Clutch adjustment

Sorry. Unable to post any images. I have an H16 type clutch - no central adjuster in the pressure plate, bolts on the springs, rather than nuts. It has a mushroom’ behind the pressure plate. Gearbox - Norton AMC - has a lever behind the inspection plate, which the clutch cable engages with. I believe that this lever is perhaps set too far up. How do I lower it? Is it possible to extract the rod from the clutch side to ascertain its length; rather than having to open up the gearbox?

Lobo said:

Sorry. Unable to post any images. I have an H16 type clutch - no central adjuster in the pressure plate, bolts on the springs, rather than nuts. It has a mushroom’ behind the pressure plate. Gearbox - Norton AMC - has a lever behind the inspection plate, which the clutch cable engages with. I believe that this lever is perhaps set too far up. How do I lower it? Is it possible to extract the rod from the clutch side to ascertain its length; rather than having to open up the gearbox?

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If you mean that the lever doesn't align with the cable then you have to remove the cable and g/b outer cover, slacken the ring nut holding the lever assembly to the inner cover, rotate the lever assemble to the correct position then tighten the ring nut (that can be tricky as the assemble may rotate as the nut is tightened) and re-assemble. Whilst you are doing that you may as well take the lever assembly off to remove and measure the rod.

hybridracer said:

If you mean that the lever doesn't align with the cable then you have to remove the cable and g/b outer cover, slacken the ring nut holding the lever assembly to the inner cover, rotate the lever assemble to the correct position then tighten the ring nut (that can be tricky as the assemble may rotate as the nut is tightened) and re-assemble. Whilst you are doing that you may as well take the lever assembly off to remove and measure the rod.

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The lever is in perfect alignment to the cable. However, it sits roughly horizontal. Should it not sit down at a lower angle? I thought it should so that it is then pulled over centre.

I thought that the clutch you have is supposed to work with the earlier gearboxes like laydown and upright which have a worm mechanism that the operating lever clamps to and therefor allows you to get the correct movement [swing]on the arm, I thought the AMC box was introduced at the same time as the clutch was changed to the later type. My '57 ES2 has the AMC box with the later clutch.

The clutch actuating mechanism of different gearboxes has different leverage. With same handlebar lever a Commando AMC, a Dommie AMC and a laydown has different movement of the rod.
A Commando box fitted with an earlier clutch will be heavy to operate. The worm gear laydown has shortest movement and easiest pull.
A dragging or heavy to operate clutch can sometimes be fixed by changing to a lever with different pivot to cable nipple distance.
The mushroom type has (at least) two rods. The mushroom part is quite short. To get the rest out you have to remove gearbox outer cover.
I should try to fit different shims on top of the mushroom with double sided tape. Then test function. When found out length needed, remove outer cover and lever assy. Take out the rod.
Grind end of rod 6mm minus shim thickness. Add a 6 mm ball bearing between rods. Gives correct length.
Of course grinding the mushroom end would be much easier but I don't know if it makes the mushroom part too short.
I've dismantled a gearbox with three rods and two balls.
I think that the older clutch where you screw the 3 bolts tight needed the mushroom to lift square. When slightly different spring tension.

Okay guys. Thanks for the input. I guess I’ll see how well it operates when I’ve got the bike up and running and then go from there.

The lever in the box needs to be as close to the cover as possible to get a good operating angle .To achieve this its best to dissconect the cable and screw in the clutch center Adjuster ( if fitted ) all the way in and back off 1/2 a turn . Or fit an extra ball/roller in the pushrod assembly.The cable will probably need a longer inner (or shorter outer) even if a correct factory item. I have 3 Norton clutches ,99,650 and Atlas ,all are 1 finger action.

Thanks, Bob. I guess I’ll be looking at placing a ball bearing in there then, as my clutch has no central adjustment. Would it be satisfactory to put a ball bearing in from the clutch side, so it sits between the end of the rod and the ‘mushroom’?

Lobo said:

Thanks, Bob. I guess I’ll be looking at placing a ball bearing in there then, as my clutch has no central adjustment. Would it be satisfactory to put a ball bearing in from the clutch side, so it sits between the end of the rod and the ‘mushroom’?

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Between, yes. Make sure it is a 6 mm ball, not 1/4". When I make rods from silver steel I harden and temper only the ends to minimize wear.

Thank you, Mike.