finding out gear ratios
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Registered User
Joined: Sep 2009
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From: Kentucky
finding out gear ratios
Im trying to find out the gear ratios in 2 different 8.25" rear axles. One is from a 1984 Ram D-100 with 225 C.I. motor with 4 speed manual tranny and the other is a 1990 Ram D-150 with the 318 C.I. with 3 speed auto tranny. Neither housing has the tag on the cover. If anyone can help me figure this out i will appreciate it. 
Champion
Joined: Mar 2009
Posts: 2,639
Likes: 4
From: Bent Mountain Va
If you want to open the rear end you can count the teeth on the pinion and the teeth on the ring gear. Divide the number of teeth on the pinion into the number of teeth on the ring gear and that is your gear ratio. If you don't want to open the rears up just jack the rear wheels off the ground and put it in neutral. Mark the bottom of a tire and the yoke of the rear end with chalk. Rotate the tire 1 revolution while counting the revolutions of the yoke. That is your gear ratio. ie (If the yoke rotates 4.56 turns for 1 revolution of the tire you have a 4.56 rear end ratio.)
Last edited by SEAL; Sep 24, 2009 at 08:54 AM.
Record Breaker
Joined: Mar 2004
Posts: 1,977
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From: DuQuoin,IL.
If you want to open the rear end you can count the teeth on the pinion and the teeth on the ring gear. Divide the number of teeth on the pinion into the number of teeth on the ring gear and that is your gear ratio. If you don't want to open the rears up just jack the rear wheels off the ground and put it in neutral. Mark the bottom of a tire and the yoke of the rear end with chalk. Rotate the tire 1 revolution while counting the revolutions of the yoke. That is your gear ratio. ie (If the yoke rotates 4.56 turns for 1 revolution of the tire you have a 4.56 rear end ratio.)
If you have an open rear jack one rear wheel up, turn wheel one revolution, count drive shaft revolutions and double them.
