Front Rotor replacement on my 84 300SD - PeachParts Mercedes-Benz Forum

meltedpanda · #1 05-14-2009, 09:44 PM

I am trying to recall everything I need for this job, but its been so long since I last did it that I dont remember if I need to get new races and bearings if I am going to change out the rotors, I know on the back I dont need them
This ol mind aint what it use to be

Please advise and thanks in advance

Chad300tdt · #2 05-14-2009, 09:48 PM

You can reuse your bearings & races if you weren't having any issues with them. Just repack them.

EDIT: You should get new seals though.

meltedpanda · #3 05-14-2009, 09:58 PM

no problem with them, but now I remember they were a royal pain to get out - is there a trick?

Mike D · #4 05-15-2009, 07:43 AM

Don't bother changing them over. Most of the new rotors come with races installed. The odds of "dinking" up the old races are pretty high because you need to drive them out using a punch and hammer.

Buy some new bearings and be done with it. If the new rotors don't have the races then install them using a race driver. If you don't have one and don't want to buy another tool (yeah, right!

) then swing them by any mechanic shop and they'll install them for you.

Chad300tdt · #5 05-15-2009, 08:24 AM

The bearings and races are inside the wheel hub which the rotor bolts to. You definitely won't get new races with the rotors. The brakes on a 1st generation w126 are exactly the same as the ones on a w123. The only difference is that the front rotors on a 126 are vented and the caliper has a shorter piston to accommodate the thicker rotor.

I put the rotors and calipers from a 126 on my 300TD.

I don't know of any trick to get the bearing seals off without ruining them.

Leave your races in the hub, clean out the hub thoroughly once you get the new rotors bolted to them (with blue loc-tite on the bolts), and then repack the bearings with fresh grease.

Brian Carlton · #6 05-15-2009, 08:57 AM

Quote:

Originally Posted by Chad300tdt

I don't know of any trick to get the bearing seals off without ruining them.

The trick is not to ruin the bearing seal...........it's not to ruin the bearing. The temtation is to pry out the seal using the bearing face for leverage. This will insure that you'll be buying a new bearing.

The proper procedure requires you to hook the seal from above and tap it out with a hammer that can impact the tool that you utilized for the hook. It's a bit of an awkward deal but it saves the bearing. I just did one on the SD and, without a good vice, it took 15 minutes of futile attempts until it finally gave up.

tangofox007 · #7 05-15-2009, 09:39 AM

Quote:

Originally Posted by Mike D

Don't bother changing them over. Most of the new rotors come with races installed. The odds of "dinking" up the old races are pretty high because you need to drive them out using a punch and hammer.

Buy some new bearings and be done with it. If the new rotors don't have the races then install them using a race driver. If you don't have one and don't want to buy another tool (yeah, right!

) then swing them by any mechanic shop and they'll install them for you.

That would be great advice in a Ford forum. (Except, maybe, the part about "dinking up" the old races!!!)

meltedpanda · #8 05-15-2009, 10:49 AM

thanks everybody. will let you know how I make out

dannym · #9 05-20-2009, 09:43 AM

does anyone have a good link for setting the rotor runnout using a dial indicator?

Nevermind, I found a couple:

Wheel bearing preload tool

Wheel bearing adjustment with dial indicator

pawoSD · #10 05-20-2009, 10:21 AM

I just tighten the rotor runnout until the wheel is hard to turn, then I back it off 1/3 a turn or so. Has worked for me on the last several times I've done that job.

tyl604 · #11 05-20-2009, 01:09 PM

Looking for clarity. Are the races (bearings) in the rotors or not?

Brian - can you send a picture of the type tool that removes the races properly - sounds like you are talking about a slide hammer?

Thx

pawoSD · #12 05-20-2009, 01:16 PM

Quote:

Originally Posted by tyl604

Looking for clarity. Are the races (bearings) in the rotors or not?

Brian - can you send a picture of the type tool that removes the races properly - sounds like you are talking about a slide hammer?

Thx

No they are not in the rotors. The rotor is bolted to the wheel hub from the inside with allen bolts. The races and bearings are contained inside the hub.

The bearings can usually be re-packed with grease and re-used. The hub seal must be pulled and replaced.

I have never had to remove or replace a bearing race. Even when using new bearings I leave the old race installed....unless its damaged there is no point in removing it.

dannym · #13 05-20-2009, 02:09 PM

Some people would argue about leaving the races in.

I removed & repaced the races the last time I changed the bearings. Only because it's so easy & I have the proper tools.

I used a metal punch to get them started then used a brass drift to get them out the rest of the way. You must use brass so you don't mess up the hub.
Then use a seal driver to set the new seal.

http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=547
http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=93424

http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=95853

I got a nice heavy brass drift from Harbor Freight but I can't find it on line.

Danny

mobetta · #14 05-20-2009, 03:44 PM

the races should be replaced when replacing bearings, on principle.

the bearings do not need to be touched at all to replace the rotors, but one may as well repack them and replace the seal, as it will be damaged on removal.

the tools needed are -

17mm lugwrench to remove tire
prybar fro bearing cap
5mm allen for locknut
channel lock pliers for locknut
19mm for calipers + 12" wire to hang caliper from sway bar
10mm allen socket + 6" extension + 18"or longer breaker bar or impact wrench for rotor to hub bolts. upon removal of hub, attach it to the wheel w/ 2-3 lug bolts so you have leverage. reinstall w/ locktite blue.
bearing grease
dial caliper and stand to set bearings.

Firewater · #15 05-23-2009, 11:26 PM

Quote:

Originally Posted by mobetta

the races should be replaced when replacing bearings, on principle.

the bearings do not need to be touched at all to replace the rotors, but one may as well repack them and replace the seal, as it will be damaged on removal.

the tools needed are -

17mm lugwrench to remove tire
prybar fro bearing cap
5mm allen for locknut
channel lock pliers for locknut
19mm for calipers + 12" wire to hang caliper from sway bar
10mm allen socket + 6" extension + 18"or longer breaker bar or impact wrench for rotor to hub bolts. upon removal of hub, attach it to the wheel w/ 2-3 lug bolts so you have leverage. reinstall w/ locktite blue.
bearing grease
dial caliper and stand to set bearings.

I am doing my front rotors and pads now as well. I however did NOT buy the bearing seals. Should I stop now before I do irreversible "progress"? I DO have the bearings however. SKF from NAPA. Could I easily pick up the seals at a local auto parts store should I absolutely need them?

I was hoping to just do the rotors and pads for now and worry about the bearings later on when I have more time, money, and experience.