The clutch head screw - also called a butterfly drive or figure-8 drive - has a distinctive bowtie-shaped recess. It is one of the rarest fastener types you will encounter, but it still shows up in specific contexts.
One-Way vs Two-Way Clutch
Clutch head screws come in two variants. The Type A (two-way) has a symmetrical bowtie shape that allows both tightening and removal with the correct driver. The Type G (one-way) has a sloped recess that only engages in the tightening direction - a flat head screwdriver can drive it in, but the sloped cam prevents reverse rotation. One-way clutch screws are a security fastener: once installed, they require a special extraction tool or a screw extractor to remove.
Where You'll Find Them
- Older General Motors vehicles (1940s–1980s) - interior trim, emblems, and body panels
- Manufactured homes and mobile homes - door hardware and interior fixtures
- Some vintage appliances and commercial equipment
- One-way variants on public restroom fixtures and anti-theft applications
How to Remove Clutch Head Screws
For Type A (two-way) clutch screws, you need a clutch head bit - available in security bit sets or individually. For Type G (one-way) screws, your options are a dedicated one-way screw extractor, cutting a slot with a rotary tool and using a flat head screwdriver, or using a screw extractor (easy-out) bit drilled into the screw head.
