Pre-1964 Dominator (Atlas) clutch ?

APRRSV

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My understanding is that pre-1964 clutches had 9 plates; 4 steel, 4 double sided friction and 1 single sided friction. From 1964 onward this was changed to an 11 plate clutch; 5 steel, 5 double sided friction and 1 single sided friction.

My question is for any of you that may have had experience with both types and whether you noticed any significant advantage/improvement in the later, 11 plate version.

I have a 9 plate version and am wondering whether it is worthwhile to purchase the deeper clutch basket and a couple more plates. I will be using this clutch with a motor with considerably more power than a stock Atlas.

Thanks,
Ed
 
I've been away from direct involvement with the various Norton bikes sinceI emigrated to the US in 1968. After riding my company-provided 650SS (a 1962 model, I was told), I don't think I'd want any higher clutch lever loads than the original. If the Commando dciaphragm-spring clutch will fit, that would be the way to go. At my current age (75+), plus arthritis, I don't think I could even manage to old 650SS clutch any more
 
I am not familiar with an 11 plate Atlas clutch .... did not know such existed.

More plates have the advantage the clutch can transmit more torque, or conversely, deliver the same torque as a clutch of lessor plates, but with less clamp force.

In theory, should you obtain a deeper basket and fit more plates, you should be able to back off the spring pressure and enjoy lighter clutch pull with no slipping. OTOH, if you have a hot engine, more plates will harness the torque with no more clutch pull than the 9 plate clutch.

I have never had a problem with slip (9 plate clutch), but have struggled with a heavy clutch pull. Using a Venhill Featherlite Teflon lined clutch cable has reduced the pull by about 25%, and the pull is now manageable, but still a four finger affair.

Slick
 
Thank you Frank and Slick for the comments. I welcome additional comments from others.

Ed
 
Slick, do you know whether your clutch basket/chainwheel has friction material bonded to the inner back surface?

Ed
 
APRRSV said:
Slick, do you know whether your clutch basket/chainwheel has friction material bonded to the inner back surface?

Ed
Click to expand...

Here is a link to the Atlas/Dommie clutch

https://andover-norton.co.uk/en/shop-dr ... odels-manx

Item (1) is the innermost friction surface. As you can see from the drawing, it is not part of the chainwheel. The chainwheel is Item (13) and DOES NOT have friction material bonded to either side of the rear surface.

Slick
 
The 1962 Parts Book lists 3 versions of AMC clutch - 3 plate 4 plate and 5 plate versions.
3 plate is for the Model 50, 4 plate is ES2 and dommie, and 5 plate is 650.

The design seems to have revised along the way too, so may be a few versions of each.
FYI...
 
According to the Mick Walker Book of the Norton Dominator in 1962 an extra clutch plate was fitted to the Atlas (page 74).
Also on page 143 he states that “well before he left Norton Doug Hele rectified the Atlas problem except the clutch, which was to remain something of a weakness.”

It all depends on how much you abuse the clutch, if you are hauling a double Adult sidecar or making quick getaways from the traffic light grand prix then you may need to pay more attention to the clutch.
You could always apply the Heinz Kegler clutch mod.
I have seen on various Norton’s the normal 4 spring, but also 5,6,and 7 spring clutchs which mainly came off a English speedway bike shop.
 
So far within my 5 spring clutches the biggest variances I find:
clutch plates 4 different thickness' .070-.086-.090-.096
friction plates 2 types and 2 thickness'
3 different diameter & length springs
2 different thickness aluminum pressure plates (thick one from Dunstall built 68)
easy to make up the 5/5 stack using the thin components
The 5/5 stack using the thick components will not fit.
All my chain wheels/basket are the same depth... these are from 68, 66, and 63 + flea market
HTH
 
Thank you Bernhard and Dave.

Dave, I assume by "my 5 spring clutches" you mean your 5 clutches with 3 springs?

Ed
 
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