Re: Odd Master Cylinder # on 1949 22nd Series

Posted by HH56 On 2024/6/24 10:13:28

It has been the experience of many on the forum both here and at PAC that silicone fluid seems to hasten the failure of the hydraulic brake switches. Unknown why this happens or exactly what fails inside but while switches used with the older fluid seems to last for years many report them lasting only a year or two with silicone. New ones bought at a local parts store do not seem to be immune.

Usual symptom seems to be brake lights become intermittent or not coming on unless brakes applied quite hard and then progressing to not coming on at all. Many replaced the switches only to have a relatively quick failure and then ultimately decide to leave the switch in as a dummy to close the port but go to a mechanical switch operated by the pedal arm for the actual light operation..