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Car Forum / BMW Cars / February 2009Strange brake problem.
My brother has a 2001 330T which occasionally has a partially seized front brake caliper - the disc gets very hot. But on checking after fighting to remove the pads, the piston moves as normal as does the caliper on the slides. He's had BMWs for several years and does pretty well all his maintenance so is quite familiar with the brakes. But this is his first one with ABS. Could it be an ABS issue? Or any other likely causes? I sort of agree with him that calipers don't seize like this and sort themselves.  Signature*OK, who stopped payment on my reality check? Dave Plowman dave@davenoise.co.uk London SW To e-mail, change noise into sound. > My brother has a 2001 330T which occasionally has a partially seized front > brake caliper - the disc gets very hot. But on checking after fighting to [quoted text clipped - 3 lines] > one with ABS. Could it be an ABS issue? Or any other likely causes? I sort > of agree with him that calipers don't seize like this and sort themselves. Hi Dave. If by occasionally you mean within days, I'd suggest he tries pulling the ABS fuse to see if it still happens. Mike. > > My brother has a 2001 330T which occasionally has a partially seized > > front brake caliper - the disc gets very hot. But on checking after [quoted text clipped - 4 lines] > > likely causes? I sort of agree with him that calipers don't seize like > > this and sort themselves. > Hi Dave. If by occasionally you mean within days, I'd suggest he tries > pulling the ABS fuse to see if it still happens. Mike. Hi Mike - it's quite random. It can happen twice in a week with very little mileage and then not for a while with lots. I'll pass on that advice. Signature*Why is the word abbreviation so long? Dave Plowman dave@davenoise.co.uk London SW To e-mail, change noise into sound. > My brother has a 2001 330T which occasionally has a partially seized front > brake caliper - the disc gets very hot. But on checking after fighting to [quoted text clipped - 3 lines] > one with ABS. Could it be an ABS issue? Or any other likely causes? I sort > of agree with him that calipers don't seize like this and sort themselves. Maybe a bad flexible brake hose that's failed inside. The old E24/E28 did this a lot on the rear hoses for some reason. Maybe when you remove the caliper to move the piston you're flexing the hose and curing the problem. SignatureWho needs a life when you've got Unix? :-) Email: john@unixnerd.demon.co.uk, John G.Burns B.Eng, Bonny Scotland Web : http://www.unixnerd.demon.co.uk - The Ultimate BMW Homepage! Need Sun or HP Unix kit? http://www.unixnerd.demon.co.uk/unix.html www.Strathspey.co.uk - Quality Binoculars at a Sensible price > My brother has a 2001 330T which occasionally has a partially seized front > brake caliper - the disc gets very hot. But on checking after fighting to [quoted text clipped - 3 lines] > one with ABS. Could it be an ABS issue? Or any other likely causes? I sort > of agree with him that calipers don't seize like this and sort themselves. ABS affects what the brake fluid does, not what the hardware does. You have a sticking caliper, or some other issue with the hardware, you do not have a problem with the activity of the brake fluid. >> My brother has a 2001 330T which occasionally has a partially seized >> front [quoted text clipped - 10 lines] > have a sticking caliper, or some other issue with the hardware, you do not > have a problem with the activity of the brake fluid. Each is dependant upon the other, and either could cause the problem. Mike. >>> My brother has a 2001 330T which occasionally has a partially seized >>> front [quoted text clipped - 14 lines] > Each is dependant upon the other, and either could cause the problem. > Mike. If the ABS is actually activated due to a hard stop, then maybe it can cause the fluid pressure to remain high on one corner of the car. Maybe. But if the ABS is not actively being used -- very aggressive stops at the edge of brake lock -- then the system is passive (unused) and it will not hold pressure high in one place. Remember, the job of ABS is to release brake pressure to a corner to prevent brake lock, then build that pressure again instantly so that the wheel slows to the point of stopping, then release again. Repeat as needed. Given the fact that the duty of ABS is to release brake pressure, it does nothing unless brake pressure needs to be released. If the car is driven in a moderate manner and not on the edge of control, the ABS should never play a role in anything. The OP is complaining that the brakes do not release. ABS will not cause this. |
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