With all the news lately about non-conforming drivers, it is a good time to discuss the USGA Rule governing the face of club heads.

The Rules Of Golf Copyright© 2005
The United States Golf Association

Appendix II,
5. Club Face
a. General

The rule reads in part; The material and construction of, or any treatment to, the face or clubhead must not have the effect at impact of a spring (test on file), or impart significantly more or less spin to the ball than a standard steel face, or have any other effect which would unduly influence the movement of the ball.

The USGA'S current method for testing the spring-like effect or C.O.R. is to measure the 'characteristic time' between the club head and the weight on a pendulum that is used to impact the club's face. The 'characteristic time' is the contact time of the collision between the weight and the club's face. A conforming club is limited to 250 microseconds of time (including tolerance allowance), which closely correlates to the .83 coefficient of restitution called for in the Rules.

The USGA states that the pendulum testing apparatus has many advantages for measuring spring-lie effect on driver faces and is portable and accurate. See TechReport Library for the complete USGA procedure for measuring 'characteristic time'.

Do you play with a conforming driver? To find out you can check the conforming and non-conforming list the USGA publishes every Monday.

But we just found out that after having initially ruled Nike, Callaway and Cobra drivers conforming, it was later determined that clubs sold by all three manufacturers were non-conforming.

You will probably never know if your driver is conforming, even if it is your responsibility, unless it is checked with the pendulum testing apparatus. However, the pendulum testing apparatus and software is licensed by the USGA to only club manufacturers. Therefore, it is safe to say you won’t have your driver checked at your local golf course anytime soon, even though the device is portable.