How do I tell what gear ratio my Chevy Vin has?

To determine the gear ratio of your Chevy vehicle, you'll need to look up the information based on your specific make, model, and year. The gear ratio is an important factor that affects your vehicle's performance and fuel efficiency, so it's good to know this detail.

What is a Gear Ratio?

The gear ratio refers to the relationship between the number of teeth on the drive gear (connected to the engine) and the number of teeth on the driven gear (connected to the wheels). This ratio determines how much the engine's rotational speed is multiplied or reduced when it's transferred to the wheels. A higher gear ratio means the wheels turn more times for each engine revolution, providing more torque but lower top speed, while a lower gear ratio means the wheels turn less for each engine revolution, resulting in less torque but higher top speed.

Finding Your Chevy's Gear Ratio

To determine the gear ratio of your specific Chevy vehicle, you'll need to consult your owner's manual or look up the information online. Here are the steps:

• Locate your Chevy's Vehicle Identification Number (VIN). This is a 17-character code that is unique to your vehicle.


• Use the VIN to look up your vehicle's specifications, including the gear ratio, on a site like Chevy's website or an automotive parts retailer.


• The gear ratio will typically be listed as a number, such as 3.42:1 or 4.10:1. This means the drive gear turns 3.42 or 4.10 times for every one full rotation of the driven gear.

Knowing your Chevy's gear ratio can help you understand how your vehicle will perform in different driving conditions and whether modifications like a different rear axle or transmission would be beneficial.

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. 

How to tell what GM rear end you have?

GM Rear End Identification Codes & Casting Numbers
On most housings, the codes are located on the front side of the passenger or driver axle tube, about three inches from the pumpkin. You will often find casting numbers on the pumpkin as well, but the ID numbers are usually on the axle tubes.

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

How to find Chevy rear end gear ratio?

Identify your GMC or Chevrolet rear end gear ratio by the RPO Codes, usually located on the placard labeled “Service Parts Identification” inside the drivers door panel or glove box.