Re: E30 driveshaft question

[Randy Walters <RandyLWalters@xxxxxxxxxxxxx>]

mdrainville@domain.elided writes:

>After removing the driveshaft from my E30 I found out that it was not
>sliding on the spline yoke. After consulting my Bentley, I learned that a
>nut (looks like a cap) needs to be loosen before any movement is possible.
>Well, they were right, After loosening that nut, it was possible to move
>the shaft on the splines.
>
>My question is: Should the shaft move on the spline with the nut tightened?
>It seem like not. But what makes me perplex, is that in the troubleshooting
>area on the Bentley manual, they say if you experience a clunk while
>releasing the clutch, it may be due to a seized spline yoke. Well, when the
>nut is tightened, the yoke is in the same condition as a seized yoke. I
>don't understand.  On my 4 Runner, the two driveshafts have a spline yoke
>that are free to move, even for the front differential that is fixed to the
>frame like the diff on my E30.
>
>So, should it slip or not?? That is the question.
>
>Thanks
>Michel Drainville
>91 318ic

 The splined shaft is supposed to slide during normal operation. It
absolutely is not supposed to be tightened so much that it locks up.
If yours was locked up,  it's either been over-tightened by someone
before you or it's seized up.

 While the differential is fixed in relation to the driveshaft, the
engine/transmission assembly is not fixed and this whole assembly
does move forward and aft on it's rubber mounts. This is the biggest
reason for the sliding splined coupling on the driveshaft (in addition to
facilitating removal of the driveshaft and the differential).  The torque
value on the coupling's clamping sleeve is 13 ft lbs which keeps the
splines snug,  but not so tight that it locks the coupling up solid. The
splines are to be lubricated with MolyKote 2,  which is a Molybdenum
Dysulfide grease normally used on CV joints.  If this joint weren't
intended to slide then BMW would not have specified a lube for
the splines.  Trust me,  this joint is supposed to slide !! 

 When i was new to BMWs, i listened to someone's bad advice and
cranked the clamping sleeve down tight on a new driveshaft i'd just
installed and when i went for my test drive i got a horrible vibration
which got worse with increased speed. I re-read the Bentley Manual
and realized this coupling was indeed supposed to slide and not be
locked up solid,  and i also called Driveline Services (where i'd bought
the new driveshaft) and he confirmed that the sleeve is supposed to
slide,  albeit with some resistance (thus the 13 ft lb torque).  Not
having the special BMW clawed tool to use on the clamping sleeve,
i pushed and pulled the joint on my original driveshaft to get an idea
of how much force is required to move it,  then loosened the new
shaft's sleeve to mimick the amount of force on the old one and 
took it on another test drive,  and this time the car was smooth
as glass with absolutely no vibration in the drivetrain.  The only
reason i'd replaced the driveshaft in the first place was because
the rear U-Joint was binding and notchy, and made an occasional
clanking noise on-off throttle.  It was still smooth and vibration-free,
but that clanking was really bothering me (the shaft had 130K on it).
 
 Since then, i've dealt with a few other E30 driveshafts and on each
of them the sliding splined coupling slid with about the same resistance
as my original one, and the original one on my second 325is.

Randy
88 325is
89 325is

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