Alloy USA Blog
Stock axle shafts are typically made from 1040 and 1541 steel and are perfectly adequate for stock applications. For performance axle shafts, we use 1541H steel, 4140 and 4340 Chromoly steel, which has been hardened to maximize the strength and ductility of the axle shafts.
1541 is a plain high carbon steel similar to 1040 but with added manganese for better hardenability, but there is not enough alloying elements in it to be classified as an “alloy” steel. 1040 and 1541 are used because it is cheap and good enough for what is required by stock axles, they heat treat 1040 and 1541 by induction hardening which is a production form of case hardening, it is fast, cheap and works very well 1541 is able to be hardened to a greater depth (better hardenability) than 1040/1050 and therefore stronger
4140 and 4340 are true alloy steels. 4140 is alloyed with chromium, molybdenum and 4340 with chromium, molybdenum and nickel. 300M is also called 4340 modified because it basically 4340 with silicon added. The strength of steel is generally directly related to the hardness, the harder you can get the steel, the stronger it is (tensile strength) buy you generally loose toughness. These alloys give the steel increased hardenability and good toughness at higher hardness/strength levels, they can be induction hardened but their purpose and advantage is that they can be thru hardened because of their better hardenability. 4340 has better hardenability than 4140 so it can be heat treaded harder and thus stronger than 4140. The 4140 and 4340 material is available in commercial and aircraft quality. Aircraft quality means it is vacuum melted to minimize the impurities but costs more. Most 4140 and 4340 axles are made of commercial quality steel.
How to Choose Ring and Pinion Gears
Torque is the main goal when re-gearing 4WD vehicles. More torque is needed to compensate for those big tires you added. And, more torque will get you up the steep hills.
The Gear Ratio Calculator below will help you select the best gears for your needs.
If you mainly drive to work and on the highway, you may want lower ratios. This will give you better gas mileage, but not as much torque. Acceleration will be adequate, but won’t roll your eyes back in your head.
If you trailer your 4WD to the trails and are spinning big mud tires in a mud bog, you’ll want higher ratios. This is great, but your top speed will be limited. Think fast and furious.
When in doubt, go one ratio higher. We tend to add weight to our trucks over time…requiring more torque. And, some of us later decide to increase the tire size just one size…
It’s helpful to know what ring and pinion is in your truck now, you may find a tag or some numbers stamped near the differential. Knowing your current ratio will determine whether you need to change the differential carrier to fit the new ring gear or not.
It’s important to know what axles you have under your rig. The factory often sold several different axle choices. For example the ring gear in the Jeep Rubicon Dana 44 axle is thicker than non-Rubicon models.
Knowing what year the axle was built can be helpful. Keep in mind that if you bought your truck used, someone may have changed the axles before you bought it.
One thing to remember is that when you buy your ring and pinion gears, you will also need a master installation kit for each set. The master installation kit includes all the bearings, pinion seals, pinion shims, crush sleeve, pinion nut, ring gear bolts, and marking compound for the install.
Your sales rep will be able to help you find the gear ratios and components you need, but you can also narrow down your choice using the Gear Ratio Calculator.