What does CARC refer to?

[Huzo]

Alright, you asked for it.

As the suspension compresses, force is applied to the skookum dinkus, which rotates obversely to the moment of inertia to the frannistan. Thusly, the applied torque is reduced inversely proportionate to the uplift return arm tension. Therefore, a balance is acquired.

Simples!

Yeah Beetle, I already knew it was simples, (I like that ad too), thing is, I just struggled a bit with getting a one syllable response to my question.
"No" is a statement, not an explanation. I'm not too concerned though, on a recent trip through Europe, I stopped by me old mate Pythagoras' place in Greece, and he gave me the guts on the path taken by the rear axle when pivoting about a single point..
Hey but who knows, it might have taken till 2017 to prove him wrong. Anyway scuzzi, I'm just adjusting my 5 point harness, I think there's turbulence ahead !
Are those crickets I hear ?

[beetle]

BTW, it does move in a flattened arc.

[molly]

I always have a little laugh when I read the technical merits of modern shaft drives. Going back to the seventies and eighties there was a wide range of bikes available with shaft drive, I had a Yamaha XJ900 and a Suzuki GS850  and a couple of mates mates rode Yamaha XS750/850/1100. No one made a big deal about the shaft drive  or complained about problems we were just glad not to have to look after a chain. Admittedly the single sided swing arm wasn't around then which may have complicated things somewhat since.

[pete roper]

BTW, it does move in a flattened arc.

No, the front trunnion is concentric with the swingarm spindle. Think of it as similar to the early Bimota chain drive systems so the output shaft was concentric with the swingarm pivots meaning chain tension was constant.

The only reason why the shaft splines have to slide at all is because of the reactive movement due to load and suspension movement. On earlier bikes like the Loops and Tontis without a reactive drive Terre still needed to be a sliding coupling because the universal joint was a compromise. The actual pivot point of the swingarm was in the middle of the floating centre yoke of the joint. The movement though was so slight given the limited suspension travel that it was coped with with a simple separate shaft and sliding sleve located by circlips on the pinion shaft, front and rear of the shaft itself.

The later Tontis have a very different shaft with a much longer central yoke on the universal/driveshaft which will diminish the sinusoidal loadings on the trunnions but I don't know if the front trunnion is actually concentric with the swingarm pivot or not.

Pete

[beetle]

WTF are you talking about Pete? I think you and I are talking about 2 different things.

[pete roper]

Maybe. Depending on how well you explain yourself will decide how pink your frame becomes...

Nah. I agree, we're probably at cross purposes. We need to sit down with meat and wine and a pencil and shout a lot!

[beetle]

Meat, wine & shouting. How very Italian. Count me in!

 

[brider]

Understandable to a degree, but pretty much everyone (including the technically minded) refers to the class of 1100/1200 cc bikes with the single side swingarm as CARCs. It's reasonable to ask a question about the class and its shared characteristics by using the term.

Thanks, that's kinda what I suspected, but wasn't sure if it referred to something like a California-regulation-sort-of-specification. that was used to refer to an era of bike models.

I'm good, thanks!

[Kev m]

OK, THIS is what has been bothering me about this acronym: Posts like THIS  one, where the discussion has nothing to do with drivetrains, but uses CARC liberally:
 
CARC: Riding Through Wintertime, Should I Concern About Oil Over Cooling?

It's nomenclature used to identify a group of bikes around a single and easily identifiable design feature.

Like 1TB vs 2TB smallblocks.

Like Tonti Calis vs. 1400s

Like a SSSA vs DSSA

Like USD vs Conventional

It's just that the various CARC models - Breva 1100, Breva 1200 Sport, Norge, Griso 1100, Griso 1200, Stelvio, Stelvio NTX etc. all share that ONE common characteristic and powertrains that are in some ways unique to Guzzi across the board.

So the use of a short, simple, colloquial nomenclature such as CARC is simply the easiest and quickest way to say it.

[Orange Guzzi]

I don't want to start an argument, but does that need a re think ?
The distance between the swingarm pivot and the rear axle centre is constant, so the axle would travel in an arc.
No ?

The wheel moves up and forward in a slope rather than an arc when compressed. It does not move very far forward though.  If you look at the diagram, you will see the spring on the drive shaft spline area to allow for the forward movement.  On the Magni set up, a Bellville/bevel washer stack is use instead of a spring.  This movement forward is less than 1/8 inch forward under compression. 

[Orange Guzzi]

BTW, it does move in a flattened arc.

Slope

[HarveyMushman]

As for the clanking? This affects earlier bikes mainly and can be improved by fitting a later type, more forgiving, silentbloc bushing at the front of the reaction arm. Another thing that AIDS on/off throttle smoothness is ensuring that there is the absolute bare minimum of free play in the throttle cables.

Needless to say, if your bike is poorly tuned and your throttle body balance is all over the shop nothing you do will improve its rattling and knocking! I have to say that I can go from negative to positive throttle on both my Griso and Stelvio at below 2,000rpm without touching the clutch in lower gears as long as I'm careful and sympathetic and it rattle and clanketh not!

Sub-optimum tuning doesn't account for the clanking one gets while working the clutch in and out, does it?  For instance, while wobbling around a parking lot at slow speed, easing the clutch in and out . . . clank.   

[Huzo]

You guys that reckon the axle moves in a slope will eventually have to stop and grab reverse. The further you go, the further you're gunna' have to back up.
If you imagine the swingarm ROTATING around it's PIVOT point with the distance between the PIVOT and the AXLE being constant ( which it indisputably is).
Now if you disconnected all the paraphernalia in the way and was able to do so, rotating the swingarm further up ( like you hit a bump) to an exaggerated degree ( say 45 degrees), would describe 1/8th of a CIRCLE and rotating it more in this manner (if you could) would eventually complete a circle, (a shitload of stuff would get in the way but can you see where I'm going ?).

Granted, there's a whole lotta' stuff inside the swingarm taking up end float, but if the centre of the front universal joint was abso bloody lutely concentric with the swingarm pivot axis, there'd be no end float assigned to suspension movement.... Again it would be like having the swingarm axis on the same axis as the output shaft on a chain drive bike. Also I'l suggest that another reason you need splines on both ends of the drive shaft is so you can get the bugger out !
The only way you'll get a "slope" or a "flattened arc" or any other bastardised definition to describe what the axle does in relation to the swingarm is to have the distances between these two points varying, (and no one wants that).
Okay... here's that turbulence !

[oldbike54]

Alright, you asked for it.

As the suspension compresses, force is applied to the skookum dinkus, which rotates obversely to the moment of inertia to the frannistan. Thusly, the applied torque is reduced inversely proportionate to the uplift return arm tension. Therefore, a balance is acquired.

Simples!

 "frannistan" , that is where an ex of mine lived , and access required both magic and luck 

 Dusty

[Huzo]

The wheel moves up and down instead of an arc

Also let's not get caught up on side issues..
THIS ! Is the point we're discussing...
Off you trot to Wal Mart guys, and grab a piece of paper, a pencil and a draftsman's compass.
Beetle, (chat to Pete).

[beetle]

I will not. There will be shouting, however. I think you and I are having a failure to communicate. It cannot move the way Mr Orange says. Impossible.

[ITSec]

CARC = Can Anyone Restore Calm? 

[oldbike54]

CARC = Can Anyone Restore Calm? 

 Can Anyone Really Comprehend ?

 Dusty

[beetle]

Good point. I will withdraw.

[Markcarovilli]

I want to know where the goat fits in.....

Mark

[oldbike54]

I want to know where the goat fits in.....

Mark

 Genus Capra ?

 Dusty

[Markcarovilli]

Si - maybe Pete knows....

[Muzz]

In regards to the CARC (or any Guzzi drive set-up) could anyone explain why UJ's are used and not CV's. I would have thought a CV would be the obvious joint to use.

[ohiorider]

In regards to the CARC (or any Guzzi drive set-up) could anyone explain why UJ's are used and not CV's. I would have thought a CV would be the obvious joint to use.

I'm not sure ..... good question.  Seems like CV joints would eliminate a 'phasing' issue.

[ITSec]

In regards to the CARC (or any Guzzi drive set-up) could anyone explain why UJ's are used and not CV's. I would have thought a CV would be the obvious joint to use.

Now that is a worthy and relevant question. Trust a Kiwi to keep focus on the issues!

[rodekyll]

Alright, you asked for it.

As the suspension compresses, force is applied to the skookum dinkus, which rotates obversely to the moment of inertia to the frannistan. Thusly, the applied torque is reduced inversely proportionate to the uplift return arm tension. Therefore, a balance is acquired.

Simples!

*sigh*

How many times do I have to say this?  A DINKUS, BY DEFINITION, CANNOT BE SKOOKUM!

geez.   Look it up.   

[oldbike54]

*sigh*

How many times do I have to say this?  A DINKUS, BY DEFINITION, CANNOT BE SKOOKUM!

geez.   Look it up.   

 You are forgetting , the laws of physics are upside down in OZ .

 Dusty

[rodekyll]

You are forgetting , the laws of physics are upside down in OZ .

 Dusty

*sigh*

How many times do I have to say this?  A DINKUS, BY DEFINITION, CANNOT BE SKOOKUM!

geez.   Look it up  down.   

Ok.  Fixed it.   

[Huzo]

Can Anyone Really Comprehend ?

 Dusty

Yes

[Huzo]

I'm not sure ..... good question.  Seems like CV joints would eliminate a 'phasing' issue.

That's a damn good one !

To the CV discussion !!! And don't spare the horses. (Sorry, kilowatts...)