The BSA A7-A10 Forum

Technical (Descriptive Topic Titles - Stay on Topic) => A7 1946-1950 => Topic started by: Craig on 29.11. 2016 22:42

Title: 5 Speed Gearbox on Longstroke Engine
Post by: Craig on 29.11. 2016 22:42

Hello All


Wonder if anyone here has upgraded their gearbox to 5 speed cluster on the longstroke engine? Getting close to the point of gearbox overhaul and would be good time to do the upgrade. Any advice, references on good parts purchased, issues that have happened?

Thanks for your time.


(sorry - know this is a gearbox question but specific to the longstroke engine)

Title: Re: 5 Speed Gearbox on Longstroke Engine
Post by: chaterlea25 on 30.11. 2016 17:24

Hi Craig
That's the first time I have heard of someone looking for a 5 speeder for the bolt on gearbox *????*
I suppose anything is possible,
It would be very expensive, have a look at , http://www.ttindustries.com/bsa_gearbox.html
I think Nova and or Quaife make them too
These are made for race bikes and highly tuned Gold Stars
I would be happy with 4 speed on the old A7

John

Title: Re: 5 Speed Gearbox on Longstroke Engine
Post by: Tomcat on 01.12. 2016 06:12

Yep, anything is possible. I have a 1948 A7 and find it cruises along nicely at 50 mph. If you wish to raise the overall gearing to reduce engine revs and vibration, I would suggest gear up the final drive one tooth. Or... just cruise along at 50mph and enjoy it for what it is. Cheers Tomcat

Title: Re: 5 Speed Gearbox on Longstroke Engine
Post by: Craig on 01.12. 2016 07:34

Thanks Tomcat

Your idea about gearing up the final drive is also a good option. 50 mph is no problem for me now but I can feel the old girl has more in her. If I open her up then the shake and rattle really start and not such a pleasant ride anymore.  (A fair amount of the riding I do is on freeways at 50 mph)

It is all going to come down to costs. I gather the 5 speed clusters are going to be pricey and am shopping around for prices now.
Any recommendations are welcome

Cheers

Craig

Title: Re: 5 Speed Gearbox on Longstroke Engine
Post by: duTch on 01.12. 2016 09:14

 I concur with the above although a five speed would probably rectify that annoying gap betwixt second/turd gears.
 Later STD gears can be fitted, but need to be done as mostly a complete set (early gears aren't all compatible)  How do I know this?

Title: Re: 5 Speed Gearbox on Longstroke Engine
Post by: metalflake11 on 01.12. 2016 09:58

As far as I know, all the after market 5 speed boxes run at a 1:1 ratio in top anyway, same as ours. This would mean same speed at same revs wouldn't it? Seems a lot of money to end up back where you started.