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

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Hi Folks,
a BMT 330ci is in the workshop - they called and want to replace the brake discs after less than 10000km. It is about 18 months old.
The car has been used occasionally within the city for short rides.
Waiting for days for the next usage, it is clear that the discs start to corrode after some days. But can this mean that you have to replace them that early ?!
I guess this is not a BMW-specific topic - except if they used the wrong material...
Any technical hints are welcome - thanks in advance! Klaus.
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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.
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wrote:

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.
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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.

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

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

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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.
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On Thu, 17 Jan 2008 00:12:18 +0000, Jeff Strickland wrote:

...or a damaged anti-lock system.
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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.
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[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.
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wrote:

Sorry for the intrusion Rowland. I just replied to a post that appeared in a group I subscribe to, I did not check the list of groups it was sent to. I share your disdain for cross posters, but I hold no animosity toward those that reply to a cross posted thread.
To drag this discussion (kicking and screaming, I might add) back on topic in the depression group, being told that your brakes need significant service after only 10K kilometers is a very depressing bit of news ...
<wink>
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You didn't begin the intrusion, so no major worries on that score. And thank you for your polite and reasonable post.

I've got to have some sort of personal reason for animus, myself. This sort of cross-posting is somewhere between amusing and irritating.

<grin>
A valid point indeed. Although if like me you've got an old motorcycle, brake maintenance every 6000 miles is entirely normal, if not `a bit less often than I'd feared'. I've been known to wear out rear brake pads in that distance, but not discs. What did it? Were the brakes dragging all the time, or what? Hard to think of a pad compound that'd wear 'em out so quickly, unless it's a mad carbon-carbon brake like they fit to racing cars.
When I had a drum braked bike, I had to fiddle with the brakes every weekend to keep the things working sweetly. They did work very well, mind - but it took a lot of work ('twas a CZ with a superb twin leading shoe front brake).
Staying on the subject of brakes: silicone grease is the magic elixer for conventional hydraulic disc brakes, so it seems. I had terrible trouble with my brakes `just not working quite right' - mild dragging, and so on. Nissin sliding calipers, fitted to a Honda VFR750 (don't ask about the VF500).
Anyway, to cut a very long tale very short: after replacing lots of bits and fettling everything multiple times to no avail, I tracked down some silicone grease and used it in the appropriate places, and `it's all sorted now'.
Because my brakes, like most motorcycle brakes, don't have a protective boot over the pistons, I give 'em a squirt with silicone spray lubricant every once in a while - that helps reduce the frequency with which the brakes need cleaning.
Don't use ordinary grease or oil or WD40 or similar for that: it doesn't do the seals any favours. And do remember to clean the disc after spraying silicone lube around the place or you'll have a very nasty shock when you first try to slow down.
Rowland.
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On Thu, 17 Jan 2008 00:30:15 +0000, Jeff Strickland wrote:

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.
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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.
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On Fri, 18 Jan 2008 17:58:56 +0000, Jeff Strickland wrote:

Tell that to the BMW mechanic I was talking to.

I was replying to a joke.

So you think it was either god or the devil?
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You need a new mechanic. If you indeed need rotors after 10k kilometers, ABS is not the reason. A stuck caliper might exist -- indeed, it probably does -- but the ABS itself is not the reason for the brakes to stick shut.
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Jeff Strickland wrote:

"ABS" may be missing the point.
The stability-control system can apply the brakes.
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