tech-article

1969 GM 3956727 Pressure Differential Switch Autopsy

I recently found this brass pressure differential warning switch on eBay. It was originally used used on a 1969 Chevrolet Corvette; the original part number is 3956727. It's purpose is to detect differences in front-to-rear brake system fluid pressure. When a pressure difference exists, a plunger inside the brass body shifts position and makes contact with a switch, completing a path to ground and illuminating a warning lamp.

1970 GM 1233464 Metering Valve Rebuild

This Bendix metering valve was removed from a 1970 Chevrolet Camaro. According to my parts catalogs the original applications include the following 1970 GM vehicles equipped with front disk and rear drum brakes: all 1970 Chevrolet, all 1970 Buick A-body, and Oldsmobile F85. The original GM part number for this valve is 1233464; it is stamped 2226261. At some point GM replaced the 3905525 valve with this part.

You can click on the pictures below to see larger versions of the images.

1970 GM 1233464 Metering Valve Autopsy

This Bendix metering valve was removed from a 1970 Chevrolet Camaro. According to my parts catalogs the original applications include the following 1970 GM vehicles equipped with front disk and rear drum brakes: all 1970 Chevrolet, all 1970 Buick A-body, and Oldsmobile F85. The original GM part number for this valve is 1233464; it is stamped 2226261. At some point GM replaced the 3905525 valve with this part.

You can click on the pictures below to see larger versions of the images.