91 Full size Bronco with 351. 35inch tires. Has stock gears right now. Not sure what gears, maybe 3.55 or 3.73. I want at least 4.10s, are the
4.56s too low or what? How can I tell what kind of rear end I have anyways?
4.10s, 4.11s, or 4.56s ??
Jul 10, 2003
4 Replies
What are you going to be doing with it? There should be an axle code on one of the stickers on the door jamb and when you find out the code you should be able to look it up. My lightning came with 4.10's from the factory and the 351 turns about 2300-2400 rpms at 70, which isn't too bad. Erik D. '94 white lightning
4.56 will work great with 35" tires. To find out your current gear ratio, jack up one rear wheel, turn the driveshaft by hand, and count the number of driveshaft rotations to turn the wheel a full 360 degrees. Divide that number by two and you have the gear ratio: 3.55 gears will be a little over seven driveshaft revolutions.
Sean
Just a warning, but it is very hard to do this. Most people say that it can be done, but it is damn near impossible to be able to be exact enough to distinguish between 3.27's, 3.55's, 3.73's, or 3.90's. They are all very close. The only true way to tell is to count the teeth on the gears or if you are an original owner and have an axle code. Erik D. '94 white lightning
Not if you mark the driveshaft - if you can't tell between 6-1/2, 7, or
7-1/2 turns you need glasses.The only true way to tell is to count the teeth on
Counting gear teeth, yes. Sometimes the tag has been lost or the gears don't match the tag because someone else regeared it already.
Sean
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