by Teeter Allen Morrison
The clutch disc has splines in the center bore that mesh over the splines on the transmission input shaft. That rigidly connects the disc to the wheels through the transmission. The disc is firmly pinched between the flywheel and the spring loaded pressure plate when engaged. When the clutch pedal is depressed, the clutch disc is released so that the engine can rotate while the wheels are stopped. High-performance vehicles use a larger diameter clutch to help prevent slippage when a lot of horsepower is transferred to the wheels. There are several ways to measure the outside diameter (OD) of a disk.
Place the clutch disc on a flat, level surface. Place two small carpenter squares, one on each side of the disk, 180 degrees apart. The squares should be placed against the disk like the ends of a book turned upside down. Measure the distance between the squares.
Place the clutch disc on a level surface with the straight edge of a dipstick on the centerline of the clutch disc and align both outer edges of the disc with the inch marks on the dipstick to obtain an accurate measurement.
Raise the rear wheels of the vehicle with the clutch to be measured off the ground and locate two jack stands, one under each axle tube near the wheels.
Remove the inspection cover from the hood with a socket wrench. Glue and glue one end of a flexible construction tape to the pressure plate cover disk. Use a small strip of cellophane tape to hold it in place.
Weave the flexible tape into the mounting brackets on the pressure plate. Make sure the tape measure obtains an unobstructed circumference measurement of the round cover disc on the pressure plate. The outer diameter of the cover disc is the same as the outer diameter of the clutch disc.
Calculate the diameter of the clutch using the circumference measurements acquired with the flexible tape. To extract the diameter from the measure of the circumference, divide the circumference by pi (3.14). For example: let’s say the circumference is 34.5 inches; 34.5 divided by 3.14 equals 10.987. This would equate to an 11-inch clutch disc.
Articles will need
- Safety glasses
- Measuring tape
- 2 carpenter’s squares
- Tailor’s Tape Measure
- Yard stick