Help Me Set Up my Brakes

[Blue85]

In general, when the light is on it means you have a leak either the front or rear circuit. If you're sure you don't (including internal to the MC) and the brakes work well, all four corners heat up, etc, then there must be something wrong with the switch or combo valve. Here's a few test ideas:

-Unplug the connector on the switch to make sure it kills the light.
-Take the switch off and see if it moves freely and makes/breaks the ground connection.
-Pull the whole combo valve out of the end and stick something in there to see if you can slide the center piston around. (maybe it's stuck?). Maybe with the switch out you can also get a pick in that bore and see of the piston moves.

This all looks like a lot of brake bleeding, though. Maybe it's quicker to swap in a known good combo valve? I've also heard of people eliminating that valve by just running a tee to the front and a direct connection to the rear. I can't tell you whether this is a good idea or not.

I don't think a good combo valve would be much of a problem with your setup. It's not much different than a stock setup. I don't think the combo valve even had different variations for the different brake options. They just used different master cylinders.

 

[Chevy305]

Bringing this thread back up as I may have found my problem. I removed the lines from the master cylinder and then hit the brake pedal. I got a steady stream of fluid out of the rear port but only dribbles out of front port. I guess this means I have a bad master cylinder?

 

[Blue85]

I missed where you said what master cylinder you are running. The newer ones supply the rear brakes from the front port, while the older ones (70's?) feed the rear brakes from the back port. The master is pretty simple - some pistons and springs and seals. If it gets stroked all the way, both ports should squirt, even with no pressure. Have you swapped parts (master, booster, pedal, rod, etc.) such that the MC might not get stroked all the way? If not, it's probably time for a new MC. Not getting flow from one port could be a torn seal and would certainly explain the brake light being on.

 

[Chevy305]

I have no idea what year my mc is from. It has a plastic reservoir if that helps. You can see it in this picture:

 

[dremu]

I know those valve covers!

Anyway, that's a typical 80's master ... see the "Illustrated Hydroboost" thread @ http://coloradok5.com/forums/showthread.php?t=306221 for more pix.

Also, I *thought* that one circuit, front or back, uses more fluid but at a lower pressure, than the other, so you could see more fluid from one side than the other in your test. If it's just dribbling, though, it does sound like a bad master.

-- A

 

[Chevy305]

I know those valve covers!

Anyway, that's a typical 80's master ... see the "Illustrated Hydroboost" thread @ http://coloradok5.com/forums/showthread.php?t=306221 for more pix.

Also, I *thought* that one circuit, front or back, uses more fluid but at a lower pressure, than the other, so you could see more fluid from one side than the other in your test. If it's just dribbling, though, it does sound like a bad master.

-- A

The front port just dribbled until the end of the pedal stroke where it made a half ass stream just before the pedal bottomed out.