Gear Ratio & diff questions

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Mar 17, 2005 | 12:43 PM

papaw123

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Gear Ratio & diff questions

I have a '91 F150 4x4 w/ 4.9 AOD. I have 33" tires with a mild lift. The original gear ratio is 3.09 and the 33s have killed the power. I am going to change gears and want some recommendations. This is not a daily driver but occasionally drive on the Interstate. With that in mind, do you think 3.73s are a good compromise? The 4.9 doesn't like revs over 3000. What about limited slip vs. ratcher lockers? In Tennessee, we deal with ice on the roads. I understand that a ratcher locker causes problems. What about the front diff? I would appreciate any ideas.

Mar 18, 2005 | 12:26 AM

justshootme84

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From: SE Texas

I think 3.73 gears would be fair/O.K., definitely alot better than the 3.08/3.09 stock ratio. IF you go any higher, say to 4.10's, you would need a different carrier for the front ring gear at least. I would definitely not put a locker in front on a daily driver, but a limited slip like the Trac-Lok may be O.K. That's what I'm considering on my Bronco front axle. It has the factory Traction-Lock L/S in the rear already. There's several recent posts in the forums on gear ratios. lockers, etc. if you do a search.