G: Gearbox (Twin) Layshafts and KTB

[vibrac]

I read this warning elsewhere and as I was colecting/selecting a set of gears on the bench ready for insertion into my new crankcase
I re read KTB to remind myself about the lay shaft "The longer spline points clutch side"
Then came the supprise both ends of the shaft were the same! as was a second one
I measured with a digital micrometer length of spline and end of shaft to end of spline- identical
they were not new from spares company I guess they are a few years old
has that dodgy difference as mentioned in KTB been machined away?

 

[stu spalding]

Hi Tim, during some clutch rebuilds I came across some C3 shoe carriers with serious machining errors that had obviously been "rescued" from the scrap bin. It seems that there is still some of this stuff in circulation. Cheers, Stu.

 

[vibrac]

I think two layshafts with identical ends the same is not a machining mistake
can anyone tell us what the two lengths are (if they differ) ?
Layshaft one is .533" from end of spline where it comes to the surface of the shaft to the point where it ends where the reduced end starts, and the ends are identical. Lay shaft 2 spline is .497" again identical ends
When Eddie said in KTB the longer spline faces the clutch so they musy have been visually slightly diferent I wonder if the 'longer end' was 1/2" and simply because of the propensity for errors they are now machined both 1/2"

 

[bmetcalf]

Is this something that the Drawings Committee comments on?

 

[Comet Rider]

Tim,
I think Richardson's comments refer to the Burman box on the singles, as that is definately different

 

[ilikevelos]

I assembled a c twin gearbox about a month ago and remember that the splines at one end of the layshaft were clearly different from the other end. Don't remember too much but clearances were screwed up when assembled backwards. Appeared to be an original set of parts with all gears marked with en36 and vincent part numbers.

 

[oexing]

I can confirm about different lengths of spline ends. Just look which way it goes in the gearbox to align with mainshaft gears.

Vic

 

[vibrac]

Yes the diferences in the length of the splines was due to the difference in the width of gears G7 and G10 I too have seen the differences some yeas ago
but what if thse two layshafts are both cut with their splines to the longest length and what was that length?
I will investigate further

 

[vibrac]

Like most things Vincent the answer is simple when its pointed out to you
Bob at the spares company said that its not the length of the spline (AS KTB says) its the length of the reduced portion/diameter of the shaft with the spline that varies
Now it clicks its that reduced diameter that G9 & G10's internal spline root sits on not the full diameter of the shaft hence the different lengths.
But in fairness to KTB "the long length of the reduced diameter of the spline faces the clutch" is a bit of a mouthfull and us owners are supposed to be smart !

 

[oexing]

Had a look at the second gear shaft not yet assembled in engine. But sorry I could not detect a difference with all gears on. Maybe I got one shaft with different ends and this one is symmetric, I don´t know. Best you check alignments of all gears when tested in gearbox.

Vic