Brake warp

[bsooley]

I installed new brake rotors and pads a couple of months ago. At first, the braking was quite good. However, over the last week I have noticed vibration in the brake pedal and steering wheel. I expect this is brake rotor warp, but have no idea what can cause such a problem. The car has not been used very often, nor has it been to any track events or been used in a manner that would require hard braking. Any help would be appreciated.

Thanks
Blair

[bsooley]

As a futher note, the pulsation is the greatest when I apply the brakes lightly at above 60kph, but seems to pretty much disappear if I hit the brakes hard.

[Bill Verburg]

try cleaning the rotors w/ scotchbrite pads or garnet paper.

You may have an uneven deposition of pad material.

[gizmofixer]

Always be sure to torque your lugnuts in a crisscross pattern when reinstalling wheels.
Uneven torqueing can and will cause rotors to go out of true.
A safe torque is 100 ft/lbs

[Tobra]

Originally Posted by gizmofixer

Always be sure to torque your lugnuts in a crisscross pattern when reinstalling wheels.
Uneven torqueing can and will cause rotors to go out of true.
A safe torque is 100 ft/lbs

what he said. I have had rotors get turned several times and still be good enough to use as they were still true.

[Britwrench]

Both 964 and 993 models can have warped hubs, so even if the disc is true, the hub will cause the vibration. Wheel torque is 130NM and with 17" wheels the wheels (ok, tires) have to be off the ground.

[meares]

i want to get new rotors....crossdrilled.....i think porsche rotors are superior to others because the holes are actually cast into the rotor instead of drilled...is this correct? should i get drilled rotors for the rears as well?

[Bill Verburg]

Originally Posted by meares

i want to get new rotors....crossdrilled.....i think porsche rotors are superior to others because the holes are actually cast into the rotor instead of drilled...is this correct? should i get drilled rotors for the rears as well?

Depends on the car.

The only n/a 964 w/ factory holey rotors is the 964RS. Any other n/a 964 only has the solid/vented disks oem. All other sourced rotrs will be drilled after the fact, do stay away from them.

For a 993 there are several holey rotor sources. The best is the Porsche distribution channel oems, There are also Zimmermans available but they don't have the factory corrosion paint on the hubs.

Another alternative is Brembo 2 piece rotors, but you would have to but a hat and associated hardware to mount them, but this is another excellent choice.

Most racers are trying to stay away from holey rotors because of the cracking issue, CDoc now has some very nice slotted rotors available for 93RS and 993tt. I don't know if they have the smaller versions available.

[meares]

will the 993s fit the 964s? stock 92 C2 cab

[Bill Verburg]

Originally Posted by meares

will the 993s fit the 964s? stock 92 C2 cab

nope