Warped Rotors -- Revisited

I just completed replacing the front rotors on my 3 Series for the second time since Christmas, and in about 500 miles.
I installed all new brake parts, and immediately had shaking in the steering
wheel under braking. The guy that sold the parts (R1Concepts, on eBay) said that the rotors should be true when they leave his shop, and he sent me a new set to replace those I already had installed.
I took the brand spanking new rotors out of the box and checked them for lateral run out. They were not true. I paid the machine shop $30 to true both rotors ($15 ea.)
When I installed the true rotors, there was no shaking at all. Now, I will be taking the first set of rotors to check them for true.
The lesson here is that brand new rotors, straight out of the box, are likely to not be true. When doing brake work at home, it pays to put the new rotors on a lathe before putting them on the car.
Happy repairs.
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I checked out your parts guy on Ebay, he's inexpensive! I used another internet vendor for my E46, paid more, but replaced all four corners, pads and rotors without a hitch.
Joe

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I wonder if this is the same issue ive been having. Ive had mine replaced WAY too soon and its happened again. The shop claimed it was "cause im braking too hard" which i know is BS lol. Hell i drive my 5s like a baby compared to my Olds i had and it never had brake issues.
Might be time for me to do it myself :(
-Branden

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Sometimes brand new rotors need to be turned.
Its probably cheaper just to replace the rotor than finding a brakes machine shop.
Buying a rotor online, you are assume the responsibility for installion and maching (if any).
Just take the rotor off as is, send it back, and ask for another one.
If only one rotor is bad, rotate them and see if the problem then moves to the other wheel.
Hope this helps!
JoshIII 1980 320i 4-cyl 1.8L with A/C snipped-for-privacy@hotmail.com

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BMW brakes are pretty easy, as brakes go. IF YOU ARE MECHANICALLY INCLINED, I see no reason at all why you couldn't do this project yourself.
If your rotors are basically new, there is a good chance they can be turned without making them too thin.
Turning old rotors is generally not a good idea because they are not very thick to begin with -- not much material can be removed before they are thinner than the min. spec. But, new rotors have enough meat on them that you can easily remove a few thousandths to make them true.

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What make were they?
--
*A closed mouth gathers no feet.*

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

Unknown, Dave. The eBay store is R1Concepts.
It appears to me that they buy blanks and machine them to order. I suppose they could simply buy rotors and turn them around from the receiving door to the shipping door. Whatever they do, they skip the last step in the manufacturing process.
On the bright side, the customer service is pretty darn good. I have a new set of front rotors on the shelf in my garage that will end up costing me $60 for the pair. They are slotted and cross drilled, and nickle plated to boot.
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Funny you mentioned warped rotors...........
A while back FORD had a spate of problems with shuddering and weaving under heavy braking (1978) What they did was to make available special brake pads fitted with a metallic grinding surface on the friction material - explicit instructions DO NOT BRAKE HARD OR DRIVE ENTHUSIASTICALLY for at least 200 miles were stuck to the box.
If one did brake in an emergency the grinding material would disintegrate and the pads operated as normal - waste of 40 yes 40GBPounds in 1978 (deposit on a house nearly)
I have no idea if these type of brake pads are available now (if they were only dealers would be entitled to sell/use them) but I can imagine if one took a sheet of medium-course emery cloth and stuck it to a set of new brake pads with a contact adhesive and then fitted them - possibly the same effect - skimming the rotors in place -----------
Interesting.....................!
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 snipped-for-privacy@h-gee.co.uk Bognor Regis, W.Sussex, England, UK
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I just got home from the machine shop. The first set of rotors were indeed warped. One was probably okay, but the other was certainly out of true.
They did not specifically measure the run out because the machine they turned my rotors on was really a sander for truing flywheels. Since my rotors are slotted and cross drilled, they could not be turned on a regular lathe with a cutting tool, they had to use some kind of sanding scheme. The flywheel sander did the trick.
The moral of the story is that brake rotors should not be assumed to be true just because they are new.

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I'd say the other moral is stick to OEM parts. ;-)
--
*I must always remember that I'm unique, just like everyone else. *

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