I am working on a 75 450SL. The left rear disc brake is pretty badly grooved on the inside of the disc. I was getting ready to order a new brake disc and brake pads. The "PartsShop" shows brake discs from ATE (Teves), Zimmerman Cross, and Balo. They show pads from PBR , Pagid, ATE,& Textar. Can anyone tell me if these are just different brands or how do I tell which kind I have on my car? The car only has 75,000 orginal miles on it and I was also wondering what normally causes the brake disc to get grooved, and just on one side the left side appears to be in very good shape. I imagine these are the orginal brakes, so is this common?
Thanks
Dug

Doug:

All the brands listed are OEM. My mechanic prefers Balo rotors and Textar pads, but I've used Pagid and are happy with them.

Serious scoring or excessive wear on one side of a rotor is often a stuck piston. If this is a low milage car, I'd suspect old, water laden brake fluid has caused the piston to seize.

Did you have any problems pushing the piston back in on that side? If so, get a rebuild kit and replace the rubber parts (seal and dust boot). This is very easy, and will restore the brakes to normal function.

If there is any corrosion or dirt you cannot remove with brake parts cleaner in the caliper bores or on the pistons, replace the caliper.

I'd also replace the brake fluid if you don't know how old it is, or if it is dark, no matter what age.

Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

Peter:
Thank you very much. I will take your suggestion on the brand names and will also change the fluid and check the piston (I have not tried pushing it back into place yet). The way you make it sound I had better check the pistons on the front and the other rear as well. This would be pretty cheap insurance if I want to stop.
Thanks again.

Doug:

The rubber eventually dies of oxidation, and the pistons won't retract, or worse, stick out and have to be forced back. They should slide back into the calipers (cap off reservior!) with light pressue from a small prybar or large screwdriver. If they won't push back smoothly and fairly easily, it is likely the dust boot is cracked through and there is dirt in the piston bore. This dirt will cause the piston to stick (no clearance), and a hard piston seal won't help much. Rebuilds are easy, and you will then have brand new brakes!

Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

You sure make it sound easy. I am willing to try. You and everyone is so helpful when questions and opinions are asked. Thanks for the help.
Dug

Doug:

The "rebuild" on the caliper consists of removing the pistons and prying out the piston seal, then installing a new seal and dust sheild after cleaning the pison and the bore in the caliper with brake parts cleaner. Unless the piston or bore is badly rusted or corroded, it is very simple.

You do need basic mechanical skills, and a source of compressed air for removing the pistons is nice (you can use a bicycle pump), but not completely necessary.

The only difficult parts are getting the piston in the caliper at the correct orientation -- there is a raised portion of the piston lip that sticks through the heat shield that must actually protude and the piston must go into the bore at a particular rotation. It's easy to get it aligned to start with, but sometimes you must apply considerable pressure with a piece of wood stuck through the throat of the caliper to get the piston to go back in, and it's very easy to rotate it accidentally. It isn't possible to rotate the piston once it's installed without the special tool (expanding pliers that fit in the hollow), so you must remove the piston and re-install it if it rotates. Not hard, but a pain. Getting the dust boot back on can be difficult, too as you cannot reach one side to tap it down.

The good part is that the only thing you can really screw up is cutting the piston seal during installation of the piston, and this will result in an instant leak, easy to see.

Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

It sounds like you have done this more than once and know the problems that can arise. I have never done a brake job before, however am willing to try. I have basic skills and a fair understanding of how things are suppose to work. I have printed off all of your instructions and will keep them close. If I have to much problems I can tow it to to shop about 6 blocks away.
Thanks