Correcting speedometer after gear swap

[Stephen Carter]

So she lives again, with 4.56 gears. I was expecting the speedometer to be a bit off, aka 3 or 4 mph at 65... but not almost 20mph lol

So does anyone know how I can correct this? I did a search and all i got was electronic vs mechanical debate.

4.56 gears, 35x12.5 tires and a really far off speedometer

 

[frankin5]

Unless 90 or 91 241c transfer-case you will have to change speedometer gears in 208 transfer-case
The other method is to have a gearbox made by a transmission shop

 

[rampage]

Your speed will always be off by a percentage. At 60 if it's 10% slow then your speedo will read 54 mph, 20% then 48 mph and so on.
You can use the speedo gear calculator and get new gears here:
https://transmissioncenter.net/?s=700r4+speedometer+gear

Not a hard or long job to change gears.

 

[Stephen Carter]

When you say it's off by 20 mph is that when you're doing 10 or 80 mph? Your speed will always be off by a percentage. At 60 if it's 10% slow then your speedo will read 54 mph, 20% then 48 mph and so on.
You can use the speedo gear calculator and get new gears here:
https://transmissioncenter.net/?s=700r4+speedometer+gear

Not a hard or long job to change gears.

Its only about 20mph fast at 65, about 7mph fast at 40...

I figured id have to change the gear in the tcase, jist dont know which one. Tci has like 20 different options lol.

 

[rampage]

Speedo gear calculator
https://transmissioncenter.net/shop/speedometer-gear-calculator/

 

[Hogback Fabrication]

Its only about 20mph fast at 65, about 7mph fast at 40...

I figured id have to change the gear in the tcase, jist dont know which one. Tci has like 20 different options lol.

The advice others offered is right on, might want to double check the percentage your speeds are off (or you have bigger problems).