Preload Vs Endplay

A lot rides on well-maintained wheel ends that are assembled correctly—figuratively and literally. What’s more, installing and maintaining wheel ends properly requires some knowledge and skill with preload and endplay. They’re both bearings settings that affect how heavy-duty truck wheels perform. Whether you’re looking to save money or reduce wheel-off incidents, you can do both by learning more about preload vs endplay.

You Can’t Have ‘Em Both

Preload settings on a bearing optimize wheel end performance by eliminating axial clearance. With this setting, pressure applied to the bearings keeps the rollers in place. This allows them to move the way they were built to move. On the other hand, endplay settings have a small amount of clearance. The space allows the bearings to move freely along the shaft. This is also called a loose setting.

Preload vs endplay both affect wheel performance. Either one can optimize performance. However, because they are pretty much opposite settings, you can’t set bearings to both preload and endplay. In fact, setting one will eliminate the other.

Why You Can’t Ignore Preload and Endplay

It’s good to understand preload vs endplay, but it’s just as important to know how they influence trucks’ operation and safety. For example, bearings with accurate preload or endplay settings promote even tire wear and extend tire life. Proper settings discourage vibrations that can affect seals and brake systems. What’s more, proper preload or endplay helps keep bearings working correctly to reduce bearing failure and help prevent wheel-off events from occurring.

Accurate Settings are Important

Preload vs endplay – whichever setting you prefer, it has to be accurate and precise. Too much preload can cause a lot of friction which leads to heat damage and, eventually, failure. On the other side of the coin, too much endplay can allow excessive vibrations and uneven movement which will also cause breakdowns at some point. That’s why precise preload and endplay settings are critical.

Special gauges are needed to measure each setting. Plus, techs can buy specialty tools such as dial indicators and calibrated torque wrenches that help them get those settings right. When setting endplay, the measurement should be between .0001 and .0005 inch. Manufacturers typically set bearings preload, but it can be manually adjusted, too. Techs can review the Technology and Maintenance Council’s Recommended Maintenance Practices manual, section RP 640, for preload guidelines.

Preload Vs Endplay – Is One Better Than the Other?

Since you can’t have both preload and endplay, and both have their good points and potential downsides, which should you choose? In some cases, it may not matter, and techs or fleet managers can choose whichever setting they feel their trucks operate best at. However, some bearings, such as tapered roller bearings, won’t work properly when set to endplay. The rollers won’t stay aligned with a loose setting. In those cases, preload is the obvious best choice.

Preload vs endplay: no matter which setting you use, they’ll both do the most good when you regularly measure and record settings. Having that information allows techs to adjust them for the best performance. Keeping track of that data is a snap with Fullbay. It’s a diesel tech’s best friend because it tracks vehicle history, handily keeping all the information in one convenient place. Plus, you can use Fullbay to schedule repairs and maintenance, order parts, and review stock on hand, too. You can even use truck history reports to compare vehicle performance under different maintenance conditions, like when choosing preload vs endplay. Fill in the form below to give Fullbay a try and learn all the different ways it helps manage repairs and maintenance.