BC

Will these fit?

http://cgi.ebay.com/ebaymotors/ws/eB...943945521&rd=1

Steve J.

The mounting holes for the rears look the same as the fronts in the photos. They are different for the 928. The 928 rears have mounting bolts parallel to the axle, front mounting bolts are perpendicular to the axle (like the ones in the photos).

BC

I didn't even see the mounting holes. Let me look again. Hmmm.

MBMB

So these might make two sets of front brakes?

Ketchmi

The piston diameter of the rears would preclude them from being used on the front even if they did mount properly.

Dave

Fastest928

they will not fit with significant mods.

Marc

Shane

What kind of Big Brake packages do you have at Devek Marc? Something front and rear vs just putting GTS ones on the front.

blau928

I know that someone has already made a bracket for these type calipers on a 928.. I have a set of the ones pictured below, and want to ask them if they could save me from re-inventing the wheel of making a new bracket...

Will these stop a train...?

Caliper Family No. CP5555

Recommended Pad: CP3894D54
Applications: Road
Features: Two piece aluminium alloy body, differential bores, aluminium alloy pistons with dirt seals, radial mounted & black paint surface.
Bleed Screw Tightening Torque.
17Nm (12.5lbs/ft).
Standard Catalogue Caliper.
Technical Info: Caliper No. CP5555-802S4 (RHT) Hydraulic Threads M10 x 1.0mm
Piston Diameters 27mm x 2 / 31.8mm x 2 / 38.1mm x 2 Mounting Centres 152mm
Piston Area 50.1cm² Offset 55mm
Disc Dia. 362mm max / 355mm min Mounting Hole ø 12.1mm
Disc Thickness 35.6mm 'PL' Dimension 62.5mm
Weight 3.0Kg Seal Repair Kit No. CP4519-CEJ

Ketchmi

Hey Blau.....

If you want to get really crazy, we have some AP Racing CP6050 8 piston calipers sitting in the display case. I think they will slow the earth's rotation slightly if used properly.

Dave

Normy

They can probably be made to fit, but they won't stop your car in much shorter a distance than stock single piston 928 brakes will. They WILL show far less fade on a race track however....the advantage of bigger brakes is better cooling.

N!

Ketchmi

And swept area Normy. When you put bigger stickier tires on the old single piston calipers will not have enough pressure to lock them up. Bigger brakes are more of an advantage than just cooling and fade resistance.

Dave

blau928

Thanks Dave....

I'll let you know... For now, I just need a bracket for the CP5555... As far as bigger stickier tires, already got those..

N,

See what Dave says... Lots more to braking than just size of Caliper piston....

Cheers,

jebdog

Some interesting comments from Brembo USA.."What about size? Is bigger always better? "Not necessarily," the company notes. "There are many factors to take into account when choosing a performance brake system. First and foremost, a brake system must be designed based on the vehicle parameters and the type of use it will experience. Brake systems are designed to operate best within a prescribed temperature range. While modern high-performance friction materials broaden this temperature range from relatively cold pad temperatures to the high temperatures experienced in performance driving situations, the use of a disc that is too large will limit disc temperatures to the extreme lower end of this range. Not only will the disc temperature not reach the optimum range, but [the disc] will also be heavier than necessary." ........ Brakes do NOT stop the car they resist the turning of the wheels. The tires then must attempt to slow the car. All energy which is inherint in a mass in motion is turned into heat most of which is absorbed and dissipated by the rotors until you exceed the available friction of the tire to the road surface and the wheels lockup. At which point the tires may as well be square blocks of rubber(which they will become) and the ability to control the direction of the skid is zero. Tires locked up have far less traction than those rolling and the rotor is no longer aborbing heat also why a smokey burnout under power is slower than tires rolling with the road at a power level which is just about to break them loose. Cars fitted with ABS will under severe braking hold the brakes very near the limit of the tires slightly exceeding then bleeding off sufficient brake pressure to get the tire turning again. For most the major "benefit" to big brakes is LOOKS ! If the brakes are able to lock up the tire then bigger brakes will not stop the car any faster. Most of which is moot for a street car where it is highly unlikely that you will ever use the brakes as hard as they are capable of being used . If you do be sure there is no one behind you !!

Normy

MY stock single piston calipers have no trouble at all stopping my car, and in fact I haven't been able to engage my ABS except on very wet sealed asphalt parking lots with lots of trying. In the past, I've had one or two panic stops in which my brakes made believers of me....

In 2002, I attended "Sharks In The Mountains", and got a chance to drive my 928 on the Blue Ridge Parkway. The constant acceleration then braking for the curve was exhilarating, but I quickly realized why Porsche put 4 piston calipers on the S4; My brakes started to fade immediately, and though I always had strong braking capability...I could tell that they were hot and bothered.

I have 300 treadwear tires on my car; I suspect that with my stock brakes and a set of Hoosier drag tires that my car would stop way shorter than a set of Big Red brakes and regular tires. Put the same tires on the car with the big red's and the differences would be statistically negligible.

-Heat both situations up on a mountain road and then this thread might make sense!

N!

Dennis K

If you want to go bigger than Big Red but don't want to design/machine brackets for the calipers, Brembo has kits for their 8-piston brakes to fit 993 twin turbos (which should fit 928S4's).

For $4.5k you can get their standard 8-pistons with 355 mm rotors:



And for $13k you can get their racing 8-piston calipers w/ 380 mm rotors:

(pics taken from fvdusa.com website)

Braking costs money. How fast do you want to stop?