87 735i brakes

[bokun59]

I have a 735i w/ about 150k miles on it. I just had the new brakes installed on all four wheel and new rotors on the front; rotors on back turned. However, the rotors got warped after only a couple of thousand miles and i had the garage turned them all again (no charge). He seems to think that one of the wheels may be at fault in causing the rotors to warp. Is this possible- or is there another problem I should investigate? The wheels are about two years old ( I believe they are Borbet or BBs from Tirerack} and the tires are brand new Bridgestone Turanza. They were installed along with a 4-wheel alignment. Several months ago the local BMW shop re-did the front suspension components. The car handles very well and rides nicely. The shaking when I stop usually begins at high speeds (above 60-65 mph at first). After a while the shudder will start at 35 mph and above. Any ideas?
Thanks.

[Antiburn]

Well are you a person that pounds on the brakes alot or do you gradually slow down. You have to tell us the truth or we cant really help you on this. Do you beat on your 7 or are you a old man driver? We really dont care what you do with your car, we jsut need to know what you do with it first.

[bokun59]

slower driver. i try to come to a gradual stop. of course, there are times that a stomp is necesary, but generally i am careful. i used to try to downshift and use engine braking, but then i read that doing that with an automatic was not, generally, a good thing to do as it could wear out the trans. faster and brakes are cheaper to fix than trans.. that habit was born out of the days when i had a stick. but i live in an area that is hilly; with a lot of turns. also, the main exit i have to take off the interstate has a nasty u-turn coming off a steep decline. usually i slow down at least a half mile from the exit and try to coast through the turn, but it doesn't always work. one of the people at the garage related that some of their customers have noticed a decline in rotor problems after they stopped taking the aforementioned exit. does that make sense?

[Antiburn]

Usually warped rotors are caused by really hard extreme braking, unline anyone will ever experence. From wha you said it sounds like a fluke incodent. You know 1 in a Million kidna thing. You might possibly have to get new rear rotors. There might be some kinda defect with them causing them to warp and get mishapen. I seriously cant help you on this one because I have never heard or seen something like this before. Good luck with this one.

[bokun59]

thanks for replying. i will see what happens.

[jeffreyb4me]

Just a few thoughts on your brakes. Many of you 'newer' owners of BMW's are unaware of the problems BMW had with warping rotors in the early to mid '90's. IT effected E32's E34's & E36's and it took a few years [and probably $100,000's of BMW warranty money] to trace the problem to brake pad composition and finally correct the problem. Once in a while I've come across an E23 like yours with this problem but it's usually the fronts and I've found it to be either an 'aftermarket' wheel problem or a bent wheel hub as the pad problem didn't effect this chassis much.
You mention the rears having been 'turned' twice now!! Working on these cars for years has taught that if the rotors are worn enough to 'require' machining, REPLACE them or you will be anyway as the thinner they get, the quicker they'll warp due to the lost mass to dissipate heat quickly enough.
You didn't mention whether the steering wheel is shaking when you brake, more info might be helpful.

[bokun59]

thank you. yes, the steering wheel does shake quite a bit. Before the last rotor turn, it shook so badly I felt like I was losing control of the steering. i do have aftermarket wheels, and i am going to have them checked this week. The rear brakes squeal a bit when I put the car in reverse to back up. does that help at all? thanks.

[jeffreyb4me]

YES and I'l return in a bit...........

[jeffreyb4me]

The squel from the rear is the pads [many aftermarket brands do, try Pagid].
Fronts:
1] though quite beefy, have the hub run-out checked, new rotors helped but the brake shimmies returned.
2]you may need another set of front rotors....this will come last.
3]your aftermarket wheels may fit the bolt pattern but not be machined to center on the hub's flange and this is CRITICAL!!! A number of quality aftermarket mftr's supply thin centering adapters and while a CORRECT fitting wheel is best, these adapters minimize centering problems. The wheel bolts ONLY hold the wheel to the hub, they WILL NOT center the wheel which is why so many BMW's suffer from shimmy.
4]your shop has redone the suspension, be sure the steering links and idler arm bushings are tight.
5]carefully follow your shops 'bedding-in' instructions for the first 200 miles....very important for pad to rotor transfer and curing.

Hope this helps, stay in touch................................jeff b.

[kennyR]

Originally Posted by jeffreyb4me

Just a few thoughts on your brakes. Many of you 'newer' owners of BMW's are unaware of the problems BMW had with warping rotors in the early to mid '90's. IT effected E32's E34's & E36's and it took a few years [and probably $100,000's of BMW warranty money] to trace the problem to brake pad composition and finally correct the problem. Once in a while I've come across an E23 like yours with this problem but it's usually the fronts and I've found it to be either an 'aftermarket' wheel problem or a bent wheel hub as the pad problem didn't effect this chassis much.
You mention the rears having been 'turned' twice now!! Working on these cars for years has taught that if the rotors are worn enough to 'require' machining, REPLACE them or you will be anyway as the thinner they get, the quicker they'll warp due to the lost mass to dissipate heat quickly enough.
You didn't mention whether the steering wheel is shaking when you brake, more info might be helpful.

the rotors are thin enough!!!! MACHINING THEM IS NOT AN OPTION FOR ME i am hard on my 7 and i accelerate hard and brake hard i have all after market 15s never in my life would i machine them