Hi all! My speedometer drive gear bit the dust today. It was a 18 tooth (tan?). Want to order a new one and adjust to the right speed. My speedometer had alway's read 10 mph faster than it should. What gear would you go with? Its a c4 from a 1979. I know there's a formula that can be used. don't want to go threw that. Just want to get it little closer to the right speed. THANK"S for any help!!

 

The DRIVE gear is on the output shaft, the DRIVEN gear clips onto the end of the speedometer cable.

Ford has used the same nylon driven gears from 1960 thru today, so all are available.

Tooth choices: 16-17-18-19-20 & 21.

You will need a 19T gear, this will slow the speedometer down between 7 to 10 MPH.

C7VY17271A .. 19T Driven Gear.

The closest dealer to you that has it in stock is: TISON MOTOR CO in Estill SC who has ONE: 803-625-2551.

 

Could not remember how much each tooth changed the mph. I would of picked 20 tooth as a guess. And your right just a simple clip that holds it on. Anyone that has this problem it's a very easy fix! Thank you for your help!!

 

Got new 19 tooth speedometer gear installed today, did not change that much with the speed, maybe 4 to 5 mph.slower. I'll try 20 tooth next time. But I'm going to wait to be sure that the old gear was just worn out or if some thing else becauseing the problem? See picture of old gear, it was not worn out evenly all around?Ford Truck Enthusiasts Forums - anderson sc's Album: speedometer gear - Picture