and adds bugger rotors all around, bias is a bit too far rear but as long as you never lock the brakes it's not an issue, the bigger m/c will lower the locking potential by lowering line pressure for a given leg input, lower stiffer car w/ effective lsd helps as well, but do be careful and an adjustable p/v on the rear circuit is advised. The Boxster to SC brakes use these same rotors but cost a lot more I wouldn't waste any money on them.

swap in a complete 930 brake set, w/ 930 23.8mm m/c. The front rotors must be the '78-80 style w/ separate wheel spacer and flat hats or aftermarket equivalents, you discard the wheel spacer for use on an SC

f4 plt

Bill:

Thanks for your comments. the car is down to 2400 lbs and I do have an adjustable brake bias valve on the car. I do not have a complete ducted set up for the front brakes but I do have vent holes in the front bumper to direct air to the brakes.

I was considering Boxster brakes only because they are easier to find then 930 turbo brakes but the 3.2 (1984+) Carrera brakes are another option. I have suggested a larger master cylinder to my shop and it will be part of the upgrade. I run Pagid pads on the car. My SC is a part time street car and my track toy.

Jack

Ed Hughes

A good set of ducted 3.2 brakes on a 2400# car will work nicely.

f4 plt

Ed:

Good to see you on, Yes that is the plan to go with the 3.2 brakes. My front bumper is already ported for ducting so that is no issue

Jack

JCP911S

I have raced a 911SC for over 10 years. PCA rules require stock brakes. The car weighs 2550Lbs, wet. I run sticky Hoosiers Rs on 7/9 inch wheels, and the competition in D/E Stock is really aggressive, so these brakes take a major beating, believe me.

With racing fluid, and Hawk Blue pads, I have never experienced any brake fade or other issues that were not related to simple parts failure. My only real problem is over-breaking and locking up the tires. Adding more brake isn't going to increase the traction of the tires.

IMHO, these stock brakes are absolutely fine for virtually any driving you could possibly do.

Before you spend huge dollars on brake upgrades, make sure all of your hydraulics are up to factory spec. Rebuilding calipers and master cylinder are relatively cheap for these cars, as are new rotors.

Also make sure you are using a quality performance brake fluid and pads, and that the brakes are bled properly.

As stated above, the best way to increase performance on these cars is to reduce weight. This is relatively cheap, and helps cornering and acceleration as well as braking.

Have fun.

Ed Hughes

People have different driving styles, and different track layouts require different techniques, so the brake thing can be somewhat subjective. I remember a talented driving friend (amateur, but driven 24 hrs Daytona, etc) once had me spend a Sunday afternoon at MSR by doing laps from slow with no brakes, sequentially faster where I needed to brake, to see the spots where I was relying on brakes and to concentrate on minimal use. So, we are always learning. Not being held down by class specs, I always preferred to have as much braking capacity as possible.

At 2400#, he's done a lot of dieting already.

Bill Verburg

As the weight goes up so goes the thermal load on the brakes

an adjustable bias valve in and of itself is not going to help w/ stock SC brakes, the adjustable feature can be very helpful when there is too much rear bias, Stock SC brakes do not have too much rear bias. 3.2 Carrera brakes do in some situations. One situation is when the brakes become locked, you want the fronts to lock at the same time or before the rears, to delay rear lock an adj. p/v is handy. The other thing that helps is to avoid lock up, the bigger the m/c the harder it will be to lock the brakes.

There are many brands of b/f available, it's best to go by is wet boiling point, Castrol SRF is the best here followed in order by EBC, Torque RT700, Mu G4-335, Endless RF650, Motul RBF600

Boxster brakes on 3.2 Carrera rotors only add to the front heat load.

It's true that the tires are the limiting factor in stopping distance but that isn't the issue that most want to address in a brake improvement project, thermal performance is.
cooling
light weight
high temp fluid & pads
limiting brake application
all do address the pertinent issue

It really takes some getting used to but the high effort brakes from an over-sized m/c really does cut down on the amount of braking done just because it is so hard to generate high line pressures.

f4 plt

I have always been a fan of larger master cylinders as increased brake effort increases brake feel and you are less likely to over brake.

High temp fluid, changed often to prevent the build up of moisture is also sound advice.

My brake bias valve is to match front and rear at lock up as you stated, I don't want the rears to lock first

As I stated my plan is better brake cooling, higher efficiency rotors, I already run Pagid pads and my search and research continue for better calipers not necessarily Boxster calipers. I need to do more study on the benefits pluses and minuses of the standard brake booster with a larger master cylinder vs a dual non boosted master cylinder set up. Comments !

The track I run on normally and has several corners that require aggressive braking that combined with the fact 11 turns in but 2 miles leaves little time for brake cooling. Plus I just like to know I have plenty of brakes ( bottom line however using brakes bleeds off speed which must be regained, old fighter pilot energy management theory)

I appreciate all the comments as nobody has all the right answers but gaining from others hopefully eliminates each of us having to recreate the same wheel.