Musts And Nevers
Must: Clean your hands before installing or even handling the clutch disc to prevent contamination of the fiber surface. After you clean your hands, clean the surfaces before installing the clutch disc. The same holds true for the pressure plate and its mating surface. It's made of metal so dirt and grease won't absorb like the clutch, but any contaminants on the surface will get pushed into the clutch material. Use a good solvent and dry all parts.

Must: Make sure the style matches when replacing throwout bearings. Mate Borg and Beck pieces with Borg and Beck, long style with long style, and so on. Double check when you buy it and keep all the parts together. You could mix them up with the clutch from your tow vehicle or another project.

Must: Always check your pilot bearing for play and/or excessive wear. The one-piece, non-roller units are hard to check for wear. For as little as they cost, buy them by the handful and you'll always be sure by changing them out. Also, is it time for you to upgrade to a roller pilot bearing?

Must: When installing a new disc and pressure plate, use a new flywheel or at least have the old one resurfaced. New metal making contact with seasoned or used metal is asking for trouble. Also, always use a new disc with a new pressure plate.

Must: Always use the correct hardware-flywheel bolts for standard and automatic transmissions are different. Flywheel bolts are usually longer as flywheels are thicker than flexplates. But if the bolts are too long, they'll hit the block and stop rotation.

Must: Use only flat washers with cap screws on aluminum flywheels. Lock, star, or any other washer types can gall and scrape the aluminum.

Must: Use the threadlockers. You don't want any of them coming loose. Make sure you've got the right strength threadlocker. Some require heat to remove.

Must: Always torque correctly
51/416-18x1-inch bolts to 25-30 ft-lb;
31/48-16x1-inch bolts to 30-40 ft-lb;
71/416-20x1-inch bolts to 70-80 ft-lb;
11/42-20x1-inch bolts to 100-110 ft-lb.
Make sure your torque wrench is accurate.Must: Check your motor and transmission for oil leaks. They can contaminate the clutch material and severely affect the performance and life of the system. The same holds for a hydraulic clutch.

Never: Weld on the clutch lever to balance a pressure plate to a flywheel. It can weaken the molecular structure of the metal and ultimately break. Instead, remove metal from the flywheel where necessary.

Never: Use the transmission and its input shaft to line up the clutch disc. The weight of the transmission can bend the metal center disc, affecting the balance of the clutch.

Never: Allow the clutch to wear below a compressed thickness of 0.280 inch. You're asking for trouble, and slipping is the least of it.

Tow Vehicles
Did you know that car and truck clutches are different? Truck clutches have 10-12 percent more grip. Aftermarket truck clutches usually have a higher clamp load than OEM units. They use a better coefficient of friction material or a more aggressive friction material. Truck units are heavier and larger than car versions. The shudder frequency, or that jerking until the clutch is completely engaged, is reduced by the small springs on the clutch disc. The higher number of springs means a tougher clutch. Most truck kits include a spline tool and throwout bearing. Some offer a pressure ring for heavy-duty towing.

Hays Clutches, a Division of Mr. Gasket