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how to find rear end gears

tabascom16

Sr. Member
Joined
Oct 12, 2003
Messages
526
Loc.
Salisbury, PA
If there is no tags jack up one back wheel and leave the other on the ground (unless you have a locker). Watch the ujoint or CV on the driveshaft while you turn the tire one full turn. However many times the driveshaft turns around you need to divide by two. 3.50 gears would turn the driveshaft around 7 times, 4.11 would turn it 8.22 times. If you have a locker and have them both up then it would be the exact rotations of the driveshaft you would count (3.5 turns for 3.50's etc)
 

broncnaz

Bronco Guru
Joined
May 22, 2003
Messages
24,341
Look at the VIN tag there should be axle codes there also if it still has the small metal tags on either diff it will have the gear ratio stamp on it,
 

SaddleUp

Bronco Guru
Joined
May 23, 2004
Messages
9,655
Loc.
Vancouver, WA
tabascom16 said:
If there is no tags jack up one back wheel and leave the other on the ground (unless you have a locker). Watch the ujoint or CV on the driveshaft while you turn the tire one full turn. However many times the driveshaft turns around you need to divide by two. 3.50 gears would turn the driveshaft around 7 times, 4.11 would turn it 8.22 times. If you have a locker and have them both up then it would be the exact rotations of the driveshaft you would count (3.5 turns for 3.50's etc)
I would do it this way even if there are tags. I've seen too many of them that had a different tag than gears to trust it to be correct.
 

bandit

Full Member
Joined
Dec 19, 2005
Messages
305
Loc.
Afton
I agree,I bought a '77 rear end a couple of years ago the tag said 3.50's,and there were 4.11's inside.The tag can stay on,even after someone switches gears.
 
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