I am noticing that the brake pedal on my '79 feels like it sticks a bit after being depressed - almost a spongy feel. Otherwise, braking is good. Any ideas??

Greg

You might have some air in the brake lines, or worse, a master cylinder sticking. I once had a car that the master cylinder formed a ring where the piston traveled and caused the piston to stick. Having your brakes fail and the pedal go down and stay there is not a good feeling! I was very lucky...no traffic and at low speed. I was able to let the car drift into a parking spot and stop as the tires touched the concrete curb.

I hope your problem is not so severe, but reading your problem brought back bad memories.

Potential brake problems are nothing to ignore. Find the problem right away. I hope it's minor.

I had a really fun problem with my first 69 Vette.

I had only had it a week or so and I was on the local bypass going about 85 in a 65 when I stepped on the brakes and the pedal went to the floor.

I pulled the parking brake handle and it did nothing.

It was an automatic so compression braking wasnt an option.. I coasted until i got my speed down to about 30 and took an exit.. unfortunately the exit had a down slope and I quickly got back up to about 50 mph

thankfully the oncoming traffic had a red light and there was no traffic coming. I swerved across three lanes before getting it back under control. I finally coasted back down and found a hill to go up to reach a "stop" and shifted into park.

I looked under the dash and found my pedal pin on the floor. The "C" clip had rusted and broken.. Allowing the pin to slide out of the pedal arm.

The moral of this story is.. Check and/or replace the "C" clip periodically and make sure your parking/emergency brakes work.

How can one tell if it is the Master Cylinder that is the problem?

You really should get your entire brake system checked out, and at least bleed the brakes and see how they work after that. The only real way to check the master cylinder is to remove and inspect it. To go that far you may as well rebuild or replace it, but check everything out first...pads, rotors, hoses and lines, linkages under the dash, etc. As I said prior...your brakes are too important to delay if you even think you have problem.

If you step on the pedal, hold it with steady pressure, and the pedal continues to drop, it's a bad master cylinder or it's leaking fluid. You can also break the line loose at the master after pumping up and holding down on the brake pedal. If you get a lot of fluid, that part of the master is working. Close the line, pump the brakes, and try the other line. If also delivers fluid, and the pedal does not sink under steady pressure, the master is likely okay. Likely, not for sure. If it fails any of these three, it's bad.

Just a point of clarification. The pedal feels firm and does NOT drop under steady pressure. Best way I can describe it is a "sticky" feel. Not spongy or soft.

Thanks