The BSA A7-A10 Forum

Technical => Clutch, Primary, Gearbox => Topic started by: Stu55Flash on 14.03. 2010 23:27

Title: Golden Flash Side Car Gearing
Post by: Stu55Flash on 14.03. 2010 23:27
My Plunger Flash has sidecar gearing. Can anyone tell what difference this makes in practice. If I strip the gearbox what do I have to replace? Is it just one gear or several? Any advice gratefully received.

Stu
Title: Re: Golden Flash Side Car Gearing
Post by: wilko on 14.03. 2010 23:43
Just up your gearbox or engine sprocket tooth count. Rarely did manufacturers change the g/box internals for sidecars.
Title: Re: Golden Flash Side Car Gearing
Post by: Brian on 14.03. 2010 23:58
I run 19t gearbox sprockets on my plungers and find this the ideal gearing. Should have a 42t rear.
Title: Re: Golden Flash Side Car Gearing
Post by: Josh Cox on 15.03. 2010 04:24
Hi Stu,

I have just recently fixed the same issue, as far as I am aware the internals of the gear box are the same.

The chain gearing is different.

Side car: 18 front, 47/49 rear.

Normal: 18 front, 42 rear.

With the side car gearing, very quick off the lights and not alot top end.

Normal: a little clutch drag off the lights, but great top end.

For the speed nuts, go bigger on the front sprocket.

Oh, suprise suprise, Brian suggested exactly that  *smile*...........

I went out for a ride on the weekend up got upto 90 MPH on the normal gearing, next weekend I'm gunna have a crack at 100, armed with not much sense and a full sack of brown Adrenalin.
Title: Re: Golden Flash Side Car Gearing
Post by: muskrat on 15.03. 2010 06:58
Go for it Josh, I see you use the refreshing brown adrenalin to get the speed. The other brown adrenalin comes out the other end when a car pulls out in front of you !!!
Cheers
Title: Re: Golden Flash Side Car Gearing
Post by: Josh Cox on 15.03. 2010 07:31
I was more referring to the later version of your brown adrenalin. *smile*
Title: Re: Golden Flash Side Car Gearing
Post by: muskrat on 15.03. 2010 08:55
What primary gearing have you got Josh ? Just took the cafe up over the ton. 23/43, 19/42 at 5400 rpm, if yours is 19/43, 19/42 she'll be doing 6500 rpm, pretty much max for a std motor.
Cheers
Title: Re: Golden Flash Side Car Gearing
Post by: Josh Cox on 15.03. 2010 09:29
18/42, OK, I will not go there.
Title: Re: Golden Flash Side Car Gearing
Post by: Stu55Flash on 15.03. 2010 19:54
Thanks for the info.

I have counted the sprockets and have 19 front and 49 on the rear.  Problem is the rear sprocket is cast with the break drum. How do I fit a 42 rear. By my calcs to keep the current rear drum and get the 2.3333 ratio I need 21 tooth front sprocket. Do these exist for the plunger? Does anyone know if front sprockets from later models fit?

Thanks

Stu 
Title: Re: Golden Flash Side Car Gearing
Post by: trevinoz on 15.03. 2010 20:56
Stu,
         You will have to either replace your rear drum or have a new sprocket fitted.
New drums don't seem to be too expensive. I think they are Indian made generally and quality may be an issue.
Trev.
Title: Re: Golden Flash Side Car Gearing
Post by: muskrat on 16.03. 2010 19:52
G'day Stu,
              you could get the sprocket turned off the drum and bore out a blank sprocket to weld onto drum.
I have done this to a later type and used bolts as scotch keys. That way your not discarding a good drum.