Another CSB but... A Strange Driveshaft

[DrinkMan]

Enjoy driving our new 1972 2000tii touring but there was a problem at low speeds with "thumping".  A quick check showed the center support bearing was shot. So, out comes the service manual, read all the (hundreds) of threads here, even watch a YouTube video. I think I'm ready to do this. Under the car, I noticed the driveshaft looked different from all I've seen here on 2002FAQ. I pulled out the driveshaft and it is completely different. There is no bolt and spline. It appears to be a threaded connection. Put it in the vise, grabbed a big bar and attempted to unscrew it. No go. My current thinking is that rather than investing too many more hours into trying to do this, I simply take the driveshaft and CSB to a local driveshaft shop, drop it off and have them take care of it. Has anyone seen anything like this?

[img]https://live.staticflickr.com/65535/52205429483_cd2b1c4637_z.jpg[/img]

 

[DrinkMan]

Note - forgot to mention - 5 speed transmission w/ limited slip.

[tech71]

That is odd... No, somebody wouldn't...Would they?

A pic of the other side of the CSB area would be helpful.

Edited July 10, 2022 by tech71

[Cabbage Fumes]

It appears someone during the 5 speed conversion used an E9 driveshaft, badly grafting the sliding yoke joint from the rear half onto the original tail section, and something equally heinous to the front section. The whole point was to use a sliding center section, which makes installing or removing the driveshaft much easier.

Edited July 10, 2022 by Furry Camel
clarification

[Mike Self]

The threaded section may also be for a precision adjustment of the driveshaft when installing the 5 speed.  Easier to shorten/lengthen (vs moving the diff on its  mounts) so that the guibo isn't stressed.  Actually kinda clever so long as the driveshaft was properly balanced, and there's a way to lock the threaded section once the proper length is obtained.

 

mike

[Tommy]

I have used that type of section from e12 when crafting shaft for my racecar. It's a lot easier to dimension and install vs. the normal. If its straight and balanced I would use it.

 

Looking the picture again...the parts look quite new and the support is shot already...makes me think it probably is not that perfectly set up. You should look for a reason for the damage.

Edited July 10, 2022 by Tommy

[DrinkMan]

We have been trying to figure out the reason for the damage. We purchased the car from an Estate Sale in Vienna, Austria. Very little detailed history of the restoration beyond knowing there was only about 350 km since engine rebuild. So far, we have only found a few problems: some ground issue in dashboard causing fuel gauge problems (I figure that may have been caused by the 19 days crossing the ocean and it is next on our troubleshooting list after driveshaft), 4-way flasher button getting stuck intermittently, and the CSB.

 

I have a theory - when we picked up the car at the Port of Brunswick and drove it a few miles to St Simons, there was a lot of vibration from the driveline. I found that the transmission rear mount (rubber isolation mount) nut on the bottom had backed off and was about to fall off (the nylock didn't work - I could turn it easily with my fingers). My theory is that the transmission vibration had caused the CSB failure. After I fixed the transmission mount, the vibrations went away and only the thump from the CSB at low speed remained. 

 

I'm going to review the driveshaft with the shop we use to make sure everything is ok and have them check the balance. I've used these guys before and they do very good work.

[TobyB]

If it's the 'gland nut' style sliding driveshaft,

the nut loosens a bit, then the shaft slides apart.

 

All the rage in the E30s and such, slowly fading out with E36s.

 

BMW has always had some odd theories on driveshafts,

and seems to change their minds frequently.

 

Neat!

t

often makes his own, too.  Out of something he found at the junkyard.

 

[tech71]

This is all pure speculation until we can see the opposite side of that CSB.

Edited July 10, 2022 by tech71

[DrinkMan]

58 minutes ago, tech71 said:

This is all pure speculation until we can see the opposite side of that CSB.

 

Not quite sure of "opposite side" so I took a bunch more pictures hoping I got the view you would like. In addition, all of the pictures I take while working on the car I throw into this album (although not all are marked for public, I merely marked all these driveshaft pictures public in case you wanted to see more, and I have pictures of it parked at the Port of Brunswick after the 16 day delay with US Customs along with the "nice" port worker who released the car to me):

Flickr Album for BMW 2000tii touring

 

 

[tech71]

20 hours ago, DrinkMan said:

Has anyone seen anything like this?

I never have, no idea how its assembled unless there's a splined shaft and compression nut hiding under that black collar bit. Which is exactly where I was hoping to get a peek, and still have not. Can you slide that bit around or is it fixed in place?

Love your car?

 

Edited July 10, 2022 by tech71

[Son of Marty]

That black collar looks like the gland nut, try unscrewing it with a pair of water pump pliers. 

[DrinkMan]

Thanks @Son of Marty and @tech71 and @TobyB. It was a gland. Slightly hidden under the remnants of the CSB. Put a pipe wrench on it, loosened it. Spline slid out nicely. Off to the press to remove the old CSB. Then put on the new CSB. Then the joy of getting the gland back and tight again (while making sure the driveshaft was the proper length). I made it sound easy but it took my wife and I about 2.5 hours to get it right (I am not going to admit how many times we loosened and redid the gland to get the length right nor all the different things we tried in the shop to help us press on the new bearing). But everyone here has been there, done that. No need to go to the driveshaft shop in the morning. Instead we have the joy of putting everything back in the car. (note, having done the same operations to an Alfa Romeo, this is not as easy. As usual, the Germans make somethings more complicated than the Italians. Not always better, just more complicated.)

 

It was a good 2002FAQ day. I read through the old threads and was able to repair our 4-way hazard switch and now fixed the CSB. Hopefully tomorrow we will get the temperature gauge to be correct with a better ground.

[Cabbage Fumes]

Yay!

Edited July 11, 2022 by Furry Camel

[TobyB]

That gland nut doesn't have to be stupid tight-

it's providing enough compression to keep the splines from wobbling,

but it doesn't claim to lock them dead solid.

So 'good and snug' is plenty.

At least, on the E30 version.

 

And it's meant to be set to length after it's bolted in place-

which is no consolation now, I know...

 

t

heh, adjustable length driveshaft, heh.