Speedo Q

[Postie Bob]

I`ve swapped my 3 speed box for a 4 speed and now my speedo is not telling me the truth  .
It`s showing about 10 ks faster than I`m going .  Is there an easy fix to this prob ?
Is the fault with the gear on the end of the cable or with the worm in the box? Or both  .
Other than the speedo , the `ol girl is going well though I`m still at a loss as to why my clutch seems to have too much pedal before it dis-engages .
Cheers, Bob

[taggraphx]

I think the gears are colour code for different diff ratios, not sure if there the same for 3 speed and 4

[Hobbit]

Ultimately, you probably should change the worm in the box as well as the driven gear to recalibrate accurately. Try the cable gear first and see.
What colour cable drive gear was in 3 speed? Is it the same one you're using with the 4 speed?


Here's a chart for the different ratios.

[Brutus]

I know that Castlemaine Rod Shop make an adaptor box to calibrate your speedo, all you need to give them is how much it is out at 100km's and the type of gearbox but it does cost around $120 from memory.
Dave

[Merlin]

all you need to do is swap the drive from the 3 spd into the 4 spd if you are using the original cable gear from the 3 spd then the only change is that gearbox drive .its easy to swap just pull the extension houslng pop the clip and slide the gear off .easypeasy   
         Cheers Merlin

[Postie Bob]

Got back to my speedo drama today ( damn , I`ve got too many projects  ) .
Thanks for the replies people .
Merlin , I removed the drive from the old 3sp and a spare 4sp I have and they aren`t interchangeable . The 4sp is splined on the inside whereas the 3sp is smooth ( different inside diameter ) . 
For the time being I will texta on my speedo face what speed I`m actually doing in sync with a known speed from another vehicle .
It`s a bugga not having a proper workshop/garage/shed to work on the `ol girl . Swapping the gearbox was a bit of a challenge and I don`t want to go there again... not to soon anyway  .
Cheers,  Bob.