1968 - 1970 Corvette: Service Bulletin: Depressed Park Windshield Wipers Unable to Park
Subject: Depressed Park Windshield Wipers Unable to Park
Model and Year: 1968 - 1970 Corvette
Source: Chevrolet Dealer Service Technical Service Bulletin
Bulletin No: 70-T-59
Date: May 5, 1971
TO: ALL CHEVROLET DEALERS
A few reports have been received on vehicles, equipped with depressed park windshield wipers, that the wipers do not park when turned off.
This problem usually is a result of heavy snow or ice accumulation on the lower portion of the windshield, resulting in heavy torque imposed upon the wiper arms during the park cycle. When this occurs, the wiper motor drive shaft is forced inward, and in some instances, the retaining ring may be forced out of its groove. With the drive shaft retaining ring out of its groove, the wipers will operate normally, except when turned off, the park cycle will continually be repeated due to the drive shaft being too far inward to allow the drive pawl to activate the relay switch and stop the motor.
Beginning with 1971 production, the wiper motor drive shaft has a wider groove and thicker retaining ring to prevent disengagement.
For service, this 1971 shaft and ring unit (Figure 1), Part Number 4960192, replaces Part Number 4911264, retaining ring, and is used to service past model depressed park wipers when the original narrow retaining ring is found to be out of the groove.
Chevrolet Motor Division
General Motors Corporation