turning rotors...?? - PeachParts Mercedes-Benz Forum

vwbuge · #1 01-22-2008, 01:47 PM

I've had my car so long that I have a second set of rotors. When the brakes need done I just get the second set turned. Less fuss and I have the parts ready to go instead of waiting for the rotors to be turned. This is on my Subaru.

I have been told several times before NOT to turn rotors on a MB. Some shops won't even do it. Why? Are the tolerances that close?

meltedpanda · #2 01-22-2008, 01:52 PM

Quote:

Originally Posted by vwbuge

I've had my car so long that I have a second set of rotors. When the brakes need done I just get the second set turned. Less fuss and I have the parts ready to go instead of waiting for the rotors to be turned. This is on my Subaru.

I have been told several times before NOT to turn rotors on a MB. Some shops won't even do it. Why? Are the tolerances that close?

they are so cheap, why turn them, i am sure MB has some safety measure in place.

Brian Carlton · #3 01-22-2008, 02:01 PM

You can get them turned. The axial runout tolerance is about .001" before you feel it in the steering. If the shop is very careful, they can achieve this. If they don't, however, you're out $30.00

New rotors are about $45.00 or so.

So, I've got to ask you a question: "Do you feel lucky"?

"Well........do you, punk?"

tangofox007 · #4 01-22-2008, 02:15 PM

Quote:

Originally Posted by vwbuge

I have been told several times before NOT to turn rotors on a MB. Some shops won't even do it. Why? Are the tolerances that close?

I have a 300D with 149k miles. I have turned all four of my original rotors twice and they are still well above minimum thickness. No unpleasant side effects have been encountered, except that the last set of pads do squeal a bit when cold.

That being said, the condition of the rotor before machining will determine how much metal needs to be removed, so every situation is different.

What "makes my day" about this topic is that countless individuals will insist that "it can't be done," but not a one of them can provide a credible reference to support their position. I have the official MB service manual for the W123; it contains no prohibition on rotor machining.

TX76513 · #5 01-22-2008, 02:16 PM

I got into this "discussion" with my Indy a few weeks ago. He swears at MB School they say not to turn them - it won't work, they will warp, etc. etc. Sorry, I turn mine one time and then replace them, doesn't cost me a dime, never had a problem

tangofox007 · #6 01-22-2008, 02:56 PM

Quote:

Originally Posted by TX76513

I got into this "discussion" with my Indy a few weeks ago. He swears at MB School they say not to turn them - it won't work, they will warp, etc. etc.

Why is a rotor that has been turned to a certain thickness going to warp any faster than one that has been worn to the same thickness?

(Assuming that both are within service limits.)

airbus · #7 01-22-2008, 03:02 PM

...just my $0.02: In Germany it is illegal to turn rotors. On any motor vehicle, that is.

bustedbenz · #8 01-22-2008, 03:24 PM

Quote:

Originally Posted by airbus

...just my $0.02: In Germany it is illegal to turn rotors. On any motor vehicle, that is.

Germans must have more disposable income.

winmutt · #9 01-22-2008, 11:57 PM

Quote:

Originally Posted by bustedbenz

Germans must have more disposable income.

You wouldnt believe what the TUV makes you go through to maintain a car there. Unbelievable.

W123 rotors are cheap, replace frequently.

TX76513 · #10 01-22-2008, 03:28 PM

Quote:

Originally Posted by tangofox007

Why is a rotor that has been turned to a certain thickness going to warp any faster than one that has been worn to the same thickness?

(Assuming that both are within service limits.)

Don't know, just his point of view. I don't think he understood what I was doing. If you start with a new rotor when you turn them the next brake change you are not taking much off.

vstech · #11 01-22-2008, 02:18 PM

your subaroo has floating calipers that move closer to the rotor. the MB has stationary calipers with dual pistons. more pressure, better breaking, and a more solid stopping ability. the rotors on the MB are the correct thickness to handle the heat dissapation of the pads. thicker rotors would force the calipers further away from the bracket, and they would also hold more of the heat from the braking system. I find it's just best to trust the engineers in this case.

tangofox007 · #12 01-22-2008, 03:00 PM

Quote:

Originally Posted by vstech

I find it's just best to trust the engineers in this case.

Do you have a reference for what "the engineers" actually say? My inclination is to trust the service limit specification-and not concern myself with how a rotor that is within limits got there.

meltedpanda · #13 01-22-2008, 05:22 PM

I actually did it once, but found I did get rotor warp when I was 8000 miles into the new pads, therefore I change them out. I do my own pads so I usually go through 2 sets before I renew rotors. I actually find that with a good set of rotors turning is not needed between pads. and yes I know - not right either ( not to turn or replace) but I have had good luck . This is all on my 300SD as well,

pawoSD · #14 01-22-2008, 05:35 PM

The rotors on the W123 and W126 are so cheap....why bother....also, they are a Pain to get off/put back on, why go through that just to turn them when you could mount shiny new ones instead?

Also, in a climate like MI, often rotors will die from rust problems before they actually wear down beyond tolerances.

TX76513 · #15 01-22-2008, 05:38 PM

....its $200 I can throw at something else

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