Determining Axle Ratio and if you have Trac-Loc
Thread Starter
JK Enthusiast
Joined: Aug 2010
Posts: 145
Likes: 1
From: Oklahoma City, OK
Awhile back someone asked about determining what axle ratio they had and if their's was equipped with Trac-Loc. Well my initial answer was to check the pumpkin tags being the old TJ owner that I was. Unfortunately to my surprised after checking my JK there I realized there isn't any tag. So, I went ahead and contacted Chrysler via Jeep's website to ask if there is a new method on determining this... Here's the answer I recieved:
"Sorry for the delay in responding Unfortunately, the only way of knowing the axle ratio on the vehicle would be the monroney lable or build sheet from the manufacturer since the data plates are no longer used."
(For those who don't know what a Monroney Label is, it is the window sticker.)
So, to sum things up, to determine the axle ratio on a JK when you don't have the build sheet, you'l need to pull the diff cover and see what is stamped on the ring gear and see if you have clutches in there.
"Sorry for the delay in responding Unfortunately, the only way of knowing the axle ratio on the vehicle would be the monroney lable or build sheet from the manufacturer since the data plates are no longer used."
(For those who don't know what a Monroney Label is, it is the window sticker.)
So, to sum things up, to determine the axle ratio on a JK when you don't have the build sheet, you'l need to pull the diff cover and see what is stamped on the ring gear and see if you have clutches in there.
JK Freak
Joined: Sep 2009
Posts: 641
Likes: 1
From: Bronx, N.Y.
How to determine gear ratio:
#1. Begin by parking your vehicle on a flat surface and placing your vehicle in park and set the emergency brake(for now.)
#2. Block the front wheels.
#3. Jack the rear of the vehicle up and set it on jack stands.
#4. Disengage the parking brake and place the vehicle in neutral.
#5. Mark the rear tire with chalk at either the top or bottom on each side.
Mark the driveshaft with chalk also
#6. Climb under the vehicle and have your 2 friends rotate the rear wheels in the same direction one full revolution slowly. As they rotate the tires watch the driveshaft as it rotates also. Count the numbers of revolutions the driveshaft turns.
#7. This number is your rear gear ratio. A 4+ will give you faster acceleration with a lower top speed(end less gas mileage.) A lower number 2.9 will give you slower acceleration with a higher top speed and better gas mileage.
How to determine if you have a limited slip differentail:
Raise both rear wheels, then turn one by hand, watch the other one. If it turns in the same direction it's a LSD, otherwise it'll go the opposite way.
#1. Begin by parking your vehicle on a flat surface and placing your vehicle in park and set the emergency brake(for now.)
#2. Block the front wheels.
#3. Jack the rear of the vehicle up and set it on jack stands.
#4. Disengage the parking brake and place the vehicle in neutral.
#5. Mark the rear tire with chalk at either the top or bottom on each side.
Mark the driveshaft with chalk also
#6. Climb under the vehicle and have your 2 friends rotate the rear wheels in the same direction one full revolution slowly. As they rotate the tires watch the driveshaft as it rotates also. Count the numbers of revolutions the driveshaft turns.
#7. This number is your rear gear ratio. A 4+ will give you faster acceleration with a lower top speed(end less gas mileage.) A lower number 2.9 will give you slower acceleration with a higher top speed and better gas mileage.
How to determine if you have a limited slip differentail:
Raise both rear wheels, then turn one by hand, watch the other one. If it turns in the same direction it's a LSD, otherwise it'll go the opposite way.
Last edited by Tiburon; Dec 2, 2010 at 01:49 PM.