SUBJECT: Wheel Bolt failures
After the recent situation at Putnam Park, involving two vehicles with sheared lug bolts, the following procedures are strongly recommended:
- Inspect lug bolts on a regular basis for stress related cracks and/or stretching, along with all other axle and suspension related hardware.
- It is recommended to torque wheel bolts to 85 foot pounds.
- Replace lug bolts after every season.
- Lug bolts should be of 10.9 hardness or better.
- When using wheel spacers, make sure that if the spacer used is supported by the lug bolts, the lug bolts are increased in length to accommodate the thickness of the spacer. Also, if the spacer is bolted to the hub first, and the wheel then bolted to the spacer, inspect the spacer and related hardware on a regular basis as well.
- If spacers are being used, another, more acceptable alternative is to use wheel studs and nuts to mount the wheel.
All of the above procedures SHOULD be included in your regular routine of inspection on your vehicle, along with checking the wheel torque BEFORE every session on the track.
National Tech Steward