Hello folks,

In reading old posts and such I don't see this answer, but see a lot of sniffing around it. In my '64 d100 truck, I use P235 15 inch radial tires and a 3.91 rear end. What number of teeth should be on the speedo drive gear in an A833OD transmission mated to this tire/rear end combo? I don't see a way to calculate it.

I just installed one with 37 teeth that was sold to me as the "right" one, but see on ebay someone says a 40-tooth gear is correct, and I have one with 29 teeth I just pulled from a tranny that came from an 84 dodge truck.

Anyone know for sure, or how to calculate it?
thanks
rock
'64d100

Not enough info. "P235 15" is not a tire size. We need to know the actual tire size, including the aspect ratio.

Tire sizes look like this: "P235/75R15" or "P235/60R15" or "P235/70R15" or...

_________________
一期一会
Too many people who were born on third base actually believe they've hit a triple.

Try this:

http://www.moparts.com/Tech/tech/pages/speedo.html

Get the excel worksheets at the top of the page and you can just type your tire size and rear-end ratio into the correct fields and it'll spit out the correct number of pinion teeth (you'll have to round to the nearest available)

PS- you didn't give a complete tire size in your post.

_________________

FOlks,
My apologies re. omitting part of the tire size ...just a plain a-- error. But thanks for effort reading and replying and that XL sheet is killer, I sure have it in my favorites now! Man, what an info source this forum is!

rock
'64d100

my 65 needs a speedo cable or at least the gear that goes into the tranny. it is the original 65 tranny. anyone know where to get that?

sb