Speedo gear

41 Picup, Thanks for responding. It's 3 speed w/OD. I believe the rear is a 3.73. The original tires were 600/16.
 
You may have to change the drive gear on the output shaft to arrive at a correct ratio. How far off is the speedo/odo now? If it's more than a few percent, you may want to correct it with an adapter in the speedometer cable. They are about $70, and install in minutes. http://www.speedometershop.com/ratio.html#ADAPT

PS -- Due to an axle ratio change, my truck is 9.5% off on the odometer. What I didn't realize until recently is that at speeds above 45 mph, my speedometer is off by 20%. So I need both an adapter and a recalibration. Worth spending a little time on the freeways with a stopwatch and pad of paper...
 
I recently took some one with a cell phone for a ride, she down loaded an app that gave the speed I was going- and confirmed that my speedo reads a bit fast...

I know the speedo drive gear is 18 tooth, for a 3.54 rear...

So, maybe I'll take a while to decide if I want to change anything- fixing the speedo would be the obvious thing...
Karl
 
I just changed my speedometer gear in my 45 1/2 ton with 3.73 gears, I was reading 9 mph high or 64 mph at 55 mph, and found I got about 3 mph difference per tooth.
 
kingskid said:
I'm running 205/75R15 on my 50 Custom deluxe. What tooth speedo gear do I need to compensate? Thanks!
Click to expand...
First you need to know how many teeth are on the DRIVE gear, the one inside the transmission. Once you know that, you can use one of the many calculators on the web to identify the best DRIVEN gear. You may never get it right on the money.
 
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