Driveshaft repair recovery questions - PeachParts Mercedes-Benz Forum

SD Blue · #1 01-09-2010, 07:39 PM

I have a couple of questions about driveshaft repair and sorting out how far I will need to go to get my driveshaft straightened out. Recently, I took my car to a shop, recommended by a friend, to have new flex plates and center carrier bearing installed, due to a slight droning noise from the center console. Well, a long story short, it was a disaster! Returned after a drive of only a couple of miles and limped back with flashers at a top speed of 10mph. Failure was blamed on the universal joint. The rear shaft was replaced with a salvage unit that was supposedly balanced. After 5 days in the shop, I picked it up a second time. After a drive of about a hundred miles, there is now a major vibration at 30-40mph but smooths out some after that. There is still a droning noise.

I've got the car jacked up and did an initial inspection, with the driveshaft still installed in the car. From what I've read here in a couple of DIY posts, it appears the front flex disc is installed incorrectly. Correct me if I'm wrong but isn't the raised ferrule, of the flex disc, supposed to fit in the flange of the driveshaft?and the raised ferrule into the flange on the rear of the transmission shaft?

I believe it is currently backwards due to a "wave" in the edge of the disc. The disc doesn't appear to be shredded but I've bought new ones out of fear that their integrity may be compromised by this.

Also, don't the shafts need to be balanced as an entire assembly? From what I've read in the Haynes manual, the purpose of marking the shafts before disassembly is to keep the front and rear portions splined to the original balance positions. How can only the rear portion be balanced?

If I have to remove the entire shaft and have it balanced, as a matched set, how much am I looking at cost-wise? This whole scenario just disgusts me at the moment.

(I don't blame my friend, he has been a prince with driving me back and forth to the shop.) I've resorted to trying to salvage this repair by doing the work myself, on a gravel driveway in the cold. Please, a little encouragement is needed.

Biodiesel300TD · #2 01-09-2010, 08:03 PM

When I bought my 240 the PO has blown out the front flex disc. When I removed the driveshaft I replaced the center bearing, and took the two halve apart and didn't mark them, so chances are they didn't go back the same way they came apart. I've now driven over 40k miles on it the way, and there are no vibrations or odd wear. So I personally don't think the two halves have to be kept in the same orientation, or in the same orientation they were on the transmission and differential. So I think that as long as both halves are balanced you should be fine.

You are correct on the raised ferrel. They should seat down into the driveshaft and the flange. I'd pull both flex discs and since you have new ones put them in properly, and see if the vibration and droning go away.

barry123400 · #3 01-09-2010, 09:02 PM

Quote:

Originally Posted by Biodiesel300TD

When I bought my 240 the PO has blown out the front flex disc. When I removed the driveshaft I replaced the center bearing, and took the two halve apart and didn't mark them, so chances are they didn't go back the same way they came apart. I've now driven over 40k miles on it the way, and there are no vibrations or odd wear. So I personally don't think the two halves have to be kept in the same orientation, or in the same orientation they were on the transmission and differential. So I think that as long as both halves are balanced you should be fine.

You are correct on the raised ferrel. They should seat down into the driveshaft and the flange. I'd pull both flex discs and since you have new ones put them in properly, and see if the vibration and droning go away.

You were just lucky. Both halves are factory balanced but as a complete unit. Not individually. The best explanation for your luck was basically either just good fortune or the original assembly was really close before the balance. It can get expensive to mess up.

As for the poster with the now miss matched shafts a recovery from a pick and pull yard may be your cheapest option if vibration is evident after the flex disk issue is solved. One has to write these things off as a learning experience.

The better option is to dump the mess back on the mechanic you paid. He has contributed to it substantially remember. Rolling around on cold gravel is probably not a good approach. Sit down and think a minute. Plus read up well on what should be what with driveshaft issues. Litterly tons of information in the archives.

SD Blue · #4 01-10-2010, 02:08 AM

Thanks for the replies guys. Well, I think I'll give proper orientation of the flex discs a try and see if I get lucky. I've done a lot of searching on the subject and found notes on proper orientation of the flex discs, replacing the bearing, etc.

As far as the original mechanic, I'm really hesitant about taking it back and feel I may be ahead by just doing the work myself. Honestly, I've had such bad luck with auto mechanics, this one is just added to the list. I guess if the flex disc change doesn't resolve it I'll see what the cost of a balance job runs. If overwhelming, salvage may be my only route.

ImBroke · #5 01-10-2010, 06:12 AM

Quote:

Originally Posted by SD Blue

salvage may be my only route.

I hope you mean going to a salvage yard and getting an entire driveshaft.

tangofox007 · #6 01-10-2010, 09:00 AM

Quote:

Originally Posted by Biodiesel300TD

So I personally don't think the two halves have to be kept in the same orientation...

How hard is it to match mark the two shafts before disassembly?

junqueyardjim · #7 01-10-2010, 11:38 AM

I am assuming that this problem is on your 84 SD? Why is it so hard for so many of you people to come up with basic information like model and year? Ok, most all 83 and later Mercedes have a marking on the driveshaft where it slips together. Two raised lines on one piece and one raised line on the other piece. The single line has to line up between the two lines. Pretty simple.

Biodiesel300TD · #8 01-10-2010, 12:26 PM

Quote:

Originally Posted by tangofox007

How hard is it to match mark the two shafts before disassembly?

It's not that it's hard, it's that I didn't know I needed to do it at the time. It certainly isn't hard, and you should do it to keep any issues from arising, but maybe not as serious an issue as some might make it if you don't.

Junkman · #9 01-10-2010, 01:51 PM

Quote:

Originally Posted by SD Blue

As far as the original mechanic, I'm really hesitant about taking it back and feel I may be ahead by just doing the work myself. Honestly, I've had such bad luck with auto mechanics,

I'm back to doing my own work. Lately mechanics I thought were good didn't torque a caliper bolt letting it back out causing the caliper to flop around. Another either didn't repair or stripped threads letting a sway bar come down. The front end shop didn't bother to adjust the steering wheel when doing an alignment. I've found that it is easier to correct the error instead of taking the time to drive back to the shop & make them do it. Current temps might temporarily modify that decision.

SD Blue · #10 01-10-2010, 06:41 PM

Junqueyard Jim,
(There is only one car in my signature.) I'll double-check the marks....the mechanic made mention of them after the work was done.

Junkman,
I can definitely see why so many folks are doing their own work. In nearly all cases I do as well. This was a timing and conditions issue...Christmas trip planned / no time to work on it and rainy weather / working on a gravel driveway with the entire car in the air.

I've found a local shop that I believe does balancing. Since it's the weekend, does anyone have a ballpark idea of the cost for doing this?

hanno · #11 01-10-2010, 07:41 PM

On an early W124 (1986 as my example) the driveshaft already has factory metal ribs that you line up when its been apart. No need to mess with your own marks. Pictures of this are in the Chassis Service Manual.

The metal ferrules that stick out of each of the six bolt holes are supposed to fit into the mating recesses of both the yoke (differential or transmission) and the driveshaft. If they are not something is going to get loose and at a minimum cause vibration.

ImBroke · #12 01-10-2010, 08:09 PM

There is ONE car listed in the sig, I figured it out. A reply to a post is always optional.