AJS & Matchless Owners Club

Firstly, IKBA, that's well known. Picking up on what others have written, how much room do you need to obtain to make the switch?

As said earlier, the pins just need to be nipped. Would it be possible to get the extra space by using a half nut and reducing the length of thread on the pins?

The reversing idea sounds good but would be a lot of bother.

JohnnyB

Pharisee wrote:Just out of curiosity... Are the cotter pins really necessary? My '54 G3/LS and '55 M18S don't have them. Could they just be, ummm... left out?

I think both your bikes will have the cast aluminium bridge that the spindle is a tight fit in and does not need the cotters.

Further thinking outside of the (gear) box: can the bottom pivot of the gearbox be moved rotated forwards and the top back on its slot keeping the mainshaft in a fixed position or are there too may other obstructions, or can the swinging arm spindle be staked in position buy drilling in a different location and placing a peg/bolt through the spindle?

Hi

The purpose of the pins is to locate and prevent rotation of, the pivot pin. If they're not fitted the risk is wear to the frame casting bore and maybe uneven wear to the bushes.

The easiest fix would be to drill and tap the casting in a convenient place so a bolt screwed in will impinge on the pivot pin and thus retain it, (a small disc of brass inserted before the bolt will prevent damage to the pivot pin from the bolt).

Regards Mick

I agree, the earlier castings were replaceable whereas the late ones are cast into/on the frame.
kind regards.

Duncan wrote:

Pharisee wrote:Just out of curiosity... Are the cotter pins really necessary? My '54 G3/LS and '55 M18S don't have them. Could they just be, ummm... left out?

I think both your bikes will have the cast aluminium bridge that the spindle is a tight fit in and does not need the cotters.

You're absolutely right.... Silly me.

Having spoken to Steven Surbey... despite the part number for the 57 front frame being the same (probably in error) it appears that the dimensions of the swinging arm mount on the seat tube are different to the 56 frame so hence the problem. Also, apparently the correct Burman gearbox will not travel the full extent of the potential movement within the engine plate on the 56 CS before it hits the swinging arm.

So the upshot is that it looks like I will have to accept the limited primary chain adjustment and will look to re-fit the AMC gearbox and see the extent of the adjustment (if any) that I will have. I will post an update when I am able.

Thanks for your support and interest.