A65 Gearbox

[Mike Farmer]

 

Hi

I have two A50/65 gearboxes and the clusters are different. I've not yet counted teeth but they are not the same.
So Question--Did any of the other unit construction bikes except A50/A65 series use the same gearbox set up with different clusters.

I'm aware that there is/was a close ration box and wonder if this is the difference.
I've heard this banded about a lot but confess that I haven't a clue about what is a close ratio box.

What are the differences in construction and what would be the difference in use..

Confused.lad

Mike

[wardy]

Hi Mike - can't answer the specifics but a close-ratio gearbox is one where the "gaps" between gear ratios are relatively small - generally for competitive use. They tend to have a high 1st gear and then small "gaps" so that engine revs do not fall much on an upshift. Can be a pain in the ar&e in traffic. 500 Gold Star singles may be so equipped

[DAVE BRADY]

Hi,

If you have a workshop manual there is a page that give the ratios and the numbers of teeth on the pinions.  It is a matter of counting teeth to make sure.  Otherwise they are the same.

Dave. 

[JulianS]

There were a number of changes made to the pre 1966 gear clusters to improve the strength.

You can see some details on the 2 parts bulletins below.

The 1965 season UK Lightning and Lightning Clubman used a close ratio cluster.

Pre 1966 box layshaft had a speedo drive worm attached.

[JulianS]

These show the close and standard ration clusters for the 1965 season.