Rear end gear ratio non-posi

[John F.]

With one wheel jacked up, turning the tire one complete revolution turns the rear-end yoke about 1 3/4 revolutions. What would be the rear ratio?

[John H.]

Re: Rear end gear ratio non-posi

With one wheel jacked up, turning the tire one complete revolution turns the rear-end yoke about 1 3/4 revolutions. What would be the rear ratio?

John -

Should be 3.55 (1.75 x 2); if you jack it up so both wheels are off the ground and have a helper so you can turn both wheels one complete turn, you should see 3-1/2 turns of the yoke.

[Duke W.]

Re: Rear end gear ratio non-posi

With one wheel stationary the driveshaft will turn half the revolutions of the axle ratio, so 1.75 x 2 = 3.5, so it looks like a 3.55, but be sure your count of driveshaft revolutions is very accurate because 3.36 and 3.70 are only 4-5 percent either way of 3.55, which is less than a tenth of a driveshaft revolution using this measuring method.

Duke

[John F.]

Re: Rear end gear ratio non-posi

With both wheels off the ground and trans in neutral the driveshaft doesn't turn at all. What am I doing wrong?

[Duke W.]

Re: Rear end gear ratio non-posi

That's typical of an open diff. If you turn one wheel the opposite wheel just turns in the opposite direction and the drive shaft stays put.

A better way is to mark the tires. Then manually turn the driveshaft until the tires make a complete revolution, while you're carefully counting driveshaft revolutions, especially the last fraction.

Sometimes only one wheel will turn. In this case, block one wheel, turn the driveshaft for one full rotation of the free wheel, then mulitply driveshaft revolutions by 2.

The turn the driveshaft until you get one full wheel rotation method is more accurate, but it works best with a Positraction axle that still has enough preload so that both wheels turn while you're turning the driveshaft.

Duke

[John F.]

Re: Rear end gear ratio non-posi

That's typical of an open diff. If you turn one wheel the opposite wheel just turns in the opposite direction and the drive shaft stays put.

A better way is to mark the tires. Then manually turn the driveshaft until the tires make a complete revolution, while you're carefully counting driveshaft revolutions, especially the last fraction.

Sometimes only one wheel will turn. In this case, block one wheel, turn the driveshaft for one full rotation of the free wheel, then mulitply driveshaft revolutions by 2.

The turn the driveshaft until you get one full wheel rotation method is more accurate, but it works best with a Positraction axle that still has enough preload so that both wheels turn while you're turning the driveshaft.

Duke

Thanks Duke.

JF