Clutch parts 1957 AMC

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mark99

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Jul 3, 2012
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I have a 1957 19S with the AMC gearbox
I am taking the clutch off to get the engine and frame fixed
The back plate of the clutch has 18 pie shaped holes in it, about an inch long
In 14 of these on my bike are what appear to be steel inserts
I assume I am missing 4
I don’t see them in this parts diagram
http://www.andover-norton.co.uk/SI%20Clutch.htm
What are they and where can I get them? Part numbers?
Thanks
 
I suspect (suspect means I am not absolutely certain) your back plate is an early design. As the AMC clutch was called on to harness ever increasing HP, it evolved into that shown in the Andover diagram. I also suspect (read the same caveat) the newer back plate can be substituted for yours. Finding the missing parts in your back plate is likely to be a challenge .... I would research further whether the substitution is in fact possible. If you can make the swap, you will enjoy having a clutch with greater torque capacity.

Maybe someone with more hands on experience with the older AMC clutches will chime in.

Good luck with it.

Slick
 
Thanks,
A new back plate is 68.50 GBP!
I wonder if some former owner was running this with the 4 blocks missing and it didn't matter?
 
mark99 said:
Thanks,
A new back plate is 68.50 GBP!
I wonder if some former owner was running this with the 4 blocks missing and it didn't matter?
Click to expand...

Are you sure the inserts on your back plate are plain steel? The new back plates have bonded friction pads all around, making the back plate one more friction plate. If your back plate has worn off all the friction material, then it matters much, as the back plate will score the backside of the basket.

You should inspect the backside of the basket for evidence of scoring.

Slick
 
Yes, pretty sure they are steel
I will take a photo of them
I will have a close look at the basket when I get it off
These little pie shaped parts were sitting in holes in the back plate
They fit closely but loose
I didn't notice at first that they were separate parts, when I put the bike back on the kick stand a couple fell out
I took the others out so I wouldn't lose them, they come right out

I would be a little worried about replacing just 4 of them, they could be a different height which could cause a problem
 
Now I think you are right, probably not steel or they would have some rust on them, hard fiber of some sort
They are for sure separate from the backing plate, they float in the holes at tiny bit and are a bit thicker that the plate


Clutch parts 1957 AMC



Clutch parts 1957 AMC
 
rats looks like one of the 2 images was posted, this should be the other, the plate without the blocks


Clutch parts 1957 AMC
 
also, does the nut in the middle, that looks like it has been jack-hammered, have to be removed before the clutch removal tool is used to pull it off?
I would assume so, but didn't see it mentioned in the one thing I read
What keeps the shaft from turning when you take the nut off?
 
Those are the famous Ferodo clutch inserts.
Developed in the 1930s to replace cork inserts - which only have a fraction of the friction capacity.
What fraction depends on where you read it.
They are like brake lining material - and be gentle with them, they probably contain asbestos.

The inserts are usually larger than the "pie shaped" holes they fit into.
It takes a real skill - or a special tool - to actually get them in there.
I've never actually seen it done, or what the tool looks like...
Just missing 3 or 4 isn't going to make much difference, but they'd need to be evenly spaced so the gaps aren't all together.
Being loose may not give a good clutch action, I'd have to think about that one.

To undo that nut, you need a clutch locking tool.
Its a long handle welded to an old clutch plate, so the clutch can't turn while you undo that nut.
Just bolting some clutch plates together will do the same job, but you may need to drill a hole in something.
The clutch body will often just pull off the shaft by hand once the nut removal has been solved.
hth.
 
I found a photo of the locking tool, I see it sits inside the basket, at the edge so the long handle can stick out
I don't have any scrap plates, I will see if anyone around here has the tool, low chance though
Some of the inserts just fell out, when I leaned it back over on the kickstand, the rest just a little wiggle, they are loose, but a very close fit
Can I use a new replacement backing plate?
Do you know off hand the socket size for the nut? It looks like it needs to be a thin wall socket
 
In lieu of a locking tool, I have engaged top gear, stepped on the rear brake, and undone the nut.

+1 with Rohan .... if you omit the four missing pads, arrange the missing ones evenly around the plate.

The clutch basket should easily come off the main shaft after removing the center nut.

Remove the three small screws, pry off the cover and inspect the internal shock absorber rubbers and the three armed spyder. The rubbers tend to get "gummy" and the spider often has broken arms.

Slick
 
I have been looking at backing plates, I have found this part number, 040584, several places
but one says:
Clutch back plate, bonded type, suitable for 1959-on 040359 sprocket only
And it doesn't look like it would work the same
The plate I have with the holes is loose around the center hub, you could remove it without taking off the hub
I guess so far I am leaning towards trying it with the 14 inserts, I have search and have not found those yet

I will try holding the brake, first I need to get a socket
I got the crankshaft nut off with the brake with no problem

I assume the primary has some oil in it (found some amounts in other posts) but mine seems to have some extra holes in the inner case
The fun of a 60 year old bike I guess
 
Part number 040584 is the backing plate I first thought we we talking about, before you put up your pic. You are correct, that part will not replace the one in your pic.

Your plate seems to be a friction plate sans the dogs on the inner hub .... at least I do not see any dogs. If so, it is then only some sort of spacer or filler plate. Most likely, your best bet is to fill the basket with a new set of plates, eliminating this plate entirely.

Regarding extra holes in inner primary cover..... close them up .... you must run oil (preferably ATF) in the primary .... the chain will have a very short life if run dry.

Slick
 
Hi Bernhard,
thanks,
the 'regular' friction plates look regular
just the very back one has the inserts
They are the hard material
I think all in all I will just try reusing them, sort of evenly spaced,
There is not really a completely even spacing of 14 blocks in 18 holes
 
mark99 said:
Hi Bernhard,
thanks,
the 'regular' friction plates look regular
just the very back one has the inserts
They are the hard material
I think all in all I will just try reusing them, sort of evenly spaced,
There is not really a completely even spacing of 14 blocks in 18 holes
Click to expand...

4 space 3 space 4 space 3 space should work fine :)
 
Most brit factories went to the Ferodo type inserts in the 1930s.
For good reason - power outputs had risen, and they advertised that the friction capabilities of the new wonder material were more,
considerably more, than the cork inserts.
That said, older machines had used cork for some considerable time....
 

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