Rear Diff.

[Lenard]

I know there is a tag on the back of the rear diff. that tells you what it is, but mine is so rusted up i can't read it anymore. Is there any other way to tell what i have?

[tjbliley]

4.10

[JeepcoMJ]

4.10

 

nope

 

4 speed will be 3.55 or 3.73.

 

if it was a factory 5 speed it would be 4.10

 

 

the only 100% accurate way is to open the diff and read the teeth count on the ring gear

[Pete M]

A quick and dirty technique is to raise up one tire (with the transmission in neutral) and rotate it twice while counting the driveshaft revolutions. If it spins around just over 4 times it's 4.10, 3-1/2 times is 3.55 and somewhere in between is 3.73.

[Geonovast]

Pete...isn't trhe driveshaft rotation amount cut in half with doing only one tire? The spider setup would do that. I would recommend getting both rear tires off the ground, and turn the driveshaft by hand.

[Pete M]

Pete...isn't the driveshaft rotation amount cut in half with doing only one tire? The spider setup would do that. I would recommend getting both rear tires off the ground, and turn the driveshaft by hand.

 

That's why you have to rotate the tire around twice. :D

 

I forgot to mention that if the axle has a posi in it, then the owner would need to jack up both rear tires and rotate them around only once.

[Lenard]

Pete...isn't the driveshaft rotation amount cut in half with doing only one tire? The spider setup would do that. I would recommend getting both rear tires off the ground, and turn the driveshaft by hand.

 

That's why you have to rotate the tire around twice. :D

 

I forgot to mention that if the axle has a posi in it, then the owner would need to jack up both rear tires and rotate them around only once.

ok thanks, i got a little kubota tractor that will lift the back end up. i love having pipes for bumpers. :D