Gear change conversion

[dave bushell]

In 1933 Scotts produced a bolt on kit to convert hand change gearboxes to foot change. Does anyone know what was in the kit? Apart from the obvious foot change mechanism, and bearing in mind that hand change gearboxes didn’t have the box drilled and tapped to fit the index plates fitted on foot change boxes, how were the gears positively located? Were owners expected to machine the box to take an index plate?
Dave

[Barrie]

There is a description of the conversion here,

https://www.scotttechnicalities.com.au/technicalities/Chapter%207/7.3%20Three-Speed%20box.pdf

[BRIAN MARSHALL]

The drawing in the article isn’t a Flyer/Rep type gearbox. It looks like a fairly early Three-Speed Super box. (The article is dated 1926, so clearly pre-Flyer/Rep/Sprint Special)
The conversion to foot-change from hand-change offered by the factory was a VERY cynical affair as the adverts failed to mention that the gearbox shell needed some precision engineering to position the indent plate in exactly the right position. What happened next was a total can of worms, because you would have both gear-lever and rear brake pedal on the R/H side ! So you then had to try and find a left-hand brake pedal, BUT you probably had a left-hand exhaust system typical of hand-change Flyers and TT Reps and Sprint Specials, and a L/H brake pedal would foul the exhaust ! If you were able to buy a later type L/H brake pedal, you would also need the appropriate gearbox tray clamps, AND a crossover shaft, shorter rear brake rod, etc.. To do the foot-change conversion properly you would therefore need to buy the bare positive-stop mechanism with pedal, get the gearbox shell machined to take the indent plate, then buy a L/H brake pedal, gearbox tray clamps, crossover shaft, shorter brake rod, and a right-hand side exhaust system !!!

There could be yet more problems, because the spring-loading of the ball or plunger for the indent plate tends to try and pull the selector bolt out of the box, and you would need the later type of selector bolt, which has a big slotted head to prevent that happening. It just went on and on, and the poor mugs who fell for the adverts would end up spending a small fortune in order for it to be a success…

[dave bushell]

Thanks Barry and Brian. I agree with Brian and his comments are as I thought. I have a couple of thr conversion sets but without the index plate or spring loaded quadrant selector arm. The drawings in technicalities didn’t make sense with what I had. The conversion wouldn’t have been such a problem with the slightly later hand change Scotts with the right hand exhausts and left hand brake pedals but one would still have the problem with preparing for and positioning the index plate.
Dave

[lewis onions]

I have a different type of foot-change mechanism which does not use an index plate. It was fitted to a 1936 flyer which I bought a few years ago but which was not running so I cannot confirm whether it worked or not – I must assume that it did though. The gearbox fitted was an earlier hand-change type with this addition bolted through the gearbox front cover bolts in a similar fashion to the Scott/Velocette foot change mechanism. It is different from the Scott/Velocette type in that it has a larger barrel which clicks into various set (and quite rigid) positions rather than simply up and down.

If I get chance I will see if I can post a photograph.

[John Bennett]

I’m still in the process of assembling a 1931 TT rep that came in large bits. The gearbox came with the detent plate and spring loaded ball in an L-shaped arm, but the bike will have hand change. Do I therefore need to change for a simple arm without the ball etc (I do have one available) and remove the plate? From what I read below, having both the detent plate and hand change is a bad combination.
Thanks

John

[dave bushell]

No need for the index plate and arm if you are using a gate and hand change. They would possibly conflict if used together.
Dave

[BRIAN MARSHALL]

You don’t need the bellcrank arm, or the indent plate, on a hand-change box as the correct indexing of the gears is provided by the ‘gate’ . I once had a 1929 Rep that had both gate and indexing plate, and the change was hard and notchy, so I took the ball out of the bellcrank arm.

[Bob Mather]

Hi,
Brian is right, just take out the spring loaded ball.
Regards,
Bob Mather.

[Eddie Shermer]

If your cranked arm is going spare, there was a post from Steve Gibbon recently asking for one!!

[BRIAN MARSHALL]

So many of the footchange bellcrank levers are cracked or broken at the base of the bit that engages with the vee in the top of the selector ‘wishbone’. Presumably they were over-hardened and brittle, or just fatigued, like me… I have figured out a way to repair them using EN8 bar, so don’t throw away those cracked and broken ones ! I’ll take one to my Eastern Section meeting on Sunday morning, to be inspected and hopefully approved by members… This does NOT mean that I will be offering this service to members !!!

[Steve Gibbon]

Yes, I am still looking for a foot change box bell-crank arm.
If anyone has one to spare please PM me.
Steve

[lewis onions]

This is the gear change unit I referred to – compared with the usual Scott/Velocette type in one of the pictures. The original lever was broken and repaired as shown.

download/file.php?mode=view&id=516

[dave bushell]

Interesting gear lever assembly. Not seen one of those before. What are the component parts? Any chance of an exploded view Lewis?
Dave

[Barrie]

I’ll lend you 2 ounces of plastic explosive Dave.

The first picture looks like a Marvo unit
The only illustration I could find originates from the 1934 spares listing, and that’s not very clear

[Author]

Posts