>Surely the only difference between pinions
>could be the number of teeth on the cog, in which case the right pinion
>would 'fit' the output shaft cog, too small a one wouldn't mesh at all,
>and too large a one not fit? Sure enough, the replacement pinion (blue
>instead of orange - 18 teeth instead of 19) fitted in the hole but the
>speedo wouldn't register anything - the pinion is obviously too small.
>The way I see it is that the gearbox output shaft has the wrong-sized
>cog on it (which fits the original pinion), whereas the replacement
>pinion is the right size for the speedo (fewer teeth would increase
>the indicated speed) but won't fit the (incorrect) output shaft cog.
>Firstly, are the above assumptions correct? And secondly, before I
>contact Rimmer Brothers for the umpteenth time, does anyone have some
>advice on my course of action? I think it either needs a new OD unit with
>the correctly size output shaft pinion on it, or a recalibrated speedo,
>either of which I would have to make sure Rimmer Brothers paid for both
>the parts and the labour, because I've had enough trying to fettle their
>incorrectly supplied parts.
Andrew
>From my experience with J-type OD's in Spitfires, there is only one correct
speedo output (as you guessed) and it runs at a different ratio than the
non-OD gearbox speedo output. Each setup uses a different speedometer and
cable. (I would have thought than Rimmers would have told you this.) Since
a J-type OD is a J-type OD I can't see how it could be any different for
the Vit. You may be able to recalibrate your speedo, I'm not sure. The
difference is quite significant, as you have observed. Hope this is helpful
(and correct!);
Bill
mah16@cornell.edu
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