How hard is it to replace the flex discs on the drive shaft (76 280C)? - PeachParts Mercedes-Benz Forum

Tomas7 · #1 01-31-2018, 05:00 PM

I noticed while I was underneath her that the front flex disc is slightly torn and I thought it would be a good idea to replace them since the car is 41 years young.
Is this a huge production? It looked to me like 6 bolts off and on.

Thanks in advance.

gmog220d · #2 01-31-2018, 08:38 PM

I've never replaced just the flex discs because the center support bracket and bearing needed replacing, too. I've always removed the drive shaft for such work. If you don't have to replace the center support then I suppose you could get away with replacing the discs without removing the shaft from the car. You'd need to figure out how to let each end of the drive shaft move enough along the axis to disengage them from the flanges they connect to, as well as give you enough room to work.

How's the center support look? The rubber bushing is usually deteriorated and missing the rubber, and the bearing is usually toast as well. Notice any vibrations coming from the drive line at highway speeds? Might be time for a complete overhaul of you car's driveshaft anyway.

FWIW the driveshaft is not too hard to remove and install. I can't imagine figuring out how to replace the flex discs without removing the shaft would be too tough.

Mike D · #3 01-31-2018, 09:15 PM

If you drop the drive shaft then there is a specific procedure to re-seat the carrier/center support bearing.

Replace the driveshaft and guibos. Install the bearing bolts snug, not tight. Lower car to sit full weight on the wheels. Rock the car back and forth three or four times. If possible, tighten the bolts with car sitting on the ground, if not, then lift the FRONT of the car enough to gain access to the bolts.

If you split the drive shaft be sure to mark the halves and re-install in the same orientation to preserve the balance.

Good time to inspect the transmission mount while you are there.

ESchwab · #4 01-31-2018, 09:46 PM

You might get some benefit from this technical article on changing the flex discs on the W210 models.

https://www.pelicanparts.com/techarticles/Mercedes-Benz/21-TRANS-Flex_Disc_Replacement/21-TRANS-Flex_Disc_Replacement.htm

Tomas7 · #5 01-31-2018, 10:32 PM

I am going to listen to advice and replace the center support bearing/bracket as well. I think that doing this, even if it looks good, falls under the category of preventive maintenance. (it cannot be a healthy part on a 1976 car).

Thank you guys very, very much.

optimusprime · #6 02-01-2018, 05:56 AM

You need to mark all the parts of the driveshaft or propshaft before removal .If its fitted wrong you wont get the balance right .You would learn more if you visit youtube videos this is a good way to see how its done . You might just replace the front and rear with a pinchbar .But centre bearing will need the prop removed .So all the prop will need taking down to make all replacments easy . Important to mark all parts beforhand.Good luck .

Diseasel300 · #7 02-01-2018, 09:42 AM

While you have the driveshaft out, check the condition of the U-joint as well. If you feel a "notch" or if it's stiff, you might consider having the bearings replaced or source a rebuilt driveshaft.

Tomas7 · #8 02-01-2018, 09:42 AM

Quote:

Originally Posted by optimusprime

You need to mark all the parts of the driveshaft or propshaft before removal .If its fitted wrong you wont get the balance right .You would learn more if you visit youtube videos this is a good way to see how its done . You might just replace the front and rear with a pinchbar .But centre bearing will need the prop removed .So all the prop will need taking down to make all replacments easy . Important to mark all parts beforhand.Good luck .

Will do. Thank you.

Idle · #9 02-01-2018, 02:01 PM

Every time I do this I knock off a balance weight. Sometimes two of them.

I don't know about every drive shaft that came from Mercedes but I have always found these weights were glued on. A bit of cleaning and some superglue is all it takes to reattach them.

Tomas7 · #10 02-01-2018, 02:53 PM

Quote:

Originally Posted by Idle

Every time I do this I knock off a balance weight. Sometimes two of them.

I don't know about every drive shaft that came from Mercedes but I have always found these weights were glued on. A bit of cleaning and some superglue is all it takes to reattach them.

And they stay on with super glue?
LOL That's funny.
Thanks for the tip.

Idle · #11 02-01-2018, 04:51 PM

Quote:

Originally Posted by Tomas7

And they stay on with super glue?
LOL That's funny.
Thanks for the tip.

Yup. I think they were put on that way.

The first time I knocked one off I thought I would have to take a trip to the welding shop. Then I noticed there were no weld marks on the parts.

There was a clear indication of where the weights had been on the shaft. They were just cleaner.

And if they had been welded on they would not have just dropped off when I banged the driveshaft around.

So I tried the superglue with a C-clamp to hold it overnight. I never had one come off.

Tomas7 · #12 02-01-2018, 05:03 PM

Quote:

Originally Posted by Idle

Yup. I think they were put on that way.

The first time I knocked one off I thought I would have to take a trip to the welding shop. Then I noticed there were no weld marks on the parts.

There was a clear indication of where the weights had been on the shaft. They were just cleaner.

And if they had been welded on they would not have just dropped off when I banged the driveshaft around.

So I tried the superglue with a C-clamp to hold it overnight. I never had one come off.

Very nice. Thanks.

Mike D · #13 02-01-2018, 06:00 PM

J-B Weld or any metal epoxy will work also. I'm not a big fan of the "super" glues.

Mostly 'cause I've stuck too much stuff to myself.

Idle · #14 02-02-2018, 01:44 PM

Quote:

Originally Posted by Mike D

J-B Weld or any metal epoxy will work also. I'm not a big fan of the "super" glues.

Mostly 'cause I've stuck too much stuff to myself.

JB Weld would be good, too. Because it's waterproof.

Tomas7 · #15 02-25-2018, 09:07 AM

Here's a tip....if you ever do the flex discs, go ahead and order the trans mount as well. Chances are that along with the flex discs, it has suffered some wear. Mine looked OK but upon closer inspection there were cracks that only showed upon me twisting and applying pressure.
Now, I have to go back underneath her again and change the mount when this could have been done in one shot.
I replaced both guibos and the center carrier bearing and the bracket that holds it.
The guibos were both torn around a few of the bolt holes. The front one looked a tad lopsided.
Oddly enough my car demonstrated no vibration.