How To Properly Measure for Drive Shaft Length

Hello guys, 

I hope this short tutorial helps you guys out. Depending on what kind of drive shaft you have, there are a couple of different methods you can use to determine your drive shaft measurement. For the first example, we'll talk about measuring for a front drive shaft for a Ford F-250 or F-350. Many front and rear drive shafts use this type of design so it works for all kinds of shafts that are built this way. We notice by looking at the design of the drive shaft that it uses a four bolt flange at the transfer case to bolt the constant velocity end of the shaft. The front of the drive shaft connects with a universal joint that fits into a yoke at the front and is held by two straps.

To measure-

We start by placing the flat part of our tape measure (the end) on the transfer case flange face. Then, we measure to where the center of the u-joint at the front will sit when the drive shaft is installed. If you put the u-joint in the front yoke, you'll notice that the flat surfaces of the front yoke where the strap bolt holes are is almost exactly where the center of the u-joint sits when the shaft is installed. So, say we're missing the front drive shaft entirely. We can measure from the transfer case flange fact to where the strap bolt holes are and come up with the same measurement. 

For one piece rear drive shafts-

Such as in a Camaro or Dodge pickup truck, we just measure from centerline of u-joint to centerline of u-joint. If the entire shaft is missing or if you need a custom drive shaft for a project car, you can measure from the transmission output seal to the center of the rear u-joint and a custom shaft can be built from that measurement. 

For a drive shaft that uses flanges at both ends-

Be it a CV shaft or not, we can simply measure between the two mounting flange faces under the vehicle to determine the length of the drive shaft. 

A couple of things to consider-

To get the most accurate measurement, it's best to have the vehicle sitting on level ground so that our measurement isn't thrown off by the suspension being in a position other than what it would be if you were driving. Also, pay close attention to the types of u-joints that are used on the drive shaft yokes. Yokes come in many different sizes and measurements, but you can determine the type of u-joint by measuring the width of the yoke and the diameter of cups that cradle the u-joint bearing caps. 

As always, if you guys have any questions, feel free to give us a call at 501-626-0570 or e-mail us at sales@proshaftllc.com and we'll be happy to help you determine the length of your drive shaft. Thanks for reading everyone!

Best,

Justin from ProShaft