Speedometer reads about 10% faster

Compared to GPS, my speedo reads high.
1997 taco that had been regeared to 4.88
What is the part that I need to swap in to get it reading accurately. It also has 33" or 32" tires on it...
Anyone have a link to a thread that illustrates it better?
Thanks!

 

That is fuckin awesome.

 

You can swap the speed sensor gear for one with a different amount of teeth. On 4WD trucks it is located on the transfer case. On 2WD trucks it is located on the transmission.
I used this thread as a reference: https://forum.ih8mud.com/threads/speedometer-correction-by-t-case-gear-change.480939/

Since yours is a 97 it may have a mechanical speedometer cable. If so, look at the charts in that thread and only look at ones that use a mechanical cable.

 

your speedometer is off because of your bigger tires (and maybe the regearing itself)
use the tire size calculator and do some experiments:
https://www.tacomaworld.com/tirecalc

 

Here are a couple links that will help you out. The part number you need is likely a speedo gear.

Why your speed is off:
Speedometers, Odometers, and Gas Mileage - All Lies!

How to fix it:
Replacing the Speedo Gear

 

Excellent! Thank you. I'll take a look through these.

Yep it is a mechanically driven Speedo with 4wd. The larger tires would make it read slower than real speed while the rehearsal would make it read fast I believe.

So yeah I think I just need a great. Just wasn't sure what her it would be and how to find the part number and where to buy it. Looks like I should be able to figure it out from those links!

 

Use Dakota Digital. It's easy to do. Only 4 wires...power, ground, and speed input and output. It will make your speedo more accurate than the tooth swap.

Dakota Digital SGI-5ELatest Design - Universal Speedometer Signal Interface Controller

https://www.amazon.com/dp/B014N07F8...colid=7O2GROMZWZRO&psc=0&ref_=lv_ov_lig_dp_it

Edit: I just saw yours is a 97. If it's mechanical then this probably won't work.

 

These are your options taken from here: https://forum.ih8mud.com/threads/speedometer-correction-by-t-case-gear-change.480939/page-2

33482-39135 18 tooth, 18x6 mark RN10*/RN110/RN13*
33482-39025 19 tooth, 19x6 mark TCR1*
33482-39045 20 tooth, 20x6 mark RN106/RN110/RN13* (ATM)

33403-39345 31 tooth, 31x11 mark RN131 (ATM)
33403-19255 32 tooth, 32x11 mark RN10*/RN110/RN13*
33403-29115 33 tooth, 33x11 mark VZN10*/VZN110/VZN13*

You need to determine your stock gear by plugging your VIN into ToyoDIY.com. You can search for "speedometer driven gear" once you have your VIN plugged in. You also need to know the stock tire size and gearing so that you can calculate the change in ratio based on your new tire size and gearing.

I believe if you have to stay with whatever "mark" you have stock.

If your speedo reads fast, that means your current speedo gear is too small and is spinning to fast. You need to replace it will a larger gear.

If your speedo reads slow, that means your current speedo gear is too large and spinning too slow. You need to replace it with a smaller gear.

 

Great info!!! My speedo is showing 65 when I’m really going 60 by gps. Stock set up was 3:58 gears and 225/75/15. Now I have 4:56 gears and 265/75/16 tires. I have the 30 tooth speedo gear in the diff. I know I’ll need bigger since my speed is showing higher. How can I figure if I’ll need the 31,32, or 33 tooth gear?

 

You can either calculate it by using exact gear ratio to tire size changes, or more simply by using the speedo gear and mph. The gears and tires will probably be more accurate, but you only have a couple options to choose from as far as speedo gears go.

1 - (60/65) =~8%
therefore you need a speedo gear that is ~8% larger.

1 - (30/33) =~9% is probably as close as you're going to get.

Also, keep in mind that your stock speedometer is usually off by a certain amount. Sometimes you can actually get it more exact when changing the gear after changing your differential gears and tires.

 

Awesome...I didn’t even know this could be done. Thanks for the info!!!

 

I planned on doing this but after I adjusted my scangauge to compensate I kinda didn't bother. Still oughta though.

 

Mine does the exact same thing

 

I just had my 1998 regeared with 4.56 nitro gears and my tires are 265 78 16. I replaced the speedo gear with the 33 tooth and now the all is with in 1MPH. Truck 2.7 with manual 5 speed.

 

Make that 265 75 16 Falken Wildpeak AT3W