Brake upgrade.

[jeffw]

Aren't the B5 & B7 discs different sizes ? If they are how are you using the B7 caliper on a B5 disc ???

[Jarv]

These threads have ended up in the same place, lol. Yes Jeff, the B7 discs are larger so if you use the brembo 8 pots on B5 discs there will be a small amount of the pad area off the edge of the disc. Not my cup of tea, but by all accounts, it works.

[jeffw]

Ummm....not sure I'd run it like that....the disc rotor isn't designed to work with the much bigger caliper and I would imagine that heavy use would shag the B5 discs very quickly. Temporary measure only I think.

[MarkB]

Ummm....not sure I'd run it like that....the disc rotor isn't designed to work with the much bigger caliper and I would imagine that heavy use would shag the B5 discs very quickly. Temporary measure only I think.

Nige_RS4 ran this setup for quite some time and said it was a good way forward.

[jeffw]

Each to their own.

[quattrokid1]

so how do these compare to Porsche 996 brakes then?

My pal has just got a front and rear caliper set for his B5 RS4
He is of the opinion that the RS6 set up cant discipate the heat quick enough from its 8 piston/ 8 pads compared to the Porsches 2 pot 2 pad caliper!!

Just wondered since I havent seen anyone take this route before.

[Andiroo]

He is of the opinion that the RS6 set up cant discipate the heat quick enough from its 8 piston/ 8 pads compared to the Porsches 2 pot 2 pad caliper!!

That's always been my concern mate, other guys will say different and could be right, but the physics of the whole scenario of 4 pistons/4pads per side never quite washed IMHO, especially for road/track use. I always have and always will be a friend of the Brembos that have been 'Porsched', plus the PF001 pads that fit the GT3 calipers are the bollox compared to 'any' of the Pagids by my experience .... Worth the ball ache to get them to fit IMHO

Cheers,

Andiroo

[dace]

so how do these compare to Porsche 996 brakes then?

My pal has just got a front and rear caliper set for his B5 RS4
He is of the opinion that the RS6 set up cant discipate the heat quick enough from its 8 piston/ 8 pads compared to the Porsches 2 pot 2 pad caliper!!

Just wondered since I havent seen anyone take this route before.

I have the 8 pot Brembo's on mine and they are superb for both track and road. I have done several track days and 3 Vmax events and they have never faded once.

Pads last around 10,000 miles with the aforementioned in mind!

[jeffw]

The thing to remember regarding Porsche brakes is that they are designed to work on a Porsche. The 911 has a large mass over the rear wheels (the engine) which allows the car to run much larger brakes on the back and have a very different braking bias front to back. The 996 runs something like 60/40 front to back bias where as most front engined cars would run 85/15 or 90/10.

All of this adds up to the fact that the 911 has 4 large brakes which have a pretty balanced braking effort. A RS4/S4 B5 needs hugh front brakes to do 90% of the braking.

If you look at the brakes Porsche designed for the nearest equivalent (mass distribution wise) car in their range (the Cayenne) you'll see what I mean. This design issue is also why the 911 can afford to run cross-drilled brakes and why none of the performance upgrades to brakes for the B5 chassis supply cross-drilled rotors but use slotted rotors. Cross-drilled for show and slotted for go (or stop !) is an expression you will hear if you ask brake designers the question, just take a look at the brakes on every front engined racing GT car that has a similar mass to the B5 and you will find slotted discs.

As to heat dissipation, this is a product of the surface area of the rotor (bigger rotors are better), the area of the caliper, design of the rotor veins (if any) and how air is circulated to the brake system. A 2-pot Porsche caliper is unlikely to dissipate heat quicker than a 8-Pot Brembo caliper.

[jimbo1234567]

i wonder if this disc and caliper combo would be of any use on a b5 looks like theyre 8 pots? http://cgi.ebay.co.uk/Audi-A8-Calipers- ... dZViewItem

[dace]

The thing to remember regarding Porsche brakes is that they are designed to work on a Porsche. The 911 has a large mass over the rear wheels (the engine) which allows the car to run much larger brakes on the back and have a very different braking bias front to back. The 996 runs something like 60/40 front to back bias where as most front engined cars would run 85/15 or 90/10.

All of this adds up to the fact that the 911 has 4 large brakes which have a pretty balanced braking effort. A RS4/S4 B5 needs hugh front brakes to do 90% of the braking.

If you look at the brakes Porsche designed for the nearest equivalent (mass distribution wise) car in their range (the Cayenne) you'll see what I mean. This design issue is also why the 911 can afford to run cross-drilled brakes and why none of the performance upgrades to brakes for the B5 chassis supply cross-drilled rotors but use slotted rotors. Cross-drilled for show and slotted for go (or stop !) is an expression you will hear if you ask brake designers the question, just take a look at the brakes on every front engined racing GT car that has a similar mass to the B5 and you will find slotted discs.

As to heat dissipation, this is a product of the surface area of the rotor (bigger rotors are better), the area of the caliper, design of the rotor veins (if any) and how air is circulated to the brake system. A 2-pot Porsche caliper is unlikely to dissipate heat quicker than a 8-Pot Brembo caliper.

Good point well made Jeff.

[simoncotton]

i'm running 380mm 4 pot movit brakes which i must say are amazing. basically there a brembo system, even though there expensive, i think there worth it in terms of performance

[jeffw]

The important point there is 380mm which is what makes the difference.

[tdiquattro]

Do 380mm brakes fit under 18" wheels?

[Corey]

Depends on the inner shape of the wheel, we have used 365 diameter discs within a 17" wheel before.