Identifying Gears?

[MusPuppis]

This is semi off-topic because the vehicle isnt a Mustang.. Its my 94 F-150. I was wondering if anyone knows how tell exactly what gears I have in the rear?

A friend has a set of 3.55's I'm thinking of buying and I'd like to sell my old set.. I just need to know what the hell they are, lol. A guy at a Ford dealership I called about it said something to the tune of "Most 2wd F-150's came with 2.73's I think" which is semi helpful but I need to know for sure.. Just dunno how to tell,

 

[stprorolla49]

jack up the car, put a piece of tape on the top of the tire, put the car in drive (off obviously), make a mark in the dirveshaft, and rotate the tire and see how many times the driveshaft goes around for one rotation of the tire....hope this helps..

 

[1991vert]

well you beat me to it. it's however many turns of the d/s it takes to rotate the tire completely one full turn.

 

[BaXTeR3221]

You guys both said the thing....its how many times tire spins for one rotation of the driveshaft....since the gears are after the driveshaft, it doesn't change, but the tire spinning does.

 

[Michael Yount]

intrc - actually, you'll want to rotate the tire one full turn and count driveshaft turns. You've described it the other way - driveshaft one turn, and count the tire rotation. That'll work, but it's often hard to tell how far the tire has rotated when it only goes for a small portion of one rotation. With 2.73's for example, if you rotate the driveshaft just once, the tire rotates just .366 of one turn. For 3.08's one driveshaft rotation = .325 turns of the tire - kind of hard to tell that apart. MUCH easier to rotate the tire once, and count driveshaft. Then, the number of turns of the driveshaft = the gear ratio. If the shaft turns about 2 3/4 turns - 2.73. If it turns a little past 3 - 3.08's. If it turns about 3 1/2 - 3.55's. Capice?

 

[BaXTeR3221]

Yep, thanx for the correction. I figured that since the gears were behind the driveshaft, the driveshaft would be the constant and the tires being the variable. But as usual, ur info is dead on

 

[Michael Yount]

Not me - stp and 91vert got to it before I did!

 

[MusPuppis]

Allrighty.. I just did as instructed and for one full 360* rotation of my tire the driveshaft turned about 1.5 times. It came around one full time and half way again. The truck was in drive with the driver side tire off the ground. The passenger was still down. I didnt think that would effect anything..

Something seems wrong here.. 1.50's? heh.

 

[stprorolla49]

yea its wrong...its b/c if only one tire is off the ground than the differential is working, and its not locked as if you were goi9n in a straight line....i think, lol....someone please correct me if im wrong....thx

 

[Michael Yount]

Try again with both tires off the ground. It helps alot to have two people, one to turn the tire SLOWLY, and another to count driveshaft turns - it's easy to miscount when you're trying to do both.

No - your truck does not have the very rare 1.50 rear gear in it.