Driveshaft problem on a 82 126 SD? - PeachParts Mercedes-Benz Forum

waybomb · #1 02-20-2007, 10:43 PM

Anybody ever work on the driveshaft of an 82 126, 300SD? I'm not home and my kid called this evening saying my SD made a noise, and wouldn't drive anymore. He pulled over. When he put it in Park, clearly the trans was still turning, because he could hear the parking pawl skipping as it went into Park after a while.

His budy pulled him home with strap. My kid say that half of the driveshaft spins, while the other half doesn't! Can this be? Any ideas what happened? I'll be home Friday to check it out, but would like to know something about this problem.

Thanks in advance.

vwbuge · #2 02-21-2007, 10:23 AM

Could have possible broken a flex disc but that would have made alot of noise and caused condierable damage.

Take a look and let us know.

Hatterasguy · #3 02-21-2007, 10:25 AM

Sounds like a flex disc let go, hopefully the damage isn't to bad.

kerry · #4 02-21-2007, 11:19 AM

Bad flexdisc wouldn't explain why part of the shaft is turning and part isn't. It sounds is if the spline that joins the two halfs of the driveshaft let go. Never heard of that happening before. As I recall, there's a big nut that holds the spline in position. Perhaps that loosened up.

vstech · #5 02-21-2007, 11:28 AM

Please take pictures and post them here when you find out what it is.
my 82 has nearly 400K Miles and I am NOT looking forward to a driveshaft breaking.
John

Hatterasguy · #6 02-21-2007, 12:52 PM

Quote:

Originally Posted by kerry edwards

Bad flexdisc wouldn't explain why part of the shaft is turning and part isn't. It sounds is if the spline that joins the two halfs of the driveshaft let go. Never heard of that happening before. As I recall, there's a big nut that holds the spline in position. Perhaps that loosened up.

They slid, with a busted disc they can slid forward. The spline never wears out, I checked mine at 250k miles and it was as tight as can be. I could not feel any play.

W126's are tough, the flex disc and maybe the center support bearing are the only parts under there that can fail.

MattBelliveau · #7 02-21-2007, 12:55 PM

Isn't there a UJ in there? If that snapped, wouldn't that make each half independant, and one end could spin while the other doesn't? I know that would be a rare case, but...

kerry · #8 02-21-2007, 12:57 PM

Quote:

Originally Posted by Hatterasguy

They slid, with a busted disc they can slid forward. The spline never wears out, I checked mine at 250k miles and it was as tight as can be. I could not feel any play.

W126's are tough, the flex disc and maybe the center support bearing are the only parts under there that can fail.

If they slide, do the two sections of shaft disconnect from each other? I agree that a spline wearing out is virtually unimaginable. However, I also can't imagine any way in which one half of the shaft can turn and the other half doesn't other than the spline failing or the two halves disconnecting.

Hatterasguy · #9 02-21-2007, 12:57 PM

Quote:

Originally Posted by MattBelliveau

Isn't there a UJ in there? If that snapped, wouldn't that make each half independant, and one end could spin while the other doesn't? I know that would be a rare case, but...

Yes, again these drive shafts are designed to handle 300hp. Our 125 diesels don't stress them one bit. The U joint on mine was tight as can be at 250k mile, zero play.

waybomb · #10 02-21-2007, 08:14 PM

Wow, I can't wait to get under there and find out what happened! I can not imagine a spline twisting. I'll let y'all know Friday or Saturday what damage I find.

Brian Carlton · #11 02-21-2007, 09:48 PM

Quote:

Originally Posted by kerry edwards

If they slide, do the two sections of shaft disconnect from each other? I agree that a spline wearing out is virtually unimaginable. However, I also can't imagine any way in which one half of the shaft can turn and the other half doesn't other than the spline failing or the two halves disconnecting.

With the nut completely loose, they can slide, but, they've got nowhere to go. Both ends are fixed. The nut can be completely loose and the shaft can't escape the spline

It can't be a flex disc failure or the shaft would fall out on the pavement and cause all kinds of problems if the vehicle is in motion or the trans is in gear.

barry123400 · #12 02-21-2007, 10:15 PM

Perhaps an assembly weld has let go in a situation where one end was inserted into a tube. That way the shaft could still turn one part component inside an outer shell. Almost any other senario I can think of part of the shaft would be on the ground.

toomany MBZ · #13 02-21-2007, 10:23 PM

Possible? Center bearing malfunction?

Whiskeydan · #14 02-21-2007, 10:41 PM

This I got to see...

After pulling a couple of MB shafts I just don't see how this could happen.

Can't wait.

waybomb · #15 02-24-2007, 09:50 AM

Well, I jacked it up. Yes, the rear driveshaft turns, and the front does not! I grab a rear tire and rotate it around and turns fairly freely. I wonder if a weldment failed in there?

The car still has the exhaust pipe shield, so I can't see what the problem is. It's too damn cold out. I'm going to farm this one out to a shop somewhere around here. Any honest shops around Saint Joseph, Michigan?