Middle Drive Shaft

Broken Mid Drive Shaft

Several forum members have experienced failures of the middle drive shaft. The failure is prefaced by a noisy whining/grinding coming from the the transmission/drive line area. If you hear any unusual whining noise coming from this area, stop as quickly as possible. The bike will still move, but it will be very noisy and continue to get noisier as the broken end of the shaft beats around inside the cage that holds the yoke and speedo sensor. It can cause serious damage. Sometimes however, the nut has just loosened and the shaft has not broken yet. If you catch it before the shaft breaks, you can simply tighten and stake the nut as described below. So if you hear it getting noisy, stop the motorcycle immediately!

Special Note - Preventative Action

There is a strong suspicion that this failure results from the nut that holds the U-joint yoke onto the shaft backing off or loosening enough to cause too much play in the shaft and ultimately cause the failure. The nut needs to be staked or otherwise fixed with a liquid thread locker product (or both) to insure it will not come loose.

Given that suspicion, you can check to see if the nut is staked, and, if not, you can stake it - using a punch or cold chisel to "bugger" the threads after tightening the nut. This will prevent the nut from loosening and coming off - causing this issue. You can also use a good liquid thread locker product to insure that the nut stays tight, or even a combination of both thread locker and staking.

If you don;t have a clue what "staking" means, here is a pic......and now you know. Just beat the nut and threads with a fairly sharp chisel to deform them slightly.

Thanks Bill (craigscreek)

It is a good idea to check the nut, especially if you have that area of the are open for other reasons. Check and stake as needed!

This will completely eliminate the issue.

INSTRUCTIONS For Fix Without Engine Removal - DIY for $75 or less - courtesy of COBB

Middle Drive Shaft repair process:

1. Support bike on securely on Bike Lift to enable rear end removal.

2. Remove Rear Wheel & Swing Arm

3. Remove Speedo Sensor from bike.

4. Remove Uni Joint (should just slip off end of shaft if nut is snapped).

5. Inspect Uni-joint for damage. If badly damaged – Replace.

6. Disassemble Uni-Yoke joint from the Cross Joint. Remove C-Clips inside each joint and supporting the U-joint so the bearing can come out, use a suitable sized socket as a drift, punch one end into the centre until it stops. You should be able to remove the bearing at the other end with a bit of gentle prying. Now gently tap the centre shaft that is exposed in the reverse direction to push out the other end. (needs disassembly as you cannot put it back on to bike assembled.)

7. Mark the Centre of the shaft end with a centre punch.

8. Drill a pilot hole using a new and sharp HSS 3mm drill bit – to approx 25mm deep. Use a Nikko Pen to mark the depth on the Drill Bit and use Drilling Oil from a spray can if needed to keep it all cool while drilling.

Be careful when drilling – snapping a drill bit off inside the shaft causes much GRIEF.

9. Drill the main hole for whatever sized bolt you intend to Tap and install. I used a 6.5mm final drill and then tapped the thread using an M8x1.25 pitch tap to take the M8x1.25 Bolt.

Make sure you don’t get any swarf from the drilling into the engine or bearing end of the shaft. If in doubt – undo the three bolts holding the end bearing in and remove that bearing assembly and clean it thoroughly. Much better to be Safe than Sorry later.

10. Insert Yoke Joint end onto Middle Drive Shaft.

11. Insert Rubber Seal into Yoke (with some fresh moly grease) and push it into place.

12. Apply Red Locktite to a new Nut and thread onto shaft. Tighten till Firm.

13. Apply Blue Locktite to M8x1.25px15mm Bolt, add spring washer, add flat washer, insert into shaft thread and tighten till firm.

14. Reassemble Uni Joint. Grease well with Moly Grease.

15. Put Speedo Sensor Cover Boot back over Uni Joint and onto Engine.

Note: It's impossible to get it back on with the swing arm in place

16. Reassemble Swing Arm etc in reverse of Removal Procedure. Don’t forget to Lube all your swing arm and relay bearings while your at it because you may as well service that seeing as its all apart.

17. Get back on the road and enjoy your bike again

Repair Procedures - Thanks to Bill (Craigscreek) for the photos.