40's pickup speedo drive gear

Brian

Brian

Well-known member
I am installing a 3.54 crown wheel and pinion into a 46 1/2 ton pickup. It has three speed open drive transmission. Does anyone know the correct speedo drive gear to use in this application?; part number would be even better!! I have looked in all my literature and cannot find this information. Thank you in anticipation, Brian
 
Brian said:
I am installing a 3.54 crown wheel and pinion into a 46 1/2 ton pickup. It has three speed open drive transmission. Does anyone know the correct speedo drive gear to use in this application?; part number would be even better!! I have looked in all my literature and cannot find this information. Thank you in anticipation, Brian
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What size tires are you using? That must be considered as well as gear ratio.
 
Brian said:
I am installing a 3.54 crown wheel and pinion into a 46 1/2 ton pickup. It has three speed open drive transmission. Does anyone know the correct speedo drive gear to use in this application?; part number would be even better!! I have looked in all my literature and cannot find this information. Thank you in anticipation, Brian
Click to expand...


Brian, 3.54 with a 600-16 rear tire uses 21 tooth speed-o drive gear...Ed
 
With tire size, we can look it up in the book. Proper drive will have its tooth count and/or tooth tooth count or ratio of rear gears right on it.
In the literature, speedo parts are around 17,000 and the chart will be found in that part of the book. Only Ford supplied tire sizes, for a pickup I think 600 16 and one size up heavy duty, are shown, so non-standard stuff like modern 15's will require research on diameter and/or a foray into Lincoln or Merc literature for more numbers!
3.54
 
Thanks for the replies boys, yes the pickup is on 600-16's. Being a pickup with open drive, it does not run the familiar 'turtle' off of the torque tube, rather the speedo drive comes out of the trans rear mount, and runs off of what appears to be a bigger gear than what is fitted to the front of an enclosed driveshaft. I have literature giving the different tooth count gears for the torque tube driven vehicles, but nothing to suit the open drive. Thanks Brian
 
I should have the info, will post it when I get back to a catalog. It is going to be an uncommon piece, I fear.
If it is unfindable, I think I can link you to a site on measuring your turns per mile and ordering a speed adaptor.
 
OK...got the book, I'm squinting at lots of little numbers.
3-speed plus 6.00-16 and 3.54(39-11). Driven gear is 21 tooth 01Y-17271-D , drive gear is 21C-17285-C with 8 teeth. Note that depending on what you had, you will probably need to change both, and that the 3.54 stuff is probably quite uncommon.
 
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