Wurring sound? from trans or final drive?

[Buffalo Bill]

Ok, bummer from my so reliable 1982 1100G.
A notable wurr from trans or final drive while riding in 5th, at 2700-3000 rpm. That's about 30-35 mph. Will do it in 4th at same RPM and load.
Sound goes away when load is decreased (coasting) and as 3000 RPM is exceeded (above 40 mph).
New sound, is this a bearing failure in the final drive?
Thanks!

[Redman]

(Subscribed)

[Nessism]

I don't know what the problem is, but I do know that the #1 problem with the drivetrain on the 1100G bikes is the secondary drive gears. There are a fair number of instances where the torque of the 1100 engine shears off the driven gear in the set.

[Buffalo Bill]

If I could ride along next to it in another vehicle, I would get a better idea what region the sound is coming from.
Now I just have to look down quick and kinda detect the area.

[Buffalo Bill]

Where should I look for parts to repair the the drive train?

[Buffalo Bill]

The sound reminds me of a time the pinion nut came loose on my 1980 Monza Spider.
I had to drive another 30 blocks of stop and go urban neighborhoods.
As long as it was under load it was fine, lot of slack and play between the gear teeth.

[GregT]

Pull the rubber boot off the front joint of the drive shaft - and see if you can move the universal joint forward and back. It's also possible you'll find the retaining nut sitting in there. They break the reduced diameter piece off the end of the secondary shaft - which is threaded for the retaining nut.

In the past i have pulled the assembly and drilled and tapped the exposed end for a large capscrew to do the same job. 14mm from memory.

[tom203]

Yes, pull back the boot....maybe you?ll get lucky and find it?s the u-joint or propeller shaft spline

[tatu]

It sounds like a shaft issue, you could maybe see something unusual in checking the lash by putting it in gear, holding the crank still on the nut and rocking the wheel back and forth. You might see or hear something that might help diagnose...?

[Buffalo Bill]

These are good suggestions for a look see. The sound is strong enough I better not ride it.

Looks like I'll have to put the plates on my track bike if I wanna do some joy riding.
Side note, spending my track money on the house this year…sigh

[Buffalo Bill]

I put the bike on a rear wheel jack and ran it in 1st 2nd and 3rd, 2000 - 2500 rpms.
I hear gear slack/play in the trans area. It's particularly clunky as the engine idles in gear.
Noticeable out of balance vibration of rear wheel with bike in 1st at 2000rpm.

[tatu]

I put the bike on a rear wheel jack and ran it in 1st 2nd and 3rd, 2000 - 2500 rpms.
I hear gear slack/play in the trans area. It's particularly clunky as the engine idles in gear.
Noticeable out of balance vibration of rear wheel with bike in 1st at 2000rpm.

Leave it on the jack/stand, put the bike in gear and rock the wheel back and forth by hand see if there's anything unusual there, try taking it out of gear and rotating the wheel by hand listen and feel for anything... Check the oil in the bevel gear, is it dirty with debris....

[Redman]

A few years ago (2017) I had need to learn a little bit about the secondary gear set.
Looking at drawings in manual were not helping me much, but eventually I figured a few things. ANd then added some notes that helped me.



Symptom I had was vibration/shuddering on hard deceleration. I haven't heard you mention anything like that, so I haven't said anything.
But others are talking about the secondary gears.

[Buffalo Bill]

A few years ago (2017) I had need to learn a little bit about the secondary gear set.
Looking at drawings in manual were not helping me much, but eventually I figured a few things. ANd then added some notes that helped me.



Symptom I had was vibration/shuddering on hard deceleration. I haven't heard you mention anything like that, so I haven't said anything.
But others are talking about the secondary gears.

Dave, I remember that thread. Can you post a linc? Thanks!

[GregT]

You can see the reduced end on the upper #1 - the driven shaft. That is what breaks off.