The BSA A7-A10 Forum

Technical => Clutch, Primary, Gearbox => Topic started by: coater87 on 21.03. 2017 22:08

Title: Layshaft and mainshaft endfloat
Post by: coater87 on 21.03. 2017 22:08

 All bushings and bearings new. Layshaft was reground and all bushings fitted nicely. Even got one of those fancy SRM nut with the seal.

 I had to use three gear boxes to get enough parts for 1 and a half.

 Both shafts have a pressed on gear, these each have a circle as a gear stop.

 In taking each box apart, I noticed that none of the gears were pressed home on the clips. They varied from maybe 10 thousand to maybe 40 thousandths. The endfloat on the two boxes that were not rusted tight was good. The third box was immobile and a complete mess.

 I just pressed the gear onto the layshaft and pressed it home. My endfloat is excessive, maybe 25 thousandths.

 It took a lot of pressure to press that home, meaning it is not going to wiggle, vibrate, or ever come back off without a press.

 I started wondering, because none of the six shafts had the gear pressed completely home if this is how BSA  controlled endfloat when these were built at the factory?

 It would be a fast, economical way to do this in my thinking...


Title: Re: Layshaft and mainshaft endfloat
Post by: JulianS on 22.03. 2017 11:00
I have found that the gearbox is quite tolerant to end float on the layshaft and I would expect the fixed pinions to be drive tight onto the circlips.

Have not seen a figure given for layshaft end float.

So I doubt that float was set by setting the distance between circlip and fixed pinion.

We increase the end float (and also slightly alter clutch alignment) by using thick modern gaskets, rather than the original type thin paper ones, between maincase and inner cover.
Title: Re: Layshaft and mainshaft endfloat
Post by: Topdad on 22.03. 2017 12:48
Fellow mentalpieces , in this instance I'd refer you to one of our esteemed ozzie  members,dutch, who as conducted exaustive tests on layshaft endfloat ,which I believe from his and other posts is controlled by a washer/shim on the first gear ,I'm doing this same job this afternoon and have a selection of washers/shims to use ,but seriously Dutch as helped me with figures etc, Bob
Title: Re: Layshaft and mainshaft endfloat
Post by: duTch on 22.03. 2017 13:56

  Thanks Bob but Settle down- I'm sure Ive said it before, but I know just enough to be (extremely)  *beer* *bright idea* *bash* *spider* *shh* *dunno* dangerous

 it's true that when I flippantly chucked all the bits in the current box it did rattle somewhat, so I had to dissect it carefully to do a full analysis, and then started to query things  *conf2*

 I also got lucky when I discovered the lack of above mentioned thrust washer when I dissected my original (Plunger box ) box that I'd grafted my RRT2 cluster into...... *eek*... but found that the constant mesh layshaft (B) gear was wider enough than the STD gear to do its stuff, and somehow saved some heartache.....but don't get me started
Title: Re: Layshaft and mainshaft endfloat
Post by: coater87 on 22.03. 2017 16:50
 I will let you guys know how this works out.

 I made up a little jig, and pressed 20 thousandths out. End float is about 8, which I am more than happy with.

 With the jig it literally took 20 seconds to set end float to a good number.