What gearing do I need up front?

Hey everybody!
I’ve got a 4:10 geared rear axle that I’m possibly going to be putting on a 4x4 build and was wondering what the best gears for the front axle would be? I will have around 37s for the tires.
Thanks for all the help!

Truck82 said:

Hey everybody!
I’ve got a 4:10 geared rear axle that I’m possibly going to be putting on a 4x4 build and was wondering what the best gears for the front axle would be? I will have around 37s for the tires.
Thanks for all the help!

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Front and rear have to match. Well they don't have to,but if you want to drive in 4wd they do.

Truck82 said:

Hey everybody!
I’ve got a 4:10 geared rear axle that I’m possibly going to be putting on a 4x4 build and was wondering what the best gears for the front axle would be? I will have around 37s for the tires.
Thanks for all the help!

Click to expand...

Need them to match or you’ll blow stuff up.

That’s what made sense in my mind although I have heard of different gear ratios front and back that don’t match. I wasn’t sure if there was a trick to finding out the difference needed but I guess that’s not possible?

84_c10_GMC said:

Need them to match or you’ll blow stuff up.

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Explosions like a Michael Bay movie!

Truck82 said:

I wasn’t sure if there was a trick to finding out the difference needed but I guess that’s not possible?

Click to expand...

If you were to run different diameter tires front to rear.
Say 31’s front and 37’s rear. You would go with 3.73 and 4.56 as general rule you multiply tire diameter by .12

Truck82 said:

That’s what made sense in my mind although I have heard of different gear ratios front and back that don’t match. I wasn’t sure if there was a trick to finding out the difference needed but I guess that’s not possible?

Click to expand...

Unless you manage to run different tire sizes front and rear that make the math math out correctly, it doesn't work like that. The only guys that run different ratios front and rear are dedicated off road rigs that never see hard ground. If you have different ratios and are in 4wd and hit hard ground, you're going to explode your transfer case (and when it explodes, the shock will likely hurt/grenade the transmission and possible one or both axles. I've seen it happen). Front and rear gear ratios have to match, period.