Gear install
You Keep What You Kill
Joined: Dec 2006
Posts: 4,902
Likes: 2
From: Huntersville, NC
4.56 gears with 40" tires will have my truck turning 2,400 - 2,500 RPM's at 70 MPH?
Lead Driver
Joined: Jun 2007
Posts: 6,757
Likes: 5
From: Corvallis, OR
Sorry, I did the tire size conversion backwards. For those RPMs at 70mph you would need about a 5.56:1 ratio. I don't know how low is available, 5.38s might be your only option.
You Keep What You Kill
Joined: Dec 2006
Posts: 4,902
Likes: 2
From: Huntersville, NC
http://www.yukongear.com/PartsList.a...gs+%26+Pinions
EDIT: Is the Dana 60 front axle a "reverse rotation" axle? If so, then 5.38 is as low as Yukan gears go.
Lead Driver
Joined: Jun 2007
Posts: 6,757
Likes: 5
From: Corvallis, OR
My truck turns 2000 rpm at 65mph with 4.30 gears and 35" tires. Then I used your goal of 2450 rpm and some math:
((your goal @ 70) / (my rpm @ 70)) * (my gears) * (your tires / my tires) = your gears
(2450 / (2000 * 70 / 65)) * 4.30 * 40 / 35 = 5.59
Those are pretty low gears, but then I wouldn't put tires that big on a 5.4L. Lowest I saw listed for the 10.5 at Randy's Ring and Pinion was 5.38.
((your goal @ 70) / (my rpm @ 70)) * (my gears) * (your tires / my tires) = your gears
(2450 / (2000 * 70 / 65)) * 4.30 * 40 / 35 = 5.59
Those are pretty low gears, but then I wouldn't put tires that big on a 5.4L. Lowest I saw listed for the 10.5 at Randy's Ring and Pinion was 5.38.
Lead Driver
Joined: Jun 2007
Posts: 6,757
Likes: 5
From: Corvallis, OR
I did my first set in December on my truck. I wouldn't recommend it unless you are a very proficient mechanic. You also need a couple hundred dollars worth of special tools to do it right. I got the Differentials book from Randy's Ring and Pinion. About $23 and a great guide.
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