removing rotors without ruining berarings/grease seals - PeachParts Mercedes-Benz Forum

JHZR2 · #1 07-28-2002, 08:14 PM

Hi,

I just had my wheel bearings done a few months ago at the dealer. I will bedoing my brake pads and replacing the rotors as well in the next few weeksm so Im starting to prepare. Since I just got the bearing work donw, I would liek to know if it is possible to remove the rotors without taking off the grease seals and messing around with my ne and newly packed bearings. Can I just remove the cap, and leave the inner and outer bearings attached to the hub and all one piece, and just slide the old rotor off, and slide the new rotor on?

Also, does anyone have the torque specs for the allen bolts that hold the rotors to the hubs?

Finally, since it is apparetnyl really hard to get the rotors off the hubs, and I dont even have a vice, is it reccomended that I spray something on the bolts and between the rotor and hub so to make the removal easier?

Thanks very much,

JMH

engatwork · #2 07-28-2002, 08:25 PM

I don't think you can change the rotor without removing the hub. You should be able to reuse the seal. Be careful taking it all apart and try not to tear it. You will need to "reset" the front bearings unless you can mark them in such a way and put them back in the same position. You will need to hold the rotor/hub pretty securely when you remove/reinstall those fasteners.

MVK · #3 07-28-2002, 10:29 PM

Sorry No can do.
You have no choice but to remove the hub.
mvk

JHZR2 · #4 07-28-2002, 10:47 PM

thanks for the info, can you elaborate about resetting the bearings?

william rogers · #5 07-29-2002, 01:43 AM

I just replaced rotors on 126, when you get the rotor and hub off car bolt them back on wheel then soak them with penitrating oil and use breaker bar on 10 mm allen socket, wheel and tire can be leaned up against something solid so that you can get enough leverage, they are usally very tight mine had blue lock tight on them, clean old lock tite off (I use wire brush on drill) and put fresh lock tite on when putting new rotors on.......
william Rogers......

engatwork · #6 07-29-2002, 07:02 AM

Do a search on the wheel bearings. I have seen people "centerpunch" a mark on the wheel bearing locking nut (on wheel bearings that were properly set) and just put the nut back to the same position with the same bearings.

#7 08-01-2002, 04:11 PM

When replacing the rotors, it is advisable to put a THIN coating of anti-seize compound between the hub and the rotor to facilitate removal next time (the rotors can sometimes "rust-weld" themselves to the hub).

Setting the wheel bearing runout is best done with a dial gauge so that you can set the runout to the precise factory spec. Typical setup would be to use a magnetic base and holder with the dial gauge. Once you have the hub/rotor assy back on the spindle of the steering knuckle, tighten and back-off the spindle nut to set the bearings in position. Then, use the magnetic base to "grab" the hub/rotor assembly and setup the dial gauge to measure the spindle. Grab opposite edges of the rotor and push/pull the hub/rotor assembly in and out and watch the dial gauge to see how much runout there is. Gradually tighten the spindle nut until the runout is in factory spec (I don't know the spec for your car). Then lock the spindle nut in place with the allen screw.

This whole process sounds much more complicated than it actually is. Whoever sells you the dial gauge and base can probably show you exactly how it works.

#8 08-01-2002, 07:41 PM

You can separate the hub from the rotor w/o a torch or oil, but it takes two strong people!

I just did this last weekend. Not fun, but it worked. Then engatwork told me about those new fangled air wrenches!

Re bearings. We didn't use a dial guage, instead set the preload by the "feel" method. I wouldn't reccomend this unless you've done it before.

400E_FAN · #9 08-21-2003, 10:11 AM

I am in the middle of replacing a seized
caliper on my rear right. I decided to order
new rotors and pads. And as I was going
to be in there I decided to do the parking
brake pads etc.

But the rotors seem to be attached pretty
firmly. Have removed the hex bolt and rolled the "star" wheel to "open" the parking brake pads all the way....and I cannot get the rotors to budge.

Do the hubs have to come off to replace
rear rotors on a '92 400E (W124)?

And if that is the case what tool do I need
for hub removal?

I did quite a few searches but this thread
was the only one I found which mentioned
that hubs may have to be removed.

Any pointers would be very greatly
appreciated!

Moderator...
If this post needs to go to another thread in one of the other forums please feel free to remove..

aldedmon · #10 08-21-2003, 10:46 AM

To remove the rear rotors on a 400E, first remove the caliper assy. Then remove the hex allen that attaches the rotor to the hub assy. Spray WD40 or other lube on the center hub area. Take a fairly heavy hammer and "gently pursuade" the rotor by tapping it lightly but firmly in a circular motion. If you're reusing the rotor, use a piece of wood between the hammer and the rotor. If not, just wail away.
Interesting observation on the removal of the front rotors, where everyone says to remove the hub. I have never had to do this(is the W124 that much different than other models. To remove the Front rotor on the 400E(W124) you remove the caliper assy, remove the center attaching hex allen and tap/kick the rotor one good time. It pops right off......

400E_FAN · #11 08-21-2003, 12:23 PM

Thanks Albert....Sounds like I will need to hit it harder...I think I have been too gentle...Circular pattern with hammer will get executed tonight....I have had it "soaking" in WD40 for 2 days and those rotors have not given up their rust welds.... I will need to take the gloves off.

I have not driven it since the last weekend and I need my driving "fix" soon if I can get it all done alongwith a full brake fluid flush.....I will report back if things are still in flux by the end of the weekend.....

Wasuchi · #12 08-21-2003, 01:11 PM

aldedmon,

To remove the rotors on a W123 you have to remove the hub to get to the bolts that hold the rotor to it. They are on the backside and can't be reached otherwise. I'm guessing the rotors on a W124 must just sit over some studs or something (I've never seen one).

aldedmon · #13 08-21-2003, 01:52 PM

Okay, I see what you're saying

Brian Carlton · #14 08-21-2003, 08:15 PM

The best way to remove the rotor from the hub, without the risk of damage to the hub or the rotor, and without a suitable vise, is as follows:

After the rotor and hub are off the vehicle:

Thread three lug nuts into the tapped holes on the outside of the hub. Place the hub down on a table sitting on the lug nuts. Insert a steel bar, 18 inches length underneath the hub and between two of the three lug nuts. This is your breaker bar. Get a hex socket bit (I can't remember the size, but 8mm seems to stick in my mind) and a suitable adaptor for a 1/2 inch socket wrench (forget about the use of 3/8). Put an extension pipe (so that the length is 18 inches from the fastener) on the 1/2 inch socket wrench. Get the breaker bar (on the underside) and the pipe on the 1/2 inch socket (on the top) aligned within about 30 degrees of each other. Pull the extension pipe with one hand and push on the breaker bar with the other hand and the screw will release. Guaranteed.

Brian Carlton
1984 300SD