330ci : Brake disc needs replacement after 10,000 km ?!

No. Any corrosion like this is simply rubbed off when you use the brakes.

It's I'd say near unique that the discs need changing at such a low mileage. 30-40,000 miles is more like it. Usually at the second pad change. The minimum thickness is stamped on the disc hub. Might be worth getting an independent expert to measure them if you can't do this yourself.

I've done about 15k on mine and they're getting towards needing replacement but that is over about 3 or four years. Possibly they're worn enough that they're suggesting that you might want to replace them while they have it instead of the "inconvenience" of takign it back in a year's time.

"Klaus T." wrote

Unless someone drove it really hard (brake hard) or took it to the track, it seems very strange that the discs would need replacing already. I have a

530i which is probably somewhat heavier than your 330ci, and I got new discs after 44k miles (5 years). They were still usable though, but the would not last through another set of pads, so I went ahead and got them done at that point.

Like others suggested, go to another shop for a second opinion or have the disc thickness measured.

You'll see little surface rust as quickly as an hour after you wash the car. That is not a reason to replace the discs. That's normal and will go away as soon as you apply brakes.

Pete

It sounds like they want to replace them because they are corroded. Not because they are worn, cracked, etc.

So, do you experience brake judder, any abnormal braking, etc? If not, I would personally leave them on there.

No. Depends how excessive it is. Overnight rust, OK, but this is not always the case. Even with left foot braking on a dual carriageway, if they are that badly corroded, replacement is the only way to overcome it. You'll also find the pads have worn funny too.

Just say NO. You'd have to live on top of a mountain to wear the brakes out in this mileage. Perhaps they could explain further why they feel the discs need replacing. Light surface corrosion does not accelerate disc wear.

"Ali" wrote

WTF???

You made it up, so why are you saying WTF???

In the interest of promoting harmony, understand that there is currently an outbreak of thread-hijacking spammers operating on Usenet, and one of them apparently hijacked 'Ali' in this thread. Not all news servers will propagate the hijacked thread - evidently Pete's did and yours didn't. Pete saw the hijacked thread and didn't know about the hijacking spammers, hence his "WTF." There's no reason to take anything personally over this.

"Not Me" wrote

Thanks for the explanation. I was wondering what was happening here, because I saw similar spam posted on other groups lately...

Pete

Ditto. Cheers, this is a new one for me.

So, who wore out the brakes, God or the devil?

I suggest that anybody that only gets 10k kilometers on a set of rotors would have to be riding the brakes 100% of the time the car is rolling, and this points to the devil.

...or a damaged anti-lock system.

ABS unlocks the brakes. A damaged ABS would not stick the brakes shut, it would let them be held shut by the driver in an emergency when the ABS would be trying to let them go. If there was no brake pedal pressure to begin with, the ABS would not be active, and would not cause excessive wear of brake parts. The pedal pressure has to be hard enough to keep the car from moving in order for the ABS to get into the game.

A damaged ABS would not cause excessive wear, but riding the brake pedal would.

Another thing that might cause "excessive" wear is a service guy that gets paid commission. There is no way in hell a car would need new brake rotors after only 10k kilometers (about 16k miles) of normal operation.

[snipi stuff]

Jolly good - very sensible post. Not sure who decided to start cross-posting this thread to uk.people.support.depression; that's not sensible.

Rowland.

Except that I've seen a locked up caliper on a BMW anti-lock system, that's a very nice description of how they work when they are working correctly.

"ABS" may be missing the point.

The stability-control system can apply the brakes.

...and no where did I suggest that the ABS applied the breaks. From what the mechanic I was talking to told me the ABS wasn't letting the break pressure release in one of the calipers after the breaks had been applied. That's considerably different than applying pressure.

A stuck caliper is a function of disc brakes themselves, not a function of ABS. Anti-lock is not the problem in this instance.

I agree that a stuck caliper will result in excessive brake wear, but the OP did not post the other symptoms, such as worn pads, heat, noise, etc. He took the car for normal service, and got a call that the rotors need to be replaced.

I'm only trying to get you off of the ABS system as the fault source. The ABS is the speed sensors, valve system, and pump. The calipers exist with or without the presence of an ABS system. I'm stuck on ABS because you said the the problem could be "a damaged anti-lock system." By definition, a damaged anti lock system will cause the brakes to not release in a panic stop or hard-braking situation, but a worn rotor that arises from a stuck caliper is much different than a damaged anti-lock system.