TM 10-3930-653-14&P Unit: mm(in) Checking Item   Standard Value Service Limit Clutch steel disk thickness  (1.58-1.67 155 (0.062-0 066) (0.061) Flatness and parallelism   Below  0.05 Over  0.05 of steel disk (0.002) (0.002) Fig. 4-284. Measuring Clutch Steel Disk Thickness (4)  Check pressure plates for thickness and flatness, and for damage or wear. If unsatisfactory, replace. Note:    When checking for flatness, put pressure plate on a surface table, and measure clearance between pressure plate and surface table. (5)  Check inner and outer diameters of clutch piston, and also its undercut width for seal ring. If damage or wear is found, replace. Unit: mm(in) Checking Item   Standard Value Service Limit 40 2-40 25 -- Clutch piston inner dia. (15831 585 121.75 -121 80 Clutch piston outer dia. (4.793_ 4795) -- Clutch piston undercut 2.51-2.62 2.92 width (0.099-0.103) (0.115) (6)   Check the clutch return spring for deterioration and signs of overheating. If unsatisfactory, replace. Unit: mm(in) Checking Item   Standard Value Service Limit Clutch return spring 54.8  mm Free length (2.16) Setting length 24.8 mm (.98) 65 kg Setting load, kg (lbs) (143.3 lbs.) Fig. 4-285. Checking Clutch Piston Fig. 4-286.  Checking Return Spring 4 - 160