 Borg & Beck |
One of the toughest factors in clutch selection is the flywheel – should it be steel or aluminum? Generally, when you run the engine rpm at 6,500 and higher, you’ll need an aluminum flywheel. The advantage of aluminum is less reciprocating weight and less spinning mass equals a higher recovery rate. A Chevy cast flywheel weighs approximately 25 pounds. A steel aftermarket, SFI-approved race version weighs between 25 - 40 pounds. An aluminum aftermarket flywheel is in the 11-15 pound range.
 Long |
OEM clutches on stock cast-iron flywheels can generate small heat cracks on the surface. This is perfectly normal unless they extend down to the center of the recess towards the bolt holes. If that’s the case, you’ll need to replace the flywheel.
Some OEM models come with a counterweight on the flywheel to compensate for the lack of counterweight in the crankshaft. Known as Detroit balance, those ‘wheels usually have a different listing in the catalogs. Make sure you know yours when clutch shopping.
 Diaphram |
There are three basic styles of clutches: Borg & Beck, Long, and Diaphragm. With all three, it is important that the related items such as the clutch disc, throw-out bearing, and the pilot tool match in style. Double check all your parts when you buy them and keep all the parts together when you store them to avoid mix-ups.
Always change the throw-out bearing when changing a clutch or pressure plate. An amazing 85 percent of all clutch wear is caused by bad a throw-out bearing. The throw-out bearing requires an air gap. The wrong gap will wear out the bearing faster, hang up and possibly wear out other parts. The recommended gap is usually between 3/16 and ¼ inch, but will depend on the style of clutch. Clearance is more critical on the longer styles.
