Gear Ratios with 32" A/Ts

[Missile Man]

I am a newbie to this stuff but I have read on some web sites that I should regear to about a 4.10 ratio to get my engine power band matched up with my larger tires.

1) I can find new gears for the rear end but isn't there a gear change needed for the front end also?

2) Where do I find or figure out the set up I need to get this done??

1990 Bronco 5.0 EFI. I think I have a Dana 44, AOE, and maybe an 8.8?? Have to check the numbers to be sure.

 

[Seabronc]

Welcome to the Zone > . Post some pictures when you get a chance, we'd like to :-B at them.

I am a newbie to this stuff but I have read on some web sites that I should regear to about a 4.10 ratio to get my engine power band matched up with my larger tires.

1) I can find new gears for the rear end but isn't there a gear change needed for the front end also?

Yes, the front gear ratio has to match the rear gear ratio or you will have a nasty experience when you go into 4X4.

2) Where do I find or figure out the set up I need to get this done??

1990 Bronco 5.0 EFI. I think I have a Dana 44, AOE, and maybe an 8.8?? Have to check the numbers to be sure.

Attached is a page from Jeff's Bronco Graveyard http://www.broncograveyard.com that will help you calculate the gear ratio you need / want. The chart is calculated for a 55 MPH highway cruise so if you cruise at about 65 the numbers change. Above the chart is a formula that you can use to calculate the gear ratio that will give you very close numbers. The numbers in the chart are based on, for ex. a 33 inch tire actually being 33 inches which is not the case. Generally a tire diameter is slightly smaller than listed, like a 33 might actually be 32.8 when mounted, but the chart will be within about 100 RPM of what you actually see on the tac. You pick the RPM you want to cruise at and the formula will tell you what gears will provide it.

Good luck,

>-

 

[Missile Man]

Thanks.

Where and how do I post a photo that will show up with my user name?

 

[White90Bronco]

The newer Broncos came with 32" tires from the factory so you probably won't have to do much gear changing.

 

[Missile Man]

I checked the label inside the drivers door and it has 235-75R-15 which comes out to be a 29" diameter tire (from an online conversion program) so I think that would mean the gearing is probably set up for 29" tires.

What do you make of it??

 

[Missile Man]

I checked the label inside the drivers door and it has 235-75R-15 which comes out to be a 29" diameter tire (from an online conversion program) so I think that would mean the gearing is probably set up for 29" tires.

What do you make of it??