sm

Hi -

On a few occassions lately, I've noticed a strange, acrid smell after coming to a stop. This might happen when the car is moving too, but I'm not positive.

Today, I saw a puff of smoke come out from my front passenger wheel well after a stop and it scared the **** out of me. These stops are typical stops and not hard at all. Also, when I touched my front wheels afterwards, they were pretty hot. The rear wheels were cool to the touch. The smell usually comes from the front wheel wells.

So could it be that after the long Boston winter, my brake caliper pistons are not retracting all the way?

Any advice is appreciated. Thanks.

SM

944Ecology

Could be sticking pistons, but could also be that the pad backing plates are binding in the caliper. The test is to retract the pistons (using a lever / screwdriver) and remove the pads. The pads should slide easily in and out of the caliper. If not, remove a bit of the backing plate on the leading or trailing edge until it does move easily. Don't remove too much material, or you will have a knock when applying the brakes in reverse, or the first time you apply the brakes after reversing direction.

gb

GlenL

Disc brakes _never_ retract. When you're not on the brakes the pads ae still gliding in contact with the rotor. (Unless something is bent or worn) So the disc brakes will be warm.

Then again, there should be no smoke or smell in normal use. I'd check the fluid level closely. Maybe there's a small leak. A stronger approach would be to pull the calipers and check it out. If the seal is leaking there will be fluid in the boot.

ttwitc9516

My guess is you have a leaking cam cover that invariably drops oil on the manifold just inside the wheel well. i just did my cam cover gasket for the very same symptoms. Stinks like ***. Not much of a job though. Unfortunately all the oil that runs out of the cam cover when you take it off drains right on the manifolds and takes several drives to burn off.

Zero10

Smoke out the wheel. Need a good description of how the smoke smelled. I've smelled burning brakes a few times (when I learned to auto-x I rode them like a granny), and they have a rather distinctive smell. That said, the location of the smoke does support it being your brakes.

Since you have 4-piston calipers on the front, I would start by inspecting the calipers. Remove them, and try to press each piston back into the caliper, and inspect for obvious leakage. If all 4 press in smoothly, and with reasonable effort, then I would say it is not the cause. Check both front calipers, to make sure they are both in similar condition.

As already said, the pistons don't retract on disc brakes, but they are pressed back slightly once you release the brakes. If one of the pistons is a bit sticky, it may take longer to be pressed back, which may cause overheating of the brakes, depending on how severe it is.

sm

Thanks guys for the help. I'll try to take a look at the calipers ASAP.

The smell is like a burning metallic type, with a hint of oil/grease.

I've also noticed a ridge on the front brake rotors, that I don't believe were there last fall. Sounds like sticky brakes to me. Funny thing is, I drove the car ~6.5 miles this morning and the wheels were cool to the touch afterwards.

On a side note, is there any performance difference between the 951 and non-M030 968 calipers? The 951 calipers have the "Porsche" molded in, whereas the 968 calipers are more boxy and have the "Porsche" stickers. I have a set of both and can't decide which to rebuild.