Must rotors be turned when brake pads are replaced? What ill-effects would happen, if any, if pads are replaced without turning the rotors?

Do rotors need to be turned by Porchse mechanics?

I was hoping the brake pad R&R would be free of any mechanic costs.

 

did your brakes pulsate before? if yes, your rotors might be warped: turn or replace. if they seemed fine, i wouldn't turn them. bare minumum, de-glaze them with some scotch-brite. gives the new pads something to bite.

there is a minimum thickness ref'd in the manuals. if they're under that minimum a shop won't turn them anyways.

but if they're still within limits it won't hurt.

when i did my brakes a couple months ago, the inside and outside of all 4 rotors had a nice 1/16-1/8" lip. the pads were too hard and wore them down. i just replaced them all with cross-drilled's...

 

No pulsating from the brakes, just an incredible squeal while stopping once they get warm. The rotors, both front and back, have about 15K miles on them.

 

-I don't turn disks.

When you turn a disk, you make it thinner. When it heats up, it will warp and now your brakes pulse.

They say that if you change your pads you should turn the disk to make it straighter and to help the pads seat; crap I say- I've never turned a disk on any of my cars and have never had a problem stopping.

Normy-

'85 S2

 

Normy, your just tighter then bark on a tree, face it!

Turn or replace if:

1. Your name is not Normy!
2. Rotors are deeply grooved.
3. Rotors are warped (run-out of tolerance) or cracked.

Pad replacement only if:

1. Your name is Normy!
2. Rotors show no or only light signs of groves.
3. Rotors show little or no signs of warpage (run-out is within tolerance) and no cracking.

MB and Mazda both recommend having the rotors turned on the car if new rotors were not used. I know one MB service manager who will have his tech run the on car rotor machine over the new one's just to make sure the run-out is within spec's. This makes for a nicer ride, better brake feel and they say the pads and rotors last longer.

JM.02

Max

Normy, don't flame me, I'm just pulling your big toe!

 

I'm from the school of always turning rotors.
Even new ones, if I believe they have sat for an extended period of time on some shelf somewhere. New rotors can be warped from stacking or long storage. Turning a new rotor is just to check the warpedness and take a light cut on them. I like to start with "true" rotors.

The minimum thickness is supposed to be a safe thickness to continue to use the rotor, but if you are a heavy braker or street racer, the above mentiond possibility of heating and warping the thinner rotor is true. Really, any stock rotor can be warped with heavy braking. My PO must have thought he was Dale friggin Ernhart. I saved the rear scorched, warped rotors to show people who visit my garage. Always good for a laugh.

 

Kewl post Max!

I just don't see the advantage of turning a rotor. If it is scored bad enough that you are concerned about your new pads....why not just buy new rotors?

Normy!

PS- I'm keeping a cold one on tap for you!

 

Hi Dave,

Turning rotors can be done by any old Midas, Firestone, etc. However, they will not turn rotors that are too thin. Rotor surfaces are not major offenders for squeal.

Brakes squeal because metal shimmies against metal. The metal backing of the pad vibrates where it touches the pistons in the calipers. I found some antisqueal adhesive pads to glue to the back of my pads. Most part stores carry antisqueal juices. These mainly glue the pad to the pistons. The main problem now would be just getting the pads and piston ends clean enough for the goo to adhere to both surfaces. The other tough part is getting the wear sensors out of the pads without breaking them. I insert a miniature set of needlenose tweezers into the metal loops alongside the protruding wire. Then tease the sensors out. Maybe pry the tweezers up with a screwdriver. It is one of the easiest maintenance jobs to perform on this car. See John Pirtle’s page for pictorial procedures.
<a href="http://members.rennlist.com/pirtle/svc.html" target="_blank">http://members.rennlist.com/pirtle/svc.html</a>
<img src="graemlins/burnout.gif" border="0" alt="[burnout]" />

 

Normy, I don't know why anyone else turns their rotors, but here is why I do mine.

1. I’m as tight as you are Normy, I’m not rich by any means now, but I can still remember when I was so broke I couldn’t pay attention. Let’s say that new rotors cost $35.00us each or $140.00 for a set of four. I can have all four rotors turned for $20.00us. That’s $120.00us savings.

Yes one could say that just replacing the pads would give you a $140.00us savings and you would be right, however your new pads will not last as long and if your rotors were just slightly warped or grooved before they will get worst very quickly and may get so bad that new rotors may then be your only avenue.

I will concede that not all break jobs require having the rotors turned.

If you’ve stayed on top of your brake wear and have a light break foot, you may not need to have your rotors turned. If you don’t have any grooving or warp-age, then I would recommend at the minimum having the brake shop run their glaze-buster over them. This will help the new pads break-in correctly. The cost of this is normally the same as having them turned, you may find that some will charge less but don’t count on it.

HTH

Max