300E - Replacing Pads and Rotors

[new guy]

I have a 1987 300E that needs new pads and rotors on the front. I don't have a shop manual or any other book to help me, but I have done this type of work before on other cars. Is there a post or technical article out there that walks through the steps required to complete this task for this car? I did see a tech article in the DIY area of this site, but it was for a newer model w/ different types of calipers, and it did not talk about the rotors. Thanks

[Ashman]

click the D.I.Y. link at the top of the page. there will be a featured article on brake replacement for 124 chassis cars.

Alon

[Ali Al-Chalabi]

Could also do a search, there is a ton of info on the W124 brakes on this site.

Also try checking out this thread for more info.

Replacing brake discs..

Why does it also need rotors, did the pads where down to metal? The only reason to replace these rotors would be if they had metal to metal contact or are warped.

If you are just replacing them because it is brake time, you may very well be wasting your money.

Good luck,

Larry Bible,

What about the discs reaching min thickness? You didn't ask how many miles are on the car, and even perfectly true discs are supposed to be replaced when min thicknesses are reached. I've always considered a good rule is that MB discs are good for 2-3 sets of pads, although I've only worked on about a dozen of them.

Okay Mike, you make a good point. Now, have you checked the thickness?

Personally, I am much more concerned about front rotor thickness than rear. Also, unless you run it at 140 on the Autobahn, you should have adequate mass for 70 or 80 MPH stops unless the rotor is almost cut into two pieces.

The pad does not reach the very largest diameter of the rotor, so you can tell by looking at that thickness step if they're getting thin without micing them. Depending on the pads you use, these rotors will go beyond a few pad sets before being too thin.

Good luck,

[new guy]

I think the rotors need replaced because the leading edge has a lip on it which is rubbing on the brake pad electronic sensor. I have been told (by the local MB dealer)that they typically don't turn the rotors on this model???? I don't have calipers to check the thickness, but judging by the lip on the leading edge, they are worn quite a bit.

This doesn't make sense. The outer edge of the rotor is not getting larger, how can it rub on anything? I guess this is possible, but I would have to see it to understand.

They are correct about turning rotors. When indeed rotor time comes, don't turn them, get a set from Mercedesshop or some other aftermarket supplier, don't turn them.

Good luck,

[Zeus]

I think what he is referring to Larry is that the pads don't contact (and therefore do not wear) the outermost edge of the rotor. As the rest of the rotor surface wears down, a noticeable lip is left behind on the outer edge, which you can use to visually track rotor wear.

As you say, that lip is somewhat useful and really doesn't hurt anything.

Have a great day,