Foot change mech, lightweight

That’s got me wondering now!

Dan

Hi John, 

Just an observation I made. 

Ratchet shaft bush can become loose at temperature. B65 041229.

For this reason washer B18 must be correctly identified and fitted. 

Washer B18, large thin, is of greater diameter than OD of bush 041229. It goes on inside of the bush so that the bush is not pushed outwards by the face cam reaction. 

B19 is smaller diameter and must not be fitted against inner face of bush B18.

Sorry this is double Dutch to anyone without the parts list and diagram.

Peter

Hi,

Happy New Year to all,

Further to Peter's post, I found this on the web about the AJS/Matchless lightweight gearbox:-

• Check for endplay - there should be thrust washers on either side of the centre web as shown in the photos.

• There may also be a washer under the circlip that hold the selector cam on. This isn't shown in the gearbox diagram, but might be necessary to control the end float.

• The thin thrust washer (041389 - B18) goes on the inside. The thicker thrust washer (041390 - B19) goes on the outside (under the selector pawl). There's also a thin washer (041323 - B14) under the securing nut.

• The thrust washers are sometimes missing. They are just washers, so you can improvise replacements. The sizes are: 041389: ID 17.9mm OD 25.4mm T 0.8mm 041390: ID 16.3mm OD 24.4mm T 1.65mm

The web site was 

https://www.ifixit.com/Guide/AJS-Matchless+Lightweight+Gearbox+Overhaul/91777

May or may not be accurate but worth checking as the box inners are much the same, I believe.

HTH,

Stan

My modified gearbox image attached

Stan,

Thank you for posting your modified and much improved exploded drawing. 

Much clearer and easier to read. If you produced it, many thanks. 

The web site you mention is a very good additional guide for early lightweight gearbox. The speaker on the film knows his stuff. 

Hi,

Thanks for the replies, but don't want to highjack this thread.

The only other two I have done are for the clutch. This was because the ones I found from Norton etc didn't reflect the correct order/quantity/type of plates. Hope they might help someone.

Stan

While I appreciate the Gearbox Drawing supplied by Stan Pyke - there were several changes to this gearbox down the years, mainly to do with the sleeve (4th) gear, and its matching selector gear.

The main change concerned changing from pegs & holes, to undercut dogs. This was done to minimise wear, and prevent jumping out of 4th gear. - which can happen to first gear for the same reason.

The first Jubilees had a sleeve gear, with 3x double holes facing into the gearbox, that 3pegs located in. It was the same system as employed by the kickstart/1st gear layshaft - so much so, that the selector gears were the same PNo 04.1276 (as shown in Stans Drawing) initially, later changing to PNo 04.4082, which was beefed up - but still used pegs.

Later, the sleeve gear was amended to having undercut dogs, altogether stronger and 4th gear was retained better. The 1st gear arrangement did not change.

So, it is possible to retrofit the later Sleeve gear, provided you also change Mainshaft 3rd selector gear as well.

(PS - this all applies to engines numbered below 106838)

I hope my sketch (attached) helps a little.