The axle ratio is a key factor you need to know to determine your truck’s towing capacity.
If you have consulted our articles on Ford F-150 towing capacity or the towing capacity of the 3.5L Ecoboost, then you know that the axle ratio is required so that you know definitively how much you can tow.
But how do you find your F-150’s axle ratio?
Can it be found from the VIN number?
Read on, for more information!
What is the axle ratio?
Let’s first review what the axle ratio is, and why it might be important to you.
The wheels of the truck are connected to the engine through the driveshaft and axle. There are other complications like clutches, transfer case, etc but we don’t need to worry about that here.
The axle ratio specifies the number of turns required by the engine to achieve one turn of the wheels. For example an axle ratio of 3.55 means that the engine turns 3.55 turns for every 1 turn of the wheels.
A low axle ratio is more efficient for highway driving and uses less fuel, all else equal. However the sacrifice is torque. Torque is turning power and a high torque is essential for towing large loads. So a higher axle ratio is preferable for towing.
A relatively high axle ratio of 4.10 will have a much higher towing capacity than the truck with a 3.55 axle ratio. However the gas economy will be less.
Where to find the axle rating for the Ford F-150 truck
The easiest, and quite frankly the most reliable, place to find your truck’s axle ratio is the door jamb sticker on the driver’s side.
The picture on the right shows an example Safety Compliance Certification Label. In the lower part you can see a two character code for the AXLE.
By finding this code you can cross-reference with a table of axle codes produced by Ford – shown below.
Table of axle codes for the Ford F-150
In the table below you can see a selection of two-character codes, simply read across to the left to find your axle ratio – 3.31, 3,55 3.73, 4.10 and 9.61 for the lightning.
You can see that codes that are purely numeric (e.g. “19“) correspond to a Non-limited slip, and codes with a letter (e.g. “L6“) correspond to an Electronic Locking slip.
|Rear Axle Ratio||Non-Limited Slip||Electronic Locking|
|9.61 (Lightning model only)||Not Available||Std.|
Non-limited slip and Electronic Locking
A non-limited slip differential (also called an “open differential”) will provide power to the wheel with the least traction. For a level paved road in good conditions this makes no difference. However if one wheel is on slick ground the power transmitted to that wheel causes it to spin. A limited slip differential helps combat this by changing to amount of power to each wheel, allowing more power to the high-traction wheel.
For the electronic locking feature we recommend this video from Ford.
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Does the VIN number tell you the axle ratio?
No. For Ford vehicles the VIN number does not give any information on the axle ratio.
You can de-code your VIN number at the National Highway Traffic Safety Administration, and you will see that there is no information there about the axle ratio of your Ford F-150 truck.
You may be able to contact Ford and provide them with the VIN number and they can cross-reference their database of manufactured trucks to tell you the axle ratio, but the axle ratio is not embedded in the VIN number.
How to find the axle ratio if you do not have a door sticker
As discussed above the best way to find the axle ratio is from the door jamb sticker, and then decode the two-letter code.
But what if the sticker is not present?
You have a couple of options.
- You can crawl under your vehicle and on the axle or the differential cover you should see a sticker or tag with the code.
- Jack up the rear of the car, put it in neutral and turn a rear wheel. Count how many times the driveshaft turns for one turn of the wheel. For example – if the driveshaft turns a little over three and a third times for every turn of the wheel then the axle ratio is 3.31. Note that it’s a little more complicated and this article gives some more information.
Frequently asked questions
How to find the gear ratio from the VIN? This is not possible from an online VIN decoder. You could try calling Ford.
What is Ford axle code 27? From the table above you can see this corresponds to axle code 3.31 for the Ford F-150
How do I know what axle my F-150 has? Simply follow the instructions in this post!
Locate the sticker in the driver’s door jamb. Find the two-character code and cross-reference with the table above to find the correct axle ratio for your Ford F-150. Note that the VIN number alone will not help you.
If you have remaining questions please contact us.
Please refer to the disclaimer for important notes and limitations on this article