73 L48 Power Brake problem
 

Hi Guys,

This is my first post here. I have a 73 L48 with power brakes. since I have had the car it has had good brakes. Pedal was high and brakes grebbed real well. My father also has a 73 L48 which doesn't have power assist and has always (as long as I can remember) had bad brakies. Low pedal and strong legs required to stop the car safely.

Anyway, I was driving my car the other day and I'm not sure when it happened but all of a sudden the pedal was very low and brakes were not as strong. If I push the pedal down hard I get stopping power but the pedal goes to the floor and the brake light comes on. I babied it home and figured that the master cylinder was bad and that I only had rear brakes working. Today I changed the Master cylinder. Made sure everything was bled out correctly and I still have the same problem. I don't see any leaks and I am not losing fluid at the master cylinder anyway so I don't think it's a leak. What else could it be? If I'm not losing fluid I doubt it's a caliper.

Anyone have any experience with this?

I'd like to know as there are three 73 L48's in my family. My brother is restoring a basket case as we speak as well as the two mentioned above! Brakes will be an issue I'm sure!

Thanks

Greg

RE: 73 L48 Power Brake problem
 

hi Greg

I have a 77 vette also with power brakes and I had the same problem when I changed the master cylinder, it didn't corect the problem either untill I spoke to a buddy of mine who owns a garage and he told me that the master has a switch that switches the fluid to either the front brakes or the back brakes in case of a broken brake line , the way to reset this switch is to pump the brakes until the pedal comes up then grab the steering wheel and push the pedal as hard as possiable this should reset the switch and your problem should be solved .

hope this helps

bruce

RE: 73 L48 Power Brake problem
 

Sounds like your proportioning valve has moved to one side. It's a safety divice. You need to locote it in the brake lines and then get someone to push down on the brakes and open one brake line and see if you have fluid pressure of you do then open the other line and you will hear a deffinate click when the valve moves back to center. you may have to buy a new one. They are cheap and come located in the center.