Posted by Paul (in NY) [12.64.120.140] on Wednesday, March 20, 2013 at 18:40:00 :
In Reply to: 4.89 gear data plate speeds?? posted by jason witzel [74.217.37.61] on Wednesday, March 20, 2013 at 17:05:41 :
That is not a 100% way to tell you differential ratio. The Diff's may have been changed or even the data plates.
Park your truck, block both front wheels so it cant roll. Put the transmission and T case in neutral. Jack (1) One rear wheel off the ground. Only ONE rear wheel gets jacked up.
Put a chalk mark on the jacked up tire at 6 oclock. Put a chalk mark on the drive shaft.
Now slowly rotate the jacked up wheel (2) TWO times around while counting the turns on the drive shaft. After 2 turns on the tire, the drive shaft will either be just short of 5 turns which will be 4.89 ratio. Or it will be just short of 6 turns which will be 5.83 ratio.
Paul