how to identify my gear ratio

[muskrat]

Hey, how do you identify the gear ratio for my Bronco's rear?

Thanks.

 

[new to bronco]

There should be a tag if no tag jack up back mark drive shaft mark wheel turn wheel one turn count number of times drive shaft turns, if you have locker 411 will be little over 4, 355 three and half with open double how many times drive shaft turns to get ratio.

 

[itsabronco]

there is numbers stamped on the ring gear that you divide into each other. but obviously the rear end has to be apart. is it ?

 

[Broncobowsher]

There is a quick way in the tech section. Works with open diffs, limited slips, lockers, spools, etc.

The exact way is to pull the gears and count the teeth. Divide the number of teeth on the ring gear by the number of teeth on the pinion gear. For example 41 tooth ring gear and 10 tooth pinion comes out to 4.10 gears.

 

[BronCowie]

another quick and dirty way: you can tape a string to your drive shaft hanging down a 2 feet or so. then roll your bronc far enough for one revolution of the rear tire. then count how many revolutions the string wound around the drive shaft. 1 revolution of the tire to 3-1/2 string winds around the shaft = 3.50:1

 

[tcjones76]

I like the string theory, no jacking, no taking apart...

 

[ugly74]

if the driveshaft turn 3 & a 1/2 times every time the tires turn one revolution, you have 3.50 gears.

 

[muskrat]

Thanks everyone. I like the string idea too. The rear is not open right now, and I hope it never is!

 

[DirtDonk]

Don't hope for that. At some point in it's life you're going to want to change the gear lube. Maybe more than once, depending on how much you drive it.
There are other ways to remove the fluid, but pulling it apart is quick and easy (as long as the rear wheel bearings cooperate that is) and allows you to check the condition of things.
After all, these things are not considered "lubed-for-life" anymore. Except maybe the life of the vehicle as long as the first owner had it.

Wheel bearings should be changed at 100k miles even if they aren't making noise, and gear lube should be changed every 25k to 50k miles or so. With 35k not being overkill. I use 25k for all my gear boxes, so it's easy to remember.

If you havent' done it before, and don't know for a fact that your PO's changed the lube, well, there's your reason for pulling a few things apart.

Paul

 

[garberz]

Don't hope for that. At some point in it's life you're going to want to change the gear lube. Maybe more than once, depending on how much you drive it.
There are other ways to remove the fluid, but pulling it apart is quick and easy (as long as the rear wheel bearings cooperate that is) and allows you to check the condition of things.
After all, these things are not considered "lubed-for-life" anymore. Except maybe the life of the vehicle as long as the first owner had it.

Wheel bearings should be changed at 100k miles even if they aren't making noise, and gear lube should be changed every 25k to 50k miles or so. With 35k not being overkill. I use 25k for all my gear boxes, so it's easy to remember.

If you havent' done it before, and don't know for a fact that your PO's changed the lube, well, there's your reason for pulling a few things apart.

Paul

Paul, who are you talking to??:? ;D

 

[DirtDonk]

Hah! Evidently just you n me buddy! Well, actually that was meant for muskrat, since he was hoping to not have to open things up and count teeth. I was just saying that with a Bronco that might be somewhat new to him, those little unknowns will come back to bite you.
Not that they would of course... ;D

Paul

 

[Madgyver]

A simple mad way....

http://classicbroncos.com/tech/whats-my-gear-ratio