Houston, I think I have a problem! – Driveshaft.

[equipo5]

I had the gear box out of my R75 and I noticed I could easily pull the drive shaft forward, and when I did, the rear end of the shaft dropped down inside the swing arm. I was able to manipulate it back into what felt like a spline. A closer look at Haynes and it seems there should be a nut holding it in place at the rear, behind a rear coupling.

Couldn’t find much on the internet but I guess its wheel off, swing arm off and ?undo those 4 bolts on the final drive.

Any thoughts?

[jagarra]

I'm interested too. When I just had my gearbox out to change the clutch, my driveshaft did the same thing.

[melville]

I think it's spozed to do that. Think about pulling the final drive. If you remove the four nuts that hold the FD to the swingarm, do you need to do anything more to get the FD clear of the arm?

[jagarra]

Mel,

I sort of think is has to slide back and forth just like a normal driveshaft on a car. As the swing arm travels in an arch the driveshaft has to slide between the universal joints to take up the difference in length.
The part that gives concern is when you look at the microfiche for the part assembly on the driveshaft, it clearly shows a collar with a nut on the end.

[Bamboo812]

No need to remove the rear drive, the nut holds the collar to the end of the drive shaft.

[Airbear]

... though it is worth checking that the nut is tight - 150 to 165Nm.



I found mine was loose last year. Fortunately Jeff of Albury (ME109) had a spare driveshaft that he was willing to sacrifice and made this neat tool to hold the spline:



To pull the FD remove the four nuts and detach the rear shock.

[Rob]

Is it a good idea to have a new gasket on hand when it comes time to put the final drive back on the swingarm?

[equipo5]

Ahh. The drive shaft has a female spline that fits over the male cog in the final drive. The female spline of the drive shaft is free to move back and forth as the swing arm moves up and down. If the swing arm is not fixed in place the female spline can slip off the male cog. The photos explain all Airbear. Thanks everyone for the feed back.

Cheers

[Airbear]

Is it a good idea to have a new gasket on hand when it comes time to put the final drive back on the swingarm?

Yes, Rob. I re-used mine a few times but the last time it just fell apart. A simple enough thing to make from suitable material (breakfast cereal pack) but I lashed out and bought a new one anyway. Hang the expense - my old dear deserves the best (sometimes).

[Airbear]

Ahh. The drive shaft has a female spline that fits over the male cog in the final drive. The female spline of the drive shaft is free to move back and forth as the swing arm moves up and down. If the swing arm is not fixed in place the female spline can slip off the male cog. The photos explain all Airbear. Thanks everyone for the feed back.

Cheers

Ian, while on the subject of the /5 drive train - there is a four speed gearbox on Oz ebay. Up till yesterday it was listed at $450, re-listed today at $350 after getting no bids. Unknown provenance but it was going when parked, apparently. Always good to have a spare box.

http://www.ebay.com.au/itm/BMW-GEARBOX- ... 1862309862