rattle under braking

schumicat · 09-11-2011, 01:39 PM

Hi guys. Car is an 82 SC. PO had brakes overhauled by reputable Porsche shop couple thousand miles ago (front/rear - new pads, rotors, brake lines, rebuilt calipers). This summer, car was on stands for 2 months to replace clutch & trans. Car is now fixed and running, driving and braking great. However, I am noticing a slight rattle under braking. I can feel it pulsing the brake pedal very slightly with the rattle. It is not loud; can only hear it with windows down, low rpm and radio off. It almost sounds like while brakes are applied that something is dragging under the car or hitting the rotor backing plates. The rattle only happens under braking, even at walking speed. I pulled off the wheels and did not see any broken spring clips or missing pins and there is lots of pad life left. I'm thinking of removing and reinstalling pads just to make sure all is together correctly. Any suggestions on what this could be appreciated.

na2ub · 10-10-2011, 05:39 AM

Rattle is likely your dust shields. Pulsing the break pedal is likely unrelated, and is due to warped rotors.

schumicat · 10-10-2011, 06:28 AM

thanks for reply. it doesn't seem like warped rotors. pedal doesn't pulse; I can just kind of feel a slight click in the pedal corresponding to the rattle. like if someone were gently tapping the pedal with a screwdriver handle. I removed and inspected 3/4 brake pads on Sat. (ran out of time to do the 4th) and all the pads, clips, pins looked fine. I also noticed the rattle only starts after a few stops from cold start so it seems to be heat related. if it weren't for that I'd think it were in the pedal cluster. I will look at the last wheel and the dust shield. I may just cut them off; I've removed them on other cars with no ill effects.

na2ub · 10-10-2011, 07:00 AM

Maybe try rotating the wheels by hand, on jack stands, to see if you can narrow down the noise.

E Sully · E Sully's Garage

Have you looked at the parking brakes.

schumicat · 10-17-2011, 11:38 AM

Ed, I checked the parking brakes on Saturday. The springs etc. looked ok but on the passenger side there was no pad material on about half of the upper pad. It looked like it had broken off. I didn't see anything loose in there that could be rattling (which remained after I put everything back together). On the chance that it may be the pad w/ the missing material, I ordered new parking brake pads. Will post update after I get them installed.

Joe Bob · Joe Bob's Garage

Pulsing thru the pedal means hi/lo on the discs or clots of pad material on the the discs. Maybe the "guys" took it for a Mad Ferris Buhler around the Lake.....

schumicat · 10-17-2011, 12:24 PM

it isn't pulsing and it isn't warped rotors, and I did the work myself. I shouldn't have used the word "pulsing" in the OP. it is more like you can feel the rattle (which is not cyclical like warped rotors) in the pedal like someone tapped the pedal with a screwdriver handle.

Quote:

Originally Posted by Joe Bob

Pulsing thru the pedal means hi/lo on the discs or clots of pad material on the the discs. Maybe the "guys" took it for a Mad Ferris Buhler around the Lake.....