os993

On 993's, the front brake calipers are mounted closer to the front of the car. Newer 911's (including GT3, Carrera GT, 996.. plus many other performance cars) have the front calipers mounted on the other side of the rotors (closer to door). Did I explain this clearly?

Anyways, which setup is better? To me, common sense dictates that our setup is better (grabbing the front of the rotors vs. grabbing the rear of the rotors), but looks like Porsche thought otherwise.

Just plainly curious.. TIA

Steve Weiner-Rennsport Systems

Hi Oleg:

The 996, Boxster, Twin-Turbo and GT-3 cars and have a different steering setup than the 993 and earlier cars.

These cars all have the steering rack & tie rods mounted ahead of the front axle which forced the brake calipers to be mounted behind the axle on the uprights/hubs. The earlier cars (993-964-911) have the steering rack mounted behind the suspension and so the calipers MUST sit ahead of the axle centerline.

Hope this helps,

Franklin229

Steve-excuse me if this sounds ridiculous ...but... Is there is anyway to mount the calipers at the bottom of the rotors? This would put the weight of all four calipers as low to the ground as possible.

os993

Hi Steve, thanks very much for your explanation - very interesting.

So, at the end of the day which setup is better, or is there no difference?

TIA

Flying Finn

I'd say in Porsche it is better (at least in theory) to mount them forward since it puts more weight towards front which is lighter as we know.

JeffES

"Front" or "back" of the wheel center makes no difference - as Steve says, it's packaging. Some open wheeled racers use low mounted calipers, but as a buddy of mine who used to work with TWR told me that they'd get beat up on anything but a perfectly clean, smooth track (no good for street use). You don't want the caliper at the top - as the wheel moves up & down you'd get a good deal of unsprung weight shift (that's not a good thing).
Hope this helps,
J

Steve Weiner-Rennsport Systems

Jeff is right,.......makes no difference, operationally speaking. Its all about packaging the various components that must attach to the hub carriers.

That said, one gains a bit better CG when mounting brake calipers near the bottom as many race cars are, but effectively bleeding brake calipers when they are mounted like that is very tough.

os993

Very interesting and very helpful - thank you!

And I always thought the caliper placement was precisely calculated based on best performance - funny what the real reason is, and that it doesn't really matter if it's for-or-aft the wheel hub.

JeffES

Steve,
Very tough??? It's damn near impossible!!! :-)
Gawd how I love open wheel cars..... but they don't love me!
J