2.3L ('83-'97) 1992 Ford Ranger speedometer cable spinning too slow

[Captaingreatvalue]

Drive gear looks great finally installed the 14 tooth gear from a mustang let’s see what happens

 

[Shran]

Changing The Speedometer Gearing - The Ranger Station

Once you change the gears in your differential, you need a new speedometer gear to recalibrate your speedometer. They’re inexpensive, and only take a few minutes to change. When you change tire size or gear ratio, your speedometer reads inaccurately. … Continued

www.therangerstation.com

lowspeedpursuit posted that previously but I am not sure you caught it. There is a math formula to figure out exactly what gear you need. You need to pick a speed - I would suggest 60mph - get your truck up to speed until the speedo is reading 60mph and then use a GPS app on your phone to figure out how fast you are actually going. Use those two numbers with the formula in the link above to figure out the PERCENTAGE of error in your speedometer, then calculate how many teeth your gear needs based on that.

You can keep throwing gears at it if you want but it's a waste of money unless you get lucky. Why not just order the right part the first time?

Also, your speedo is not going to be off by much at low speeds because it's always incorrect by a percentage... not a fixed number. 7% of 10mph is not much, 7% of 70mph is quite a bit...get my drift?

 

[scotts90ranger]

In my case there's a chunk of freeway near work that has a 5 mile speedo check section, anytime I go through it I check my odometer, every 1/10 mile is 2% or you can figure it out fancier from there... mine's 2% off now which is acceptable and not fixable without changing tire size but it was 7% off before I changed speedo gears...

 

[Captaingreatvalue]

@Shran and everyone I won’t be ordering any more parts for this ancient technology if this doesn’t work out at least get me close I already ordered an 80 mph GPS round speedo from Amazon for 35 so either way I’ll be alright just wanted to share what I’ve learned

 

[Captaingreatvalue]

Hello all I have finally installed the 16 tooth gear and have determined it is a problem with the drive gear inside the transmission I have already purchased those cheap 80 mph speedometers from Amazon and will just install that in its place with a piece of cardboard painted black I will post pictures later. Looking at the speedometer cable spin while driving with this 16 tooth gear it goes from 0-25 faster than the actual speed is when increasing speed to 35 it starts to slow down going to 45 mph shows 37 going 55 shows 40 going 65 shows 45 that’s the fastest I ever got this speedometer going also found out this is speedometer was replaced by the previous owner as he was having issues also…. Good bye ancient technology