Still on the 1991 560SEL, the bolt attaching the brake rotor to the hub seems to be on tight. I used PB Blaster to loosen it up. I'm afraid if I torque on it too hard it may strip. On another website, a guy uses a brass hammer to strike on the edge of the rotors to help break the rotor loose. However, he first loosens the bolt holding the rotor to the hub which is my problem. Can I use a heat gun to help loosen up the attachment bolt?

I really don't want to strip this bolt out.......

You can use heat gun. not sure how much good it will do though. No big deal if you strip it, just drill head off and then knock rotor off (if you are replacing rotors).

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Jim

Using eye protection! Take a punch and strike the center of the bolt inside the six sided hole, not on the face of the bolt, rather hard several times. Then take a pointed punch on the face of the bolt outside of the six sided hole on the flat part in the direction that you want the bolt to turn. If you can, have a helper wearing EYE PROTECTION apply moderate torque using the bit in the six sided hole while you strike it around in the loosening direction. It will come out.

Good luck!!!

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"Rudeness is a weak man's imitation of strength" - Eric Hoffer

After a few minutes of PB Blaster, the bolt came right out! Great, however, the rotor seems to be stuck on the hub. I took the parking brakes off and proceeded to place a small 2X4 on the hub and struck the hub in various places with a sledge hammer. The hub still doesn't want to come off! What to do????

HM:

Are you working on the rears? You have not said so.

Are you replacing the rotors? Do you have new ones?
If you have new rotors, place a block of wood thru the caliper opening on the inside face of the rotor. Hit the wood with a hammer to knock the rotor to the outside. Turn the rotor a few degrees, hit again. Turn, hit, turn, hit.

Put PB Blaster around the hub flange...wait a few minutes and do what Frank R said.

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"Rudeness is a weak man's imitation of strength" - Eric Hoffer

Yes, I am working on the rear rotors. I have new Brembo rotors to install so I will try your instructions and report back.

Your idea worked, after a few hard hits with a sledge hammer against a small piece of 2X4" lumber from the backside, the rotor came free!

Question, on the new Brembo rotor, should I use brake cleaner to remove the factory coating? Another guy said to use water with some dish detergent to remove the factory coating. Someone else said leave it alone.....

First, detergent with fine ScotchBrite, then brake cleaner. Do not use anything that contains oily components.

It depends on what type of coating is on the rotors. The rotors we used to get had some sort of light oil coating that needed to be washed off. But, some rotors these days have a rust preventing zinc coating. The ones I last installed said to leave it on.

Brembo says:
Huskyman, you should find out and advise just what type of coating you have.

If it is zinc, this link has some good info. If plain steel with oily surface coating, Frank's advice is good.

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Graham
85 300D,72 350SL, 98 E320, Outback 2.5

The Brembo package says to use brake cleaner to clean the rotor prior to installation. Question, should I use Permatex Threadlocker Blue on the caliper bolts? Also, the Brembo box says to clean the hub of any rust then install the rotor and check the runout using a dial caliper. I have this type of dial caliper, can I use it to check run out?

https://www.napaonline.com/napa/en/p/SER3754/SER3754

Use the brake cleaner on the rotors. Use a wire brush, preferably a wire wheel and drill, on the hub to get the rust off. Then use a light coat of grease on the hub to keep the rust off and to keep the rotor from rusting on the hub in the future. This trick works amazing. I even apply a very thin coat of white lithium grease to the hat of the rotor to keep it from rusting. It works amazing, just dont get any on the part of the rotor where the pads rest.

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1990 190E 3.0L

OK, I lightly coated the rotor hub with white lithium grease inside and out being careful not to get it on the braking surface. I also used Mercedes Benz brake pad grease on the sides of the pads, the back of the pads and the holes in the pads where the pins install. I then coated the pins with mercedes benz brake pad grease. I'm having trouble reinstalling the brake pad anti-rattle spring. Any ideas on how to reinstall it properly?

Install both pads, and one of the pins. Then slide first end of spring under the pin. The 2 short ends of the spring rest on top of the low part of the pads so that the top of the spring is flush with the edge of caliper. Next, press down on the other end of the spring and slide the other pin through the caliper hole and brake pad hole and over the other end of the pin.

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1990 190E 3.0L

HuskyMan, the gray primer on the rotors should be left as-is. Braking will remove the primer from the brake pad contact surface only, and the other surfaces will not rust.

When hammering on rotors to loosen them, it's best to install one lug bolt a few turns to prevent the rotor from flying off.

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Fred Hoelzle