Flex Disk Replacement

[HuskerBenz]

I'm going to replace both front and rear flex disks on my '83 300SD. The old disks were showing some threads, so they're toast.

The rear disk is easy enough to get to, but I have some questions about the front......I plan on removing the rear trans. mount for better access. Does the transmission have to be supported when the mount is removed? Where does one support it from? Does the driveshaft have to be supported if you do one disk at a time, or can the driveshaft support bearing take a temporary cantilevered load?

I'm also going to do the rear diff. mount. Looks simple enough, or are looks deceiving?

Thanks,
Christian

[vwbuge]

You may as well replace the rear trans mount also. I think they are only a couple of bucks. I think the trans can be lifted slightly by just using a jack and a piece of wood. I had my entire shaft off when I replaced mine because I was replacing the support bearing also. It may be easier just to drop everything. Just be sure to mark the shaft where it comes apart so you can put it back together. Not really a hard job, just cramped if you are working under the car on your back.

[The Gears]

Just finished the entire job, front and rear disks as well as the center bearing and mount. I did not remove the trani mount as there is room to get a box end wrench up to the rear of the disk easly. looking toward the front, on the left side of the trani X member there is good access for a flat wrench to hold the locking nuts. Use a couple of extensions and an impact wrench or a 1/2" drive breaker bar to reach the bolts after removing the rear drive shaft section.
The front shaft with disk attached will come out to the rear over the X member. 5 hour job. Lifting the car is the hard part.

[compu_85]

My body has 202k on it, and both flex disks are showing cracks. I have new ones to install. Should I just replace the center bearing while I'm in there?

-Jason

[The Gears]

Originally Posted by compu_85

My body has 202k on it, and both flex disks are showing cracks. I have new ones to install. Should I just replace the center bearing while I'm in there?

-Jason

yes and the rubber that supports it.

[pawoSD]

When I did mine I replaced everything. Both discs, carrier, and bearing. Better to do it all at once. I had already replaced my trans mount the year before, but if that hasn't been changed I'd do that too.

[Dee8go]

Do you have to pull the drive shaft all the way out to do the center bearing? I did the front flex disc on mine, but still have the rear one to do yet.

[tobybul]

As everyone seem to have said, it is best to drop all of the driveshaft. This means also dropping the center mount. And if you have not replaced the center bearing and mount, this would be the time to do it.

I believe its easier to work on the flex disc replacement when the front and rear driveshafts are off.

Not sure what year your D is but when separating the driveshafts, make sure that they are put back exactly the way they were removed. At least from 84 on up, MB put notches on both shafts to show where to line them up. If yours does not have it, put your own mark. Vibration can result if not lined up.

Also, make sure that when you put back the center mount that both bolts holding the mount to the body are evenly lined up on the slot of the mount. Otherwise, the mount can end up slightly cocked. This can cause a hum or mild vibration at certain speeds and lead to premature center bearing failure.

[compu_85]

I know you have to keep the 2 halves of the driveshaft in alignment, but do you also need to keep the drive shaft lined up with the transmission and diff?

-J

[tobybul]

Originally Posted by compu_85

I know you have to keep the 2 halves of the driveshaft in alignment, but do you also need to keep the drive shaft lined up with the transmission and diff?

-J

not that I know of.

[Dee8go]

I think the center support bearing on my SEC is hidden under the exhaust heat shield, so I haven't looked at it. I don't know what the situation is on the 300TD.