My bike pulled some nonsense on the highway!

[MattySull]

Hi, I hate for this to be my introductory post but I need help badly.
I've got a 1980 R65 with 70k on the clock that I thought was in decent condition.
Earlier today I drove about 15miles at a sustained 75mph in 5th gear. And the bike hits me with a high pitched whine that sounded similar to a throwout bearing whine but much much louder. The throttle does nothing so I immediately disengaged the clutch and the whine dies as I coast to the side of the highway.
I get off and there is a bit of white smoke coming from the rubber boot between the transmission and driveshaft. It doesn't last long and I noticed that nothing in the area even seemed to be very hot as you would expect with friction induced smoke.
The bike was able to limp home just fine for 2 miles max.
I would guess something that needed grease never got it and now needs replacement.

Does anyone have any tips on what could be the issue?

[Bob_Roller]

My first guess would be stripped transmission input splines .

But, I've been wrong before !

With the bike on the center stand and the transmission in gear, can you rotate the rear wheel ?

[MattySull]

I tried that with a different method earlier, sitting on bike turned off in gear clutch engaged, and it would not move.

I will keep that in mind when taking it apart next week.

[tvrla]

Did the whining continue for the last two miles home at slower speeds?

I'm curious if the transmission got really hot and what you saw was the road grime smoking off?

Could you place where the noise was coming from?

Was performance down when this happened?

[MattySull]

Did the whining continue for the last two miles home at slower speeds?

I'm curious if the transmission got really hot and what you saw was the road grime smoking off?

Could you place where the noise was coming from?

Was performance down when this happened?

The whine completely stopped but I was driving around 30mph max.
The noise sounds like it was coming from the driveshaft boot to the final drive area but I was wearing earplugs at the time so it was hard to point out an exact location.
Performance was murdered, I couldn't accelerate at all so I pulled the clutch lever and coasted to the roadside.

The whine has more resonance than a transmission whine, I can't really explain it very well. It sounded more like a WW2 air siren at a consistent pitch than anything else.

[Red_Hen]

WW2 Siren Sound - yours must be military issue!

Hope you get to the bottom of this quickly.  Sounds to me like a gearbox / spline type issue.  Let us know what you find out!

[nhmaf]

IF it was the transmission input splines - you'd be dead inthe water right there, and the noise wouldn't go away.
Since you saw smoke at the rubber boot of the driveshaft, I'd first suspect that your U-joint there has either failed or is in the process of disintegration.  Or, possibly you lost/broke off one or more of the bolts that hold it to the transmission output shaft flange..  Or,shudder, the bearing in the output shaft has failed, and you'll need a transmission rebuild.

The input shaft spline failure will make a gawdawful racket, but once those splines fail, you'll lose the ability to apply any power into the transmission from the engine, no matter how much you rev the engine (and revving the engine will only make it grind things further into oblivion).   BTDT...

I'd first look at what's inside the boot, check for bits of broken bolt and/or u-joint imminent failure.   I'd also drain the transmission gear oil and look at it (and the magnetic drain plug) for any pieces of metal..

[Ed Miller]

You could put the bike on the centerstand and block up the rear wheel so it doesn't touch anything.  Start the bike in neutral and shift it up the gears.  With no resistance on the rear wheel it won't stall, and you don't need high revs so you can listen and try to pin point any noises.  

[tvrla]

It's easy enough to open up the driveline - I think that's where I'd start first - especially since the noise seems to emanate from there.

And if it's not the drive shaft, getting into the next area to check will require drive shaft removal so you won't be down anything.

Checking the oil for swarf is a good suggestion.

[MattySull]

Thanks for the tips. I am going to look at it tonight. I'll drain the transmission oil, driveshaft oil, final drive oil in that order and then remove the rubber boot (which has smoke coming out of it) to see what I can find.

I'll try to take some nice pictures of the magnetic trans drain plug and whatever is under the boot.

Wish me luck!

[montmil]

... Wish me luck!

Luck to ya, Mate.

[MattySull]

Checking in.

The driveshaft oil and final drive oil looked great with a nice golden color. No metal chips etc.
The transmission came out a grey/black metallic sheen color which I'm guessing was way overdue for a change. On the magnetic plug there were 3 bits of metal that were about 1/32th of an long and the rest was a fine metallic grey paste.

I moved the boot as far as I could out of the way and didn't see much wear of the u-joint at all.
I did notice that the transmission output flange, u-joint, and driveshaft had a bit of rotational play, about 1/4". The whole thing rotates.

Is the driveshaft supposed to be tight/rigid so that you cannot rotate it unless wheel is turning?

Other than all that the problem isn't apparent and I've essentially gotten nowhere.

[Bob_Roller]

There's usually some play in the drive line, your's doesn't seem too out of the ordinary .

Try removing the rubber timing hole plug on the left side of the engine and see if you note any fresh metal shavings in there .

[tvrla]

The driveshaft and ujoint are directly tied to the final drive. If the rear wheel doesn't turn, but the ujoint does - you've got a problem!

I think you've homed in on the issue.

Also, I'd keep an eye on the transmission - it's not a good sign having anything other than fuzz on the magnet. Check it every engine oil change. It may be nothing, or it may be the beginning of a teardown.

But it's not your current problem. There's definitely something wrong with the driveshaft.

[nhmaf]

I think that there can be a very slight amount of backlash/play in the driveline in the swingarm, but it is *very* slight.   It might be that something is going amiss in the cush drive (spring tensioned drive link) in the driveshaft inside the swingarm - though this sort of failure would typically leave some bits of metal that I would think would tend to come out when you drained the swingarm.  Hmmm.

As wirespokes said - anytime you find more than just some very fine metalliz fuzz on the gearbox's magnetic drain plug, something isn't going well - but may have some time before it becomes critical - or you may not.   I'd refill it with good clean 80W90 gear oil and drain/check it again in ~ 500 miles or so, provided that you can get to the bottom of the driveshaft issue.