R/R Front-Rear brake pads/rotors 84 300SD - PeachParts Mercedes-Benz Forum

meltedpanda · #1 02-09-2004, 04:00 PM

OK I am thinking of doing this myself. On a scale of 1-10 is this a newbie kinda job. I have average skills. Is there a step by step procedure out there somewhere. Everthing else I have done on this car seems straight forward. Thanks in advance

Q · #2 02-09-2004, 06:18 PM

The hitch here is that you have to pull the front hubs to get the rotors off. There are plenty of posts on how to reinstall bearings. The tidbit of knowledge that I wish I had possessed when I first did mine was to bolt the hub back to the wheel once removed, in order to have something to apply resistance to while removing the rotor bolts. I would have a breaker bar and I think an 8mm (CORRECTION: 10mm) allen socket handy to remove the rotor.

porkface · #3 02-09-2004, 06:26 PM

the bolts that hold the rotor have 10mm heads. good luck, chuck.

meltedpanda · #4 02-10-2004, 01:46 PM

These bearings were "repacked" last brake job, however this time the rotors need replaced, based on last observation of thickness. Do the bearings have to be repacked again?. I read somewhere this was a 60K mile interval.

psfred · #5 02-10-2004, 01:53 PM

It is necessary to take the hub off the bearings to get the rotor off, and I'd be very hesitant to replace the bearings without completely removing and replacing the grease -- the possibility of getting grit in there is just too high.

Peter

meltedpanda · #6 02-10-2004, 04:31 PM

I am trying to learn and have realized this may be a bit over my head, so the next question is can this job be done by a very good general mechanic that works on all car types or just MB type mechanics.
Thanks again

afmcorp · #7 02-10-2004, 04:39 PM

this sounds like a good place to chime in.

just did my 87 420sel this past weekend. what i found when i measured the old rotors was their thickness was 1.070" I had bought the rotors etc: in a kit) then i measured the brand new balo rotors they were 1.100". on the new rotors they are marked with a minimum thickness of 25.4 mm or 1.000 inches. so... the old rotors still had .070 left to go and were only .030" under the new ones. so i just did the pads. i'm a machinist by trade so i've got very accurate tools to measure with. just as a side note i put over 2000 miles on the pads after the warning light came on and i could probably have gotten another 500 miles.

the only thing i encountered was it was extremely hard to bleed the brakes. i have a motive power bleeder and at 20psi nothing. so i had the wife stand on the brakes you know 1.2.3 hold and nothing so then i told her to stomp hell out of the pedal and finally got some fluid. after that they bled fine and the pedal is just fine plenty solid and slightly above the gas pedal.

i just felt there should have been more pressure in the brake lines.

#8 02-10-2004, 05:20 PM

First of all I'm surprised that you need to remove the hub to change rotors. The MB's I've worked on (and they have never included a 126 car) have had a screw that you can remove that holds the rotor to the hub, making it unnecessary to remove the wheel bearings. That said, it is always a good idea to pack the bearings at this time, just to see that they get done regularly.

Secondly, on most MB's, when bleeding using the two person method, I have found it necessary to bleed with engine running. Maybe this is because my helper is usually my wife or my daughter, one is a weakling and the other only weighs 90 pounds.

Good luck,

porkface · #9 02-10-2004, 05:50 PM

larry-looking at the cars you own, i cant believe you haven't done brakes on the 81 and the euro 84-both are 123s, right? it's the same as the 126 on the brakes. off i go, chuck.

RKreutzer · #10 02-10-2004, 06:34 PM

Hi meltedpanda,

there is a mechanic selling CD's on e-bay that covers that job. They run I believe less than $10 and it is a 30 min video showing him do the pads and the rotors. He has also videos about removing the door panels and some vacuum stuff.

Once you see how it is done, you will be able to do it yourself. You can do it without repacking the bearing, but you need only the dust seals which are under $ 10 for the 2 and MB grease, which I believe was under $10 from the dealer. Just be careful tapping in the seals.

Good luck

Reinhard Kreutzer

afmcorp · #11 02-10-2004, 07:14 PM

Hi Larry

I forgot to mention that i did have the engine running which is why i was surprised that it took such an effort to push the brake fluid out the bleeder. i even took the bleeder screw out to be sure i was releasing the cone design and it was also unobstructed.

this was my first time on a benz. i also didn't mention that once the fluid would come out using the brake pedal the 20 psi power bleeder did push a little fluid out.

meltedpanda · #12 02-10-2004, 09:53 PM

Ok guys (gals) good discussion BUT, my question was , if I do not do this can a good mechanic without Benz experience complete the task? Is this a pretty straight forward rotor and pad , repack bearing job or do they need to be a member of this listserve for all the "details"
Thanks again

RKreutzer · #13 02-10-2004, 10:02 PM

"A good mechanic" certainly can, otherwise he ain't good...

Q · #14 02-10-2004, 10:11 PM

It's an easy job. Just be prepared. You can do it yourself with rigth tools and paitience. Any mechanic should be able to handle it with no problem. The only special knowledge is how to set the bearing preload/play (whatever you want to call it). I just went by feel. Some people might cringe, but all I did was reassemble everything and tighten the bearing retainer nut with pliars until I could feel resistance when turning the rotor/hub. I then backed the nut off a bit and tapped the axel with a hammer. Tighten again. Loosen again. Tap again and then turned the nut until I could not tell that there was any play at all when moving the rotor/hub in and out. Set the allen bolt that locks the retaining nut and it has not given me any problems.

meltedpanda · #15 02-11-2004, 08:53 AM

once again, thanks. I think I will ask my local mechanic that has been in busisness for 25 years to do the job, and I will also ask to watch, for next time....