AMC/Commando clutches and layshaft

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pommie john

pommie john

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I'm finally considering a CNW electric start on my featherbed Atlas hybrid.

The CNW kit has a belt drive including the clutch hub and I'm not sure if it wil fit onto my layshaft.

I have an AMC three spring clutch on mine and I have an idea in the back of my mind that there's a difference in the layshaft for Commando and earlier AMC.

Am I right? Will I need to change the gearbox layshaft to fit the CNW clutch?
 
You mean the main shaft
Yes the main shaft is longer on a commando gearbox
And the commando clutch sits up against a circlip
The commando mainshaft will fit straight in
You'd probably need a longer primary belt?
 
Yes, mainshaft, my mistake. Thanks for the info. It’s a bit of a bummer because I was hoping to use a quaife five speed that I have lying around that’s also got an AMC clutch on it. I think a quaife mainshaft will be harder to find.
 
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pommie john said:
Yes, mainshaft, my mistake. Thanks for the info. It’s a bit of a bummer because I was hoping to use a quaife five speed that I have lying around that’s also got an AMC clutch on it. I think a quaife mainshaft will be harder to find.
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I would get in touch with Matt at CNW to see what he thinks about your install.He is always very helpful.
 
pommie john said:
Yes, mainshaft, my mistake. Thanks for the info. It’s a bit of a bummer because I was hoping to use a quaife five speed that I have lying around that’s also got an AMC clutch on it. I think a quaife mainshaft will be harder to find.
Click to expand...
Quaife mainshaft! A few months ago I would have just said go to Mick Hemmings. Sadly no. But, the parts were still made by Quaife for the boxes that Mick built and repaired, so try approaching Quaife direct for the part.

The question for the longer term is definitely, 'who will continue building Quaife gearboxes now that Mick has passed?'
 
CNW has a Fetherbed E start kit? Tell me more as I cannot find any info on their website.

Slick
 
texasSlick said:
CNW has a Fetherbed E start kit? Tell me more as I cannot find any info on their website.

Slick
Click to expand...
Well…

I am wondering if their Commando kit will fit if I put a. Commando mainshaft in my transmission.
Is there any reason why it should mot fit given that my engine is inclined forwardlikw a Commando?
 
pommie john said:
Well…

I am wondering if their Commando kit will fit if I put a. Commando mainshaft in my transmission.
Is there any reason why it should mot fit given that my engine is inclined forwardlikw a Commando?
Click to expand...
Does your bike have commando chaincases ?
 
pommie john said:
Well…

I am wondering if their Commando kit will fit if I put a. Commando mainshaft in my transmission.
Is there any reason why it should mot fit given that my engine is inclined forwardlikw a Commando?
Click to expand...
Does it have the same bolt pattern where the primary attaches to the engine case? Is the distance from the crank to the mainshaft the same?
 
gortnipper said:
Does it have the same bolt pattern where the primary attaches to the engine case? Is the distance from the crank to the mainshaft the same?
Click to expand...

Good question. Without a Commando engine to compare it with it's hard to say. I'd better take some snaps and see what the forum thinks.
 
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I superimposed the slimline inner primary from AN site over the commando one, and then scaled the pics and rotated so that the bolt holes were roughly aligned. It looks like at a minimum you may need to re-drill the inner primary on the CNW kit to align with the mounting holes.

AMC/Commando clutches and layshaft


Still need to figure out the the dimensions - post the distance from the crankshaft to the main shaft, on center and I can measure the distance on my CNW kit.
 
gortnipper said:
I superimposed the slimline inner primary from AN site over the commando one, and then scaled the pics and rotated so that the bolt holes were roughly aligned. It looks like at a minimum you may need to re-drill the inner primary on the CNW kit to align with the mounting holes.

View attachment 82672

Still need to figure out the the dimensions - post the distance from the crankshaft to the main shaft, on center and I can measure the distance on my CNW kit.
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That's amazing! Thanks so much.


The distance between the centre of the crankshaft and the centre of the clutch is 234mm.

Google tells me that's pretty much the same as a standard 750 Commando.

I think this is going to work!
 
This is the back side of my stock inner primary. The chain case mounting holes are 110mm on center to each other.

The crankshaft hole is ~83mm.


IMG_20211110_165521.jpg
 
This is the inner of the inner cover on my recent install. Note how there are cut outs on the inside for the locking tabs. You may have to contend with those if you have to re-drill the holes.

If you measure it up and it is contentious, I would contact @cNw and @G81 Can Cycle - maybe they could CNC you a special inner. ;-)

AMC/Commando clutches and layshaft
 
This time I centered the crank and main shaft on the CNW inner. Look at where the bolt holes line up (1, 5, 9 o'clock).

1636518462949.png


And how much extra is on the outside of the CNW vs the Dommie inner.
 
If the CNW option doesn't work out you and you are on Facebook, you may want to check out this thread...

FB links invalid

A very nice (home made) conversion.
 
Last edited by a moderator:
pommie john said:
Good question. Without a Commando engine to compare it with it's hard to say. I'd better take some snaps and see what the forum thinks.
Click to expand...
Where did you source the plates? Plates supplied as 'featherbed commando' should allow you to fit a Commando primary case.

If you made them yourself, maybe not.
 
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