Planet 9

stiles_s · #1 03-07-2009, 10:42 AM

i'm tracking down a noise in my '08 987s. it's a metallic squeak that happens at lower speeds and is relative to wheel speed (not engine speed). Applying the brakes effects the noise a bit, but the thing that really triggers it is parking brake application @ speed. Why would parking brake application feel so different from normal brake?

Question: how does our parking brake work? Two most common types:
a) applies pressure to the normal rear brakes, or
b) operates on a drum brake inside the rear hub

Anybody know? For some reason I thought it was "b".

FWIW, I leaned on the parking brakes a bit at around 50-60mph to try to burn off whatever rust might have been there. Seems to have a) made them really hot

and b) quieted the noise down.

Thx!

The Youngn · #2 03-07-2009, 11:06 AM

It the drum brake inside the hub option

stiles_s · #3 03-07-2009, 11:12 AM

Originally Posted by The Youngn

It the drum brake inside the hub option

Thanks, I found this too: http://www.planetporsche.net/cayman-...ir-photos.html

This is just an FYI for folks who are getting the "my brakes make noise after I washed & parked my car" issue, and it doesn't go away by applying your brakes. Somehow I got some moisture into the parking brakes, and they got pretty noisy. We'll see if my sledgehammer "fix" worked (heating them up at "speed").

Scott.

beez · #4 03-07-2009, 11:44 AM

Originally Posted by stiles_s

Thanks, I found this too: http://www.planetporsche.net/cayman-...ir-photos.html

This is just an FYI for folks who are getting the "my brakes make noise after I washed & parked my car" issue, and it doesn't go away by applying your brakes. Somehow I got some moisture into the parking brakes, and they got pretty noisy. We'll see if my sledgehammer "fix" worked (heating them up at "speed").

Scott.

I would be very careful when doing this - these little brake shoes are only made for holding the car in a parked state, and not at all designed to be applied while the car is moving. They're not very big, nor are the linings on them very robust, so while that might help quiet them down, it will most certainly shorten their life - maybe considerably. I doubt it's the source of the noise anyway - when not applied, the shoes are far enough away from the "drum" that you would need one hell of a layer of rust on them to make contact.

Look to see if you have a small rock or something else stuck in there between the brake rotor and the shielding.

brad

stiles_s · #5 03-07-2009, 12:10 PM

Originally Posted by beez

I would be very careful when doing this - these little brake shoes are only made for holding the car in a parked state, and not at all designed to be applied while the car is moving. They're not very big, nor are the linings on them very robust, so while that might help quiet them down, it will most certainly shorten their life - maybe considerably. I doubt it's the source of the noise anyway - when not applied, the shoes are far enough away from the "drum" that you would need one hell of a layer of rust on them to make contact.

Look to see if you have a small rock or something else stuck in there between the brake rotor and the shielding.

brad

What, you mean they're not engineered for e-brake turns during rally tarmac stages? I'd better stop that

Thanks for the rock tip. I jacked up the car last night and couldn't repro with the wheel off, nor could I see anything stuck in the shielding. Nor was there anything obviously wrong w/my wheel bearing...