B job gone bad

[CanadianX5]

Had the X lowered / wheel spacers and brakes done today.
I was late getting there so the local shop hid my keys for me.
Anyway I hop in and start driving......... ........... probably the most horrible, embarrassing metal on metal sound I've ever heard.
So I pull over and take a closer look.
I noticed that he resurfaced/machined the front rotors.(sound is only coming from fronts.I also noticed that the back rotors have a small lip at each edge. Is it possible that OEM rotors can't be resurfaced? Does anyone here have any idea what he did wrong?

[JV]

Where did you have it serviced? Independent shop?

JV

[fln8tive]

Noise on braking only or all the time?

[X5Flyboy]

This is not a Canadian/American car - BMW designs the rotors to be replaced with the pads and are not designed to be refaced - they are too thin to safely machine down - check out the threads about brakes here - rotor replacement also requires the replacement of the brake sensor - pads (4 sets), rotors(4), and sensors(2) are required for a complete brake job - it also would not hurt to have brake fluid and lines checked out

[CanadianX5]

Independant shop, noise is all the time.
I'll let him know that they cant be resurfaced.
Will new front rotors fix the problem?
The back is fine from what I can tell.

[hayaku]

check your pads.. make sure you still have some pads.. make sure your mechanic actually has pads still in there and that the job is not still half way done...

when my pads wore out and i was dumb enough to think the sensors would work, the metal backing plate was scraping on the rotor making that noise of metal on metal all the time...

[jek889]

The sound could be the new pads wearing in. This is common when you change pads but keep old rotors. Have you tried bedding in the brakes, assuming they are otherwise functionintg correctly?

[CanadianX5]

I tried bedding them. The pads are in there, I can see them. The noise its making isn't break in noise. I put about 100km on since I picked it up to see if it would go away but its still just as loud. ( try to imagine small chunks of nails mixed in with the brake pad material ) I'am heading out of town tomorrow for a week so the mechanic has some time to fix it.

Some guy said to me at a stop light " Hey buddy , can you hear that? You might want to get that noise looked at"

My face went a little red but I said thanks.

[CanadianX5]

Had it fixed today. Took 5 mins. The dustguards behind the rotors were touching. I figure they got bent when he hammered of the rotors to resurface them.

[Teutonaddict]

Originally Posted by burkleymh

BMW designs the rotors to be replaced with the pads and are not designed to be refaced - they are too thin to safely machine down - check out the threads about brakes here - rotor replacement also requires the replacement of the brake sensor - pads (4 sets), rotors(4), and sensors(2) are required for a complete brake job

BMW may recommend that rotors and pads be changed simultaneously, but there is no valid design or performance reason to do so, IF the rotors or pads are not at the minimum spec thickness. The reasons they tell us to do them at the same time is to: (1) minimize 'come-back's (rework), and (2) maximize profit.

If you are a DIY brake person, then change rotors and pads when they fall below spec thickness. If your pads wear out at 2X the rate of your rotors (as a % of usable thickness), then you would be wasting hard-earned money to do them all at once. Now, if your pads and rotors are approaching the end of their useful life at the same rate, then replacing pads and rotors at the same time makes good sense.

Following this logic, then the brake wear sensor(s) only need replacing when pads are replaced, and not when rotors alone are replaced.

You are correct that turning the rotors on a lathe is NOT a good move. When they get below spec, replace 'em!

-Dave