takkie

Hi,

plan on replacing rotor tmr - but i want to make sure i have all the right tools. From the audipages link - i think i have all the socket/wrenches neccessary.

The only thing i am unsure of is the rotor - what shape/size is needed to take off the rotor? I have not yet seen any DIY guide for taking off Rotor on a ML350 yet... if someone know of one, pls share.

Is front/back the same size/shape procedure as far as taking off rotor? i know the front is vented, and the back is solid - does it make it difference, procedure wise?

Thanks,

sheepdog8

I haven't yet done the brakes on my ML, but I did put all new brakes on the front of my son ' sold 98 E320 last year. Check YouTube vids, usually pretty helpful before you get your hands dirty. On the E I just took the wheel off, best I can remember a 19mm thin wall socket for wheel studs. Then the disc was only held on with 1 Torx bolt flush with the rotor. About a T30 maybe. I had to spray penetrating oil around the center of the disc where it met the wheel bearing cap due to light rust. Used hammer to tap around edge from back of disc & it just comes off. Other than the 1 restraining bolt, the disc just fits tightly & you have the wheel also holding it on. Torque for the wheel studs is about 90 ft/ lbs. I had to hit the back of that disc hard to work it off, but wasn't too bad of a job. Way cheaper than dealer!

sheepdog8

There is a good quick vid on YouTube. It looks the same as the E class I did. He said need a 9mm & 20mm for caliper & the disk is held on with 1 T30 Torx.

N_Jay

The rears on my 2008 GL320 needed 18 mm to take off the caliper bracket to get the rotor off.
I have heard the fronts may be 20 mm.

takkie

alright. thanks. I dont have any Torx bits, i should get some before taking off the wheels.

thanks

thunderbirl

Just did my 2008 W164 all around. The rotors were original with 115k on them. I'd replaced the pads about 60K ago. I've done rotor replacement many times over the years on other cars. This replacement was physically quite challenging - mostly due to the size of the hardware.

In the front, you'll need a 21 mm impact socket for the caliper bracket and 9 mm allen hex for the caliper slide.
In the rear, you'll need an 18 mm impact socket for the caliper bracket and a 7 mm allen hex for the caliper slide.

The caliper bracket bolts have blue loc-tite on them. The right rear and left front are really hard to apply enough force by lifting on the wrench. I used another jack to force the wrench upward on those! The others were encouraged with a heavy mallet on the breaker bar - hence my preference for impact sockets!

There is room to use a standard wrench rather than an impact socket. You can use standard allen hex wrenches or you can get the socket drive versions. The sockets work ok, with the exception that the lower caliper slide bolt may pin the ratchet drive into the lower suspension arm on the rears.

The Torx head connecting the rotors to the hubs is a T30. You'll also use an 11 mm wrench for the bleeder valves.

I used Centrix 125 series rotors. They were perfect with every hole and nuance of the OEM. I went with ceramic Akebono pads - just to see what happens!

takkie

lkchris

It needs to be a particularly compact impact wrench.

At the rear, if you use an allen driver socket, it needs to be a stubby one. And of course you should use an allen driver socket if you're going to tighten using a torque wrench.

Mercedes specifies that the bolts mounting the caliper carrier brackets to the hub and the screws securing the rotor to the hub be replaced, not reused. Have these on hand before starting. Do not listen to shadetree mek-a-niks who claim this is unnecessary, they're not engineers. Use bolts obtained from Mercedes, nothing else.

You're going to need a fairly heavy hammer to beat the rotors unstuck from the hub (rust). Mercedes specifies thorough cleaning of the hub mating surface with a wire brush to ensure the new rotor fits flat to the hub.

The "procedure difference" as regards the rear rotors is ... be sure parking brake is off! You'll need to transfer the rubber plug from the old rotor to the new one ... plug for parking brake shoe adjustment access hole. Unless you've driven a lot with the parking brake on, there should be nothing else required as regards the parking brakes.

You're going to need probably a tool to push the pistons back into the calipers so new fat pads will fit. This risks overflowing the master cylinder, so be watchful. The Lisle tool from Pep Boys works as well as anything for this.

N_Jay

Those large bolts are tightened nowhere near their yield point.
My guess is that MB says to replace them in the "official" instructions is; (In this order)
1)Bbecause at MB labor rates it is cheaper to put in new, bolts with locktight from the supplier then to has a mechanic clean teh bolts sufficiently to apply new locktight.
2) Because the may be rusted or teh head buggered juts enough to make assembly (or the next disassembly) a royal PITA
3) Because some over conscious lawyer is risk-control asked "Could a previous mechanic have possibly done something that could make that bolt somewhat less "safe" then designed?"

texterted

Put a dab of blue loctite on those large caliper bolts on reassembly. I had one come loose once on mine!

N_Jay

Put on more than a dab,

lkchris

N_Jay

I would love to know your background which provides your expertise.

I am a degreed engineer, and previous product manager, and had Mercedes as one of the companies I provided OEM products for.

That said, I have zero connection with brake systems or the OEM suppliers of the parts of MB braking systems, however as a shade tree mechanic, I have worked on, replaced and modified disk brake systems on many cars including the fashioning of caliper mounting bolts for brake conversons where the factory supplied bolts were unsuitable for some reason.

I have also removed and replaced countless caliper mounting bolts over a 40 year history with cars and have never seen a bolt that had become damaged or deformed from its normal and proper operation, nor had any break, or come loose.

Other than that I an willfully ignorant.

dfghhgfd

The cars are German. In Germany they basically replace everything at the dealership no matter what.
While in the Air Force in the mid 80's I was stationed in Germany and had bought a 1967 Porsche 911 that had some carburetor problems that required the carbs to be rebuilt. Age being one of the main problems. I had some American catalogs that sold Porsche parts that listed actual Porsche part numbered carb rebuild kits. I thought I'd try going down to the local Porsche dealer and get them so I wouldn't have to wait for shipping time from California to Germany, not to mention it had to be cheaper than paying shipping to the US and back to Germany again. At the Porsche dealer the master parts guy told me in no uncertain terms that there was no such thing as a carburetor rebuild kit! I asked if they just always replaced the carbs for even minor issues and he answered 'Ya'. I got him to humor me and at least look up to see if there was such a thing as I had a Porsche number from the US and that I was just a stupid American, anyway. He again told me how long he'd been doing his job and he was sure there was no such thing, but he'd look. After fumbling around with the microfiche he exclaimed some vulgarities in German that basically were 'I'll be a son-of-a-*****'! He had never seen or heard of there being a rebuild kit for any carburetors on a Porsche, yet there was the official Porsche microfiche with a part number and a picture.
Moral of the story is that although there are items that are designed to an exact tolerance and do not accommodate reuse, like turning you breaks or head bolts, there are others that are just replaced because that's how they've always done it in Germany.
That's my 2 cents.