Counting on The Spline – Why Axle Spline Count Matters

Counting on The Spline – Why Axle Spline Count Matters

By Justin Banner

You’re instantly told that more splines are better, but why is that? Let’s talk spline count and why its important to your off-road vehicle.

 

The basic idea is that splines are ridges or teeth on a shaft that mesh with a mating piece to transfer torque. That is the job of the splines on your axles: they allow the differential to rotate the shafts to supply motion. When you add more of them, the size of the spline and groove shrink to match the diameter of the shaft and keep a whole number count. So, why don’t they sheer off the moment you apply torque versus a smaller count with bigger spline teeth?

 

Think about it as you lock your index finger on one hand between the index and middle finger of the other. When you push the one index finger into the middle finger of the opposite hand, it’s easy to force it to move. Now interlock all you fingers together on both hands and try again. You’ll find that it’s much harder because you’re now trying to move more than just a single finger. The basic principal is the same on axle splines.

 

Even with larger splines, the total surface area that’s being used to transfer torque is lower. This means its easier to break, chip, or twist an axle with a lower spline count as there is less area being used to drive the axle. Higher spline counts gives the axle more surface to transfer the load of the torque from the differential.

 

There is also the side advantage that an axle with more splines will also be physically bigger. At least in most modern axles that use similarly sized spline teeth. So, it will have the diameter to take more twist before breaking apart. That also means that the axle with more spline teeth might not fit your axle housing, so count and diameter of the axle should be taken into consideration prior to purchase.

 

That’s not the only determination in axle strength. It’s alloy is also important along with heat treatment technique to the metal, its age (if you’re buying used), being a flange or c-clip axle retention, how its finish machined, and many other factors to weigh before you buy.

 

That’s why we’re here to help! Schedule a time to get your axles installed, get advice on what type to get, and more at Vicious Off-Road!