transmission gear ratio question

[SteveC]

Ok i got a chance to pull what was left of the speedometer cable off the np-435 im putting in the 67 and i was wondering if there was a way to tell what rear axle ratio the plastic gear was for?? i dont know the tooth count off the top of my head. Luckly the tag is still on the transmission i dont have those numbers either but i can go out to the garge and get them if needed.

The rear axle on the 67 is a 4.10 if that helps any.
Just trying to get ducks in a line so when i go to order a new speedo cable if i have to order a different gear.. thanks

[Jake11]

This is a best guess/what I would do kinda answer.
Count the teeth on the gear ya got. Use it and see how close/far off the speedo is. Go up or down in teeth count.
Try to find one! Mines 5% slow. Good luck Jake

[SteveC]

i see denis carpenter has the gears for sale so ill go out later and count the teeth and maybe call them to see what they say

[mrtleavitt]

Any Ford dealer should have these gears as well, at least the ones in Utah do. They used them in the 80's if not the 90's as well. They might know which gear goes with which gear ratio, but I don't know.

[ToughOldFord]

I thought I sent you this info already?

This guy has the speedometer gears, you can get the full set as shown in this listing or check his other auctions for individual gears. His listing also has links to sites that have gearing calculators that'll help you figure out which one you need.

http://cgi.ebay.com/ebaymotors/6-FORD-S ... enameZWDVW

[SteveC]

if you did i some how lost all the info or completly forgot i had it.... thanks again for that link. Sometimes my brain is on leave with out telling me

[Hawkrod]

Keep in mind that tire size affects which gear you need as well as rear end ratio. If you have stock diameter tires you can actually go to Ford and buy the correct gear for the rear end gear ratio you have but if your tires are not teh stock diameter you are better off waiting until you can drive it and determine how far off it is. Hawkrod

[SteveC]

i finally got a speedometer cable.... had to order one for a bronco but got one.... took it for a drive with the gps and the speedometer is off by around 5 mph

i cant for the life of me remember if it is a 16 or 18 tooth gear in there.
but using this formula
New Teeth = (Current Teeth x Speedo Reading)/Actual Speed.

New Teeth = (16 x 30)/25 that tells me 19.2
New Teeth = (18 x 30)/25 that tells me 21.6

i went ahead and with the link tougholdford gave me and ordered the set of gears... and will jsut have to test out the 19 and 20 tooth gears and see which works better.