Looking at the WD Triumph range 3SW, 5SW and 3HW. They all have identical gearboxes and gears, same gearbox, rear wheel sprockets and tyres. The 3SW has a 18T engine sprocket 3HW has a 19T and the 5SW has a 20T.
The gear ratios given for the 3SW and 5SW are different, ie top gear =5.8-1 3SW, 4.95-1 5SW. which makes sense.
How is it that the 3HW is shown with exactly the same ratios in all four gears as the 5SW?? Ron
The ratios stamped on Norton boxes are those of the gears within. Changes to the sprockets affect the overall gearing but not the gearbox ratios.
I'd be inclined to suspect that pre-war civilian models had differing clusters and somewhere along the line, the information was not corrected.
It's a bit like WD16H compression ratios. They had a compression plate, but the quoted ratio is always the same as pre-war civilian. Were they lower, or was there a difference to head or piston that they failed to record in the Spare Parts Lists ?
In simple terms Lex. How can two bikes with identical gearboxes etc but with different size engine sprockets have exactly the same final drive ratios? (3HW and 5SW = 4.95-1)
Just laziness by the guys who made the manuals I guess, but it's not too difficult to calculate all the ratio's, if you have all the sprocket sizes, (in top gear it's 1:1) I did the same when I fitted a Jawa clutch to my big 4.
