I am helping a friend with his 99 F250 Superduty Diesel and need to know what rear gear ratio it has for the size of the front brake rotors. So with a diesel longbox extended cab, is there a gear ratio that limits my options??? thanks

 

How does the gearing affect his brakes,....?

Should be 3.73 gearing on a 99 w/ a diesel.

 

evidently Ford used 2 different Front brake rotors depending on the gear ratio. Now I designed brakes for 10 years and never once recall using gear ratio in the calculation for the braking capacity, specifically this year. GVW yes.

 

Napa does it too but if you look on the screen the 3.73 to 4.30 are for 250's and 350's and 4.56 to 4.88 and even lower are for 450 to 550's

On my V10 the part number was the same for 3.73 through 4.30.

 

Like Boxcar said. They give you the option on the look up, but the part number they come to may be the same. I don't envy the people who input the data into those Databases, it's a lot of work and they get very little wrong. It's just collating the data provided in manufacture catalogs/app guides into the websites categories.

 

Look on the tag bolted to the diff cover. the ratio number is in there. You can also call your local dealership parts center with your vin# & they can tell you.

 

Now that makes a lot more sense.