Axle Shaft Shorten & Respline | Check These 5 Things

Ever wanted to send us an axle for shortening or a bolt pattern change? We get this call probably a million times a day.

Truth be told its a totally viable option for a lot of projects, BUT the axle needs to prove itself worthy of the job.

There are a series of checks we perform on each axle we get, and it would be worth your while for you to check these things too. That way you don't this phone call, "Hey your axle is totally unusable, sorry you spent money to ship it to me...."

Ok we won't be that mean, but we will feel bad that you shipped us an axle you can't use. Shipping can cost you an arm and a leg, and not only that they could totally loose your package! Lets make sure its worth it before you ship us that potential boat anchor.

First lets check that the diameter is even usable for the spline.

The first thing you need to do is measure the DIAMETER of your spline. Rock it back and forth and make sure you are getting an accurate number. Now, we need know how much shorter the shaft needs to be. Take that number, lets say for example 2", and measure from the end of the shaft 2" down. Now we measure the diameter there.

If its the same diameter or larger than you spline diameter, you have passed this first check! But if its smaller than your spline diameter, you are out of luck. You either need to rework the job or find a new axle.

The other side of this coin is the diameter where you want the spline, can't be too much larger. Axles have a process of heat treat that makes the outside harder than the inside. So the more we machine off the diameter, the weaker the axle gets. The magical number we work with is about 0-0.100.

Example: Your spline diameter is 1.290 (Chevy/GM 30 spline) and you want to shorten your axle -8". So you measure your diameter 8" down your shaft from the end, and it measures 1.590. That's a 0.300 difference, three times our tolerance. We won't machine that. BUT if you measured 8" down the shaft and you got 1.330, that is only a 0.040 change. We can do that! So again the difference can't be any more than 0.100 and can't be smaller than your existing spline diameter.

NEXT you need to take a look at the bearing journal.

Often times guys are needing to remove bearings, replace seals, or whatever, and they need to fuss around the bearing journal. However you need to remove the bearing, do what you gotta do. BUT DON'T SCRATCH THE JOURNAL. That's an important surface that a bearing is pressed onto and has a very tight tolerance. If there any knicks or canyons from cutting off bearings we will not work on your axles.

Next thing we check is if your axle is straight. If you mock up you axle in the rearend, making sure all your brake hardware is removed, you can put a travel indicator on the wheel side face of your axle. If it moves more than 0.010, you have a bent axle and we won't use it.

Lastly we want to emphasize to never weld on your axle shafts. From tacking your studs on to cutting them down the middle and welding it back together. This creates big problems with heat treat, and creates a liability that we will not work with. Its a big safety issue, and even if you are ok with the risk, there are others on the road/track/coarse who did not sign up for that risk.

One other unique situation that is worth mentioning: In the case where we are picking up an existing spline, DO NOT SHORTEN THE AXLE YOURSELF. We require the center to pick up the old spline and chase it back. If you cut the shaft off, which removes that center, we have no way to guarantee a good spline fitment and tooth contact. Which means the chances of the shaft not being able to be installed or for the fit to be sloppy and break are much higher. So let us chase the spline back and cut it to your new specified length.

That's it! Feel free to call us if you have questions!