Pinion gear change out

[El Gringo Loco]

I changed my BJ40 gearing to Nitro Gear set from stock to 3.71-1. Anyone done this. I am interested in ascertaining the new top criusing spees on flat California freeways, what rpm it runs at, and did your fuel consption change. B series motor and stock 4 speed transmission. Thanks for your assistance. 1979 BJ40

 

[charliemeyer007]

You should be able to calculate rpm/gears/tire size to mph. I think there is app thing around here some where or at least a good working example of doing the math in the last month or so.

4.11/3.71 is about 11%

 

[pb4ugo]

There are many rpm calculators on the internet. Be sure to measure the actual tire diameter and not use its advertised size. They are different.

 

[El Gringo Loco]

You should be able to calculate rpm/gears/tire size to mph. I think there is app thing around here some where or at least a good working example of doing the math in the last month or so.

4.11/3.71 is about 11%

Could not find but appreciate your help

 

[jim land]

If you have 31" tire or less, 3:70 is good, but if you have 33" 4:11 will help your low HP engine

 

[charliemeyer007]

nitro gear's calc

Nitro Gear Ratio Calculators

Nitro Gear Ratio Calculators

nitro-gear.com

 

[El Gringo Loco]

If you have 31" tire or less, 3:70 is good, but if you have 33" 4:11 will help your low HP engine

30"

 

[El Gringo Loco]

30"

What kind of cruising speed are you getting with your ser up and rpm on flat freeways

 

[jim land]

If you plan to keep 30" , maybe you can go 3:70 if you drive mostly flat road