Should Moto Guzzi consider a belt in place of the CARC shaft?

[Triple Jim]

Sorry, a U joint is a constant velocity joint only when the input and output shafts are perfectly aligned.

And if it's a double U-joint with the input and output shafts parallel, or at the same angle, (10 degrees at each joint, 20 degrees total, for example) as I posted above.

[Daniel Kalal]

The topic is interesting, so I put this together (which reinforces what Jim has said, above).

Let's look at the output shaft rotation velocity, where the input rotation is always a constant value of 1.



Using the example of 10 degrees, you can see that a shaft with a single u-joint (such as a small block) will speed up and slow down (by a factor of .015) twice with each rotation of the shaft.  That's vibration.

Now, if we add a second u-joint we can see what happens if that output angle is either -10 degrees or +10 degrees: the vibration goes away.  That is; there is no change in rotation velocity.  Even if the output angle does not match the input angle (+/-) you still have an advantage over just a single u-joint.  In this case, if you're off by 3 degrees out of the desired 10, the vibration will still be cut in half.

[Rough Edge racing]

  Anyone who builds hot rods or 4x4 vehicles knows what Jim is talking about...

  This short video might help....https://www.youtube.com/watch?v=gmV4qwLfOMY

[Kiwi_Roy]

So that's why we have the alignment paint mark on the splines for the VII Spot shaft.
Thanks for the explanation.

[Penderic]

Inboard brakes the next development? Move the weight of the brake hardware and if possible, the weight of the gear hub to a more central location? Might improve the suspension.

And add a PTO take-off for the lawn accessories! 

[twhitaker]

Inboard brakes the next development?

Audi did that 45 years ago.

[Dogwalker]

Audi did that 45 years ago.

Lancia, 79 years ago.

[Triple Jim]

Inboard brakes the next development? Move the weight of the brake hardware and if possible, the weight of the gear hub to a more central location? Might improve the suspension.

The problem I have with that is if something like a U-joint breaks, you lose braking for that wheel.  I really like brake parts to be in very close proximity to the wheels.

[Kev m]

Ironically I skipped this thread when it was posted a few days ago because I felt the question was patently ridiculous (sorry Willow, nothing personal).

I mean, as addressed:

1. The CARC is dead.
2. Even if it wasn't, well, shaft drive seems to work just fine for Guzzi.

I've often professed my preference for either Shaft or Belt drive motorcycles, so maybe I shouldn't be quick to judge the concept.

But then I noticed when reading through this I got stuck on one point - the realization that with the CARC dead, should no replacement Single-Sided Swingarm (SSSA) surface in the near future, Guzzi will have abandoned the easily serviced rear wheel.

I mean, by all reports accessing the rear wheel on the Cali 1400 line is a "right front bottom" or something like that.

And though rear wheel access on the V7 (and presumably V9) line isn't any sort of nightmare, it IS un-necessarily complicated. I mean, I really shouldn't have to remove a muffler or a shock, NEVER MIND a REAR DRIVE UNIT in order to swap a friggin' tire.

Which reminded me how ridiculously easy it was to quickly drop the rear wheel on a CARC. I mean, seriously:

1. Put it on the centerstand.
2. Unbolt/pivot the brake caliper out of the way (and that wasn't even really NECESSARY).
3. Pop off plastic hub-cap, then loosen the lug nuts.
4. Remove wheel!

Damn, I miss that.

I have to admit that I actually LIKE the looks of twin-shock bikes from a "classic lines" standpoint. But I could forgive a single shock rear suspension for that kind of ease of service!

[Tom]

Cool!  I bet that thing is easy to ride.  Leave in one gear and work the throttle for mountain roads.  Any more info?

[kirby1923]

[IMG]Inboard brakes the next development? Move the weight of the brake hardware and if possible, the weight of the gear hub to a more central location? Might improve the suspension.

And add a PTO take-off for the lawn accessories! 

And the E type Jaguar!

[Dogwalker]

Cool!  I bet that thing is easy to ride.  Leave in one gear and work the throttle for mountain roads.  Any more info?

It's a caf� racer made by Gianni Gagliotti, ex official pilot with the Beta 250 enduro in the '70s and ex Paris-Dakar pilot with the Morini 500 in the '80s, starting from a Nuovo Falcone. The pictures had been taken at a rally organized by the magazine "Motociclismo".

[lucky phil]

The topic is interesting, so I put this together (which reinforces what Jim has said, above).

Let's look at the output shaft rotation velocity, where the input rotation is always a constant value of 1.



Using the example of 10 degrees, you can see that a shaft with a single u-joint (such as a small block) will speed up and slow down (by a factor of .015) twice with each rotation of the shaft.  That's vibration.

Now, if we add a second u-joint we can see what happens if that output angle is either -10 degrees or +10 degrees: the vibration goes away.  That is; there is no change in rotation velocity.  Even if the output angle does not match the input angle (+/-) you still have an advantage over just a single u-joint.  In this case, if you're off by 3 degrees out of the desired 10, the vibration will still be cut in half.

This might be easier to understand.
https://www.youtube.com/watch?v=gmV4qwLfOMY

Ciao

[Triple Jim]

This might be easier to understand.
https://www.youtube.com/watch?v=gmV4qwLfOMY

Ciao

Rough Edge racing posted that link in reply #62.  You're right, it's a very good demonstration.

[Rough Edge racing]

  My experience with Guzzi U joints is on Tonti frames...The Guzzi U joint functions exactly the same as the two u joints on the shaft in the demonstration video...
 Older Jeeps and 4x4 trucks have a single u joint on the front driving axles and some of you have probably experience the "bind" occurring when making a tight turn on a hard surface with the front axle engaged. WW2 Jeeps had CV front axle joints just like a modern front drive car...They were replaced by a single U joint in the CJ civilian Jeeps, probably a cost factor...
 If you talk to enough Harley riders you will get stories of sudden belt failures ,many on low mileage belts. Some are from a small object getting between the belt and pulley...Some are likely from misalignment or other butchery, and some are just bad luck...
  When it comes to surviving abuse from racing or riding in hostile situations, a chain is King...

[jcctx]

Don't see it anymore but an enclosed oil bath chain set-up is very durable. Should be able to incorporate into single sided arm easily enough. Must be some reason I haven't thought of it is not used by someone???????

[Triple Jim]

Fully enclosed chains had a small following in past decades.   There were even conversions kits to add the feature.  I think the complexity offset the advantages.

[jcctx]

Fully enclosed chains had a small following in past decades.   There were even conversions kits to add the feature.  I think the complexity offset the advantages.

More complex than an open chain; but surely less than a shaft???

[Tom]

IIRC, the main reason is that it was ugly.

[ITSec]

Fully enclosed chains had a small following in past decades.   There were even conversions kits to add the feature.  I think the complexity offset the advantages.

Mostly in wonky dual-sport and off-road bikes with limited displacement, from what I recall. Bultaco, Jawa, some others. I don't recall any enclosed chains on bikes with substantial displacement (i.e., more than 500cc).

[huub]

Mostly in wonky dual-sport and off-road bikes with limited displacement, from what I recall. Bultaco, Jawa, some others. I don't recall any enclosed chains on bikes with substantial displacement (i.e., more than 500cc).

didn't you get the yamaha TR1?

[Lannis]

Mostly in wonky dual-sport and off-road bikes with limited displacement, from what I recall. Bultaco, Jawa, some others. I don't recall any enclosed chains on bikes with substantial displacement (i.e., more than 500cc).

BSA A10 650cc twin models came with enclosed chains as an option.   Good for the chain, but fiddly when maintenance had to be done.   Most chain cases disappeared after two or three chain/sprocket replacements, I suspect.

Lannis

[leafman60]

It's a caf� racer made by Gianni Gagliotti, ex official pilot with the Beta 250 enduro in the '70s and ex Paris-Dakar pilot with the Morini 500 in the '80s, starting from a Nuovo Falcone. The pictures had been taken at a rally organized by the magazine "Motociclismo".

Very nice!

[ITSec]

didn't you get the yamaha TR1?

I had to go look that one up - in North America, it was sold (in a reduced displacement version) as the XV920R, a Virago/Seca derivative that was spectacularly unsuccessful. It was only on the books two years, and many were unsold when it was withdrawn. I don't recall having ever seen one on the street...

[Penderic]

Driveline efficiency is important ....


...sometimes! 

[kingoffleece]

Harley had an enclosed chain on the then 1200 bikes in the early 80's if I recall correct.

[Lannis]

Harley had an enclosed chain on the then 1200 bikes in the early 80's if I recall correct.

By gar, you're right, I'd forgotten about those.   My new '84 ElectraGlide (last shovelhead) had a belt, but some of the other bikes had an enclosed chain which made changing the rear tire a huge pain unless you drilled a hole or two in the case .... not many of them survived the second tire change!

Lannis

[Tom]

Driveline efficiency is important ....


...sometimes! 

Somehow, I find this disturbing and enticing at the same time. 

[ITSec]

Somehow, I find this disturbing and enticing at the same time. 

Actually, looking at the fact they rider has white hair, it got me thinking of Dusty's recent adventures...

[oldbike54]

Actually, looking at the fact they rider has white hair, it got me thinking of Dusty's recent adventures...

 Nah , mine is prettier 

 Dusty