CLUTCH PLATE GMC (STANDARD EXCHANGE)

Clutch Plate GMC CCKW (Standard Exchange)

11½" diaphragm-type clutch disc

★ <cite index="28-20,28-21,28-22">A professionally reconditioned clutch plate can last at least 35 years with correct use and adjustment</cite>. This exchange system offers an advantageous solution for restorations where the old plate is used as base material.

⚠ Important

• <cite index="22-1,22-23">Adjust the clutch so that it just disengages at approximately 1" (2.5 cm) above the floor and continue adjusting it this way</cite>
• <cite index="1-4,1-16,1-17">Typical defect with CCKW clutches: the diaphragm spring breaks, creating uneven pressure on the clutch plate and causing the clutch to seize</cite>
• <cite index="1-20,1-21,28-2,28-3">Cause: incorrect clutch pedal adjustment — excessive pressure on the pressure spring can easily damage it and lead to premature failure</cite>
• <cite index="22-31,22-32,22-33,37-12,37-13,37-14">The pressure plate must not simply be machined flat — it must be fitted with shims and machined in specific steps, otherwise you create worthless material</cite>
• <cite index="47-15,47-16">Wear indicator: rivets visible → replace. Cracks in dampers or loose segments cause vibrations and noise</cite>

Application

Suitable for GMC CCKW-352 (short wheelbase, 10'6") and CCKW-353 (long wheelbase, 13'6") 2½-ton 6x6 lorries from the Second World War. Also applicable to GMC CCW-353 (6x4 variant) and DUKW amphibious vehicles with the same clutch.

Installation notes

<cite index="47-10,47-11,47-12">Mount the plate with the raised hub facing the gearbox. Tighten the pressure plate bolts diagonally to prevent warping. Centre the clutch plate with an alignment tool before tightening</cite>. <cite index="47-13">Always check for oil leaks at the crankshaft and input shaft oil seals — oil on the lining reduces friction</cite>.

Compatibility

<cite index="2-33,21-4,32-23">The CCKW flywheel is recessed — only the original 11½" clutch can be used, a larger clutch does not fit</cite>. <cite index="31-8,31-9">A 10¾" Chevrolet clutch is NOT suitable for GMC</cite>. Note: later GMC 302 engines (1950s, M-211) have a different flywheel with 6-bolt attachment instead of the 4-bolt CCKW version.

Historical context

<cite index="5-19,5-20,23-22,23-23">GMC used a diaphragm-type clutch in the CCKW and DUKW, where the dish-shaped diaphragm spring fulfils the function of the 'fingers' in finger-type clutches</cite>. This design was characteristic of most WWII vehicles from General Motors, including the Chevrolet G-506.