Brake Pad/Rotor Replacement
 

I have a brake pad indicator light on in my 87 560SL. Some mechanics have told me that I can just change the pads. However, I thought on this car one had to do the rotors and pads together. Please advise.

To get the longest life from your pads you probably want to have your rotors turned by a reputable shop. If they have too much wear you will need two new rotors. This is the case with any make/model vehicle.

Cost wise
 

It may be cheeper to buy new rotors than the turn the old ones. Rotors aren't that expensive.

May Be a Shade Tree, but -

In my experience, the quickest way to ruin a rotor is to put it on a lathe and cut it down.

Unless rotors are heavily scored (because the pads wore completely down to the rivets - CARELESSNESS) or the rotor is warped (excessive heat - ABUSIVENESS) I would never turn them. Even then I would give serious consideration to replacing them and eating the expense as punishment for bad driving.

Being purely objective, don't brake techs have a vested interest in making the turning of rotors (at twenty bucks a pop) a routine part of pad replacement?

A consumer is at a disadvantage here; e.g., "If you say not to turn the rotors, I can't guarantee the job" or, when you give in "These are right on the margin, if I take 'em down any more they're out of spec but to save you some money, we can put 'em on and see if they hold up without warping. If they start shuddering & overheating, I'll cut you some slack on new rotors" or the ultimate "It's your vehicle but if you run through a school crossing, I ain't responsible".

If your brake tech is telling you that it is an absolute must-do even in the absence of rotor scoring or warping, I would go somewhere else or change the pads myself.

Been "done" by bad guys.

M. Allen

Thanks for the replies. I never thought to have the rotors ground...I thought one had to REPLACE the rotors when replacing pads.

I know that on BMW's they recommend that you replace the rotors everytime you replace the pads. not sure if that applies to benzes

What's the downside of replacing pads without milling the rotors? Back in the old drum brake days, we used to buy rebuilt pads for a shade tree install and never gave a thought to turning the drums (as long as the wear grooves weren't too ridiculous). I suppose there might have been some marginal loss of braking power until the pads seated completely, but I never could tell any difference--they'd lock if I needed them to.

By the way, how many miles should do front pads (the standard soft variety) tend to last on a 107?

Update
 

Brake-pad indicator came on because the front caliper had seized and was rusted out...purchased a rebuilt set of front calipers, new rotors and pads all around...the rotors had totally had it....expensive...but unfortunately necessary.

The mechanic I bought two of my deisels from told me that you shouldn't turn a MB rotor since you will run the risk of having them warp. How true this is, I don't know. For the price you might as well buy new ones...they aren't that expensive. As far as replacing them each time you change the pads, I don't see why you would do this unless you wear down your pads to the point where you have metal on metal and have worn grooves in your rotors. I would think that if they don't have deep grooves in them or a large lip on the outer edge, you should be good to go for a while. I believe the Haynes manual gives the specs for the rotors and they can be checked with dial indicator. Just my two cents worth.

Mike

2 issues.
 

1. Thickness. There is a minimum spec and the new rotors do not have much room to turn them down. It is okay to change pads without turning the rotors. They should not be turned. Check thickness with a micrometer.
2. Runout. They should be replaced if they are out of spec on radail runout. This is what the dial indicator is for.

Steve

To add to what Steve said: I believe MB recommends NOT turning rotors. Their idea is to change the rotors only if too thin or warped. Otherwise, just replace the pads and sensor wires.