Drive train vibration

[rgafitanu@gmail.com]

I have a vibration that starts around 50 MPH. It is a rolling/pulsating vibration that gets faster as the speed increases. When I release the acceleration the vibration is continuous (not pulsating). It is not present in other gears at the same rpm which makes me believe the cause is downstream of transmission. I had the same vibration before I changed the rear axle to 3.27 last November which may single out the drive shaft and components.
The car had a partial restoration in 1989 and sat until 1 1/2 years ago when I bought it and continued the restoration. I changed almost all rubber things. However, the flex disc and the shaft bearing support appeared in good condition (see pictures). It is a W111 so the shaft would probably be longer but I am hoping somebody has some information. Next step would be to mount a small camera at the shaft to capture the location of the vibration, I guess.
Any input is appreciated.

Thank you

[gimp]

I had a vibration that would start at about 60 miles mph and get worse as I picked up speed.
Had the wheels balanced and everything checked underneath, but the vibration persisted.
Finally bought a new set of tires and the problem was solved.
Frank

[Cees Klumper]

To check Frank's suggestion, maybe swap the wheels fromt and back to see if anything changes.

[rgafitanu@gmail.com]

I know that the topic is older but the vibration is still there. I managed to fit a small webcam next to the drive shaft. To me it looks that the drive shaft is vibrating in tune with the noise. So, am I looking at removing the drive shaft to get it to a balancing shop?

[stickandrudderman]

Check the "spider" and centre bearing at the front of the propshaft.

[rgafitanu@gmail.com]

The spider and the central bearing "look" good and new, see pictures in the first post. I don't know how to check the bearing with the shaft installed. Is the clip visible, I'm not sure if I did the attachment right.

Radu

[mdsalemi]

My own two cents here:

1. Replace the flex-disk, and ensure that all the bolts going through it are correct and torqued to specification.
2. Send the drive shaft out to one of the Mercedes-Benz driveshaft specialists for a balance and rebuild. The rebuild will include changing the U-Joints.

PM me and I'll give you two contacts for drive shaft specialists. One of them I've used...twice.

[Iconic]

Ragu G,
1. In the initial picture it shows the bolts in alternating orientation. That is not correct. All six bolts should be in the same orientation. In other words, all six nuts should be on the transmission side.
2. It looks like there might be washers between your flange and flex disk. That would not be correct also, but I cannot tell for sure.

If #2 is correct, then I could easily see the flex disk "wearing out" prematurely. I don't know why #1 is important, all I know is I read it is important ... so I paid close attention when I replace mine.
I'll ask others to comment if these issues would cause a vibration.
Good luck !!
Mark

[mbzse]

Check the "spider" and centre bearing at the front of the propshaft

Radu, it is important to assemble the parts correctly, like Colin, Mike and Mark suggest in their replies to you. For instance read the Workshop manual or even take a look in the Tech manual of this website
https://www.sl113.org/wiki/DriveShaft/FlexDisc

A question, what is the flange w holes that is visible in your picture (marked in pic attached)?

[rgafitanu@gmail.com]

I realized after reading more posts that my bolts are in the wrong orientation. I wasn't considering the flex disc as a culprit because it really looks very good, straight and unstressed but that's easy to replace.
The car had an attempted restoration in 1989 and I am not sure if the drive shaft splines have been matched on reassembly. I hope that the mpg file works and you can see it. I should position the webcam towards the flex disc to see if it's vibrating.
I have no clue what is the plate that you mention. It is #88 on the EPC diagram and it is present only for the W111, the W113 doesn't show it. I am actually very curios to find out what was it used for. The holes appear to have had a function.

[naniroma0]

Hello,
This solved the problem?

[rgafitanu@gmail.com]

I replaced the flex disc, the mid bearing, rubber and the half spheres located at the transmission connection. I couldn't find a shaft balancing shop in New England that would balance an MB shaft so I just put everything back with the splines in the original position. The vibration is almost gone and it does not bother me anymore.
The plate that I was asking is actually used to tie the exhaust down pipes to it.

[naniroma0]

Hello,
thanks for your answer