1963 Corvette: Service Bulletin: 3 and 4-Speed Transmission Clutch Gear Bearing Retainer Failure
Subject: 3 and 4-Speed Transmission Clutch Gear Bearing Retainer Failure
Model and Year: 1963 Corvette, Chevy II, and 1000 Series (except with 409" engine)
Source: Chevrolet Technical Service Bulletin
Bulletin No: DR #605
Date: June 26, 1963
TO: ALL CHEVROLET DEALERS
The 3 and 4-speed transmissions used in all 1963 Chevy II, Corvette and 1000 Series (except with 409" engine) incorporate an aluminum clutch gear bearing retainer. This retainer, under severe operating conditions may "gall" thereby preventing the clutch release bearing from sliding freely, resulting in high pedal effort and subsequent failure of the clutch disc and release bearing due to lack of operating clearance.
Transmissions date coded S0508 (Saginaw), M0515 (Muncie), and M0515 (Warner) and later incorporate a cast iron retainer.
The aluminum retainer used in early transmissions which shows signs of being worn or galled as indicated by high or erratic pedal effort should be replaced with cast iron retainer, Par No. 604932.