brakes - BMW Forum

6-speed · 01-08-2004, 02:07 PM

Hello!
I just joined the forum.
I hope you guys might know what to do about the brake vibration problem. The front rotors on my 540i warp very quickly. I had the dealer fix it and now I'm on my third set of rotors in 2 months. They were good about replacing it but I think there is another problem somewhere that's causing the rotors to warp so quickly. Does anyone have any ideas, like bad ball bearings? Please help. Thanks.

ghead

Mach 5 · 01-08-2004, 02:30 PM

The only thing that comes to mind is incorrectly torqued lug studs. This has been known to warp rotors. Are the calipers in good shape? If they are dragging they could cause too much heat to build up in the rotor and possibly warp them.
Ben

bruceatlam · 01-08-2004, 02:30 PM

I would start right now by pulling the front wheels and checking the run out of each rotor to see if it's out of spec. I don't know the spec is but anything over 0.005 inch is high in my mind. Did the dealer tell you what it was on your last set?

Are they putting on new rotors or are they turning the existing rotors?

Next time they put on new rotors, the first thing that I would do is check the run out of each when they're new. That'll give you a "Baseline" when they're new.

6-speed · 01-08-2004, 02:39 PM

Thanks for replying. The dealer had told me that there was some rust between the new rotors and where it attaches to on the car. I didn't really believe them but since they fixed it under warranty, I said ok.
They are replacing the rotors with new ones. I'm pretty sure because I have seen turned rotos and these rotors did not look turned.
I also am going to assume the calipers are in good shape because the car only has about 28000 miles on it. I also don't hear any noises except what sounds like wind noise from the right rear view mirror when the window is rolled down a little.
I'm sorry but I don't know what run is on a rotor. Thanks.

CBA · 01-08-2004, 05:58 PM

the run out could not possibly be bad every time they changed them..

have them inspect your calipers if that turns out fine then maybe you got a heavy foot..

6-speed · 01-12-2004, 02:49 PM

Thanks. I'll have them look at the calipers next time I take the car in.

TECH · 01-13-2004, 11:51 PM

Do you frequently get the brakes hot, and drive through water?

6-speed · 01-14-2004, 01:26 PM

no, I'm a fairly calm driver, especially since there are cops everywhere on the highway.

CBA · 01-14-2004, 02:49 PM

heating them up wont really put a noticable rounding in the rotor.. it would just completly glaze the shit outta the pads..

chuck540owner · 01-15-2004, 05:55 PM

It is possable that your tires are at fault. I had a car that ruined rotors every 5000 miles until I finally wore out the tires and replaced them. I couldn't believe it but no more pulsing brake pedal. In my case the problem started when I bought a set of cheap tires but any tire can be defective.

6-speed · 01-19-2004, 01:44 PM

Didn't you feel a vibration in your steering with those bad tires even when you were not braking?

chuck540owner · 01-19-2004, 02:13 PM

No, only during braking. The pedal and steering wheel would pulsate.
When I replaced the tires the rotars were going bad again but amazingly they trued themselves and I had no further problems.
There is a difference between warping rotor and wearing unevenly. Warping would be the result of overheating. Do you live in the mountains? Long downhills? Wearing problems can be a bunch of different things.
My problem was uneven wear.
Don't go buy a set tires based on this. It's just food for thought.

6-speed · 01-19-2004, 03:39 PM

well, i had summer tires when the probelm first began and since then I have put on brand new dunlop snow tires and problem is still the same. Most of my drving is on flat interstate.

6-speed · 02-27-2004, 08:58 AM

So, I took the car in to the dealer. First they said I needed to replace all 4 rotors, even the ones they just fixed 2000 miles ago. They would also not warranty their own work from last visit. I had to ask them to check into it further and then they told me there was nothing wrong with the brakes or anything else. They said it's the aftermarket wheels and snow tires. Took it to the tire shop and they said there is nothing wrong with the wheels and tires. I'm out $100 for BMW diagnostic fee and the problem has not been resolved. ??????????????????????????????? and I thought the BMW dealers are supposed to know what they are doing.

EXtech · 02-27-2004, 05:49 PM

Improperly cleaned mating surfaces (rotor to hub), improperly cleaned mating surface of wheel (hub, rotor, back of wheel), improperly torqued lug studs or a malfunctioning caliper. And since it's not just one rotor warping and all calipers are not likely to fail at once, i would rule this out. Severely worn front suspension components can also contribute to the cause, but I wouldn't suspect that on a car as new as yours. Quite frankly, I've always been very supsect of the continental tires BMW puts on the cars. They are junk and their specs vary GREATLY from one tire to another. They have been known to lose their balance very quickly as well. Also, if you are driving a standard and whenever you let off the gas to come to a stop and don't allow the trans to slow you down also (by pushing in the clutch) that means you are souly relying on the brakes to stop the car and not engine/trans also. You take alot of strain off of the brake components by allowing the engine and gearing to slow you down also. Obviously this is most important coming down from high speeds and not puttin along in traffic. As you can see, many things can contribute to your problem.