Hi Guys , I have a 77 C3 with brakes that will only stop my heart !
I was looking at it when I popped open the cap on the master cylinder I topped it up and when I pushed the brake pedal there was a squirt of fluid from the front half of the bowl and it was landing in the Back half of the bowl.( That looks Weird ) I thought .
I put the cap on again and began the task of bleeding and bleeding and bleeding and the air still came . I started with the farthest away rear right and when the bubbles were nearly gone I went to the rear left then front right then drivers front .
They were still rubbish .
So I pulled out the master cylinder . The seals look New , the bore is 1"1/8 on the side it has 1*5460346 . Were these a good Unit ?
Am I looking at a new Master cylinder Unit ?
Is it the ratio valve ?
Where would I go next . I put a Full gallon of fluid through it so far !
Thanks Guys.
Maurice.

 

Welcome to the forum. I dont know anything about the part number from your old master cylinder but if I were you I would go to the parts store and just get an overhauled one. They are pretty inexpensive. Make sure you do bench bleed the new master cylinder before installing it on your booster. The valve you are talking about is mounted on the frame kind of below the brake booster. You can shine a flashlight down between the brake booster and steering column shaft and see it. There is a sticky post which gives you everything you want to know about bleeding your brakes. When I bought my 77 I rebuilt all the calipers and replaced the master cylinder and bleed them and I have not had any problems with my brakes. When I hit the brakes they will stop you right now.

 

wnmch has good advice but for the word "overhauled' one"

NEVER buy a reman master make sure it's brand new. Bench bleed it. Then read the sticky thread above this that explains the bleeding procedure. Remember the rears have two bleeders on each caliper. HTH

 

Just a reference to the squirt of fluid , is this a sign of something , is the master-cylinder cooked ?

 

I have seen a squirt of fluid from the master cylinder before. Nothing to worry about unless it lands on paint. Your problem is more likely in one or more of the calipers. If you bleed and bleed a caliper and still get bubbles a seal(s) is probably leaking.

You didn't give any information about the condition of your braking system, but if you have stainless-steel lined brake calipers (almost everybody does by now since all rebuilt calipers have SS bores these days) I'd recommend buying an O-ring rebuild kit from Vette Brakes. The original design lip seals are OK if you drive the car every day or race and rebuild your brakes frequently, but when they sit for a while they will start to leak.

Another factor in brake performance is rotor runout. Even if the seals don't leak fluid the pulsing of a rotor with excessive runout (and we're talking about a few thousands of an inch) will allow air to enter the system without any fluid leaks.

IMO the Vette Brakes O-ring system is the biggest improvement you can make to the stock brake system. The seals won't collapse and leak after sitting and they tolerate rotor runout without allowing air into the system. The stock braking system was very advanced for its time and probably performs better than some new systems, but there were a few details that needed improvement for cars that have become classics and are not driven regularly.



Rick B.

 

New ones do that too.
It's just the piston seal going by the small piston bore feed holes that momentarily shoots the fluid up.

A simple test for the master, pump it several times really fast and on the last pump hold it with as much pressure as you can, if it slowly goes down during a minute, it is bad.

If it kept it's height the first test and if you step on the pedal again in a few minutes and it goes down further on the first pump than in the first test, then you just have air in the system or a leak somewhere else.

 

With the lid on.

 

Well guys, Thanks for all your help ! I pulled out the master cylinder again and did the bench bleed ( Great Idea, never heard of it before ) It was dripping from the rear of the piston shaft . So I think seals may have been taking in air .I also took off the drivers caliper just to see if it was siezed but it seemed free and It has SS pistons .
The car is only taken out every so often, so I am causing my own problem .
It was after my first trouble I lost confidence in the car .One day last year I was stopping hard and it was pulling hard right , It turned out to be a loose A-Bar bolt which moved back as the car was pushing forward .It was a tricky job trying to put it back but the car was always pulling right since . Its just wecking my head to get it sorted out !
Its a super car so I just want to get it back to a comfortable drive .
I am on the wrong side of the atlantic ( Waterford Ireland) so should I replace the front rear split valve aswell or do they give trouble normally ?
I will try Vette Brakes.
I need to ship everything............Oh what i would give for a Napa or Bennets Over here And a Gas station with American prices !