Which rear end gear?
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Forum Name: Shops, Barns, Varmints, and Trucks
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URL: https://www.allischalmers.com/forum/forum_posts.asp?TID=164899
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Topic: Which rear end gear?
Posted By: Brampton 02 gt
Subject: Which rear end gear?
Date Posted: 08 Oct 2019 at 5:12pm
Looking for advice on which gear ratio to select.
F250, gas 6.2l with 6 speed.
Comes with 3.73 but can order a 4.30 rear gear set. Increases fords tow rating to 15,500 up from 12,500.
Everything else on truck is same with heavy springs etc.
I don,t presently tow at these weights but might in future if we upgrade campers.
I am worried about fuel mileage increase but can,t find any reliable numbers anywhere. I daily drive the truck and only tow 2-3 weeks a year. I know this won,t compete with a Tesla in mileage but don,t want to go from poor to really poor if I opt for the 4.30. Extra towing capacity and acceleration sure is tempting. However.
Thoughts appreciated!
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Replies:
Posted By: steve(ill)
Date Posted: 08 Oct 2019 at 5:39pm
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3.73 to 4.30 is 15% change........... that means if the motor was running a 2000 RPM at a give ground speed, it will be running 2300 RPM with the 4.30 gears......... Normally with a 3/4 ton truck you would expect a 4.30 gears to get the pulling power.. But if your not pulling except a couple weeks out of the year, the 3.73 might make more sense for gas milage........... You can always keep the truck in 5th gear if your pulling and need lower gearing.
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Like them all, but love the "B"s.
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Posted By: steve(ill)
Date Posted: 08 Oct 2019 at 5:42pm
I have a F150 with same transmission and 3.55 gears and it will pull GREAT for most applications. ... not too many trailers over 13-14,000 pounds.
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Like them all, but love the "B"s.
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Posted By: Dave H
Date Posted: 09 Oct 2019 at 3:30am
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I been running an F250 6.2 with 4.30 diffy since 2012. Also used for towing the 10K fifth wheel camper.
I just punch the computer to look at what it says on mileage once in a while. Towing from central IL to just south of Myrtle Beach I always average between 8.7 and 9. Usually the 8.7 number.
Yesterday I punched the computer after running around on county roads and a little highway for a few months and it showed in the high 13's, usually 14.3 though.
I doubt if I could get 15 running empty at 65 to 70.
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Posted By: PaulB
Date Posted: 09 Oct 2019 at 4:00am
The weight rating is for the TOTAL combination, not just the trailer. As mentioned above, if you’re only giong to pull a trailer a couple times a year, get the faster rear and never used 6th when towing.
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If it was fun to pull in LOW gear, I could have a John Deere.
Real pullers don't have speed limits.
If you can't make it GO... make it SHINY
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Posted By: klinemar
Date Posted: 09 Oct 2019 at 5:51am
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I bought a 95 f350 sigle rear wheels with 3.55 gears. Had a 460 motor which was a notorious gas guzzler. Mine got 14 mpg but did not have good towing capability because of high gear. With 5 speed manual when towing a big load I was constantly shifting between 3 and 4 th. The 2018 Ram I just bought has more horsepower and torque than the 460 out of a 392 cubic inch engine. I coupled this truck with a 4.10 gear and when not towing I get 17 mpg and the Ram pulls better than any truck I have ever had! Averages 10 to 11 mpg when towing depending on hills.Wife and I took our tongue pull camper to the Upper Peninsula this summer on a maiden voyage and the Ram exceeded my expectations!
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Posted By: jaybmiller
Date Posted: 09 Oct 2019 at 5:53am
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what PaulB says ! also, have the proper license ! MTO can fine you large in Ontario for pulling more weight than your license is rated for. Knew someone hauling a small backhoe(C 580), got stopped(random check), a 'light' license,had to leave trailer and hoe roadside,get 'heavy recovery' to haul it home, $$$$$ sigh, gotta love living in Ontario... Jay
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3 D-14s,A-C forklift, B-112
Kubota BX23S lil' TOOT( The Other Orange Tractor)
Never burn your bridges, unless you can walk on water
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Posted By: Thad in AR.
Date Posted: 09 Oct 2019 at 6:22am
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Depends on where you live and what the truck will do. Around here low gears will gain mpg due to the hills and curves. 90% of my driving is less than 40 mph. My work truck doesn’t see interstate travel 2 or 3 times a year. I drive in tow haul most of the time.
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Posted By: Ken(MI)
Date Posted: 09 Oct 2019 at 4:59pm
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I've had three Fords with the 6.2, loved the engine, hated the mileage, go with the taller gear, you won't be sorry if mileage is a concern. I currently have two Rams, a standard cab 3500 4x4 and a crew cab 2500 4x4, both have the 6.4 Hemi, the 3500 has 3.73 gears and empty gets about 14 mpg average, 17-18 on the highway empty, the 2500 has 4.11 gears and runs about 1 - 2 mpg less, but it's also heavier, take about 5-7 mpg off either for towing, both tow about the same. The Ford's used to drop to about 7-8 mpg towing the same loads, regardless of rear end gearing, 4.11 gears used make that 6.2 drink the gas around town. I still have one for a shop truck and drove it last weekend, avg. mileage on the display was 11.2, mostly city driving, 6.2, 3.73 rear end, 4 x 2 F250 standard cab. Good luck with your decision.
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