What gears do I have?

[Jeremy_Cherokee]

I've got a 1990 Jeep Cherokee on a 5 1/2" lift and 31" tires. I'm trying to get a new speedo gear so that I don't get another ticket and I don't know what gears I have. I am almost certain that I don't have stock gears because I run about 70mph (guessing based on other traffic) and I'm only running maybe 2000 rpm.

My question is how can I tell which gears I have. I now you can turn the drive shaft and count the revolutions per a single revolution of the tire but if it makes 4 revolutions it could be 4.10s, 4.56s, or 4.86s. Is there a difference, physically, in the gears that I could check when I service the differentials this week?

Thanks!

 

[XJensen]

spin the tire 10 times then 41 drive shaft revs is 4.10s, 45.6 is 4.56

Move the decimal and cut out some error.

 

[Jeremy_Cherokee]

Ahhhhhhh...I've been out of school too long ... that should have been a no-brainer. Thanks!!!

 

[5-90]

Automatic (AW4) should be 3.55, manual (should be AX-15 for you) should be 3.07.

Dana diffs usually also have a tag held on by one of the cover screws - with the ratio "in the clear" on the bottom row. You can also check your front diff - it's a Dana, and should still have the tag. The rear will match by about one "point" (front 3.54, rear 3.55. Front 3.08, rear 3.07. And like that.)

 

[RCP Phx]

Is there a difference, physically, in the gears that I could check when I service the differentials this week? Thanks!

The gear tooth count will be stamped on the ring gear!