80 Front Ttb Bronco Gear

Giovanni · Apr 29, 2004

Dear Friends,

I'm written from Peru in south america, I need your help!

I have an '80 Bronco with a 351M with some modifications, I want to put 33" tires on it and I have two questions:

1.- I think to change the gears to 4.11 but I don't want to loose power and milage as well.
Is that the correct ratio to get it??

2.- I disassembly the rear end and I found that the ratio is 3.50 on the 9"
What is the ratio for the front DANA gear in this truck?

Thank you very much for your help,
Giovanni Pierinelli

freak · Apr 29, 2004

The ratio for the front will be the same as the back.

zakcode · Apr 29, 2004

350's will do but 411's will do a little better keeping you closer to stock gearing...

Justshootme84 · Apr 29, 2004

Giovanni, the front ratio is also 3.50:1. As much as it costs to swap gears, I personally would not change to 4.10:1 if you are only going to use a 33" tall tire. The stock gears are close enough for that size tire for normal driving, and the mileage difference is not that noticeable in my opinion. When you go to a 35" tire or need to do alot of towing or climbing hills, then it may be worth swapping to a 4.10:1 for 33" or 4.56:1 for 35" tires. I am running a 35x12.50R15 tire with my stock 3.50:1 gears. The speedometer is not correct, but I still have some power for offroad.

Justshootme84 · May 2, 2004

Since youy have mostly desert, rocks and a few mountains, you may need the 4.10:1 gears eventually. I would first get the 33's and try them with your stock gears. After a few trips, you will know if you need taller gears or not. But I think it will still be a sublte or small gain to swap gears. Good Luck, and post your results!!!