I need help I’ve got a c3
and I have replaces all brake calipers
All brake hoses
new master cylinder bench bleed
new brake booster
mans iv got vac because I unplugged from booster and put my finger on tube and it’s SUCKING
but I’ve gravity bleed manually bleed
and my brakes are so strong it feels like if I hit them it will throw me threw the window WHEN OFF
soon as I crank it goes almost to the floor barely can fit your foot underneath it what am I missing here I’ve been doing this everyday for 3 WEEKs
It should not be this hard to get brakes when I’ve replaced everything

 

Yes, yes it is this hard. I've been on this forum for over 15 years now. At least once a month someone just like you comes on complaining they can not get there brakes bleed.
If you do a search you will find countless threads on the topic.
Get a pressure brake bleeder. Modify the top plate so it fits your mastercylinder and pressure bleed your brakes.
Done.
Do NOT try to vacuum bleed your brakes if you have lip seal Calipers.

 

I have had great success with gravity bleeding brakes. After you gravity bled, and ran the engine, and pushed the pedal to the floor, did you note the fluid level in the master cylinder? Did it go down? And did you at the brakes, the wheels, to see if you were leaking fluid? Do not get in a hurry with the bleeding. Hang out.

 

after bleeding I checked it each time and topped it off and never let it run out I’m going to try the pressure plate and if that do t work idk

 

Not so sure you still have air in the system because you have no mention of a "spongy" pedal. That is a dead giveaway.
Sound like yours are rock solid, until . . . . .

Only thing that comes to mind is the new booster rod length. When I read about someone installing all new booster and / or MC, I question whether the correct model year MC was purchased or is it just a "Fits all C3s".
GM changed design of the back of the MC. This can cause issues where the booster rod connects.
Some model yrs have adjustable booster rods.
Some model yrs have two choices for the clevis / brake pedal.
And some have no adjustments whatsoever.

I question if your new booster rod is on the short side. Hence the (firm) pedal to the floor but too low.
The distance between the back of the MC and the booster rod itself , known as a "gap: should be 0.060 (or about 1/16")

To check your gap, you can remove the two MC mounting nuts. Leave brake lines attached. Pull MC away from booster. Put a gob of Silly Putty on the end of the rod. Install MC, just snug the nuts down and remove MC again. See if you can remove the putty and try to get a thickness measurement.

There is a specialty tool that sets that gap perfectly. But it requires complete removal of the MC and bleeding all 6 bleeders again.

 

no the rod can not be adjusted the master has a cone like end and it is rock hard when car off
it goes spongy or to the floor soon as you crank the car

 

Well its not that hard once you find the area where air is trapped.

#1 insure the booster > MC push rod does has the proper clearance or. This I test using the following procedure. Connect a bleeder tube to the front left caliper, open the caliper bleeder and check how much pedal travel is required to start fluid movement.
this I insure its happens ASAP.

Next place that is the most important
#2 NO AIR IN THE MC. To reduce time of this next step m Bench bleed the MC. NOW THIS IS NOT THE FINAL STEP FOR THE MC.
Once installed in the car and the system is full with fluid do this.
Get the last bit of air out from the brake master cylinder. - CorvetteForum - Chevrolet Corvette Forum Discussion

#3 Then pressure bleed the calipers. I found while gravity bleed can work for some, I dont have the patience to wait to see if this works.

I use my car for track days and check the brakes / bleed before every track day.

Before bleeding the caliper I clamp the brake pads into the caliper to force the caliper pistons into the caliper. This forces any air in the caliper piston into the brake line path.

I use this to pressure bleed. Set to ~ 20-30 PSI. I connect a 10ft clear tube to the caliper to see air bubbles in the tubing. Bleed about 20ft of fluid before checking the MC and refill before it empties.
If you let the MC empty you need to go back to step 2.


Last step before you remove pressure from the MC, is to remove the clamps on the brake pads / caliper piston, to force fluid into the pistons. Once the pads are force on to the rotor, remove the pressure at the MC.

Once you have bleed all the caliper bleeders ( 2 on each calipers ) you should have great brakes.