It is generally known there are two types of selector fork assemblies for B/M Series 'heavyweight' gearboxes...

The difference is that the 'cam tracks' were made in two different widths with track pins to suit...

Today I have been going through gearbox parts to make up another WD gearbox and from roughly 25 selector fork assemblies I found two that are different to all the others...

These differ in the forks themselves, specifically the distance between the 'legs' of the selector forks...They are approx. 1/16" (.062", 1.5mm) narrower than all the others...

This would require a selector dog correspondingly smaller in diameter at the root of the groove machined to allow them to fit the forks...

All of my gearbox parts have come from complete gearboxes I have previously stripped down....

The two odd selector assemblies are the type with the wider tracks...A previous look at the parts lists showed these were used prewar, then replaced by the type with narrower tracks and then reintroduced post war at some point.

Can anyone shed any light on this anomaly?....It's something I've never noticed previously..

It's worth noting these are selector assemblies from the 'heavy' type gearboxes, not the from the lighter B Series boxes... Ian

email (option): ian@wright52.plus.com

G'day Ian,

I've got a box of selector forks from NOS to unusable at my workshop. I'll have a look over them tomorrow.

Hi Ian. Could those forks possibly be out of a late 30's hand change gear box?

email (option): Fuzzyempire@hotmail.com

I'm not an expert on pre war BSAs but I thought the selector shaft was a bigger diameter (and with matching forks) in those boxes...Could be wrong there though...

Later today I'll post the dimensions across the inside of the selector fork 'legs' of the two types....Ian

email (option): ian@wright52.plus.com

Panic over!..Another cock up on my part...Somehow these selectors got into the wrong box... ....

They are, in fact, the selector assemblies for a pre war B Series box...The same shaft and with selector forks that look the same apart from that crucial dimension...(To suit the smaller dogs in those gearboxes)

So the 'odd ones' aren't in fact odd at all but fit B26/B29/B30 etc. gearboxes from just before the war...

After building the B30 I sold all the surplus gearbox parts I had but I guess these two slipped through the net...Ian

email (option): ian@wright52.plus.com

Here's a picture of the B30 gearbox internals showing the offending item....Ian

email (option): ian@wright52.plus.com