Wider twin gear ratios

ET43

Well Known and Active Forum User
Non-VOC Member
Hello Folks,
Does anyone know of anyone making a twin gear cluster with wider overall ratios. This would allow a lower bottom gear for round town use and a slightly higher top gear for motorway use, needless to say on my outfit. Or, has anyone attempted to do the G6 Mod as described by PEI whereby a ? smaller G6 is produced to widen the overall ratios.
Many Thanks, ET43
 

Tom Gaynor

Well Known and Active Forum User
VOC Member
Wider gears

You can't get a higher top except by changing the sprockets (which of course also raises all the ratios. This is because all "British type" boxes have a direct drive top, which by definition is 1:1. It was only with the advent of Japanese boxes that "overdrive tops" came into common use. Maybe modern Triumphs have them, but I don't know of any others. You could however look at the ratios of the various 5-speed options because it isn't unusual for them to spread the ratios better and have a lower bottom than the 4-speed they replace.
 

petermb998

Well Known and Active Forum User
Non-VOC Member
Wider Gears

Having fitted a 5 speed cluster to my twin I have found that 1st gear is higher then the original 1/2.6.
The Surtees Box is 1/2.458 and makes 1st gear set off a bit high in the revs.
the intermediate gears seem well placed. top is 1/1 as standard.
peter
 

ET43

Well Known and Active Forum User
Non-VOC Member
Hi Tom, and thanks for the reply. I have evolved gear ratio tables for pretty well all HRD and Vincent machines using all RWS's from 45 to 60 T, and some with smaller gearbox sprockets for trials use. I also have ( in 40 years on ) tables to work out altered ratios and speed and revs if anything is altered. If anyone wants copies, I can send them via snail mail as this local yokel does not know how to send attatchments, yet! Cheers, ET43
 
Top