8.25 rear end

[Jon Melhuish]

Hi all
I have a 74 duster with a 8.25 rear end ,can someone tell me how to identify what gear ratio is in it ?

 

[72plymouthscamp]

Look for a tag on the diff cover if its not there remove the cover and rotate the ring gear till you see the markings.

 

[Jon Melhuish]

Look for a tag on the diff cover if its not there remove the cover and rotate the ring gear till you see the markings.

THANK YOU

 

[fishy68]

Another way (but it takes 2 guys) is to put it on a rack or jack it up high enough to get under it good and rotate both tires exactly 1 turn while counting the revolutions of the driveshaft yoke. Example: If the yoke turns approx. 3-1/4 turns it's a 3.21 ratio. If it turns a little less than 3 turns it's a 2.94 ratio. etc.

 

[Logan]

For an open carrier you can, put a chalk mark on one drum. Make the other drum stationary. Rotate the input shaft 10 times. Count how many times the free drum rotates- Say, it looks like about 8.2 times. The ratio will be approximately:

10 rotations of the input shaft times 2 divide by drum rotations
or,

10 x 2 / 8.2 = 2.44 ratio

If you want the answer to be more accurate, rotate the input shaft 20 times:

20 x 2 / 16.3 = 2.45 ratio

Rotate the input shaft as many times you want. Just multiply input shaft rotations x 2 and divide by the drum rotations to get the ratio.

[The reason you multiply by two is to account for the fact that one drum is stationary.]

Finally, you look up the ratios that were available from the factory and you'll easily see which one you've got.