PeachParts Mercedes-Benz Forum - View Single Post - W123 axle R&R job--some questions?

Jeremy5848 · #43 12-31-2006, 01:46 AM

Quote:

Originally Posted by dieseldan44

Jeremy5848, can you list the parts you needed to purchase in addition to the axles? You mentioned new diff seals and washers (as well as bolts that you re-loctited). Any other 'good idea to fix while youre there' parts?

The side cover (output) seals in the differential were bought from a local foreign car parts place (Smothers) here in Santa Rosa. I waved my hands and they looked in their computer and came up with their part number "MER 0039978347 Final Drive Seal." They had to order them but I was able to pick them up 24 hours later. Two seals and tax cost me $16.57. They were perfect matches for the old seals. I'm sure you can get them from Phil. I would have gone that route but was in a hurry. I don't have the factory part numbers. I made an install tool from ABS pipe; others have used a big socket. The factory has a special tool (of course).

An important note: the early design of the W123 cars (and probably others) called for spiral grooves to be worn into the end of the axle to keep oil from leaking through the seal. The later seal has a design that makes the grooves unnecessary. This is discussed in the FSM. It would be possibly to buy bargain seals that turned out to be the old design. Be careful. I wish I had a photo of the lip of the seal, showing the lines. The FSM shows them, I think.

The bolt, spacer, and washer that hold the axle to the brake hub may be reused. Mercedes uses a strange name (I forget) that doesn't sound at all like it might be a washer. I turned mine over and reused it. Next time it should probably be replaced. The metal will eventually become brittle.

I also replaced the rear sway bar links because they needed replacing and I was in the area, so to speak. Check the rear brake pads and rotors, also the emergency brake hardware. Look for leaking brake hoses and also for leaking fuel tank to steel fuel line hoses. Make sure all of the body drains that empty under the back of the car are clear. There are also some rubber parts that are part of the subframe but I'm not qualified so didn't look. Others have mentioned some rubber parts in the drive shaft as well as a diff input seal.

Make sure you clean the sealing surfaces of the diff and the cover really well and make sure there are no burrs. The silicone sealant (any kind) that is used is the only seal -- no gasket. After cleaning, wipe down the surfaces with alcohol to remove any remaining oil or grease.

Ditto on cleaning the drain and fill plugs. I used teflon tape, not sure if it was really necessary. Anti-seize might be a better idea, especially for the fill plug, which is a steel plug in an aluminum cover.

Take your time. Clean underneath first. Support the car securely. "Measure twice, cut once." The axles aren't terribly heavy but if one end comes loose unexpectedly, damage to you or to the diff can result. Put oil on the new side seals before you drive them in and before you insert the axles. Don't lose the clips. Remember the spacing washer, take it off of the old axle and put it on the new one, don't confuse left and right spacers, they may be different thickness.

The factory recommends replacing the four bolts that hold the diff carrier to the floor of the car. That is apparently because they don't trust people to remember to clean off the old bolts and add new blue Loc-Tite. The bolts don't stretch in use so there is no reason to not re-use an undamaged original. Same for the brake caliper bolts (two per caliper) if you decide to remove them (makes getting at the outside end of the axle easier). Don't let the calipers hang from the hoses. Use a piece of wire as a hanger. I also found that the caliper would sit up out of the way on the shield. See photo. I left the wire hanger on, just in case.