Replacing Brake Rotors
 

Hi Folks,

My '93 W124 300E needs new brakes and its time for new front rotors. I've done some searching on this forum and from the info I've found, I'm confused as to whether replacing the rotors requires repacking the front wheel bearings or any kind of work like that. I didn't see anything about that on my MB service manual CD (maybe I'm not looking in the right place). I've done brakes on FWD cars before and the rotors on those come right off without having to touch the bearings. I don't know about these RWD cars though. So, what's the story with replacing rotors on these cars? Any other tips on brake work for this car would be greatly appreciated as well. Thanks in advance for your help.

It is not necessary to remove the hub from the spindle to replace front rotors on the 124 series car. Simply remove the wheel, unbolt the caliper and suspend it out of the way with a wire, don't hang it by the hose or let any tension be placed on the hose. Then remove the allen head screw that holds the rotor to the hub, and remove the rotor.

Before placing the new rotor on the hub, clean the hub THOROUGHLY with a wire brush and get it shiny, squeaky clean. Put the rotor in place on the hub and put the allen screw back in place.

All that said, this would be a perfect time to go ahead and remove the hub, clean everything up in solvent, repack the bearings and put it all back together. You can get a tube of grease from the MB dealer for not too much money that will have just the right amount for both front hubs, so you will know that you put in the correct type and amount of grease.

If you have any further questions, post them here.

Hope this helps,

DO NOT INTRODUCE SOLVENT INTO THE BEARING AREA ! :eek: The solvent cleans well but also breaks down the grease and any residue left behind will break down the new grease and liquify the grease and possibly cause failure. When doing brakes, if your rotors are not warped and in specs i would not change them, get some Brakecleen spray and clean it all up, replace the pads and sensors and make sure to torque everything and re-fill the brake fluid and your good to go/stop. :)

Jerry is correct in everything he says except I think he misunderstood how I meant to use the solvent. I would ONLY use solvent when taking the hubs completely off and completely disassembling. You then use solvent to TOTALLY clean everything and then blow away the solvent before packing bearings and putting grease down in the hub between the bearings.

You certainly should not use solvent and let it contact the grease if you are not going to pack them, or leave any solvent in place after cleaning, but before packing with fresh grease.

Thanks for the clarification.

Have a great day,

It's not that difficult a job - generally. The degree of difficultly is almost entirely a function of whether your rotors are stuck. Sometimes they just fall right off - other times it's like they're welded on. There quite a few posts on breaking them loose - wd40, sledge hammers, heat, etc. If you're lucky you won't have to worry about it.

Parts Suggestion
 

I just had the front rotors and pads replaced on my '97 W210 car. I bought Balo rotors and Textar (yellow box) pads from Phil who can be found at "FastLane" above. I was very pleased with the quality and the braking is very firm and true.

I had trouble removing seized/stuck rotors, and almost gave up after using a rubber mallet, hammer, heat, and a bottle of WD40. Then I came across the "bolt trick" in which you place extra bolts through the caliper bracket holes from the wheel hub assembly until they rest upon the back of the rotor. Then put nuts on the bolts and turn the bolts into the rotor until it pops off! This is MUCH easier and cleaner than any other technique I’ve come across. Complete details at http://www.vfaq.com/mods/BrakeRotors.html .