1500 Input Shaft

[Mad Mart]

I am in the middle rebuilding a 1500 single rail box but I needed a new input shaft as some teeth are chipped on the original. I managed to source one from Steve last Sunday but there are a couple of anomalies that we spoke about at the time. One being the longer splines and also the missing shoulder above/in front of the splines. Today, however, I counted the number of teeth and the original has 16 whereas the replacement has 17. I have had the shaft fitted and it works fine but I'm wondering if I should use it? Also, what gearbox did it come from?

[Mad Mart]

I have just been speaking with Richard (the old one) and he has several old input shafts and they all have 17 teeth (all from Dollies). My 1500 box is originally from a Spitfire so I wonder if Spit boxes only had 16 teeth?

[Richard the old one]

I decided that I would check the number of teeth on the old damaged input shafts that I have and I must confess that I must have counted the first tooth that I marked with snow pack twice so the correct number is 16 teeth.

[Mad Mart]

Thanks for the correction Richard.

So how would this affect the output if indeed it does?

The actual gear ratios won't be affected. As far as I can see it will just slightly increase the speed of the laygears?

Input shaft/ 4th gear = 16 or 17 teeth
Laygear = 29 teeth

[cliftyhanger]

I'll have a punt here, based on selling Mike Papworth 2 non od single rail boxes for core.
One turned out to be a midget box, he recognised it from the input shaft. And was adament it was virtually useless for spares for Triumph boxes.
However, I also have a good friend who builds boxes locally. He reckons there are several variations of single rail layshaft clusters and corresponding other gears. And despite some parts suppliers implying there is only one part number, that is not true.

[Carledo]

Thanks for the correction Richard.

So how would this affect the output if indeed it does?

The actual gear ratios won't be affected. As far as I can see it will just slightly increase the speed of the laygears?

Input shaft/ 4th gear = 16 or 17 teeth
Laygear = 29 teeth

having 1 extra tooth WILL affect the indirect gear ratios slightly. But my brain is balking at working out whether it will raise or lower the gearing.

You know the source of the parts and I know Jon had Spitfires as well as Dolomites, but these boxes could have come from literally anywhere from a Marina to a 1500 Midget and all points in between. Is it possible the shaft is from a 1300 Dolomite single rail? I dunno TBH. Maybe you need to talk to Mike Papworth to get a definitive answer.

Steve