General => Douglas Motorcycles - General Discussion => Topic started by: RobertC on 21 May 2008 at 16:28

Title: 2 3/4hp Tapers
Post by: RobertC on 21 May 2008 at 16:28

I wonder if anyone can help save me some time! I need to find out the degree of taper for the following on a 2 3/4hp machine (it has a 2-speed gearbox if that makes any difference).

Gearbox primary drive (the side that is threaded 13/16x28tpi LH)
Gearbox final drive (threaded 7/16x20tpi)
Crankshaft taper for flywheel

By the way, does anyone know of a supplier for the 13/16x28tpi LH nut?

Thanks for any help

Title: Re: 2 3/4hp Tapers
Post by: Chris on 21 May 2008 at 17:46
Hi Robert
    I cannot say that I have actually measured each of the specific tapers you have listed but from experience all tapers that I have machined on Douglas crankshafts and gearbox shafts in the past have been 5 degrees.
Title: Re: 2 3/4hp Tapers
Post by: Doug on 22 May 2008 at 04:16

While I was repairing a TS 2-speed gearbox I took some dimensions and made a drawing of the main shaft. The angle is five degrees as Chris mentioned.

While not specifically measuring the angle of the taper on the sleeve gear (I only had to re-bush it) I did record diameters and lengths as best as possible. Trig-ing those out, I get something more like 3.5 degrees.

Tapers are a bit fiddly, if they are off just a little bit the fit is awful. So best to match up against what bits that you might have (if possible) rather than worry about a theoretical value.

Title: Re: 2 3/4hp Tapers
Post by: RobertC on 26 May 2008 at 19:11
That's great, thanks very much.