I have been checking the gearing on the speedo drive to see what the difference will be.
the Spit has a 6 tooth gear on the output shaft as does the ford. The spit has a 23 tooth gearwheel on the speedo output and the ford has a 22 tooth.
This gives the spit a ratio of 3.83 turns of the gearbox output shaft to 1 of the speedo output.
The ford work out at 3.66 : 1 This is a difference of 4%.
This would make the speedometer over reads by 2.8MPH at 70MPH, 2.0MPH at 50MPH, 1.6MPH at 40MPH and 1.2MPH at 30MPH. To me that does not seem that bad so i might well not bother getting the speedo recalibrated.
Just to add to all this there are speedo gears with 21,22 and 24 teeth available but not 23 ! would be nice if i could find one of those.
More gearbox progress.
I have also cut down the selector shaft and re pinned the gearstick selector fork. And as i guessed I'm now missing 2 gears ! Doh. However this is not entirely unexpected, the problem lies with the fact there is a bearing missing. I cut the original out when i modified the nose casting. Once this bearing is replaced I'm sure the shaft will turn more and bend less giving me back those 2 missing gears. If it does not i do have a plan B. More of that later probably.
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