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Old September 5th 08, 10:15 PM posted to alt.autos.bmw
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Default E39 Vibration on Braking - help please !

On Fri, 5 Sep 2008 13:05:56 -0700, "Jeff Strickland" > wrote:

>
> wrote in message
...
>>I had a similar problem and still haven't quite fully resolved it. I
>> have an E39 with 75K. At around 60K I had both my front rotors
>> replaced by the dealer in Miami. This was around December 2007. Since
>> then I have gone through 2 other front left rotors trying to resolve
>> the vibration problems.
>>
>> First time around I had visible warpage on the left rotor. That rotor
>> was replaced by the dealer at now charge. About three weeks later the
>> vibration returned. Took it to the dealer again and they said I had a
>> bent hub on the left wheel. So I had that replaced (luckily I have
>> CPO) though I had to buy the replacement rotor because the warpage was
>> caused by the hub, so I was told. Dealer said both pads and right
>> rotor were within spec.
>>
>> Two weeks later I am back at South BMW in Miami with vibration issues
>> again. This time I am told that my thrust bushing "might" be the
>> cause. The pads and rotors are inspected and they are within BMW
>> specs. As for the thrust bushing, they want the tiny sum of $475.00 --
>> So I found a small independent BMW mechanic that did the job for $200
>> -- But the vibrations are still there.
>>
>> As I was ready to throw in the towel, I found an article on StopTech
>> about the bed-in process. Well I tried this and wouldn't you know, it
>> actually reduced the vibrations considerably. So I did it again -- and
>> the vibration has only occasionally appeared. So that is why I say I
>> still haven't quite resolved it. I may very well have had a bad hub
>> that caused the first rotor to warp, but the proper bedding in process
>> has probably made more difference then the thrust bushing (which
>> weren't visibly bad).
>>
>> Regards,
>> Rick

>
>
>I drive an E36 convertible. My brakes -- all of them -- were worn below the
>min thickness stamped on them and the pads were down to about 3 or 4 mm
>remaining. Stopping was smooth and sure, even though the parts were
>obviously worn out.
>
>I bought all new rotors and pads from an eBay Store, and the front rotors
>were not machined well and caused a serious vibration out of the box. I
>called to complain, and another set of rotors arrived on my doorstep within
>a few days.
>
>I took those brand new rotors to a machine shop and found they were machined
>wrong. I paid $30 to have both rotors machined true on both sides, and they
>work very well now. I brought the original set of rotors to the same machine
>shop and found the same machine work was needed for them. Another $30, and I
>have a set of rotors to use when the need arises.
>
>My point is, it is possible to remove a few thousandths of rotor material to
>make them true, and this distinctly a possibility that should be considered.
>Take your new rotors and simply have them measured and turned if needed to
>make them true.
>
>Good luck.
>

At one time here in the UK FORD supplied brake pads that had a special grinding
or bedding in surface on the contact faces.

Warning were given NOT TO DRIVE and BRAKE HARD in the first 200 miles of use.

These were pre - no-asbestos pads I must add and the rotors were not changed
every other brake pad change ('72 - 86).

This actually ground the surface of the rotors to match the brake calipers etc.
and - by Jove old chap - if dammed well worked and got rid of 90% of front end
vibration issues.

I did once use a similar setup on an old Jag once by sticking some emery cloth
to the pad surfaces and made sure I drove very lightly for a couple of weeks -
the emery eventually wore off and I presume would have ripped off as did the
special surface on the FORD pads did if one hit the brakes in an emergency.

The judder and wobble on the jag was cured -

Just an idea - NO WARRANTIES GIVEN USE AT OWN RISK.

Hugh
--

Sir Hugh of Bognor

The difference between men and boys is the price of their toys.

Intelligence is not knowing the answer but knowing where and how to find it!

Hugh Gundersen

Bognor Regis, W.Sussex, England, UK
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