SDL driveline vibration
 

Now that the cold has arrived in NY, the driveline vibration on the SDL is definitely more noticeable.

When cold, there is a moderate vibration in the driveline from 1700 to 2200 rpm and it lessens to a minimal vibration at 2600 rpm and above.

However, when fully warmed up, the vibration lessens to less than moderate.............almost minimal at 1700 to 2200 rpm and is almost unnoticeable at higher rpm's.

My questions to anyone who has experienced this:

1) Center bearing

2) Universal joint

3) both??


While I can certainly replace everything under there while I'm in the process...........any insight from folks who have changed one or the other would be appreciated.

I'm contemplating purchasing a rebuilt and balanced driveshaft and just exchange the entire deal..........unless someone has a better idea on isolating the issue.

This under acceleration? I have it from about 2550-2800rpm under high throttle acceleration, nothing on cruise. I haven't started messing around yet as my suspension/driveline is pretty much shot.

I'm guessing it's related to the flex discs and/or the center support bearing.

Seems like something rubber...cold weather = harder rubber, right?

i also have a high throttle situation vibration around 2200-2500,if i ease thru this rpm range i have no vibration or verrry little.

It's much worse under acceleration. On cruise, it's very slight. On the way back from CT tonight, it was barely noticeable. Even at lower rpm's, it's barely a problem........once the vehicle gets a good run.

I wonder if it's worth changing the center support with the bearing rather than completely exchanging drive shafts.........

I can't imagine a U-joint getting better after it "warms up".......??? Anyone??

What about flex discs? Like wallknight said, colder weather, harder rubber. Maybe the discs are on the decline and cold is making it worse? I'm just guessing.:o They'd be easy to replace ...

Possible, but, I don't think a warmer flex disc is going to allow the driveshaft to take a different position with respect to the desired rotating centerline.

The center bearing support.......however.......

It's only about a $10 part... but the labor will make you :mad:

My brother got me a deal with one of the fellows at the dealership. He'll do the job on the lift on a Sunday.........I'm not struggling on my back on the cold floor.......just need to decide whether to bite the bullet and get a completely new shaft........or not. If the U-joint turns out to be toast.........I need the new shaft.

Either way you'd need the flex discs and bearing, I'd give it a shot first since you have the lift handy. Can probably knock it out in a few hours at the most.

I would need to feel it. But its probably not the U joint. Mine was perfectly tight at over 250k miles, and even with my replace everything attitude I didn't change it.

I would suspect the center bearing or center bearing support, or worn engine/trans mounts causing the whole thing to be out of alighnment a bit.

Replacing the flex discs is a good idea on any W126 at this point.

Yep, I might roll the dice with a center bearing, center bearing support, flex discs, and trans mount........all at once........and see if I can avoid the replacement of the drive shaft........it's a costly item..........$350. or so.

The mechanic can do all of this in two hours with the lift. Too good a deal to pass up.

Keep us posted if that solves the issue.

I think that would fix it for you Brian. These drive shafts are real tough and designed to handle the 300hp the Euro 560's pump through them. A 603 doesn't really stress anything.

With mine I found that the center bearing support was worn and let the drive shaft sag a bit insted of holding it on center. The bearing was also a bit worn and dry, I guess that was to be expected it had a lot of time on it.

I have a similar vibration on my 1986 SDL 190k miles. Occurs at 40 to 55 MPH criusing along and also in second gear under acceleration just before the 2-3 shift. I removed the belly pan and found I could move the driveshaft within the rubber center bearing support almost 1/2" either up or sideways. It's resting position was definatively sagging downwards from a central position. Additionally my rear flex disc though not original OEM has very light hairline cracks in the rubber between the bolts. The center bearing turns very smoothly.

I am ordering the center support and both flex discs. Hopefully this will cure the vibrations. I will post my results when done.