Brake light switch

[OldFoggey]

A few weeks back I replaced the brake light switch on the master cylinder because the brake lights wouldn't come on. One of the part numbers I found as a replacement was something like 201-1087. That worked but I still had to apply the brakes fairly hard to get enough pressure to have the switch make contact. Looking at different forums I found by Googling brake light switch I found that everything from Volkswagen to Porsche have used hydraulic actuated switched at one time or another. I checked the threads on the old switch I removed and found them to be 1/8" threads. Looking at pictures of different switches with those threads I saw a switch that appeared to have a smaller diameter hole than the original. Advance Auto sells the part number but doesn't stock it so I ordered one from eBay. The part number is SLS-33 and fits a 1976 Porsche 911 plus several others. Comparing the original switch to the new one the hole where the fluid enters to actuate the switch is about 1/2 the diameter. Evidently my theory of pushing the brake pedal displaces a set amount of fluid depending on how far it's pushed but that the fluid being forced into a smaller area increases the pressure because now my lights come on with much less pedal pressure. The switch was about $7.95 plus $1.95 shipping. I'm really happy with the faster response of the brake lights and will be ordering another switch to have on hand.

Don

[lovehamr]

Good info O/F.

[Rick Parker]

Several available at NAPA......Local