help with gearing on a 240 truck.

[gregamorton]

Hey guys I have run 2.47 2.50 2.75 and 3.00 in all my half ton trucks with big v8s with good mileage and high hwy speeds. My 74 f100 has a 240 3 speed with factory 3 speed on the column with 3.70 gears and a 28" tire. I have driven a a few 300 trucks with high gears and they pulled fine. My truck is just a low cruiser. Is there any 240 guys on here that has went to a hwy gear and did you like the way it felt with power and cruise speeds. I am looking at a 2.75 set up to 3.25. I have a 2.75 set and am looking at a 2.80 set and 3.10 on ebay right now. This is a driver with no pulling or added weight!

[guerra]

I cant answer any questions.... But I'am really digging your truck.

[gregamorton]

I have had three people tell me the truck would look real good after its painted! Its amazing the trucks worth more like it is to the right person. It is super fun to drive! I just never liked the engines to turn so fast. Its around 3200rpm at 70mph. I drive it most of the time at 55 anyways but that is still around 2400-2500rpm.

[guerra]

Well the fact that its not painted is whats cool about it.. That and its in the weeds!!

[ultraranger]

Ever consider installing an overdrive with the 300?

If you had an overdrive (AOD/AODE), 3.70 rear gears, 28" tall tires and a highway speed of 60 MPH, your cruising RPMs would be about 1,812. Your final drive equivalent would be 2.52:1. --this figure is determined by multiying the rear end ratio by the transmissions overdrive ratio. (3.70 x .68 = 2.52).

A 4R70W has an overdrive ratio of 0.70. With 3.70 rear gears that would be a final drive of 2.59:1.

3.25 rear gears (with .68 O.D.) would have a final drive of 2.21:1 and highway RPMs would be 1,591.

3.00 rear gears would have a final drive of 2.04:1 and highway RPMs would be 1,469.

Lower rear gear ratio (to a point) maintains truck's low-end pull ability but actually equates to a higher rear gear equivalent than just swapping out 3rd members, and reducing overall cruising RPMs at the same time.


http://ultrastang.com/info3.php

[gregamorton]

ultra if I do it will be a rug od 3 speed. Thats what I just installed in my 71 crewcab. I love the way the 3 speed shifts as it is the best of all the trucks I ever had. I like to keep stuff stock if its working good. I have been looking into the newer 5 speeds but more than likely would swap to the np435 and go with a 2.75 gear. You can always take off in granny and shift easy at 3-5 mph. I think the np and 3 speed would use the same factory driveshaft also.

[gregamorton]

ultra thanks for the web site with all the gearing thats helpfull!

[averagef250]

The last 240 F-100 I drove had umpty million miles on it, head was worn out so prolly down on power a bit. It had 3.25's and 31" tires with a T18 and did pretty good. My 300 F-100 had 3.50's and 31"s with a T18 and I felt it was a great combo. It cruised 70 fine and would get moving with a 5000 pound trailer in tow in second gear no problem.

[gregamorton]

thanks dustin! Do you like the t18 over the np435? I was thinking most of your posts showed t18.

[averagef250]

I like the feel of the 435 much better plus the 435 has always had the normal shift pattern. The T-18 has the weird reverse in the older years.

T-18 and 435 are pretty much the same thing, just a slightly different design. The 435 has a synchro design that's unusual and feels a little different from anything else, I like them, you may not.

[gregamorton]

The best shifting 4 speed I had was in a 1978 behind a 302. the original owner was a old fellow and I assume he drove it easy. the tranny shifted super smooth and felt like a new transmission. I think it was a np435.

[Youngfordkid]

i have the 240 with a mild cam, and stock 435 trans and 3.70s. i have no problem crusing the highway. it does spin a little fast at 75, but i stay around 65-70 and she does fine. hills can be a diffrent story. i like the 435, even though the syncros are worn out, it still is fun to drive. an overdive like the ranger tourque splitter is somthing i have been looking at, the tutorial here on the site is a good one, and explains it all.