While trying to replace my transmission mount I noticed that, first, I couldn't get a wrench on the top nut to get it off and, second, that there is a harmonic balancer-looking thing on my drive shaft that is bolted on to the flex front flex disc.

Mine has a shiny metallic outer ring and black rubber, like a engine or tranny mount, connecting the ring to the drive shaft.

The rubber on mine has come apart in two places but the ring is still attached.

What is this thing and should I replace it?

Also, how do you get that top nut off the transmission mount?

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1993 W124 300D
-297K on the clock as I type this.

Do you mean the flex disk?

http://catalog.peachparts.com/item.wws?sku=W0133-1613916&itempk=104024&mfr=Lemfoerder&weight=2.35

Sixto
87 300D

No.

It's bolted onto the drive shaft using the same bolts that hold the drive shaft to the flex disc.

It sits right above the transmission mount nut and that's why I can't take the mount off without removing this balancer thing.

It needs to be replaced but I don't know what it is.

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1993 W124 300D
-297K on the clock as I type this.

Sounds like the balancer type ring that is found on some cars with manual transmissions, I don't know what the proper MB nomeclature for this part is though! If in the EPC you look up the 124.130 models after 1989 under the propellor shaft you can see a picture of it in the parts diagram #176!

To get to the transmission mount top nut you will at the very least have to disconnect the flex disk from the tranny yoke, then loosen the 46 mm driveshaft nut. Then you might be able to collapse the shaft enough to lever the end of the drive shaft off the tranny output shaft nub which will allow you to push the flex disk and driveshaft upwards enough to get at the tranny mount upper nut. If not you may also need to drop the tranny cross member to allow the tranny tailshaft enough drop to get at it. Worst case, disconnect the driveshaft at the differential and then the center bearing carrier bracket so you can pull the driveshaft backwards enough to clear the nut!

The nut is 19 mm and there is not much clearence to turn it, I have and use a wrench from and old BMW tool kit that works perfect for this job. Its a "dog bone style" that's got a 12 point 19 mm ring wrench with a very slim profile and thin ring, other end is similar just 17 mm. Good luck!

I will definitely just remove the cross member and lower the whole thing.

If that ring weren't there I could get a socket on it this way.

So, you think that ring is normally what you find on a manual tranny car?

I wonder why in the hell I have it on mine?

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1993 W124 300D
-297K on the clock as I type this.

I have only seen them on MB cars with manual transmissions, the one you've describe and the one pictured in the EPC that I mention is the type that are installed on the 1986 300E 5 speed manual transmission cars that I have. There is a similar type ring only heavier/beefier that I have seen installed on 123 5 speed GETRAG manual transmission cars with OM615/OM617/M110 engines.

It may have been factory for your year car or perhaps the driveshaft was replaced. The ring itself is a seperate part most likely only available from MB I'd bet.

Its a vibration damping device. You can run without it but there will be a bit more vibration. I have run them both ways and really cannot tell the difference, so if you find its giving you trouble you can probably ditch it without much risk.

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

That's good to know because the one on there now can't be doing much anyway in it's current state.

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1993 W124 300D
-297K on the clock as I type this.

I don;t know the exact name of it either. What it should be called is "useless."