Driveshaft sleeve?

[zhandax]

I didn't get the driveshaft shakes on the 540i until I hit around 180-190k miles. It has gotten so bad by 193K that I was worried that it may lead to other problems so I had it replaced a couple of weeks ago. My indie mentioned that he had only gotten one bad one in 19 years from Powertrain in Oregon and, since I had gotten the driveshaft for my E28 from them and it was trouble-free for the next 170k miles, I was hard pressed to disagree. I picked the car up two Fridays ago downtown around 4:30 and the traffic was so bad I didn't get above 45mph the whole way home. I didn't get on the freeway that weekend and it was warm on Monday. It was a bit cooler on Tuesday, and I noticed a bit of a roar over 70mph but it went away as soon as I cracked the window. Wednesday night, it was in the 40's and I heard a roar over the cracked window and felt a vibration which almost certainly came from the driveline. I called the indie the next day and he said 'bring it back in', and tomorrow I will be able to take it to him. I have noticed that it degrades in cooler weather and improves in warmer. The temperature differentiation leads me to believe that the installer either didn't pre-load the center bearing or did not do so sufficiently. However, in looking at the RealOEM drawings, it seems there is a sleeve which fits either in front of the driveshaft or around the front spindle as it goes through the guibo which may also contribute to the problem, depending on whether it can shorten or not. I don't see any indication that this sleeve was replaced. Is there any possibility that this might be the issue, or is it just a case of lack of pre-loading? The roar is undoubtedly the resonance from the vibration which attends this occurrence. The roar subsides but the vibration intensifies on deceleration in an exit lane. After a full stop, there is no roar and no vibration again until the car once again crosses +- 70mph.

[ahlem]

What happens when you shift into neutral at high speed? Automatic?

[zhandax]

Yes, it's the ZF auto. If it was a manual, what would I be looking for when I shifted into neutral?

[whiskychaser]

Is your old driveshaft still around? If the sleeve is anywhere it may be stuck in the end of that.

[zhandax]

Unfortunately, I took it to my indie (don't like working under a car a couple of feet off the floor) and he sent the old shaft back. However, since I think the optimal course at this point is to take it to someone else for remediation (long story), I will order one before I go just for insurance. My main suspect is the center bearing is not pre-loaded. I also have to wonder if the CV was greased. This adds another possibility, but one for which it is relatively easy be prepared; Thanks! Since I do most of my work and only take it in for the stuff I don't like to do (driveshafts, transmissions, clutches, etc,) I didn't realize that his business manager had retired in the last year or so. Can't say I have much confidence in the new crew.

[whiskychaser]

Its not really clear from realoem so here is a pic of the output flange on a 5HP18.The 5HP30 is similar but meatier. Lining it up without the spacer could be a bit of a pig, especially if you are holding up the driveshaft. With the spacer in place, you just slide the output shaft on and bolt up. Job done.
http://i290.photobucket.com/albums/ll280/whiskychaser/outputflange.jpg
pp260-8/9 of Bentleys shows the spacer is captive in the driveshaft and recessed slightly- which is probably why I never lost one :)

[zhandax]

If it is harder to get it on without the sleeve, it seems less likely he left it off, but I blew $10 and ordered one as insurance about a half hour ago. I do know that the guy who installed it was in a hurry (or a complete idiot, but the name sounds familiar, so if it's the same guy, he has worked on my cars before successfully). The first thing that the new 'shop foreman' told me when I picked it up was that he snapped off half my exhaust studs in the process. I think he intended to relay the difficulty of the job and didn't realize I knew the difference. Then the bozo they had test drive my car when I took it back tried to tell me that the center bearing just naturally centered itself and didn't need to be pre-loaded.

[ahlem]

The reason to shift into neutral is just to see if there is any difference when you change the load on the drive train.
Some times that allows you to identify better where the vibration might be coming from as would down shifting and up shifting ( not at 70 mph however)

[zhandax]

What type of precautions are required to shift into neutral at around 85mph with an auto?

[whiskychaser]

What type of precautions are required to shift into neutral at around 85mph with an auto?
I'd take the precaution of checking the manual for the max towing speed as IMHO you are doing the same thing.