BA Gearbox mainshaft end-float

[Bennet Longman]

I am investigating an intermittent transmission noise on my Mk1 '52 Sq.

The first port of call was to check if the nut on the end of the main shaft. All looks good but I noted the end float is 20thou. Does this seem reasonable?

It is a long time since I had the BA box apart but IIRC the output gear is held in the roller bearing by a large retaining nut and the mainshaft passes through the sleeve. Not clear what controls the float of the mainshaft in this gear.

[chris.shearwood]

All looks good but I noted the end float is 20thou. Does this seem reasonable?

Waller says end play should be 1/64" - 1/32" so your 20 thou is in the correct range.

[paul.jameson]

The end float of the mainshaft is determined at the kickstart end. The step at the end of the splined section of the mainshaft goes against the inside of the kickstart end bearing. On the outside of the bearing is the sleeve which the kickstart ratchet gear runs on. This sleeve is held in place by the nut on the end of the mainshaft but is not clamped tight so hence the end float.

[Bennet Longman]

I have the Waller book from the AOMCC website now and thanks for the good description. Think I will re-assembl, refill with fresh oil/grease and perhaps look to the clutch/primary if the noise reappears.