Wildguzzi.com
General Category => General Discussion => Topic started by: brider on October 16, 2017, 09:12:27 AM
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I see this everywhere, searched under "CARC meaning", and it looks like NOBODY asked this question. Must be a really dumb one, but I'm askin' it anyway.
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'Cardano Reattivo Compatto' - Compact Reactive Driveshaft
I think use of the acronym CARC, and writing it on the bike, was a symptom of Aprilia's cartoonish scooter marketing mentality but I'm sure it made the bike more appealing to those who might otherwise have bought Suzuki's SRAD :wink: :grin:
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It’s the style of rear drive on late models with single sided swing arm.
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CARC is the Guzzi version of the BMW bevel box where a reaction arm keeps the rear from rising/falling with addition/reduction of power. Earlier shaft drive systems were noted for the rear rising as power was applied. The Guzzi version has been generally trouble free whereas the BMW box....well, I would not own one.
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CARC is the Guzzi version of the BMW bevel box where a reaction arm keeps the rear from rising/falling with addition/reduction of power. Earlier shaft drive systems were noted for the rear rising as power was applied.
Guzzi's first such system was introduced on the Daytona in 1993, the CARC setup was the second iteration.
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Clanks And Rattles Continuously :evil: :grin:
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Surely someone at Guzzi had a sense of humour when coming up with the CARC acronym as a hidden recognition of the contributions of Carcano (Giulio Cesare Carcano - engineer with Guzzi from 1936 to 1966, inventor of the DOHC V8 engine and the air-cooled V-twin that became synonymous with Moto Guzzi)
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It is a acronym and a modified version of the Parallelogrammo swingarm patented by Magni. It separates the rear gear box from the swingarm. The wheel moves up and down instead of an arc because of the "torque arm" attached to the frame. This arm prevents the wheel from driving under the motorcycle and causing the rear of the drive shaft driven bike from rising when the throttle is opened.
There are various versions and they have been used on other Brands besides Moto Guzzi. Including Kawasaki. It works great. I have a the original Magni version on my Tonti framed bike. The bike will squat down under hard acceleration going straight or coming out of a corner. They do require maintenance because of the many moving parts. I spay chain lube on the moving parts and grease the drive shaft u-joints regularly.
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Clanks And Rattles Continuously :evil: :grin:
I like that one.
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(http://thumb.ibb.co/cNh41R/CARC_drawing.gif) (http://ibb.co/cNh41R)
(http://thumb.ibb.co/dHFP1R/CARC.jpg) (http://ibb.co/dHFP1R)
(http://thumb.ibb.co/dduHMR/Moto_Guzzi_CARC_system.jpg) (http://ibb.co/dduHMR)
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Thanks for the cutaway.
As I understand it the cylinder shape in the driveshaft is some sort of shock absorber?
It certainly does Clank & Rattle at low speed.
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My thanks to all of you for the answer to a question I nearly asked at the rally this weekend.
I say "nearly", because the volume of valuable and arcane information being offered all around me was so interesting that I knew if I asked that question I'd get all of the above in a similar manner, and my data intake buffers were already set to max and getting warm.
Nice user friendly explanations, which is an art in itself. :thumb:
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That cut away picture, the innards look pretty stout to me. I'd like to think it's one of the better engineered motorcycle shaft drive setups.
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Thanks for the cutaway.
As I understand it the cylinder shape in the driveshaft is some sort of shock absorber?
It certainly does Clank & Rattle at low speed.
While it appears that the shaft is a single piece it is in fact an inner shaft and an outer 'Tube' for want of a better word. In between the two there is some sort of synthetic rubber material that bonds the two together which acts as the driveline shock absorber.
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!
Pete
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Me too!
And it's superior in all meaningful ways to the BMW design.
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And I thought it was an expression used by owners when they found chunks in the rear drive oil.
CARK!
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Yes .... but CARC is gone, and Paralever is still in use by BMW. My 1991 R100GS with Paralever has been soldiering on for the past 155,000 miles (not km.) It appears to be a more fragile design than the CARC, since the final drive 'pumpkin' itself floats on bearings and pivot pins, whereas Guzzi does their magic internally. Paralever was first introduced on BMWs in 1988, on their R100GS of that year. In the USA, the 1990 model K1 was the first 'modern' BMW to be equipped with the Paralever. They (R100GS) did experience driveshaft problems, typically U joint. Some didn't make it to 30,000 miles before requiring drive shaft replacement. Mine didn't fail until 122,000 miles. A BMW Forum member referred me to a shop in Wisconsin that could replace the U joints. So far so good. 33,000 miles on the repaired driveshaft. It may be time to pull it and have it inspected by an experienced BMW mechanic, since these shafts can get out of phase. The front and rear halves of the shaft are joined by some sort of non replaceable rubber coupling, and after 26 years of use, it's probably time to replace the entire shaft.
Bob
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The wheel moves up and down instead of an arc because of the "torque arm" attached to the frame.
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 ?
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No.
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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?
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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?
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.
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No.
Well I guess I must be wrong...
We'll see.
Can you bring an explanation to the table ?
See, I'm a bit vague on this stuff, but I'd have thought... For the wheel to be travelling vertically, the distance from the axle to the awingarm pivot would have to decrease as the swingarm reached horizontal and then lengthen again as it took up an angle upon rebound.
How'm I doing ?
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Also CARC
Concern About Rear Carnage !
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First rule of CARC: Do not talk about CARC.
Huzo, shaddup!
:whip2:
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Nah, you're right. The CARC system isn't like the earlier Egli system, nor is it like the BMW system, although the principle used to negate the torque reaction is the same.
One of the nice things about it is that because the entire reactive bridge is supported in what are effectively the wheel bearings as the suspension moves and the reactive forces act upon the bridge it simply speeds up and slows down the rotation of the bearings minutely.
Unlike the earlier systems there isn't a sliding coupling on the shaft that can lead to the trunnions of the driveshaft being misaligned. The front yoke is retained on the output shaft by a circlip and the length difference created by the reactive movement and suspension travel is catered for by the rear yoke sliding on the pinion shaft.
Problems with the CARC bevel box and driveline are rare. The commonest ones being the pinion nut dumping its preload. If this happens and the bike continues to be ridden it will destroy the crown wheel and pinion in very short order. If caught early it is an easy fix and the component can be saved. It happened to mine on the Griso in Sydney and I rode it back to Bungendore. I only noticed when I rolled off the throttle and it H-O-W-L-E-D like a banshee! I nearly shat meself! Luckily because it had been under load virtually the whole trip when I took the box to bits the CW&P looked fine. The problem is of course that the CARC is supposed to be 'Unrepairable' :roll eyes: and therefore you can't buy the peg nut and lock washer to repair it.
Only of course you can, because the peg nut and lock washer are exactly the same parts as the lock nut and peg washer used to hold the crank sprocket on to the front of the crank on a T3/LeMans/SP 1000 so you just buy them, clean everything up, install the new washer and nut, (With some green 'You're never bloody coming off again you bastard' Loctite.) and just torque it to the industry standard for this sort of application which is 60-80 inch pounds. Bend the locking tab up on the washer, reassemble it, reinstall it and fill it with oil and see if it sounds like cats screwing on the over run or not! Mine has done 30,000km since I McGyvered this repair and its still going strong and silent.
Pete
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First rule of CARC: Do not talk about CARC.
Huzo, shaddup!
:whip2:
Now you've done it !
Wheel moves vertically or in a minute arc ? :clock:
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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!
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You forgot that there is often a goat involved......
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60-80 INCH-pounds?
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60-80 INCH-pounds?
Yes, the bearings are pre-loaded by a collapsible spacer rather than a solid spacer system as used on earlier designs.
Pete
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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 ! :boxing: :bike-037:
Are those crickets I hear ?
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BTW, it does move in a flattened arc.
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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.
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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
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WTF are you talking about Pete? I think you and I are talking about 2 different things.
(http://i35.servimg.com/u/f35/18/91/78/64/image17.png)
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Maybe. Depending on how well you explain yourself will decide how pink your frame becomes... :evil:
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! :laugh:
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Meat, wine & shouting. How very Italian. Count me in!
:drool:
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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!
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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.
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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.
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BTW, it does move in a flattened arc.
Slope
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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.
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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 !
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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 :rolleyes:
Dusty
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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).
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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.
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CARC = Can Anyone Restore Calm? :popcorn: :boozing:
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CARC = Can Anyone Restore Calm? :popcorn: :boozing:
Can Anyone Really Comprehend ?
Dusty
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Good point. I will withdraw.
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I want to know where the goat fits in.....
Mark
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I want to know where the goat fits in.....
Mark
Genus Capra ?
Dusty
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Si - maybe Pete knows....
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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.
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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.
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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!
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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. :rolleyes:
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*sigh*
How many times do I have to say this? A DINKUS, BY DEFINITION, CANNOT BE SKOOKUM!
geez. Look it up. :rolleyes:
You are forgetting , the laws of physics are upside down in OZ .
Dusty
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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. :rolleyes:
Ok. Fixed it. :whip2:
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Can Anyone Really Comprehend ?
Dusty
Yes
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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...)
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WTF are you talking about Pete? I think you and I are talking about 2 different things.
(http://i35.servimg.com/u/f35/18/91/78/64/image17.png)
So let's go back to one thing.
Does the rear wheel move up and down in a circular arc, or some other path of motion.
That.... is (or was), the question.
And the correct unambiguous answer, without a blanket of "humour" was given.
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Not telling.
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Let me have a go
The distance from the swing arm bearing to the centre of the wheel must be a fixed dimension as it is defined by the swing arm casting
So the bearing centre to bearing centre must describe an arc as the swing arm goes up and down
However, the torque provided by the engine/bevel box is reacted by the reaction rod.
Ito do that it uses essentially pin joints in 4 locations (2 on the reaction rod and one at the swing arm to frame bearing and the rotation inside the bevel box PLUS as sliding joints either end of the drive shaft
So the CARC mechanism can't change the way the wheel travels but it can change the way bike reacts reacts to applied torque
Just my 10p
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The distance from the swing arm bearing to the centre of the wheel must be a fixed dimension as it is defined by the swing arm casting
So the bearing centre to bearing centre must describe an arc as the swing arm goes up and down
' Never said otherwise.
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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.
Well in that case we are agreed.
I can still hear crickets in North America !
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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.
Some parts do, some parts do not. There are a lot of moving parts in the set up. Some parts are even rotating at high rpm's at a right angle.
One test I did, I removed the shocks, dropped the swing arm down until the u-joints started binding and then raise it until they started binding. The total range of motion as measured at the axle was around 8 inches. With shocks mounted, the axle is 1 inch below center line of the output shaft. Magni does not have any specs on this min/max. Just a warning not to bind the u joints.
Magni called the system Parallelogrammo.
So what good is all this? The torque arm pushes against the frame if mounted on the bottom of a Magni swing arm and pulls if mounted on top the swing arm. This pushing or pulling compresses the suspension rather letting the wheel drive under the bike and raising the back of the motorcycle.
The Magni uses snap rings on the splined ends. Bellville/springwashers are stacked up between the rear u joint and rear snap ring to push the splined drive shaft forward and keep some pre load on it. It rattles. The pictures of the carc appears to use a coil spring to push the drive shaft on direction.
I recently came across an article regarding changing the length of the torque arm to change the swingarm geometry. I did not read it yet. Moto Guzzi has a spec. on the ball eye end mount distance. The Magni is fixed as an equal distance as the swing arm. It would be interesting to see what affect changes in this distance would have on the rear end.
Carc, it work, rattles and still needs chain lube.
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Well in that case we are agreed.
I can still hear crickets in North America !
This is an Ozzie argument , us Northerners have learned not to get involved , well , except for Tris . You never know about the Brits , although he is correct .
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This is an Ozzie argument , us Northerners have learned not to get involved , well , except for Tris . You never know about the Brits , although he is correct .
There is no argument.
This started as a response to the statement that the rear axle moves up and down in a straight line, and I said it is in an arc.
All the trudging down side tracks to muddy the waters won't change a damn thing. It's a tactic often used when you realise you've been wrong, so you keep talking about something else until you stumble onto something that's correct and then dwell on that.
I highlighted the topic in question a couple of times. The Guzzi set up in question is not a parallelogram and never will be.
(EDIT):
For the axle to move vertically with slight lateral displacement, there would need to be vertical struts on each end of the horizontal swingarm and torque reaction arm, those two would have to be the same length and parallel as would the swingarm and reaction rod, and each corner must be pinned.
Similar in appearance and function as a draftsmans drawing apparatus.
THAT ! Is a parallelogram(o)...
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There is no argument.
This started as a response to the statement that the rear axle moves up and down in a straight line, and I said it is in an arc.
All the trudging down side tracks to muddy the waters won't change a damn thing. It's a tactic often used when you realise you've been wrong, so you keep talking about something else until you stumble onto something that's correct and then dwell on that.
I highlighted the topic in question a couple of times. The Guzzi set up in question is not a parrallogram and never will be.
You got no argument from me on that now did you ? Sorry if you missed my attempt at humor , always thought you Ozzies saw the absurdity of life the same as me :grin:
Dusty
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Can't Always Ride Correctly.
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You got no argument from me on that now did you ? Sorry if you missed my attempt at humor , always thought you Ozzies saw the absurdity of life the same as me :grin:
Dusty
Hi Dusty.
I'm happy to put my sense of humour side by side with most run of the mill souls, and history will decide where I placed on the scale. It wasn't your attempt at humour that was under the microscope.
What irks me, is when I'm given a one word response to a question like post #17 with a response like #18 and metaphorically dismissed with a wave of the hand, and subsequent responses from here and abroad answering the question that wasn't asked, using "humour" to replace sound geometric knowledge.
The one and only point that I had any interest in arguing centres around #17 and #18. Although I have confidence in my train of thought, there will be some on this forum that would like to know the facts, versus the opinions of a smattering of semi informed luminaries, (some of which are actually "revered", I've been recently informed)...
I'm fortunate that Pete decided to post on the subject, that got most of the Wolves off my back..(most).
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Now that is a worthy and relevant question. Trust a Kiwi to keep focus on the issues!
What do/did you see as the issue/s ?
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Huh ? Oh , someone was wrong on the internet :shocked:
Dusty
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Here, direct from N.A.
The wheel moves in an arc as Huzo noted.
The CARC doesn't rattle unless it is broken. It's the transmission.
But y'all keep "discussing" it. :laugh:
:popcorn:
Hunter
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Huh ? Oh , someone was wrong on the internet :shocked:
Dusty
Wait! What? NOOOOOOOOOOO!!!!!
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Wait! What? NOOOOOOOOOOO!!!!!
On Wild Guzzi no less , I am still reeling :shocked: :laugh:
Dusty
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Here, direct from N.A.
The wheel moves in an arc as Huzo noted.
The CARC doesn't rattle unless it is broken. It's the transmission.
But y'all keep "discussing" it. :laugh:
:popcorn:
Hunter
Having fun ?
I sure as hell am... :popcorn:
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Nothing wrong with being incorrect, I'm sure it must be possible to get over it !
If it ever happens to me I hope I accept it in good, ummmmm....Humour!!! :laugh:
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Nothing wrong with being incorrect, I'm sure it must be possible to get over it !
If it ever happens to me I hope I accept it in good, ummmmm....Humour!!! :laugh:
Would you like a list so we can all have a good laugh Peter :evil:
Of course I am only kidding , being a bit of a freak for accuracy myself ...
Dusty
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Having fun ?
I sure as hell am... :popcorn:
But of course!! Fun knows no continental boundary!
:popcorn:
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Why oh why can't we settle on a location (Mandello 2021 ?) and bring a list of each other's major mistakes on the forum and slang it out on the shores of Lake Como...I've got mine written on the back of a postage stamp so I'm ready.
I would just love for that to happen, imagine the sparks !!! FANTASTIC :boxing:
I'll be there for sure and would love to re ignite some threads at Monte's Cafe' and the biggest tosser can be thrown into the lake over the road..
Priceless !
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I made a prototype of the Magni swingarm to full scale. I am going to lay it out in auto cad also to get the exact results. But in the mean time, I was surprised with the results. There is a lot going on and much I would assume to be negative secondary affects.
I found that the axle does not move in an continuous arc or a slope, but a sideways bell curve. The axle does not rotate around the swing arm pivot point in a concentric circle. The axle does not move at the same speed as it goes thru the range of travel. The axle does not maintain the same distance from the front swingarm pivot point. Depending on where the center line of the rear gear box spline shaft is located relative to the transmission output spline shaft, several things can change. If the axle is below the transmission spline shaft with the shock fully extended, the axle will slow down as the two spline shafts reach alignment and then speed up as the axle rises above alignment. Then I found that the distance between the swingarm pivot point on the frame and the axle changes nearly 1 inch in 3-1/2 of shock compression. This again depends on the starting point of the axle. If the axle is below the center line, the swing arm will get longer as the spline shafts align and then get shorter as the shock fully compresses above the center line. This can make your bike get go from short, to long, to short. This shortening and lengthening along with the changing speed of compression and rebound has to affect the dampening function. The shock speeds up and slows down at various points of a full stroke. Not just at the beginning or end. Changing the length of the torque arm affected the speed of the shock at different points along with raised or lower the rear of the frame.
While the concept stops the driving of the wheel under the frame, the raising and lowering of the axle affect the speed thru the stroke and the dampening function of the shock. There is a 1 inch or more change in the distance between axles.
I have been wanting to dig into this geometry question for a long time. You all got me motivated. In my mind, I knew there was much more going on. One of the test I did, see how a 1 piece swing arm of the same length move thru the range of travel of the shock. The shock speed changes as it moves thru the range, the distance between the pivot point and axle stay the same. The amount of change in the length of the bike is about half of the Magni swing arm. I found the function of the shock speeding up and slowing down to be related to how perpendicular the shock is to the swing arm. The lower shock eye moves forwards and backward more, the further the top of the shock is moved in front of the bottom eye. The range of motion of the axle is also more than the range of shock travel if the shock is not perpendicular. Over 1 inch on the 3-1/2 travel shocks on my bike or 4-1/2 inches plus. Keep this in mind when slamming a bike with shorter shocks or moving the lower shock eye back to lower your bike. The clearance between the fender and tire needs to be more than the maximum shock compression.
Any corrections welcome, I am about learning new things and being corrected when wrong. Spelling, grammar and punctuation, that is another issue. I need lots of help in that area.
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What do/did you see as the issue/s ?
Huzo, as I understand it, (and I could be wrong) part of the problem with a shaft drive set-up is the UJ. Although it is not the crux of your original post it does have a bearing on the solution.
My Breva has the drive shaft running through the swing arm which acts as a torque tube. A UJ (as I understand it) does not actually revolve at a constant speed and actually speeds up and slows down. This would mean that although the reactive forces, and your CARC is a much more refined version of what is on the Breva are dealt with, there is still the problem that there is not a constant force being exerted on the joint in question. Normally, this is solved by using two UJ's in the drive train and cancelling out this effect. A CV allows the shaft to tun at a constant speed, and using a CV instead of a UJ in the system (to me at least), would infer a much more even strain on the drive train.
I am a bear of little brain, but I have yet to hear my hypothesis shot down.
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Yes Orange, that is all quite true. You do accept though that the Guzzi arse end is not a parallelogram as is the model you constructed, do you ?
A damn interesting thing to play with all the same.
BTW, I reckon your spelling is damn good. Only two mistakes if you can accept "thru" as an acceptable abbreviation.
They are on line #4 and line #24 :bow:
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I thought that your post on the CV was a good time to stick a knife in mine and go on with your direction.
The pro's and con's of CV versus UJ are above my head but I'll bet my flat tappets that Roper can educate us on the topic.
Sounded like a damn good talking point to me.
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So do we know why the CARC is going away? it's so-called non-serviceable nature ,maybe?
And are the new bikes going back to an earlier design, or a new improved one?
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Because it doesn't *look* like what crotchety old men and hipsters think the arse end of a motorbike should look like, because it's more expensive and because people, just generally, are stupid and as thick as pig dribble.
What will it be replaced with? 1950's technology to appeal to demographic #1 listed above.
Pete
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Orange,
Sounds like you're onto a brilliant piece of engineering deduction. I wonder if your calculations take into account the wheel in contact with the pavement as opposed to being free wheeling, "floating", as the suspension goes up and down. Not sure how to think about a wheel accelerating under load, but it can't spin up without transferring force to the road.
Well done,
Matt
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Orange,
Sounds like you're onto a brilliant piece of engineering deduction. I wonder if your calculations take into account the wheel in contact with the pavement as opposed to being free wheeling, "floating", as the suspension goes up and down. Not sure how to think about a wheel accelerating under load, but it can't spin up without transferring force to the road.
Well done,
Matt
Some times the shock is loaded from the top, sometimes the bottom. Bumps push the shock up and wide open throttle push the shock down. Shifting all the weight to the road.
I measured between the axle and swing arm pivot point. The swing arm pivot point is fixed and the axle can move forwards and backwards as it moves thru the range of motion allowed by the shock length while extended and fully compressed.
We are talking Magni, not Carc.
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Some times the shock is loaded from the top, sometimes the bottom. Bumps push the shock up and wide open throttle push the shock down. Shifting all the weight to the road.
I measured between the axle and swing arm pivot point. The swing arm pivot point is fixed and the axle can move forwards and backwards as it moves thru the range of motion allowed by the shock length while extended and fully compressed.
We are talking Magni, not Carc.
I think I get what you're saying. In all fairness, you're way out ahead here. I am humbly reminded of my personal light bulb going off long ago when I realized "Oh, the differential does it's job in part because the wheels are in contact with the road", or "Oh... the gears in the transmission are still turning because the wheels are turning too". Thus my not so surprising insight is, "The cantilever mechanism (CARC or Magni) will behave differently depending on whether the wheel is in contact with the ground or not". I'm reasonably certain you've already thought of that.
Matt
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I think I get what you're saying. In all fairness, you're way out ahead here. I am humbly reminded of my personal light bulb going off long ago when I realized "Oh, the differential does it's job in part because the wheels are in contact with the road", or "Oh... the gears in the transmission are still turning because the wheels are turning too". Thus my not so surprising insight is, "The cantilever mechanism (CARC or Magni) will behave differently depending on whether the wheel is in contact with the ground or not". I'm reasonably certain you've already thought of that.
Matt
Well yes, but the path of the rear axle, RELATIVE TO THE FRAME does not alter.
The linkages are constant length and the geometry remains the same.
(It's an arc...) That's what the "ARC" stands for in "carc" !!! :wink:
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Compact Reactive Shaft Drive – also known as Ca. R.C. or CARC – introduced with the Breva 1100 in 2005 emulating the BMW Paralever design and serving the same function.
Nothing related to the famous Carcano who designed the V8 and the first 90 degree VTwin sold first as a 1976 model.