No pedal after master cylinder replacement
 

1974 C3. Master was replaced and system was power bled numerous times. I took it home jacked up the rear. Wire in the 2 holes. Level bubble towards windshield. Now to bleed the 2 bleeders on the master cylinder should the car be up in the air in the rear or level on the ground. Still no pedal. Thanks. Tom

FWIW: Master cylinder must be bled first before you start on the calipers.
:thumbs:

Yes. I know. I was referring to the 2 bleeders on the master cylinder. I want to bleed them next before I start on the calipers.
Should the car be level or rear end up to finish the master cylinder.

level. did you bench bleed the master before install?

I had it installed at the local corvette club shop. I would think he would know to do that. Of course I told him about raising the rear of the car to get the air out of the master.

To bleed the MC while on the car like this
https://www.corvetteforum.com/forums...-cylinder.html

Now you need to see air bubbles coming from the bleed holes . It may take a good 30 minutes before all the air is out. Press the pedal very slowly and watch for air or fluid coming from the bleed holes.

Also make sure the bleed holes are not plugged in any way. You will know this by a quick push on the pedal it should shoot brake fluid up in a stream. ( Please take care that fluid doesn't splash on your car ).

Once you feel the MC is free from air, then I usually connect a tube from the front driver caliper bleed screw back into the MC. Pump the pedal until you get no air in the line.

Then once you are ready to bleed the calipers you can lower the car. Bleed the longest brake line to the shortest brake line. Make sure you bleed each bleed screw, usually 2 per caliper.

I had the same problem. I changed the calipers, lines and master. Bled the brakes for a month, every way known to man. It turned out the rod that goes into the rear of the master needed adjustment. The plunger in the back of the new master was a little different. I adjusted the rod and I had brakes. Heres what I went thru.



https://www.corvetteforum.com/forums...bleeder-2.html

Thanks guys. I’ll try this weekend. No power booster. No power brakes, steering or air. Basic 74

How did you bring it home with bad brakes? Drive it?
Define No Pedal - goes to the floor and does not stop, or has mush brakes.

Define Power Bled. Was it pressure from the master, or using a mighty vac at the calipers or.......?

Yes. Drove it home with no brakes. Only a mile. They hooked up a pressure bleeder to the master after replacing it and it pushed fluid out the calipers. They did it numerous times. Can’t build pressure by pumping the brakes. Pedal goes to the floor. Only minimum pedal resistance. I bleed the master as described with level Ext. Now I’ll move on to the calipers. Then I’ll check the engagement rod. Hopefully this will work. Tom. Thanks for all the info. Appreciate it.

I would check to see if the master is defective.

You need to make a plug for where the brake lines go into the master.
With those sealed off, you should be able to bleed the master and get a ROCK hard pedal.

Is it possible the shop installed the wrong M/C? There is a difference between power and manual. Jerry

I’ll check. They are “supposed “ to be good but now I’m not sure. My race car engine builder has done tons of vetted and he will come to up to the house if I can’t figure this out. I’ll check the invoice to see the part number. Thanks

A power brake master has a bigger bore, it would give a really stiff pedal.

Did you check the rod. Or you can adjust the clevis at the brake pedal if you can't at the master.

No it wouldn't.

This!

Why not?
It has a bigger bore (1-1/8 vs 1") and moves more fluid per distance of pedal travel.

It wouldn't give a stiff pedal like a bad master. It would stop harder. I have swapped them when I had the problem and honestly didn't know the difference. But that isn't the issue here as the OP has bled the brakes and has no pedal. If the plunger in the master is different than the original he will never get a pedal unless he checks and adjusts the rod in the booster.

Funny you guys mentioned that it might be the wrong master cylinder! I texted the shop and they think they ordered the wrong one. I’ll check it out this week.