Driveshaft...here we go

[Runninn1]

Don't let the number of posts be deceiving... many many bikes here and original owner of 86 r65 w/75k miles. Anyways, when I arrived home yesterday the driveshaft was making the lovely 'crunching/clicking' sound...ugh! I turned the back wheel (bike on centerstand) and the 'noise' appears to be coming from the driveshaft/tranny junction. The driveshaft will turn one way Ok and I then spin it the other and it will stop, start as if a spline or is messed up and catching.   Where to begin??? I have the service manual and replaced the tranny about 10 years ago...but it's looking like a tough month ahead. Help!      Thanks :-/

[Bob_Roller]

I would drain the oil from the drive shaft area and see if you have metal in it .

[Justin B.]

On my '95 R100RT I had a "clunk" coming from that area when I pushed it and it was the output bearing in the transmission.

[Tony Smith]

The simple fact is that you will not know until you open it up and have a look.

Having said that, you might get lucky and simply have a failed universal joint.

If it does prove to be the universal joint the bad news is that BMW thinks you should buy a new shaft, the good news is that it is rebuildable, but I'll hold off on discussing that until you know what your problem actually is.

[Runninn1]

Finally had the driveshaft pulled and one of the bolts had disappeared that held the driveshaft in place! Lucky??? I found it inside the driveshaft  (D/S) swingarm. Anyways, should I use Loctite Red to hold the D/S to the back of the tranny?
Also, the drain bolts on the rearend are stripped, will helicoil be the best option?  I am humbled once again....

[Runninn1]

Missed critical wording.. (above post)...use the Loctite Red on the bolts to hold the D/S to the tranny....

[Tony Smith]

Finally had the driveshaft pulled and one of the bolts had disappeared that held the driveshaft in place! Lucky??? I found it inside the driveshaft  (D/S) swingarm. Anyways, should I use Loctite Red to hold the D/S to the back of the tranny?

No you should not!
What you should do is buy 4 new bolts and throw the ones you have into the bin. If you do not already have a "crows foot" adapter for your torque wrench, get one of those too. Remember to set the crows foot at 90 degrees to your wrench and then after carefully cleaning the drive flange, insert the bolts DRY and torque to the correct figure.

These are "torque to yield"  bolts and should only be used once.

Also, the drain bolts on the rearend are stripped, will helicoil be the best option?  I am humbled once again....

You should really have these welded up and then drilled and tapped, but that is an expensive exercise.

I'd use "Keensert" or similar, bearing in mind that the actual length of thread will mean that you have to cut the keensert down.

The good news is that in the interests of sealing you can use as much blue loctite as you want when running the keeensert into your freshly drilled and tapped hole.

There is not much room so you will need to use an intermediate tap to start the threads and then almost immediately swap to a bottoming tap. If you do not already own the gear you are going to need then the cost to set yourself up to fix it is going to cost more than paying a good engineering works (NOT under any circumstances a run-of-the-mill dealership mechanic). Then there is the cleanup so you will need a gasket and seeing as you are there, some seals (full kit from motobins for around $AU40). Whilst a keen home mechanic can renew the main (axle) seals, you need expensive special tools to get the front one out.

Unless you are super keen this is probably a job for an engineering shop, or perhaps an independent specialist BMW tech.


if you are interested, here is some blurb on keenserts

http://www.specialty-fasteners.co.uk/content/doc/lib/1122/completekeensertcatalogue-2.pdf

http://www.repairengineering.com/keensert.html