R & P ratios

[jpbrennan]

Hello I have a 1995 Jeep Grand Cherokee 5.2L Limited, I have been trying to find out what the gear ratio is so that I can change the speedo gear so that I can stop getting tickets for going 4 to 7 miles faster than what it reads. The reason I am asking is that the tags on both diff's are missing and there is no info in the repair book that i have (chilton and haynes) any help would be very greatful. and the tires and wheels are not stock.

[pantera84]

There are a few things you can try.


Some manufactures and after market gears have the ratio's stamped on the outside of the ring gear. If you have Dana axles(Which I think you do) there should be the ratio.

If you have Dana axles there should be a Bill of Materials number of the axle. The number will be found either stamped near the pinion yolk or its on a tag bolted to either the left or right hand support housing if it is IFS. It's on the tubes if it is solid. You can contact Dana with that number and they can tell you everything you need to know.

I'm not sure about Jeep, but some manufactures will have a axle code on the tag inside of the drivers door. You can take the axle number or letter and compare it to the owners manual. Providing the gears are stock.

Then there is counting the teeth on the pinion and the ring. If you where to have 3.73 gears. There should be 41 teeth on the ring and 11 on the pinion. Take the 41 divided by 11 and you will get 3.727272. Which is 3.73.

Hope some of it helps.