Basic rotor replacement/wheel bearing question (300D)
 

I want to replace my front calipers and rotors. The calipers are pretty banged up, and the LF rotor is also. I have a 85 300D (W123). I have never replaced the rotors on this car, but have read up on the process and the annoying bearing repacking need. The question is ...

Do I need any new seals or "races" to simply change out the rotor and repack the bearings? I do not have any bearing noise. Or can I just go in there, take out the bearings, clean and grease, and put them back in there?

I already received the reman calipers and rotors, but I did not order any seals or bearing parts. Thanks!

You do need the grease seal to retain the inner roller bearing. It's impossible to remove it without trashing it. Furthermore, it lives in a hostile environment and probably is due for a change anyway.

Any parts store should have the seals and bearings. You won't know if the bearings can be reused until you inspect them after cleaning.

Ok. Thanks.

And what about the dial indicator? I have read up on the need for it, but am still a little confused. It's only for tightening the hub right, so as not to crush the bearings? I have a torque wrench. Loose concepts floating around in my head. Can you tell?

The spec on the axial play is .0005". Very difficult to actually feel .0005". So, the indicator will allow you to get very close to the spec.

I've never used one. Try to remove every bit of clearance, but still feel the very slightest movement of the hub when you're done. This will still be too much play (probably .002" or so) but, the difference isn't worth the argument.

Whatever you do, do not go below zero on the clearance. You must feel the rotor move or verify the clearance with the indicator. Any bearing preload will shorten their lives dramatically.

Thanks Brian. Sorry for the stupid question, but how should I test the rotor movement? Just by grabbing it and moving it like I would if I was checking bearings normally?

Similar........but........it's a M/B and you are substituting the finesse of your fingers for a proper dial indicator.........so.........adjust technique accordingly.

Basically, you have to adjust it down very gradually until you can feel no movement and then back it off just the slightest bit.