Rear End! Please Help.
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Rear End! Please Help.
Ok these are the specs on my truck it is a 1979 Ford F-150 4x4 step side with a 460 engine that all I know for now. Ok the question is I need a new rear end and I am not sure how to match them up or figure out what I need to look for any information would be helpful thanks.
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I am not sure of the gear ratio of the axle. It does not have a tag so I understand you have to count the teeth and find out the gear ratio. The current one has locked up not sure what is wrong with it. Also the truck has like a 6 inch lift kit is there a part i need to get to cause this from happening again?
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From: Boyne Mich
So have you taken any of it apart yet? in order to count teeth or read the ring gear information the axles need to come out and pull the third member.
If you only need the Ratio in order to find another complete axle then jack up the front end ( bc the rear is locked) and rotate the tires to count drive shaft revolutions. Probably will get either 3 -1/2 rotations for a 3.55:1 gear or just a bit over 4 full revolutions for 4.11:1.
If you only need the Ratio in order to find another complete axle then jack up the front end ( bc the rear is locked) and rotate the tires to count drive shaft revolutions. Probably will get either 3 -1/2 rotations for a 3.55:1 gear or just a bit over 4 full revolutions for 4.11:1.
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From: Hattiesburg, MS
On a serious note...you can swap the center section from any 31 spline axle with the correct gear ratio. If everything is still original, VIN tag will tell you the ratio. Otherwise, you gonna have to pull diff to check.
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From: Hattiesburg, MS
The correct procedure is to jack up only ONE tire and multiply driveshaft revolutions by 2. OR, since we are talking about a front axle, lock the passenger hub and unlock the driver hub. Rotate driveshaft by hand and watch the universal joint inside the steering kunckle. Count how many times you must rotate the driveshaft for the axleshaft to make one revolution, then multiply it by 2.
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The correct procedure is to jack up only ONE tire and multiply driveshaft revolutions by 2. OR, since we are talking about a front axle, lock the passenger hub and unlock the driver hub. Rotate driveshaft by hand and watch the universal joint inside the steering kunckle. Count how many times you must rotate the driveshaft for the axleshaft to make one revolution, then multiply it by 2.
why does it have to be multiplied by 2 and why can only one wheel be lifted, I figured mine out by lifting both wheels rotated the rear driveshaft and counted the number of times it turned 3.5 ish
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From: Boyne Mich
Again the front axle will have the same Ratio. Maybe there's a tag in it.
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From: Boyne Mich
i believe you can do it either way. The point to make here is if you do both tires then make sure they turn evenly. Meaning the differential spider gears are not turning one tire more than the other. To avoid that problem he's saying stop one tire completely so you can only pay attention to the one tire that is turning. But by doing that, the spider gears double the rotations on the tire, So you have to multiply your drive shaft count by 2. Or let the one tire go around twice.
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i believe you can do it either way. The point to make here is if you do both tires then make sure they turn evenly. Meaning the differential spider gears are not turning one tire more than the other. To avoid that problem he's saying stop one tire completely so you can only pay attention to the one tire that is turning. But by doing that, the spider gears double the rotations on the tire, So you have to multiply your drive shaft count by 2. Or let the one tire go around twice.
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From: Hattiesburg, MS
So, in a nutshell...
Limited slip or locker: lift both wheels
Open diff: lift one wheel.....multiply by 2.
As for WHY you multiply by 2, Drac has a pretty good explanation.