Non-Conforming Drivers

According to Appendix II, section 4c of the Rules of Golf, "The design, material and/or construction of, or any treatment to, the clubhead (which includes the club face) must not: (i) have the effect of a spring which exceeds the limit set forth in the Pendulum Test Protocol on file with the USGA, or (ii) incorporate features or technology, including, but not limited to separate springs or spring features, that have the intent of, or the effect of, unduly influencing the clubhead's spring effect, or (iii) unduly influence the movement of the ball."

This is the part of the rulebook that caused so much controversy when new rules were being developed and applied in the mid-2000s: the spring-like effect. High-COR drivers, low-COR drivers, legal drivers, illegal drivers. And COR ... what exactly is "coefficient of restitution" anyway?

What you need to know is that just as there are non-conforming golf balls, there are non-conforming drivers. And the USGA and R&A maintain lists of non-conforming drivers.

If your driver is on that list, it means that the driver exceeds the limit of COR put in place by golf's governing bodies. According to the USGA and R&A, the COR of a driver may not exceed a measurement of .830 (above that, they say, and the driver begins to act as a spring) in any competitions played under the Rules of Golf, including handicap rounds.

Ready to view the lists of non-conforming drivers? These links take you to the lists on the USGA and R&A websites, respectively:

USGA List of Non-Conforming Drivers
R&A List of Non-Conforming Drivers

Both governing bodies also publish lists of drivers that do conform to the rules on springlike effect.

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