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
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.
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
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 Vetter, ATP/CFI
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 Vetter, ATP/CFI
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 Vetter, ATP/CFI
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 Vetter, ATP/CFI
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.
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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