We learned this proper harness wrap procedure after failing a tech inspection before a0 hill climb race several years ago. The tech inspector was kind enough to give us a paper copy of how to properly wrap the shoulder harness around the roll bar. This is not a difficult process to perform but we never realized we had wrapped our harness improperly. 

This is a copy of a Schroth illustration found in their instruction manual. Note that the belt initially enters the three bar buckle from the far right, is threaded under the far right bar then over the middle one and then under the far left bar. The harness then loops under the horizontal roll bar over the top and back under the far left bar on the buckle, over the center and under the far right. At this point the harness is then looped back over the buckle to under the far left bar and leaves a minimum of 4 inches of belt after exiting the buckle.

As you can see, the process involves running the harness from the seat through what is called a three bar buckle, then around the horizontal roll bar tubing and then back through the buckle before returning back over the buckle for a third time. This prevents the harness from loosening once it is properly adjusted. This is a critical step and will contribute to retaining the driver firmly in the seat in the event of an accident.

In a related point about the actual lap belt, among attachment options is this hoop style harness connection rather than bolting the triangle shaped metal ring flat on the floor. This arrangement aligns the belt to the driver position and note that the ring is oriented in the direction of the stress to prevent the ring from rotating under load.

This process may seem cumbersome at first, but if you study the procedure, it’s fairly simple. This does require a three bar buckle that is properly offset to accommodate the thickness of the multiple wraps. It is attention to detail like this that could make a big difference in driver safety should an accident occur.