Brake bind/squeak on pull-away...?
Discussion
I have noticed a small recurring binding noise/squeak when I pull away. When the car has had a chance to warm up and I then pull away slowly standstill it makes the noise.
I am assuming it is a very slight brake bind from one of the rears - is this normal / common???
(Car is 89 Carrera 3.2 btw)
What do you guys think?
I am assuming it is a very slight brake bind from one of the rears - is this normal / common???
(Car is 89 Carrera 3.2 btw)
What do you guys think?
Sticky piston in one of your calipers?
After 15 years it wouldn't be too surprising, especially with the amount of salt on the roads at the moment exacerbating the situation probably.
Try touching the wheels (not disks!) after a couple of miles from cold. Does one wheel feel noticeably warmer than the other 3?
VS
After 15 years it wouldn't be too surprising, especially with the amount of salt on the roads at the moment exacerbating the situation probably.
Try touching the wheels (not disks!) after a couple of miles from cold. Does one wheel feel noticeably warmer than the other 3?
VS
verysideways said:
Sticky piston in one of your calipers?
After 15 years it wouldn't be too surprising, especially with the amount of salt on the roads at the moment exacerbating the situation probably.
Try touching the wheels (not disks!) after a couple of miles from cold. Does one wheel feel noticeably warmer than the other 3?
VS
I'll give it a go - would there be any noticeable pulling from a steering/performance point of view if this were the problem?
I think they all suffer from that, at least to a certain extent. If it's nothing more than irritating, then I think it's par for the course. Bear in mind that it could be a sign of the pads nearing life end.
Don't trust the indicator light to tell you that the pads are worn unless you know that the sensors have been installed. You don't get the sensors with the pads unless you ask for them. You have to glue them in yourself.
Opinions will enevitably vary, but one of the causes of the minor squeak is the alloy calipers and steel shoes. They have different co-efficients of expansion, and combined the two materials will have some tendancy to corrode.
My theory is that you stomp on the brakes, the shoes have no choice but to grab the disks. The generated heat causes the alloy calipers to expand faster than the pads. As the caliper assembly cools, it grips the pads tighter, in conjunction with the oxide, and there is less of a tendancy for the pads to fall away from the disks as they should.
The pads themselves have several features to help stick the pistons to them. The better this works, the less squeak.
It's also worth bearing in mind that the rear disks have a static backing plate to stop muck getting onto the discs. The backing plate hasa small lip on it so that it encloses part of the periphery of the disk. I have had the odd small stone get between the disk and the backing plate before. Because of the lip the small stones don't fall out on their own.
Don't trust the indicator light to tell you that the pads are worn unless you know that the sensors have been installed. You don't get the sensors with the pads unless you ask for them. You have to glue them in yourself.
Opinions will enevitably vary, but one of the causes of the minor squeak is the alloy calipers and steel shoes. They have different co-efficients of expansion, and combined the two materials will have some tendancy to corrode.
My theory is that you stomp on the brakes, the shoes have no choice but to grab the disks. The generated heat causes the alloy calipers to expand faster than the pads. As the caliper assembly cools, it grips the pads tighter, in conjunction with the oxide, and there is less of a tendancy for the pads to fall away from the disks as they should.
The pads themselves have several features to help stick the pistons to them. The better this works, the less squeak.
It's also worth bearing in mind that the rear disks have a static backing plate to stop muck getting onto the discs. The backing plate hasa small lip on it so that it encloses part of the periphery of the disk. I have had the odd small stone get between the disk and the backing plate before. Because of the lip the small stones don't fall out on their own.
dilbert said:
I think they all suffer from that, at least to a certain extent. If it's nothing more than irritating, then I think it's par for the course.
Thanks Dilbert, it is more of an irritant than a major issue. I really wanted reassurance that it is a common known problem, ie I dont need to rush it to the expensive Porsche doctor for a checkup...
I'll live with it for a bit and get it checked next time she gets serviced. Its not gettting any worse and isnt causing any strange handling / driving issues so fingers crossed its just another 'characteristic'...
Dom
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