[H2rizz]

Does anyone know the reason my brake light [the same one as e brake light] comes on sometimes when brakes are applied fairly hard? They are power brakes and seem to work ok. 69 ss ps,pb,big block stick car.Rick

[cool rocking daddy]

Originally Posted by H2rizz

Does anyone know the reason my brake light [the same one as e brake light] comes on sometimes when brakes are applied fairly hard? They are power brakes and seem to work ok. 69 ss ps,pb,big block stick car.Rick

Low level of brake fluid in master.

[H2rizz]

what if its not? bad switch maybe? Thanks-Rick

[Luwi67]

If the fluid level is good then maybe the brake linings are severely worn causing too much stroke triggering the switch.

Seems as if the switch is doing what is supposed to do

[Garfields Maro]

When one circuit, either the front or the back develops a leak, it won't hold pressure causing the switch to go off center and the light comes on.

[Steptoe]

Combine most of the posta above and u have it
Basdically (little over simplified) the switch is a spring loaded switch that depends on equil pressure either side. Front and back circuits
If the pressure drops between either the front or rear brake circuits the switch piston moves off center and the warning light comes on.

Yes very worn pads/ shoes could do it.. espec if the rears have not been adjusted correctly... ie back of the E brake then adjust , then re set the e brake
The most likely is a leak somewhere....a slave or even internally inside the MC...
What ever, if the light comes on under any sort of braking...and u may not even feel any issue, something is wrong and get it fixed.
You should be able to reproduce the light coming on/ fault stationary, with excessive pedal pressure.
The chances of it being the switch are extremely remote.

[H2rizz]

Thanks . I will let you know what I find.-Rick

[JohnZ]

Air in one half of the system will cause exactly the same symptom (pressure differential, triggering the switch/light). Bleed it.

[yellow69RS]

I had this in mine after I switched to silicone brake fluid. I did everything I could think of... EXCEPT follow the directions on the brake fluid. I talked to another mechanic that had same issue until he flushed the system with alcohol (like the instructions said). I never had an issue with it the three years I drove it and I heard the solution after it was parked 27 years ago.

Jeff

[H2rizz]

The inner piston of the master was disengrated and triggering the light. Replaced it with correct delco mc but would like to rebuild the origional. Does any know who makes a complete rebuild kit?

[Steptoe]

Cool the warning light worked corrctly

would like to rebuild the origional. Does any know who makes a complete rebuild kit?

Inspect the bores very close.. the slightest blemish, scratch, before and after a hone, do not re kit...people die...
The best way if wish to re build is to get it reselieved with stainless....
The days of pulling the seals out run a hone down the bore are well gone, 30+yrs ago..
Reselieving of old orginal salve/ mastercylinders is usually done where new replacement are no longer made... ie Jowett Javlen brakes... Jowett closed their doors in 1954... or orginality of a matching numbers/ date coded car is esentual