Gear change
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Freshman User
Joined: Jan 2018
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Gear change
I have a 92 f150 302 engine, e4od trans. 3.55. Gears. I'm considering a gear change . I live in rural Co alot of long up hill grades. I trailer two atv and equipment. My truck is doggy on the hills. I'm having trouble deciding between 3.73 or the 4.10. I'm concerned about excessive rpms. I very rarely drive over 65. My truck is totally stock. Has anyone done this swap. What would you all recommend. I'm leaning towards the 4.10 to justify the expense of the swap. What rpms would my truck run at 65 with the 4.10 gears. Also it's a 2wd trucker. Thanks
5th Wheeling
Joined: Apr 2019
Posts: 37
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Can't say without knowing your tire height but here's an easy way to calculate it.
(New ratio / old ratio) × rpm at desired speed = new RPM
So if you're currently running 2500 RPMs at 65 and you have 3.55 gears and want 4.10:
(4.10/3.55) x 2500 = 2887
So with 4.11s you'll be running 2887RPM @ 65 mph with all else being the same.
For 3.73
(3.73/3.55) x 2500 = 2627
(New ratio / old ratio) × rpm at desired speed = new RPM
So if you're currently running 2500 RPMs at 65 and you have 3.55 gears and want 4.10:
(4.10/3.55) x 2500 = 2887
So with 4.11s you'll be running 2887RPM @ 65 mph with all else being the same.
For 3.73
(3.73/3.55) x 2500 = 2627
Elder User
Joined: Dec 2016
Posts: 854
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From: Mid Missouri
I had the same setup as you when I still lived in Colorado and changed mine out to 4.10. With stock 29" tires I run around 2,500 RPM at 75mph. I wouldn't go any higher than 4.10, especially if I had tires larger than stock. In fact, if I still lived out there and had the 302, I'd go with 4.56.
More Turbo
Joined: Oct 2006
Posts: 632
Likes: 40
I went from 3.55 to 4.10 in my 92 F250 4x4 460/E4OD. Love it for towing heavy, no regrets. If running empty on hwy sort of feels like it needs another gear but I was used to the 3.55's so probably why. Love the 4.10's. This is with 265/75/16 tires. Mine turns 2000 RPM at 65 MPH. I did reset PSOM best I could to match tire size/rotations per mile.
Last edited by BLK79; Jul 21, 2019 at 01:28 PM. Reason: added info
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