NEW Brake Rotors on BMW...ALWAYS???

I've had two mechanics tell me that when i do a brake job on my 530i that i have to replace my rotors......whether they are worn or not. Basically, I'm
told that if you replace the pads, you have to replace the rotors. What's so special about BMW brakes? A car is a car and a disc brake is a disc brake. Other cars don't have this requirement.....
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They generally last for *two* sets of pads. But the minimum thickness is stamped on the hub. Measure with a micrometer to see how much left.
Find a new mechanic who doesn't just waste your money.
--
*If you don't pay your exorcist you get repossessed.*

Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
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On Fri, 28 Apr 2006 07:20:32 +0000, kevin.lavery wrote:

With the sage advice of posters to this newsgroup, I recently replaced the pads and rotors on a friend's '98 E328i sedan with 90,000 miles. From her records, it appears this was the second set of pads. Rotors were grooved and brakes were becoming noisy. Rotors and pads are now new and braking is quiet. Soon the pads will have seated themselves and all will be like normal.
If a part is worn or acting up, replace it. Our cost for doing all 4 sets of pads/rotors was 20% less than what the mechanic was going to charge to do only the front ones.
The job is simple enough just about anyone can do it. Find some sunshine and give yourself a few hours and it's done.
Nothing like a car that works well.
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I call this the "Bill Gates Syndrome". Your mechanics don't see any reason why they shouldn't be rich too and you have been selected to help them in their endevor.

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kevin.lavery wrote:

Kevin,
I've gone through several sets of brakes with my 328. Generally what happens is the pads wear down to nothing and the rotors are at or near minimum thickness at that point. If the rotors are above the minimum specs you CAN replace the pads only but it's a fool's errand to do so, because the rotors will be below minimum thickness for a majority of the lifespan of the new pads.
While you're certainly entitiled to operate the brakes in that way, don't be surprised when they warp. And then don't be surprised when all that shimmying in the front end causes damage to the seals in your steering rack and you have to replace that for nearly $1000US. (Same warning goes for tires -- if your front-end is shimmying fix it immediately!)
BMW pads and rotors are designed (properly, I might add) to wear roughly equally, so that the proper way to do brakes is to replace both components at the same time. And contrary to the advice given elsewhere in this thread, the way to make your mechanic rich is to be a cheapskate and only do the pads....because the car will be back on the lift in 10-15K miles to fix the rotors and you'll pay twice for the labor to disassemble the brakes.
See the BMW section on my site for more.
-Doug
-------------------- Doug Vetter, ATP/CFI snipped-for-privacy@yahoo.com http://www.dvatp.com --------------------
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That may be your experience - it's not mine. With normal use two sets of pads before discs need replacement. If you're wearing them out equally, perhaps you need to modify your road driving.
--
*Some days you're the dog, some days the hydrant.

Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
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Dave Plowman (News) wrote:

Two sets of pads on the same rotor? Are we talking about OEM parts here? Have you bothered to use a tool to measure the rotors or do you just say "they look good enough"? My rotors have been within 10% of limits each time. In fact, the last time I did the fronts the rotors were below spec.

The physical characteristics of the parts and the rate at which the materials wear in relation to each other is a matter of composition, which is set during manufacturing. Short of subjecting pads and rotors designed for street operation to track conditions, there is no driving techique that will change that relationship.
For what it's worth, it takes about 5-6 sets of pads to wear down the rotors on my airplane to minimum specs, so I don't replace rotors on it or my cars as a reflex. The rotors get replaced when they go below specs -- simple as that. And while it's certainly possible to run rotors below specs, it's not wise.
-Doug
-------------------- Doug Vetter, ATP/CFI snipped-for-privacy@yahoo.com http://www.dvatp.com --------------------
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To the same disc, yes.

Usually, since I never buy cars new. And certainly don't pay main dealer prices for things like pads and discs. But do buy OEM.

If you read my previous posts in this thread there'd be no need to ask such a stupid question.

Then I'd suggest you are not a normal driver. And find it strange that BMW make a car whose brakes become unsafe before any warning is given. I'd suggest you take it up with them.
--
*I have my own little world - but it's OK...they know me here*

Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
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Dave Plowman (News) wrote:

You're right -- I apologize. However, you needn't be nasty -- I was merely asking a question to help clarify your statements.

Unless I learned nothing in physics class, nothing I do as a driver has anything to do with how much the rotor wears in relation to the pads. For that reason, I can't see why you and I would have such different wear rates -- which explains why I responded to you in the first place. But just to frame my response I'll say that I am no Andretti -- I drive "spirited" at times, but never abuse my brakes. In fact, I drive a lot of highway miles so I get 30K out of my front brakes and around 60K out of the rear set. From what I've heard, this is quite typical.
As for the warning, I never said that the brake wear indicator had tripped, and even if it did, it would only warn if the pads were worn to minimum limits -- not the rotor. That said, my rotors have been within 10% of minimum specs even when the pads have been above minimum specs. This would indicate my rotors wear at nearly the same rate (possibly faster) as the pads. I'm not stating anything other than my observation.
And as for your comment in your other message regarding the fact that I have most of my work (including brakes) done by others, I don't see how that has anything to do with the price of tea in China. When I was young and had more time than money, I did all my own work. Now that my time is limited, it pays for me to pay others to do my work. And speaking of my mechanic, he's worked on BMWs for 30 years and has more knowledge, training, and experence than 99% of the people in this group I'm sure. Needless to say, he knows how to use a micrometer.
-Doug
-------------------- Doug Vetter, ATP/CFI snipped-for-privacy@yahoo.com http://www.dvatp.com --------------------
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Think your comment about me not knowing how to measure a disc was equally as rude. So I tend to respond like for like.

It is fairly typical. As is discs lasting for two sets of pads. ;-)

Unless you do the measurements yourself and know how to use that data, you're relying on a third party who may well have a vested interest to replace things. As happens at most dealers.

--
*A nest isn't empty until all their stuff is out of the attic

Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
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Dave Plowman (News) wrote:

While I agree in principle (most dealers are thieves), my technician has proven to be the most open and honest guy in the business. He's saved me thousands of dollars in repairs, and I'm not the only one who's noticed. Just had lunch this weekend with a fellow BMW enthusiast and he volunteered the same observation. In his case, the technician informed him he had a bad MAF sensor. Instead of charging labor for installation he showed him how to do it himself and told him what part to order at the parts desk. Even reminded him about the 20% CCA parts discount. Doesn't get more honest than that. And that's why I keep going back to him.
As for the rotor specs, my technician did give me the raw data on the discs for the first couple of brake jobs but I don't recall the numbers. I remember thinking that was kind of neat, since no one (dealer or indy) ever did that for me on any of my other cars. And then I realized it was just his personal operating procedure when he would give me printouts from the BMW diagnostic computer when I had various faults and the alignment and roadforce balancing specs when I had new tires installed. You can see some of this data on my website.
If there's any downside to my dealer right now it's that the family that owned it has decided to sell the franchise because BMW corporate told them they had to build a $12M building and go "high volume". And this only after BMW agreed to leave them alone if they did the $3M renovation they did four years ago. The family unceremoniously told BMW to go "F" themselves. A local dealership conglomerate has purchased the franchise (pending the closing of course) and I'm afraid things are about to change for the worse. Sad to say, but the plague affecting BMW's recent designs has reached the very top of the organization and its business practices. Guess my next car will be a Porsche.
-Doug
-------------------- Doug Vetter, ATP/CFI snipped-for-privacy@yahoo.com http://www.dvatp.com --------------------
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[snip]
My comment wasn't meant to refer to your guy but was general. Sorry to imply it did.
--
*If you tell the truth, you don't have to remember anything.*

Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
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A quick glance at your website shows you appear to get everything done to your cars by your 'mechanic'.
I DIY things like brakes.
--
*Whatever kind of look you were going for, you missed.

Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
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Nice website Doug.

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PoppyCock!!

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No, not always, but usually. It is not uncommon to need rotors with every brake change for spirited drivers, but the more sedate among us can get the rotors to last through 2 sets of pads.

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Jeff Strickland wrote:

Mine "lasted" through two sets of pads, but were pretty warped near the end. I'll never own another beamer, but since I keep cars for eons, I'll prob. be driving this one for years to come. However, I'm getting to know it (and how to repair it) pretty well.
--


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My BMW experience(s) has(have) been the best automotive purchase(s) I've ever made. I'm thrilled with the service requirements, and the relative ease of services that I can do at home. I'm not able to adjust valve lash or rebuild heads, that sort of thing, but the brakes are by far the easiest brakes to service of any automobile I've owned. They come apart easily and go back together again. The parking brake is the only weak link, and its adjustment procedure is my only gripe -- they could have made the mechanism differently and the adjustment would be much easier as a result. Oil changes and tune ups are a breeze. The coolant system is a bit tight, but otherwise well designed and easy to service.
Yep, I could sell BMWs -- I like them so much.
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