Have not seen this written about before:

1990 300E. I replaced the front and rear flex disks. Did not replaced bearing or carrier as I could detect no play there.

Symptom before were clunking due to mucho play in front disk. Rear disk was OK but I replaced it anyway, since I was there.

Had no vibration before, just clunking.

Now, no clunking but I have a vibration.

In the morning, when the car is cold, there is a very obvious driveline vibration from 35mph up. Only when coasting or light throttle. As the car warms up it fades away and stays away as long as the car does not cool completely off again.

???

Thanks

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2012 E350
2006 Callaway SC560

Was the driveshaft separated during the replacement of the flex disc?

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Jim

No. I did not take the driveshaft completely out and did not separate it.

Also, I installed the flex disks with the writing toward the shaft, like the originals were.

And, I properly placed the two different length bolts in the front flex disk.

Thanks

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2012 E350
2006 Callaway SC560

i had the exact problem with my 1990 190E. How did I get rid of the vibration? I sold it! Sorry.
Good Luck, I never did figure it out.

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Christopher Henkel
1990 190E 2.6 - Arctic white SOLD
1986 190E-16v - Blauswartze
1993 300CE - SOLD
2003 W208 CLK 320 Cabriolet - Magma Red

I guess you had to collapse the driveshaft to get the flex discs out? To do so, you probably loosened the big (48mm?) nut in the middle of the shaft where the front and rear halves meet.
The manual calls for 30-40Nm when re-tightening this nut. That is very little considering the size of the nut. Actually, this is on purpose as the driveshaft needs to adjust slightly in length to relieve stress. When the nut is too tight, stress may cause vibrations.
Bruno

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_
1992 300TE 160 kmiles

Well, I did not touch the big nut at all. The front shaft slid back just enough with the nut as is.

Thanks

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2012 E350
2006 Callaway SC560

Check your motor mounts and transmission mount.

John Mlynick
92 190E 2.3 140,000mi

Motor/Tranny mount sounds probable, wouldn't the vibration be present all the time if it was the drive shaft?

Any ideas on how to tighten the big 49mm nut to the torque spec without the ability to get a torque wrench on it? I have two or three torque wrenches, but I can only put sockets on them and a socket will not fit on the nut with the two halves of the shaft in place and I do not have a crawfoot adapter in the 48mm size or even know if one that size exists.
How can I torque it to specs?

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Christopher Henkel
1990 190E 2.6 - Arctic white SOLD
1986 190E-16v - Blauswartze
1993 300CE - SOLD
2003 W208 CLK 320 Cabriolet - Magma Red

It is an essential characteristic of oscillations/vibrations that a very small amount of initial vibrational energy 'feeds' on surrounding energy, channeling it into the vibration mode. Often, a very small correction is all that is needed to eliminate a strong vibration. In your case, NOT replacing the center carrier is the clue I would follow. Likely, even if you notice little play, the support has deteriorated, allowing just enough movement to amplify small power-line vibrations. Cruising above 35 mph requires enough power from the engine to feed the vibration if there is any weakness in the driveline support.

Steve

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'91 MB 190E 2.3
'08 RAV4 Ltd 3.5
'83 Lazy Daze m'home 5.7

When you say "..writing to shaft, like the originals.." IF you see any writing that says
"VORNE" that side mounts to the front. There is a chance someone got one of the old ones backward. Other than that, uuhhh... what everybody else said.

For the nut, big crescent or one like it, fish scale, little thread lock on the threads, helper or two to hold the shaft... I helped a friend with his like that a couple years ago - so far so good.

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1987 300D (230,000 mi on a #14 head-watching the temp gauge and keeping the ghost in the machine)
Raleigh NC - Home of deep fried sushi!

For the first three days after I replaced the disks, I would get the vibration just as described, exactly the same every morning, until things warmed up.

This morning I backed out of the garage and headed down the road. This time there was NO vibration.

So, either it was sitting in the "right" position overnight and will vibrate tomorrow, or it has healed.

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2012 E350
2006 Callaway SC560

You have to leave the center bearing bracket mounting bolts, rear trans mount bolt, and drive shaft slide nuts loose and push the car foward/backwards a few times for the drive assem to center/align itself..
...then you tighten everything up.

Sorry to hear about your vibration, mine was the center support. If ya spent the money on the flex, change the center support. It's only 30.00 and the labor. Read my write up it will help.

Where is the write up? DIY?

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Christopher Henkel
1990 190E 2.6 - Arctic white SOLD
1986 190E-16v - Blauswartze
1993 300CE - SOLD
2003 W208 CLK 320 Cabriolet - Magma Red