Clutch or not to clutch

Hello everyone who cares to read this,

I have a slimline frame with a per unit triumph motor and still to source and fit the clutch backplate and cover. Also still to decide on what type of clutch drive.
It seems dry belt is a way to go, any thoughts and tips on this would be highly appreciated ?

Cheers

Steveb

Steve,

A belt drive clutch will allow more options in terms of the primary drive cover, many of the standard Norton or Triumph sealed covers are difficult or impossible to fit in these special applications.

When I make engine plates for a hybrid I usually prop up the engine and gearbox then cut templates out of cardboard. If you want to use standard chain covers, you'd need to check the distance between the crank and mainshaft centres and whether the horizontal alignment is level on the covers' donor bike. I never do that because I run the primary chain in the air with a bit of chain lube from a spray can. I've never used belt drive, however it sounds like a much better option if you don't have to change gearing too often.

My first triton was a pre unit with Norton box and Norvil belt drive , that was about 30 years ago. If I was building a similar bike today I would use the same set up again.

Re belts. A great many years ago I wrote some bumph on the subject in an attempt to correct the ,being very polite, misinformation being put about by 'some' people who I suspect were trying to influence the buying decisions of prospective belt system customers. I lost interest in shoving it on the web but a friend did put it on the web using a free site which ran out a while ago but he has put it on another site and whilst it is not complete in places the belt section is complete...You might like to read it before making any decisions. Personally I do not care what anyone buys or uses as I do not make or supply to the general public belt systems and have, in my olde age retirement, NO interest in doing so.

http://a20b767e.magix.net/#xl_xr_page_1

Coo, thats 2 WW2 aircraft with superchargers whining away flying over so far today making magnificent sounds, nearly as good as Bob Mac on the 1961 250 Honda 4 in the TT or even Dicky Dale on the Guzzi V8 a few years previously in the days of my youth.......I really must soon make it to Duxford soon for one last visit.

Are you using a Triumph gearbox?

J. M. Leadbeater said:

http://a20b767e.magix.net/#xl_xr_page_1

Click to expand...

Very interesting reading.

What is the specification for the belt spline commonly used on Newby etc. belt drives ?

The tooth form is the Uniroyal / Gates High Torque Drive (HTD) developed originally in the late 1970s and , according to the people I consult in the belt industry, the most suitable for our usage where torque, tension and belt speed fluctuations occur all the time. Also the HTD tooth form being deeper than the trapezoidal tooth form belts used by some belt system makers is far less liable to ratcheting (jumping pulley teeth).

I believe Mr newby employs the GT3 version of the HTD belt as it has much higher power ratings than the original HTD or later GT2 versions. Personally if I still rode motor cycles I would always fit a DRY running primary drive belt system simply because I can then obtain a correctly working clutch that possesses all the qualities a clutch is suppossed to possess. I.E. it will......
1 NOT slip when fully engaged even when hot.
2 free off INSTANTLY and without drag whenever required even when hot.
3 be EASILY operated by the uses at all times.(2 fingers MAX)
4 possess the LIGHTEST rotating weight reasonably possible. Not that anyone at Norton BSA or Triumph in their later days remembered this!!

Please remember that ALL the belts we employ were DESIGNED to be employed DRY and were NOT designed to be employed with oil and that any form of lubrication between a belt and pulley significantly increases the risk of ratcheting occurring.

Suggest everyone remembers when deciding to buy a belt system the comment made in a Supercycle magazine regarding some USA belt system makers at the time...unfortunately it has also applied for many years to some UK belt system manufacturers and dealers. ( I do NOTinclude Mr Newby among them)

‘Unfortunately in the motor cycle belt world the makers have fairly muddied the waters as far as the consumer is concerned. They have laid out claims they know to be false, always exaggerated and they engage in an inordinate amount of competition ridicule. All this is done to justify and promote the belt each maker can easily obtain.’
(Super Cycle Magazine 1977 and it very probably applies just as much these days).