Why do my driveshaft bolts keep falling out?

[Guest Anonymous]

I just lost the second driveshaft bolt in 3 months. I have all new nylocks on them.. Why do they keep falling out?

[Guest Anonymous]

(nt)

[Guest Anonymous]

The driveshaft coupling bolts on my 5er are locking, but not using nylok. They are just slightly oval shaped, and have a partial interference fit on the bolt. These are from Steve d'Gerolamo's Ultimate Garage, probably the same as what BMW sells. If I remember right, my '02 has the same setup.

I've never had one come the slightest bit loose. Steve says they are one-time use, but I reuse them and still get good engagement.

Locktite is another good solution.

Make certain you put the bolts on in the correct alternating pattern. The reason for this is to permit you to tighten them from the flange side, thereby preventing any twisting of the rubber. Putting residual strain on the donut itself. It won't last long if you strain the rubber.

[Guest Anonymous]

How does that effect guibo wear?

[Guest Anonymous]

to hold the head and tighten the nut only. The advantage in putting all the nuts on the tranny side is if your karma is bad and a nut comes off, the bolt can't work itself part way out and resculpt the rear of your transmission.

Cheers!

John N

[Guest Anonymous]

Bimmers for 25 years always puts the guibo bolts in at 12 -4 -8 o'clock from one side and the others go in from the reverse. I've never had one come loose when done this way. Although the loctite's probably not a bad idea, I've never used it and have not had one come loose.

[Guest Anonymous]

nuts against the flange. Turn the nuts not the bolt. This avoids putting any permanent residual strain on the giubo. Giubos which have a residual strain from installation don't last very long. Last time a hack mechanic (at the dealer no less) installed a giubo incorrectly on my 5er it lasted about 5000 miles before it came apart.

[Guest Anonymous]

URL: http://www.bmw2002faq.com/store/index.html

if one of the bolts comes out that is facing forward, it will rip the shit out of the tranny/mount. if they fall out going backwards, they just fall out. its not a big deal to hold the nut while turning the bolt head, *or* vice versa.

-Rob

[Guest Anonymous]

BMW engineers probably assume that - once assembled correctly - the bolts would never come out. Meanwhile, back in the real world we have learned never to say never.

They also may be expecting that turning the head turns the shaft inside the bore, which may in itself put residual strain on the giubo.

That being said, I think giubo's are a bit cheaper than transmissions.