1987 22rte Digital dash
I'm running 33s ...speedometer is off about 10mph... at 70mph by GPS, I'm reading 60mph on the digital dash.
anyone know how to correct this?
please no guessing at what might fix it
I would appreciate solid, knowledge answers to correct this.
(don't mean to sound like a jerk)
thanks

 

Is the speedometer drive in the transfer case mechanical or electrical? (Does it have a cable or wires coming out of it?)

 

I don't know I've never looked at it...I assumed it was electronic since it's a digital dash? I figured if it was cable others with the same issue would have simply put in a different number tooth gear, but haven't found any info that makes it look that easy.

 

After a lot more looking
I'm pretty sure it's a gear drive
17 toother... I'm about 10mph under at (60mph) so I guess I'd need a 19 tooth?

 

Will this 33403-69135 gear work in the A340 auto Trans?

 

Well, you could re-gear the differentials. 4.56 would be pretty close to stock. Most people run 4.88's with 33's which is a very slight overcorrection but leaves you with a bit more pep.

If you're set on re-gearing the speedometer drive, you'd need a smaller gear. I had the same issue. I ran a 33403-69175 gear in my 1987 4Runner 22RE with 5 speed. It worked perfectly for a few days but since the gear is smaller there is less tooth engagement. The metal teeth on the transfer case output shaft stripped the plastic teeth on the speedometer drive since there was barely any engagement. If you really want to make it work you'll need to find a corresponding larger drive gear for the transfer case output. I decided that was more work than I was willing to put in and didn't even look into whether that existed.

 

Forgot about another option which is probably better than playing with gears in the trans. There are correction boxes you can buy.

https://www.yotatech.com/forums/f116...l-pics-195986/

https://www.ihpartsamerica.com/store...O-GEARBOX.html

https://speedometercablesusa.com/gear_box_adapters.html

 

Thank you

 

It's definitely a mechanical drive from the transfer case. I've not heard of anyone changing these out to adjust for tire size changes.

The VIN for my '87 4Runner Turbo pulls up 3348239135 for the drive gear, and the note in the catalog says "N=18", so I assume 18 tooth. I'm not positive on the math to figure out what size you would need, though.

 

I think I had this outfit build my correction box:
https://www.speedometerserviceportland.com/
Super quick turnaround. They'll have you drive 10 miles (measured by something other than the odometer in the truck), then you just tell them the odometer change over the 10 miles and they'll figure out the gears.