BMW M5 Forum and M6 Forums banner

1 - 5 of 5 Posts

·
Registered
Joined
·
259 Posts
Discussion Starter #1
...on my 2000 M5. Is this a job only for authroized BMW service centers or is a rotor a rotor? There's a Goodyear tire center close to me and I was thinking about taking it there. I would assume it would be cheaper. Is a rotor turn job the same on our Beast's as an everyday car or is this a job for BMW?
 

·
Registered
Joined
·
12,928 Posts
billrM5 said:
...on my 2000 M5. Is this a job only for authroized BMW service centers or is a rotor a rotor? There's a Goodyear tire center close to me and I was thinking about taking it there. I would assume it would be cheaper. Is a rotor turn job the same on our Beast's as an everyday car or is this a job for BMW?
Nothing unique about the rotors that I am aware of. You will prob only get to turn them once, then replace with new the next time. The rotors don't seem to have that much extra "meat" for turning more than once. New ones are around $200/corner.
Regards,
Jerry
 

·
Registered
Joined
·
5,239 Posts
Are you sure you need them turned at all? Pulsating/vibrating brakes are most often a sign of uneven deposition of pad material on the rotors. I don't believe in turning rotors - they last much longer if you can avoid it. If a rotor is truly warped (again, very unusual) then I would prefer to replace it anyway.

Lots of discussion on this site about this topic. If you've never read it, I highly recommend reading The "Warped" Brake Disc and Other Myths of the Braking System- even though it is on a vendor site the article was written by one of the most respected (and published) race team engineer/managers that ever lived, Carroll Smith.

In my experience, dealers LOVE to turn rotors and recommend it with every pad change, needed or not. They probably believe (and they might be right) that this reduces the number of people who come back complaining of squeaking. However proper pad installation and reasonable gentleness in breaking the pads in should prevent squeaking anyway.
 

·
Registered
Joined
·
5,353 Posts
IIRC, you're not supposed to turn BMW rotors. You mic them to be sure they have sufficient thickness and if they do, you continue to use them. If not, you replace them. The friction surfaces are too thin to allow any turning. I hope Zeckhausen jumps in on this, as I think that's where I heard this from. I agree with Greg about uneven deposits; much more likely than uneven runout or warping.
 

·
Registered
Joined
·
2,482 Posts
Need4Spd said:
IIRC, you're not supposed to turn BMW rotors. You mic them to be sure they have sufficient thickness and if they do, you continue to use them. If not, you replace them. The friction surfaces are too thin to allow any turning. I hope Zeckhausen jumps in on this, as I think that's where I heard this from. I agree with Greg about uneven deposits; much more likely than uneven runout or warping.
The rotors have 1.6mm of allowable wear. If you turned them and removed 6 thousandths of an inch each time, you could turn them more than 10 times without exceeding the limit. However, most places that turn rotors, such as Pep Boys, hire teenagers who don't have any idea (or don't care) how to set up the lathe properly. If the rotor isn't held flat, the lathe will introduce runout.

But here's the main reason not to turn rotors. Typically, a vibration problem in the brakes is caused by several ten-thousandths of an inch of thickness variation due to uneven pad deposits, not several thousandths of an inch of runout. So you don't really want to hack off several thousandths of an inch of rotor material, just to clean off a few ten-thousandths of an inch of pad deposits.

You're far better off if you can make the problem go away (for free) by re-bedding the brakes. See: http://www.zeckhausen.com/bedding_in_brakes.htm

The key to avoiding this in the first place is to use a street pad that isn't known for causing serious pad deposition when driven agressively. For example, the EBC Greenstuff pads should be avoided. They are notorious for "pad poop" on your rotors. Also, avoid driving your car on the track with street pads. While the Axxis Ultimate pads are fantastic on the street, they are serious trouble if you take them to the track and run them hard. Switch over to a track pad like Hawk HT 10 when you do your driving schools and open track days. And use the following technique when switching back and forth in order to remove unwanted pad transfer material: http://www.zeckhausen.com/avoiding_brake_judder.htm
 
1 - 5 of 5 Posts
Top