I have been bashing my head against a wall for months trying to find the answer to this question. I did a frame off restoration on a 65 F100. To bring it back closer to stock a got a I-6 300 out of a newer truck and mated it to a NP435 4 spd on the floor. The engine/tranny combo that was in the truck had a different speedo cable and gear setup so I got a speedo cable from a junkyard but the plastic gear that was on it was toast. I can't seem to find what the correct gear (color and number of teeth) I need to get or find a place that can supply it even if I did know. Turning the wheels and counting the driveshaft rotations the rear end seems to be a 3.00:1 and the rear tires are 31" dia. Please help!

 

Number of teeth on speedometer gears (DRIVE-located on output shaft - DRIVEN-at end of cable) based on rear axle ratio/trans type/tire size.

Nylon speedometer DRIVEN gears available from Ford, same 1960/1990's. 16 thru 21 teeth available, prices range from 2-7 bucks each.

3.00-1 with NP435 not listed in truck parts catalog for 1965/70 F100 ~ 1971/72 F100 with 3.00-1/NP435 G78x15 bias ply tires:

CODD-17271-B .. 18T Gold or Yellow DRIVEN Gear / MSRP: $6.45 each.

 

Do you know how many teeth I need for my setup? Do you have a part number? All the Ford dealers' parts guys haven't been able to help.

 

I figured this would be the case (lazy uncaring parts clucks), so...see post 2 for edited in info.

 

This is a commonly asked question. We need to make this link available on this site.

Speedometer Calibration Program - Method 1

 

Thank you so much NumberDummy. In 25 minutes you answered a question that 6 months of internet searching, 4 parts stores and 3 Ford dealerships couldn't help with.

66f-100 I had seen that link in a couple of previous posts but I didn't have speedo revolution per mile or number of drive gear teeth so It didn't help. Though a sticky post with a bunch of this info would be a good idea.