How do I find my Chevy axle ratio?

The axle ratio is an important specification for your Chevy vehicle, as it determines the relationship between the speed of the wheels and the speed of the engine. Knowing your Chevy's axle ratio can help you understand its performance characteristics and make informed decisions about modifications or towing capacity. In this article, we'll guide you through the steps to find your Chevy's axle ratio.

Locate the Axle Ratio Information

The axle ratio for your Chevy can typically be found in one of the following locations:

• On the driver's side door jamb sticker or placard


• In your owner's manual


• On the vehicle identification number (VIN) tag, usually located on the driver's side dashboard or door jamb

If you can't find the axle ratio information in these locations, you can also check the vehicle's build sheet or contact your local Chevy dealer for assistance.

Understand Axle Ratio Terminology

Axle ratios are typically expressed as a ratio, such as 3.73:1 or 4.10:1. This ratio represents the number of times the driveshaft rotates for every single rotation of the wheels. A higher axle ratio, such as 4.10:1, indicates that the wheels will rotate more slowly compared to the engine, providing more torque and better acceleration, but lower fuel efficiency. A lower axle ratio, such as 3.73:1, results in higher top speeds and better fuel economy, but less low-end torque.

Identify Your Chevy's Axle Type

Chevrolet vehicles can be equipped with different types of axles, such as a standard rear axle, a limited-slip differential, or a locking differential. The axle type can also affect the available axle ratio options. Consult your owner's manual or speak with a Chevy dealer to determine the specific axle type in your vehicle.

Consider Axle Ratio Modifications

If you're looking to improve your Chevy's performance or towing capacity, you may consider changing the axle ratio. This process typically involves replacing the ring and pinion gears in the differential. It's important to note that changing the axle ratio can have a significant impact on your vehicle's handling, fuel economy, and other performance characteristics, so it's best to consult with a professional before making any modifications.

By following these steps, you can easily identify the axle ratio of your Chevy vehicle and make informed decisions about any potential modifications or upgrades.

How do I tell what gear ratio I have in my Chevy truck?

You can find your Chevy truck's gear ratio by checking the "Service Parts Identification" sticker for the RPO (Regular Production Option) code, which is usually on the driver's door jamb or in the glove box. Other methods include counting the teeth on the ring and pinion gears or performing a wheel-rotation test if the RPO code is missing.
 
This video shows how to find the RPO code on your Chevy truck: 21swtbm123YouTube · Dec 17, 2014
Method 1: Check the RPO code sticker 

• Locate the sticker: Find the "Service Parts Identification" sticker. It's typically on the driver's door jamb or inside the glove box. 
• Find the code: Look for a three-digit code that starts with "G" for the axle ratio. 
• Decode the code: You'll need to look up the specific code to find the corresponding gear ratio. Common codes include GT4 (3.73), GU6 (3.42), and GT5 (4.10). 

Method 2: Count the teeth on the gears 

• Access the differential: Remove the cover of the rear differential to access the gears. 
• Count the teeth: Divide the number of teeth on the larger ring gear by the number of teeth on the smaller pinion gear. For example, if the ring gear has 41 teeth and the pinion gear has 11 teeth, the ratio is approximately 3.733.733.73 (41÷11≈3.72741 divided by 11 is approximately equal to 3.72741÷11≈3.727). 
• Check for a stamping: Often, the gear ratio is already stamped on the ring gear, so you can just read the numbers directly. 

This video demonstrates how to count the gear teeth: 1mWebWheelerYouTube · Apr 10, 2018
Method 3: Perform a wheel-rotation test 

• Prepare the vehicle: Safely jack up the rear of the truck and place wheel chocks on the front wheels. Ensure the truck is in neutral. 
• Mark the driveshaft: Place a mark on the driveshaft and on one of the rear tires. 
• Spin the tire: Rotate one rear wheel exactly 10 times, counting each full rotation. 
• Count the driveshaft turns: Count how many full rotations the driveshaft makes during those 10 tire rotations. 
• Calculate the ratio: Multiply the driveshaft rotations by 2 (since the tire was spun 10 times) and then divide that number by 10. 
  • For example, if the driveshaft turned 333333 times while you spun the tire 10 times, the ratio would be approximately 3.33.33.3 (33÷1033 divided by 1033÷10). However, to use the 10-turn method, you'd calculate it as: (33×2)÷10=6.6open paren 33 cross 2 close paren divided by 10 equals 6.6(33×2)÷10=6.6. This is not correct.
  • A more direct calculation is to spin the wheel one time and count the driveshaft turns. If the driveshaft turns 3.733.733.73 times for one wheel turn, you have a 3.733.733.73 gear ratio. 
  • If you have an open differential, you must spin the driveshaft turns by 2. 

How do you tell if you have 3.73 or 4.10 gears?

You can tell if you have 3.73 or 4.10 gears by manually counting, checking the differential cover for a tag, or finding the ratio stamped on the ring gear. The most direct method is to lift the rear wheels, rotate one tire one full revolution, and count how many times the driveshaft turns; 3.75 turns indicates 3.73 gears, while slightly over 4 turns indicates 4.10 gears.
 
This video demonstrates how to check your gear ratio by counting the driveshaft turns: 48sBent Motorsports OffroadYouTube · Sep 22, 2023
Method 1: Manual count (with the vehicle jacked up)

1. Jack up the vehicle: Safely lift the rear of your vehicle and secure it on jack stands. Ensure the wheels are off the ground. 
2. Mark the driveshaft and a tire: Place a mark on one of the rear tires and a corresponding mark on the driveshaft. 
3. Rotate the tire: Rotate the marked tire forward one full revolution. For an open differential, you may need to lift only one wheel and have someone hold the other stationary, or lift both wheels and rotate one tire twice while the other tire is on the ground. For a locked differential, lift both rear wheels and have one tire rotate once while the other rotates once in the opposite direction. 
4. Count the driveshaft turns: Count how many times the mark on the driveshaft has rotated. 
   • 3.73 gears: The driveshaft will turn approximately 3.753.753.75 times for one full tire revolution. 
   • 4.10 gears: The driveshaft will turn a little over 444 times for one full tire revolution. 

Method 2: Check the differential cover tag 

1. Locate the tag: Look for a small metal tag that is usually bolted to the differential cover. It may be on one of the bolts. 
2. Read the ratio: If the tag is still present, the gear ratio will be stamped on it. It will likely be a number like "3.73" or "4.10". 

You can watch this video to learn how to find the differential cover tag: 51sFlawed OffroadYouTube · Apr 18, 2022
Method 3: Read the ring gear stamps 

1. Locate the ring gear: This requires removing the differential cover to get a clear view of the ring gear.
2. Find the numbers: Look for two numbers stamped on the teeth of the ring gear, such as "41" and "11". 
3. Divide the numbers: Divide the larger number (teeth on the ring gear) by the smaller number (teeth on the pinion gear). 
   • 41÷11≈3.7341 divided by 11 is approximately equal to 3.7341÷11≈3.73 
   • 41÷10=4.1041 divided by 10 equals 4.1041÷10=4.10 

This video shows how to read the ring gear stamps to find the gear ratio: 46sJL LIFE OFFROADYouTube · Nov 18, 2022

Does the VIN number tell you the gear ratio?

You may be able to tell the gear ratio from a vehicle's VIN by using an online VIN decoder, though not all manufacturers include this information in the VIN itself. If the gear ratio is included, it will likely be in the Vehicle Descriptor Section (VDS), which are the 4th through 8th digits of the VIN. For many vehicles, a sticker on the driver's side door jamb or on the vehicle's build sheet or owner's manual is a more reliable way to find the gear ratio. 
How to check the VIN

• Use an online VIN decoder: Enter the full VIN into a free online decoder. Some manufacturers have their own decoders, such as Mopar's decoder. 
• Look for the gear ratio code: Some VINs will have a code within the VDS that represents the gear ratio (e.g., "3731"). 
• Consult the manufacturer: If the VIN decoder doesn't provide the information, contact the vehicle manufacturer for assistance. 

Other methods to find the gear ratio

• Check the vehicle sticker: Look for a sticker on the driver's side door jamb or on the vehicle's build sheet. This sticker often contains detailed information about the vehicle's equipment, including the axle ratio. 
• Look at the differential: Some differentials have a metal tag with the gear ratio stamped on them, or there may be a sticker on the axle itself. 
• Consult your owner's manual: The owner's manual or other paperwork from the vehicle's purchase often lists the gear ratio. 

Where do I find my GM axle code?

you guessed it, Axle and Differential specs. The GM RPO Codes label is usually located inside the glove box or on the Driver's Side Door Jamb (on the B-Pillar). The silver placard will be labeled “Service Parts Identification” and includes a bunch of three-digit codes.