1972 F-100 transmission swap

[Cody_311]

Me and my Father are rebuilding a 72 f-100 ranger, and I have a few questions about it.

I have done alittle searching on this site, and can't seem to find two things I was looking for.

1. What is the rearend gear ration of this truck. It's a factory rearend.

2. It has the 3.03 transmissions in it, and it was converted to a floor shift. It's a good tranny, but it just doesn't suite our Daily driving needs. We would like to put a mustang foxbody/5 liter transmission, or something that would promote alittle better fuel economy. We are kind of new at this, and the truck is in great condition, and we would love to be able to drive on the interstate at 65 mph without being at 4000 rpms.

Hope someone could help. Thanks a lot.

[Dropped 68]

Your current final drive ratio is 1-1. There should be a tag on the housing bolts of your rearend, that will state what the ratio is (assuming it has not been changed.) This links you to a site that will allow you to put in your rpm's at a given speed to figure out what gears you have, or what a different set of gears would do for your Rpm's at a certain speed.
http://www.corral.net/tech/gearcalc.html


They only list t-5 transmissions on this particular site, but just key in fourth gear as your choice as the T-5's 4th gear is 1-1 ratio.

You can also do a search on gear ratio calculator and find other sites.

[splavin90]

the rearend ratio depends on your truck, look at your vin, or your rearend tag

http://www.fordification.com/data-1972.htm

[Cody_311]

the rearend ratio depends on your truck, look at your vin, or your rearend tag

http://www.fordification.com/data-1972.htm

Thanks you guys.

I looked at that link when I was doing my search, and just now, and I can't seem to find a place where it says rear-end ratio's . I know the gear ratio's of the transmission. I was more along the lines of asking what 5, or good 4 speed transmission would bolt up with the truck. Something with an overdrive proferably. I find a lot of mustang tranny's, but they all have the same 5th gear 1:1, and the 3 speed has them same.

[Cody_311]

Just one last question. We have found a really nice 93 mustang tranny, with a king cobra clutch. Almost brand new. The only issue with it, is the guy tells me the 5th gear is a 1:1 ratio. Did they even offer this from the factory? Or is this guy just talking out his A$$.

[72hiboy4x4]

a quick google search shows that these aftermarket T-5 trans have these specs:
mustangsplus.com
Close ratio 1st through 4th
•600 lbs./ft. torque capacity
•Gear ratios: 1st 2.87; 2nd 1.90; 3rd 1.34; 4th 1.00; 5th 0.68
•Input shaft is 26 spline; Output shaft is 31 spline

I would guess the stock trannys are similar. but do your research!
Or if the tranny is out, put it in 5th gear, turn the input shaft one turn, and count how much the output shaft turns. 1:1 means it will turn exactly one turn, 1:.68 means it will turn a little over 1/2 turn.

[72hiboy4x4]

Heres another link showing that these are overdrive trannys from the factory.

http://www.mustanggt.org/gttranny.htm

5-speed T5 (1990)9
F0ZR-7003-AA 3.35 1.99 1.33 1.00 0.675 3.15 300 2

5-speed T5 (1991-93)9, 10
FZZR-7003-AA 3.35 1.99 1.33 1.00 0.675 3.15 300 2

AOD (1984-1993)11 2.40 1.47 1.00 0.667 -- 2.00 ?? T

[Cody_311]

That's all I needed to know. Thanks you.

[foghorn]

I went from a 3.50 to a 2.50 gear and my speedo was 20 mph off with the 3.50 and now its almost dead on the money with the 2.50 gears. But i might go to the 3.00 as i think the 2.50 is just a bit to tall. My gas mileage was less than 11 with the 3.50 havent drove it enough yet to say what the 2.50 is giving me as of yet.

foggy