Changed gears from 3.08-3.73s now the speedo is way off. What do i do to fix it?

[lucaswolfgang814]

94 2wd 4l ranger. Changed from 3.08-3.73s to tow my boat. The speedo is approx 10mph high now. How do I fix this issue?

 

[racsan]

Need to change your speedometer cable drive gear. (goes into transmission) I went from 3.45’s to 4.10’s and also changed from 14’s to 15’s. got a pkg of assorted gears from fleabay, every tooth count (color) but red- and it turned out the red gear (forget the tooth count) was the one I needed. On the plus side you have to “speed” by the speedometer reading so you think you’re driving too fast but youre not, now I have to watch because indicated speed is now actual. Mine was 7mph off at first (but 20+ with the stock 14’s)

 

[19Walt93]

Count the teeth on your current gear and multiply by 1.2 and you should be in the ball park.

 

[Dirtman]

Info on correcting the speedometer here

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

 

[lucaswolfgang814]

Thanks for the info. I'm no mechanic. How hard is it to change?

 

[racsan]

easy, 1 bolt that holds the cable retainer, and a metal clip for the gear.

 

[scotts90ranger]

Yeah, I think it's just a 7/16" wrench to do it and a small screwdriver or pick, maybe some brake clean or something to hose it off before you pull it out...

 

[1990RangerinSK]

Count the teeth on your current gear and multiply by 1.2 and you should be in the ball park.

Maybe he'd rather be on the beach.

 

[cbxer55]

Info on correcting the speedometer here

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

Very useful information since I will be going from 3.73s to 4.10s soon.

 

[Dirtman]

1995+ need to be done via a scanner. There is no gear.

 

[scotts90ranger]

It's more complicated than that, that's what I thought too but my '97 has a gear even though it doesn't have a cable... I think it's '98 up, Ron will probably jump in...

 

[19Walt93]

The years that use a speed sensor plugged in where the cable used to go have a gear on them which can be changed. I'm not sure what year went to a programmable speedometer that got it's signal from the rear end speed sensor.

 

[lil_Blue_Ford]

Interesting enough, going to 4.10 gears and 35” tires in my choptop made the speedo correct... or nearly so.

But yeah, you have to change the gear. Pretty sure it’s 98+ that you have to use a scanner to program changes to the speedometer. Forscan is capable of that. My green Ranger will probably need some adjustments after I get it back together, going to have 3.73 instead of 4.10 and went to 31’s instead of the metric tire size.

Glad it’s possible to use a GPS to verify speedometer readings and stuff, I remember the old method of run on the highway at a specific speed and clock times between mileposts so you could calculate it all out, yeesh.

 

[cbxer55]

May still see them on highways, five mile speedometer check zones. And also the Police set up these white boxes here from time-to-time. They tell you how fast you are going as you are approaching them. Interestingly enough, the speedo on my truck as it is now is off three mph at all speeds. When I pass one in a 25 zone with my speedo reading 25, the box says 22. In a 45 zone reading 45, the box says 42. In a 75 zone reading 75, box says 72.

Find out here soon if my 98 has a gear or not.