Gear specs

[Graham Williams 5Participant @grahamwilliams5]

Have been asked if I can make a new magneto drive gear for a Velocette motorbike, it's a M series alloy motor, to replace a fibre type gear in the timing gearchain. Does anyone know the gear specs, PA, DP and the teeth are angled I believe.

[Graham Williams 5Participant @grahamwilliams5]

Velocette timing gears

[EmgeeParticipant @emgee]

Hi Graham, if gear information is not forthcoming you can always measure another gear in the train to help calculate the DP as a starting point, if the original mag drive gear is available but striped of teeth you should still be able to count the number of teeth..

Emgee

[John MCParticipant @johnmc39344]

92T 32DP, 20deg. PA, 16deg. LH helix. Top dia. 3.063", Ptich dia 3.00", Root dia 2.922", all+0 -0002".

Hope this helps.

John

Edited By John MC on 31/12/2017 12:36:33

[HopperParticipant @hopper]

Once again, the breadth and depth of knowledge on this forum leaves me gobsmacked. Well done and Happy New Year.

[larry PhelanParticipant @larryphelan54019]

Hopper,I second that !!

[Graham Williams 5Participant @grahamwilliams5]

Thank you John MC, number 2 cutter available at RDG as I don't have 32DP, he'll have to cough for the cost of that if he says OK. You must be a Velocette motorbike engineer to have that knowledge to hand?????. I'm with Hopper and Larry Phelan but it's an old saying if you don't ask you don't (in this case find out).Happy New Year everyone.

Cheers

Graham

[John MCParticipant @johnmc39344]

Graham, rather than making a gear why not buy a manual AR gear and modify that to carry the AT device? Not easy but you will be using a gear with properly generated teeth rather than the less than adequate formed teeth.

John

[Graham Williams 5Participant @grahamwilliams5]

John. Yes that would be a better approach, Just did ebay search but nothing there then went onto Velocespares site, 2 listed there, a lightened one? + another which is listing 11 degree angle, are there 2 different angles used on the gear (depending on model/year?) then?

Graham.

[duncan webster 1Participant @duncanwebster1]

Can someone explain? 92 t at 32 dp should be 2.875" pcd. If I divide by the cosine of the helix angle I still get 2.991" not 3" as JohnMC post. (I'm sure he's right by the way)

[BazParticipant @baz89810]

I am most probably wrong but I thought that RDG gear cutters are 14.5 PA

[not done it yetParticipant @notdoneityet]

Duncan,

Maybe you are not adding 2 to the tooth count before dividing by 32?

Or maybe these gear calls are too complicated for me!

 

Edited By not done it yet on 31/12/2017 20:30:04

[Graham Williams 5Participant @grahamwilliams5]

Baz, missed that, 14 1/2 degrees is what RDG have, but CR Tools in Sheffield list both 14 1/2 and 20 degree PA, probably very expensive. Given the suggestion by John to modify a 'manual' magneto drive gear, that appeals the most, will have to ask if the angle on the one on the motorbike can be checked so as to completely eliminate the 11 degree mentioned on the other web site.

Cheers

Graham.

[John MCParticipant @johnmc39344]

Posted by Graham Williams 5 on 31/12/2017 18:41:52:

John. Yes that would be a better approach, Just did ebay search but nothing there then went onto Velocespares site, 2 listed there, a lightened one? + another which is listing 11 degree angle, are there 2 different angles used on the gear (depending on model/year?) then?

Graham.

I believe that Veloce used spur gears in the early M series, then 11deg helix before finally settling on the 16deg helix angle The gear dimensions I have given will fit the Venom and Viper models, You could try Grove Classic Motorcycles for a gear.

[duncan webster 1Participant @duncanwebster1]

Posted by not done it yet on 31/12/2017 20:26:45:

Duncan,

Maybe you are not adding 2 to the tooth count before dividing by 32?

Or maybe these gear calls are too complicated for me!

Edited By not done it yet on 31/12/2017 20:30:04

you don't add 2 to get the pcd, that's to get the OD

[Author]

Posts