Spot clutch issue?

[Chuck in Indiana]

Are you planning on pulling the transmission cover?

I've heard many, um, things about 5th gear, many of which may be overstated. It would be fun to see..I know you mentioned a 5th gear sound (though they really do all do that, sir) which might be normal, or a bearing-or some might say teeth.

Sure. It's out.. might as well have a look. The Kid is dealing with a health issue with his mom, and I have plenty of other projects to waste time on until he's back to work on it. 

[Chuck in Indiana]

So, I'm assuming fifth gear is as Pete so euphemistically calls it, "rooted?"

[Wayne Orwig]

And I thought my hearing was bad. That had to be making a LOT of noise.

Why does it almost look like rust on the output shaft?

[Chuck in Indiana]

And I thought my hearing was bad. That had to be making a LOT of noise.

Why does it almost look like rust on the output shaft?

Don't ask me, I'm a rookie at all this..  but remember, it laid on it's side in the barn for years..

[Aaron D.]

Interesting, pitting like that is usually associated with lubrication issues. How many miles on this bike?

It isn't terminal at all, though it's unlikely to "heal". How are the other gears?

Fun. Been a while since I did this stuff.

[Vasco DG]

Aaron? It's totally and utterly 'Donald Ducked'! You can't be serious!

When fifth is that bad there is usually further damage. Next in line is usually third and the primaries, after that it's a lottery and tends to depend on where and how it is ridden. If there is any damage to the clustershaft it'll be a lot cheaper to just fling in the internals of a helically cut five speed.

Pete

[Chuck in Indiana]

Aaron? It's totally and utterly 'Donald Ducked'! You can't be serious!

When fifth is that bad there is usually further damage. Next in line is usually third and the primaries, after that it's a lottery and tends to depend on where and how it is ridden. If there is any damage to the clustershaft it'll be a lot cheaper to just fling in the internals of a helically cut five speed.

Pete

Third looks er ok to my untrained eye, but not absolutely pristine. Brad's dealing with his mom's surgery right now, but has experience in helicopter transmissions. I sent him the above picture and he said he wouldn't fly it..  Probably the cheapest way to go is to swap in the internals of a helical 5 speed?

[Vasco DG]

Once there is pitting it will go downhill rapidly. On the road you really won't notice the difference between the straight and helically cut box, it just won't sound as butch!

Pete

[Aaron D.]

Pete, it may well be gone in this application-though in other gear trains I've worked on the equipment vendor would say it was possibly getting near the end of life, and accessibility or  noise might be the determining factor as to whether it should be replaced. But pitting like that isn't considered failure, just a symptom.

But again, it looks lube related, and if that's the case, other damage may well be already happening.

I'm interested in figuring if the oil is failing because of shock from the drive train, or insufficient oil.

[Vasco DG]

Shock from the drivetrain is the killer. Three dog engagement and no Cush drive at the rear wheel and the very unforgiving stacked washer Spring on the face cam on the input shaft all combine to beat the snot out of the gears when going on/off throttle.

It's unlikely, but not impossible, that fifth in particular may get starved of oil simply because the straight cut teeth don't fling it up that end as effectively as the helically cut teeth in other five speed boxes? It's also notable that the later helically cut, five dog boxes also have a tendency, (Although not as pronounced.) to damage fifth gear and they too have a different helical tooth form to the earlier five speeds which in my experience are immune to the fifth gear eating issues.

Gotta disagree on the severity of the damage though. Once the case hardening is gone wear will be rapid and it's only a matter of time before some sort of catastrophic failure will occur.

Pete

[Aaron D.]

I don't think the case hardening is gone. But only a test will tell that tale. Besides now that they are in there, with Chuck's skills, I can't imagine them putting it back in there.

Anyway, I noticed on my own gearbox that when the lube is filled as normal, no oil gets picked up by 5th if you turn the thing over-very different from the other Guzzi boxes.

[Chuck in Indiana]

So, Pete, you're saying he should be looking for an early rather than late 5 speed to swap parts in? We were talking last night about worse case scenario (looks like it might be here) and he was worried that late 5 speeds are scarce.

[Vasco DG]

Apart from the difference in pinion helix the other changes of any importance are the early boxes use six dog engagement and a dirty great coil spring for the face cam shock absorber while the later, 1100 Cali, five speeds use the stacked washer spring system and five dog engagement. There *may* also be an issue with the needle rollers used at the back of the input and front of the clustershafts. I think that change occurred later though.

My suspicion is that an earlier, six dog, box would probably be of higher quality than a later five dog box but that is conjecture on my part. The coil spring shock absorber is also a more forgiving but less robust mechanism than its later replacement.

Pete

[Chuck in Indiana]

Ok, thanks for that, Pete.. I'll pass the info along.

[dxhall]

My '96 Sport also suffers from Dreaded Gearbox Whine.  I haven't taken it apart because I''m afraid of what I'll find.  If I wanted to replace the '96 stuff with later helical 5-speed stuff, from which years and models should I take the newer gears?

[Wayne Orwig]

It's also notable that the later helically cut, five dog boxes also have a tendency, (Although not as pronounced.) to damage fifth gear and they too have a different helical tooth form to the earlier five speeds which in my experience are immune to the fifth gear eating issues.

My 2004 EV, helical gears, started screaming in fifth gear. After a few thousand miles I went in and replaced the gears. You needed a magnifying glass to see the problem. The hardened surfaces on the gear teeth were filled with cracks. I don't think any material had left the gears. Just that the cracking made a lot of noise.

[Vasco DG]

My '96 Sport also suffers from Dreaded Gearbox Whine.  I haven't taken it apart because I''m afraid of what I'll find.  If I wanted to replace the '96 stuff with later helical 5-speed stuff, from which years and models should I take the newer gears?

All the five speeds are pretty much the same internally apart from the differences I noted above. The reason you'd want to swap the internals rather than just swapping in the complete box are simply that you want to get rid of the crappy ATN9 bearings and the end case on the Spiney boxes doesn't have the spigot for the UJ boot.

Pete

[dxhall]

Anyone have a low-mile 5-speed box they'd like to part with?   I'd sure like to lose a little of the agricultural feel and sound of the Sport.

[cruzziguzzi]

Anyone have a low-mile 5-speed box they'd like to part with?   I'd sure like to lose a little of the agricultural feel and sound of the Sport.

Is there no gearing difference between a "Spot" and other 5 speeds?


Todd.

[Chuck in Indiana]

Is there no gearing difference between a "Spot" and other 5 speeds?


Todd.

A little, but not enough to worry about is my understanding.

[cruzziguzzi]

A little, but not enough to worry about is my understanding.

Makes me then wonder if my '95 Carb-ifornia is a good potential swap should ever the Spot go south. Here, I assume the same year California does not have straight cuts...?


Todd.

[ailgev]

Three Differences Between The Cases Of A 1100 Sport And Other Cases. As Pete Said The Rubber Boot Spiggot Is Removed On The 1100 Sport Box. The Two Top Mounting Bolts At The Bell Housing End Have Been Machined To Around 35mm Length To Accept The Triangle Mounting Plate And Machining Has Been Done At The Rear Mounting Point Of The Case To Accept The Rear Mounting Boss.

I Machined My Replacement Box To Fit. Not Much Work But Easier Just To Use The Existing 1100 Sport Cases. I Can Put Some Photos On If Anyone Is Interested.

[Vasco DG]

Excellent catch. I didn't know about the case machining for the mounting plate. Thank you.

Pete

[Chuck in Indiana]

Three Differences Between The Cases Of A 1100 Sport And Other Cases. As Pete Said The Rubber Boot Spiggot Is Removed On The 1100 Sport Box. The Two Top Mounting Bolts At The Bell Housing End Have Been Machined To Around 35mm Length To Accept The Triangle Mounting Plate And Machining Has Been Done At The Rear Mounting Point Of The Case To Accept The Rear Mounting Boss.

I Machined My Replacement Box To Fit. Not Much Work But Easier Just To Use The Existing 1100 Sport Cases. I Can Put Some Photos On If Anyone Is Interested.

Sure, put em up. It's more accumulated knowledge to share.

[flapjack]

Very interesting thread.  One of these days I'm going to have to get into my early Dayona's box and the information here will be very helpful.  Thanks

Jack