Who would buy one of these AMC gearbox clutch centers?

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I corresponded with a manufacturer of replacement parts recently over a photograph of this "servo" clutch center and told him what a great improvement it is in operation over the standard clutch center with straight splines. Very light lever pressure, does not slip under load because torque increases it's clamping power, and it releases and slips when a lower gear is engaged abruptly to keep the rear wheel from locking.

I am sure this manufacturer is wondering what the market for these would be. A simple bolt-in swap at a fraction of the cost of converting to a Commando-style clutch and belt drive setup.

I used one for a dozen years in a 650cc Dominator and don't ever want to use a standard clutch again. Would you buy one for your bike with an AMC gearbox?

 

bwolfie

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I would for the commando clutch. I keep thinking about having one made, but never get around to it.
 
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Cush dampers in the hub? I want a belt set-up with a cush-damper for my P11. Cush engine sprocket in other post has my interest as well. Just don't want to run a cush set-up 0n the rear wheel. No money now anyway so....
 
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What does the hub cost?

I'm pretty happy with the clutch action of my Ranger, but know it slips if I really 'get on it'. I've tightened the springs to the point that its pretty solid when engaged and not too hard to disengage, but I know there is room for improvement.
 
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I would assume it would work a lot smoother if the mating angle would be used on the clutch discs. Sir Eddy.
 

madass140

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unfortunately there is a bit of work machining these whether straight or curved, its the internal machining .
and of course they need to be hard, replacements for the standard clutch are about $80, getting someone to machine a batch of the "spiral" hub would be rather costly even doing a small batch. BUT if they work well and someone did make the effort then it would probably be a successful venture as long as he could get the $'s for them. they would need to be CNC machined and then hardened.
 

madass140

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I just had a look at a standard one, the internal shape is cast , casting them in steel would be a bit costly I reckon, so yes they would need to be fully machined from solid bar, I could look in to machinig them, I would like to be convinced that they do really work, at least they would be a good replacement for all the worn out ones out there.
is their much info on this type?
 
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madass140 said:
unfortunately there is a bit of work machining these whether straight or curved, its the internal machining .
they would need to be CNC machined and then hardened.
No, you do not need a CNC machine :!: :!:

You can do the outside spiral on a milling machine with a dividing head with the spiral cutting gears attached.—don’t ask me how I know.

The real drawback with this clutch centre is it will make mincemeat of your clutch plates….so if I was you, and I’m not, I would forget it.

If your clutch is slipping when engaged fully home, you might have another problem causing it;
like too weak/worn out springs, friction p[lates;
You are not using a semi synthetic or full synthetic oil in your primary chain case are you :?: :?:
 

bwolfie

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Someone posted this a while back. Some good info. Wouldn't bee too hard to copy.

 
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I'd be interested if it could be adapted to fit a Triumph. If it can, I'll take 2 :D

Webby
 

madass140

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"No, you do not need a CNC machine "
of course not, but if I was doing a batch of them or even one for that matter I wouldnt be machining them manually
thats what they made CNC machines for, I'm a machinist with access to CNC machines .
if you read my post it was the internal machining I mainly was referring to not the outside .
Please elaborate on why you say the clutch plates would be chewed up.
 

bwolfie

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The spline area on the plates would need to match the angle of the center splines. The square edge would start to wear and eventually mate up to the angle, but then the gap would be huge and all would go downhill from there. Ideally you would need a set of clutch plates made to match the spline angle on the center hub.
 

madass140

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I thought that was to be the only answer, has this theory been tested?
are there any comments regarding the wear etc when using this design?
 
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bwolfie said:
The spline area on the plates would need to match the angle of the center splines. The square edge would start to wear and eventually mate up to the angle, but then the gap would be huge and all would go downhill from there. Ideally you would need a set of clutch plates made to match the spline angle on the center hub.
Would it be easier to round the plate "splines"? It's the pressure that holds the clutch, not the splines, right?
 
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This is my experience with the servo clutch in the photograph:

Between 15-20 years ago Heinz Kegler was telling me how he had let one of the three servo clutches he had acquired when he worked for Norton go with a 650ss bike he had sold. He gave me the guys contact information and when I talked to the guy he said he was not really interested in the clutch, it was supplied with his bike extra in a box of bits. So I bought the whole box of parts from him clutch included.

I was riding a 1961 650 Norton on a daily basis and the clutch was a hard pull at the lever if I had the screws tight enough to stop any slip under hard use, the clutch lever pivot was beginning to wear oval! Also even though I was right-handed I could peg one of those machines you see at amusement parks that test your grips with my left hand.


So I popped the Servo Clutch in the bike and tightened the screws up so the pressure plate stayed flat when the lever was pulled, and so that the lever pressure was very light and comfortable to pull, it was just a guess. Well it worked great from the start. My lever pivot stopped wearing, the clutch never slipped under power, just when it was supposed to on fast downshifts into a low gear or when chopping the throttle in gear while coasting down steep hills.

I used the original clutch plates from 1961 with the servo clutch for over ten years and never had one problem with them, I ever took the bike to a drag strip for multiple runs one weekend.

So now I am spoiled. Once you run an AMC clutch with a servo center like this you will never want to go back to the old one ever. It makes the lever pull like that on a modern bike and you simply quit thinking about it. I wish I had one of them for each of my old Dominators and each of my father's old Matchless bikes. With the light spring pressure you can forget about stretching or breaking clutch cables and wearing out all the parts between the lever and the pressure plate.

If someone is making and stocking batches of AMC clutch centers currently and the splines on them are being CNC machined, then it just does not seem like it would be that much effort to alter the CNC programming to cut the splines with the specific spiral needed to convert it to servo action.

So in the end, there are many benefits to this clutch and zero drawbacks. All that has to be done to use stock clutch plates is to machine the splines a bit narrower to make up for the angle, which is a detail that a good CAD program should do easily. And yes they would be hardened material if they were going to last a long time.

Besides the loose servo clutch in the photo, there is also one in Heinz Kegler's old Daytona 88 race bike, which was used in the bike throughout the sixties and early 1970's for road racing, it also works like a charm with very light lever pressure and the bike shifts like a dream, and despite it having well over 50 horsepower and a hard hit when it comes on the pipe it does not slip a bit.

If someone has a basically stock Norton or Matchless road bike that they enjoy riding very often, then one of these servo clutch centers will double the enjoyment they get out of it, especially in stop and go traffic, by cutting the lever pressure by what feels to me in half.
 
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The parts supplier mentioned at the beginning of this thread said that when he gets a chance he is going to test the servo clutch himself and see first hand the improvement it is over the standard part.

So there is some real hope that someday these may come on the market. If you know someone that might have interest in these tell them to put there thoughts on it here as the more interest drummed up among Norton and Matchless riders for this item the more likely and more quickly someone might put them into production.


Thank you.
 
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[quote="madass140 Please elaborate on why you say the clutch plates would be chewed up.[/quote]

Perhaps I misunderstood an earlier post about a Commando clutch;

“my Heinz cut Commando hub was strictly experimental, and it quickly wore the male tangs out of the Barnett friction plates”

See;
slipper-clutch-t11685-15.html
 
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