How to replace front rotors on 83 300TD?
 

Hi there, I used the search but couldn't come up with the info.
I need to replace the rotors on my wagon, they are wrapped, and I get the pulsation when I stop. The pulsation is changes with the speed so I know it is the rotors.

When I took the wheels of, including the calipers, I couldn't figure out how to remove the rotors. Do I need to remove the hub too?
If yes I'll appreciate a link which shows how to do it.

Thanks in advance,
Yossi

You need a manual. You have to take the front hub apart. That means cleaning, packing and setting the preload of the bearings. I'm sure it's in the archives but if you haven't at least seen it done you don't want to do this without pictures to guide you.

Sixto
95 S420
87 300SDL

There is an Allen screw or two between the lug bolt holes that retain the rotor to the hub. It is not necessary to remove wheel bearings and hub unless you wish to clean and pack them.

Good luck,

No Larry, I think your thinking of the 300E.

On the W123 the hub must be removed to replace the front rotors.
Remove the caliper
Remove the bearing grease cap
Use an Allen wrench to loosen the large nut
Remove the nut.
Then pull the hub/rotor assembly off the steering knuckle.
To remove the rotor turn the hub over and you will see 5 Allen head bolts that hold the rotor to the hub.
You will probably need an impact wrench to dislodge the bolts.
Install the new rotor to the hub and torque, use locktight.
Now that you have the hub off it is a good idea to repack or replace the bearings.
Assemble the setup and set the wheel bearing nut as per Mercedes methods.
For this do a search on wheel bearings in this forum.
Here is the Service Manual section for the job.

http://skinnerbox.steaky.org/Service/W123/Index/Groups/42BrakeSystem.htm

Dave

Yes, you will need lots of luck to get the rotors off with the hub still installed.

My bad. I was indeed thinking of the 124 car. It's been a LOOoong time since I changed a 123 rotor. In fact, I don't think that I've ever changed a 123 rotor. The only time I've replaced a pair was when I took the entire front suspension off my 240D Euro parts car and put it on my Euro 240D and it was over 500,000 miles. As I recall I pulled the calipers and hung them on wire and then pulled the whole front suspension, one side at a time at the control arm bushings, then just put the whole mess under there, so I never changed a rotor on a hub. I have removed the whole hub and rotor a few times to grease and pack and that's it.

Since IMHO the 123 is a way more trouble free car than a 124, I probably have as much repair time on my relatively low mileage 300E as I do in the entire 800,000 + miles in 123's.

Have a great day,

Here's a trick I used to remove the 5 allen bolts that hold the rotor to the hub: After you remove the hub/rotor assembly from the spindle remount the hub to the wheel you removed with a few of the lug bolts. Having the hub mounted on the wheel gives you the leverage you need to be able to remove the allen bolts using hand tools. You can stand/sit on the wheel while you work and the wheel holds the hub for you. Spray them down with liquid wrench or PB blaster first as that will help with the rust and use locktite on them when you replace them as that was used originally on them when they were assembled. They are still hard to remove but will break free with a 2 foot breaker bar.

Good luck!

Good tip for the DIYer that has no impact wrench.

Have a great day,

Or, you could simply put the rotor in a vise and get at the allen bolts that way. I've done it several times--easy as pie. To install the new rotor, put it in the vise with a rag to protect the surface.

Joe B.

I was thinking of the DIYers with limited tools. Many of them won't have a vise.

Have a great day,

Have you used an impact wrench on the socket head cap screws? Can the screw withstand this without stripping? I would be very hesitant to do this.

Instead of using the impact wrench, I put two lug nuts into the hub and shoved a breaker bar between them for counter torque. I run the breaker bar with the socket bit on the top and run the breaker bar through the lugs, on the bottom, and let it rest against my leg for leverage.

I also do the same exact thing :D

I've used an impact many times.....about 1 out of 6 times the allen head strips out.....If you heat the bolt head to red first, they always come out.

But I dunno about north of Detroit.......


.

Thanks for your replies
 

Hi There,

I have the manual CD's and the book. I couldn't find the relevant information how to remove the hub. I understand what I need to do and I'll go at it once the bearing kit will show up. I decided to replace them, even without visual inspection, since spinning the rotoer without the wheel makes all sorts of noises.
I followed the link that was provided in the link and couldn't find the relevant information how to remove the hub. If you have the job number I'll appreciate it.
Wanted to thank the detailed description how to do the job + tip regarding re-mounting the hub to the wheel in order to release the allen screws. I prefer not to use power tools if I can help it(I do have a 5HP air compressor). I hope to post pictures once it is all done.
Thanks,
Yossi
PS. I guess that they used the blue NOT the red locktight?

Please be sure and torque the allen bolts to the proper torque. If memory serves correct, it should be 100ft/lbs. (yeah, you'll have to put some "butt" into it).

Have fun!