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Old 03-01-2016, 09:02 PM   #7
Eric
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Join Date: Jul 2004
Location: Hudson Valley
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Continued...

With the driveshaft out, you have an excellent opportunity to install a short shifter and replace all the loose bushings in your shifter assembly.
Do that now.
A hook-shaped hose-remover tool with a screwdriver-type handle is an excellent tool for unclipping the "bastid clip" that holds the gear shift carrier to the back of the transmission.

Before you install your new driveshaft, you need to install the vibration dampener.
This is not as easy as it might first appear.
There is probably a correct way to do this, but if so, I do not know what it is.
The splined bolts have to end up pulled all the way into their holes, up against the dampener, with the dampener tight against the driveshaft flange.
When I have encountered bolts like this in the past, I have seated them by either a few sharp blows with a sledge, or by pulling them in by tightening the fasteners. I tried both and neither provided a satisfactory result.
In the end, I pulled each one in using an air wrench, then gave the nuts a good pull with a long ratchet, then gave them another eighth of a turn with the air gun. This is probably the wrong way, but it was all that would work.

Once the driveshaft is assembled, note that the splined connection will act like a shock absorber: It will move either in or out, but very slowly, and with cruel disregard for the amount of force you put on it. This means that if you hold it at an upright angle, it will slowly get longer, then when you are trying to put it in place over your head, it will be too long and won't shorten no matter how hard you push it, then once you've gotten it shorter, it won't lengthen again as you pull on it with all your might. It won't wedge in place and stay there long enough for you to reach the handful of bolts that's just sitting a few feet away unless you've gotten it to the right length.

Reassembly from here appeared to me to be completely straightforward.
Cirrus, above, described a procedure for preloading the center bearing.
I knew nothing about that, and just tightened it in its least-stressed position.
I am not sure whether this is a bad thing or not.

BMW gives torque values in a lengthy technical bulletin that applies to all models in the time range, and they all seemed rather low. I just gave everything a good strong pull, and probably made them 50% tighter than BMW would have.

In addition to a new exhaust flange gasket, new muffler hangers (2 rubber thingies, and one rubber whositz) are never a bad idea, as the old ones slowly stretch over the years.

Once my car was reassembled, I found that it drove amazingly smoothly, and, in fact, some slight vibrations that I had attributed to the engine lugging were also gone.

This is a repair that I should have I done a long time ago, and I'm glad that I finally did it now.

- Eric
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