not so special rear end ratio question

[tomgeorge2000]

Hi All,

I have searched the forums for this and have found all the usual antecdotes for finding rear end ratios (tag, door code, etc.) My sitiuation is a bit unique.

I am wanting to replace the whining rear end in my 02 V6 2WD Explorer. I have the 3:51 (3:55?) ratio.

I found a guy with an '04 rolling chassis, V8, 4WD. There is no body (door code), and he says there is no tag on the rear end. He does state that the hitch receiver is the small receiver like i have (As opposed to the regular, large receiver on the Explorers with the tow package).

Anoyone know offhand if this is going to be a 3:51 ratio based on just this info?
We are going to do the wheel-spin test, but looking for some insight from the group.
TIA

 

[Kazer]

well youve got a 50/50 chance of the donor being a 3.55 or 3.73. theres a carrier break between 3.55 and 3.73 for the front differential (ie you cant regear a 3.55 front end to 4.10) so there may be a size difference in the 3.55 and 3.73 front ends so you might be able to measure that?

Also, seeing as the front diff is a dana and the rear is the ford 8.8, have you checked to see if the front is tagged with a ratio?

 

[Ronin8002]

you could always spin the pinion or the driveshaft by hand and count how many rotations it takes to turn the tires one time. About 3 and half times = 3.55 gears and about 3 3/4 times = 3.73

 

[Kazer]

ronin, could that be done with the truck on jack stands and the wheels left on?

 

[Ronin8002]

Either way. As long as you can see the driveshaft or pinion flange to count the revolutions then it's all the same

 

[tomgeorge2000]

Thanks all for the replies. Great idea on looking at the front diff. Never thought of that. I am going to do the spin test too just to make sure. Will keep you all posted.

 

[tomgeorge2000]

Well good news is there was a tag on the donor and it is a 3:55. Now as long as the splines have not changed size from 2002 to 2004, all i have to do is swap out the pumpkins and keep my fingers crossed.

 

[Ronin8002]

the splines did not change...you'll be able to swap it right in

 

[Kazer]

where did you end up finding the tag?

 

[tomgeorge2000]

the splines did not change...you'll be able to swap it right in

thanks for the info. Probably tackle this over the weekend!

 

[tomgeorge2000]

where did you end up finding the tag?

He found it on one of the cover bolts. I guess he didn't look very hard the first time.