322mm front brakes
05-22-2007, 09:48 AM
#16
Rennlist Member
Originally Posted by Blu RS
Gents. May I offer another solution? I run 332mm front rotors, yes that's 332mm, complete with Big Reds on a 17" Cup wheel, and clearance is very, very tight, but it fits. I continue to carry my stock 964 collapsable spare. I also purchased and carry with my tool kit a 1" (one inch) bolt-on spacer along with requisite five additional steel lug nuts. The spacer came from Performance Products years ago, but there should be numerous vendors offering this particular item. With the spacer mounted, the stock collapsable spare mounts and runs in the front wheel well just fine without any obstruction. Note that you will not need to run the spacer in the rear when you get a flat, only in the front.
05-24-2007, 04:41 AM
#17
Instructor
The original rationale was that if 322mm was good, then wouldn't 332mm be better? Would not the additional diameter provide slightly better braking with the same amount of effort from the master cylinder? Years ago, I decided to become a guinea pig for a 332mm "system" to find out. Although I'm still running that old 332mm "system", nonetheless it's now obsolete and no longer manufactured. A couple of my photos of the early system can be found in Bruce Anderson's 911 Performance Handbook Volume II, although I don't have the page numbers handy at the moment. In it's time, it was clearly an impressive brake package, and likely was the largest rotor that had appeared on a contemporary street car up until that point. That was pretty cool. Nowadays though, 332mm is a dwarf compared to the massive 355mm and 380mm+ racing rotors that are out there.
Getting back to your point, the caliper casting works with a 332mm rotor but not without modification to the pads. Unfortunately, the pads must be custom trimmed of pad material both top and bottom, and the bottom of the backing plate has to be trimmed back to clear the aluminum carrrier "hat". Nonetheless, the brake system works well, if not too well. Evidently it is possible to have too much front brake, and a 332mm front rotor does make it rather difficult to find a solution for the rear brakes that provides adequate front to rear brake balance. Heat dissipation is not a problem. Heat dissipation was addressed by removing the front brake splash shield plates, otherwise the additional mass provided for additional heat absorbsion, if not dissipation.
Conclusion. The modest additional rotor diameter certainly provides additional leverage, which in theory and practice means slightly more efficient braking with the same brake master cylinder. The project has drawbacks. Custom pads are one, and a major PITA . Secondly, I fault the the front brakes for being too good, so I've spent some effort to improve the rear brake balance to match the front. Those techniques include the use of the CUP rear brake bias line, more aggressive pad compounds in the rear brakes, upgrading the mastercylinder to 993 specification, etc. It's better now, the car brakes well, yet it's not perfect, so there's still some more to play with!
Getting back to your point, the caliper casting works with a 332mm rotor but not without modification to the pads. Unfortunately, the pads must be custom trimmed of pad material both top and bottom, and the bottom of the backing plate has to be trimmed back to clear the aluminum carrrier "hat". Nonetheless, the brake system works well, if not too well. Evidently it is possible to have too much front brake, and a 332mm front rotor does make it rather difficult to find a solution for the rear brakes that provides adequate front to rear brake balance. Heat dissipation is not a problem. Heat dissipation was addressed by removing the front brake splash shield plates, otherwise the additional mass provided for additional heat absorbsion, if not dissipation.
Conclusion. The modest additional rotor diameter certainly provides additional leverage, which in theory and practice means slightly more efficient braking with the same brake master cylinder. The project has drawbacks. Custom pads are one, and a major PITA . Secondly, I fault the the front brakes for being too good, so I've spent some effort to improve the rear brake balance to match the front. Those techniques include the use of the CUP rear brake bias line, more aggressive pad compounds in the rear brakes, upgrading the mastercylinder to 993 specification, etc. It's better now, the car brakes well, yet it's not perfect, so there's still some more to play with!
05-24-2007, 10:01 AM
#18
Rennlist Member
Originally Posted by Blu RS
The original rationale was that if 322mm was good, then wouldn't 332mm be better? Would not the additional diameter provide slightly better braking with the same amount of effort from the master cylinder? Years ago, I decided to become a guinea pig for a 332mm "system" to find out. Although I'm still running that old 332mm "system", nonetheless it's now obsolete and no longer manufactured. A couple of my photos of the early system can be found in Bruce Anderson's 911 Performance Handbook Volume II, although I don't have the page numbers handy at the moment. In it's time, it was clearly an impressive brake package, and likely was the largest rotor that had appeared on a contemporary street car up until that point. That was pretty cool. Nowadays though, 332mm is a dwarf compared to the massive 355mm and 380mm+ racing rotors that are out there.
Getting back to your point, the caliper casting works with a 332mm rotor but not without modification to the pads. Unfortunately, the pads must be custom trimmed of pad material both top and bottom, and the bottom of the backing plate has to be trimmed back to clear the aluminum carrrier "hat". Nonetheless, the brake system works well, if not too well. Evidently it is possible to have too much front brake, and a 332mm front rotor does make it rather difficult to find a solution for the rear brakes that provides adequate front to rear brake balance. Heat dissipation is not a problem. Heat dissipation was addressed by removing the front brake splash shield plates, otherwise the additional mass provided for additional heat absorbsion, if not dissipation.
Conclusion. The modest additional rotor diameter certainly provides additional leverage, which in theory and practice means slightly more efficient braking with the same brake master cylinder. The project has drawbacks. Custom pads are one, and a major PITA . Secondly, I fault the the front brakes for being too good, so I've spent some effort to improve the rear brake balance to match the front. Those techniques include the use of the CUP rear brake bias line, more aggressive pad compounds in the rear brakes, upgrading the mastercylinder to 993 specification, etc. It's better now, the car brakes well, yet it's not perfect, so there's still some more to play with!
Getting back to your point, the caliper casting works with a 332mm rotor but not without modification to the pads. Unfortunately, the pads must be custom trimmed of pad material both top and bottom, and the bottom of the backing plate has to be trimmed back to clear the aluminum carrrier "hat". Nonetheless, the brake system works well, if not too well. Evidently it is possible to have too much front brake, and a 332mm front rotor does make it rather difficult to find a solution for the rear brakes that provides adequate front to rear brake balance. Heat dissipation is not a problem. Heat dissipation was addressed by removing the front brake splash shield plates, otherwise the additional mass provided for additional heat absorbsion, if not dissipation.
Conclusion. The modest additional rotor diameter certainly provides additional leverage, which in theory and practice means slightly more efficient braking with the same brake master cylinder. The project has drawbacks. Custom pads are one, and a major PITA . Secondly, I fault the the front brakes for being too good, so I've spent some effort to improve the rear brake balance to match the front. Those techniques include the use of the CUP rear brake bias line, more aggressive pad compounds in the rear brakes, upgrading the mastercylinder to 993 specification, etc. It's better now, the car brakes well, yet it's not perfect, so there's still some more to play with!
I see. I was thinking the cons might outweigh or equal the pros. I will look up the info in Anderson's book. I guess the new craze now is fitting the new Cayenne Turbo front brakes to 911's. Makes the big reds appear puny.
Thanks for sharing the info.
05-24-2007, 11:53 AM
#20
Rennlist Member
Originally Posted by Slantnose!
...Cayenne Turbo brakes, huh?
That's amazing.
That's amazing.
Should be interesting to see one in action.
