Thats about the only way you can bleed most Corvettes. Its the only way I can get all of the air out of my streetrod too.

 

only way to do it...unless your m/c is mounted below the level of the calipers / wheel cyl. Then it's under the vehicle with a vacuum pump
Works but what a PITA !

 

Intriguing, all my years I have never heard of this proceedure. My 34 is real PITA to bleed as it has a master below the floor and four wheel Wilwood cailipers. These calipers each have four bleed screws, two on top and two on bottom. Do I just open the bottom bleeders, or all of them?

Vince

 

I would think just the top ones as the air is going to go to the top.

 

Intriguing, all my years I have never heard of this proceedure. My 34 is real PITA to bleed as it has a master below the floor and four wheel Wilwood cailipers. These calipers each have four bleed screws, two on top and two on bottom. Do I just open the bottom bleeders, or all of them?

Vince

If the master cylinder is below the level of the brake calipers, this procedure will not work. If not you would need to open the top bleeders.

Steve :welcome:

 

If the master cylinder is below the level of the brake calipers, this procedure will not work. If not you would need to open the top bleeders.

Steve :welcome:

Master is below the floor, but is almost at the level of the calipers,so it probably will not work.

ince

 

the only thing better than gravity bleeding is pressure bleeding.

I used a 1/4" plate with a schrader valve ( like a tire valve) in the middle and a Schwinn tire pump, it has a pressure gauge. I pump it up to about 15 psi and bleed away!

Fast too!

Wifey is happy to loose that job!

 

I have found it works best with a dry system.

After doing major work and all the brake lines are dry I just fill up the res., open the bleeders, and go get a snack and a drink. I check the res. every 15min or so to make sure it doesn't go empty. I normally don't do it that way just because of how long it takes (I vacuum bleed normally)

 

Here is a twist on bleeding brakes: vacuum / pressure. I would have trouble alot of times with under the floor M/C cars even with the pressure bleeder and one day after I charged up a new AC system, I thought why not do brakes the same. I put an extra line on my pressure bleeder adapter plate with an inline valve. I purge all of the fluid out of the system. hook a vacuum pump and vacuum jar to the extra line. Evacuate the system down to 20 to 25" vacuum. shut the vacuum valve. The pressure bleeder is hooked to the standard fitting on the adapter plate. I open the pressure bleeder valve slowly and fluid is drawn in to the system, filling the vacuum. I pump the pedal once or twice to seat the pads and I'm done. I don't even open the bleeders. Works great, doesn't waste any fluid if you are doing a brand new system and that pedal is harder than chinese algebra the first time. An added benefit is that you don't take the chance of getting fluid all over a newly painted caliper or suspension part. I have done a few 4 wheel disc cars but no disc/ drum setups yet. I'm not sure that the wheel cylinder seals will seal when I put the vacuum to them. If anyone has any opinion about this, let me know. thanks for reading this,mikey

 

I did brake and front end work in tire stores and dealerships for years, taught Mechanics at the high school level for 13 years and Like 302/Z28 have never heard of "gravity bleeding brakes" or seen it performed.
Admittedly the old tried and true "pump and hold it" method doesn't work well on some systems.
Pressure bleeding will work most of the time and I have had good luck with the hand vacuum pump system although it is a bit slow.
I'm not saying that it won't work in some applications but I can't see it working in the majority of rigs.
If you pressure bleed a system I think 25# is the max pressure for most bleeder tanks. If you used the tire valve on a spare mc cap be carefull that you don't run out of fluid or you would be pushing air back into the system.

 

I was taught gravity bleeding when first starting out about 20yrs ago. Sometimes it's just about the only thing to get things working when you have no pressure bleeder, esp if your pedal pumper is an idiot. Vacuum bleeders never worked well for me.
Gravity bleeding and vacuum bleeding will not work well with residual valves in the system. I've seen it recommended in old shop manuals for disc brakes as early as 1970, or possibly earlier.

 

It also helps to tap on the calipers and wheel cylinders when bleeding
a system for the first time. It releases the tiny air bubbles that stick
to the insides!

 

I've Owned 7 Older Corvettes...

2-13-06

Only Thing I Can Add After Reading All Great Posts:

Older Corvettes Are Famous For Trapping Air At (Between) Dual Master Master Cylinder & Metering Block (Rarely Goes Bad) Causes (Adds To) Problem_

I Ended Up Replace (Metering Block My 1968 Corvette) And Use All Stainless Steel Calipers & Master Cylinders------BUT: Dual Master Cylinder Must Have Dual Bleeders_

I Follow Procedure Bleed Right Rear,Left Rear ,Right Front, Left Front Calipers-- Then Bleed Dual Bleeders Rear 1st, Front 2nd--Making Sure Master Cylinder Fluid Is At Level _

Colder Weather Adds To Above Problems- Corvettes- Calipers Originally Had Plastic Pistons In Them,i.e. Let Air In (Expansion & Contraction) Biggest Reason To Go All Stainless_

Due To and Of EPA Bullsh*t Even Todays Brake Fluids Are Diluted (Made Cheaper) Other Additives,etc.Only Adds To Continuing Problems...

Vincent Auto

 

One time I asked an old-timer I knew to help me bleed the drums in my 67 Tempest.... he agreed and showed up... I already had the car on stands.... I asked him to get in and pump 'em up and he just laughed.... he opened the bleeders, filled the master to the brim and said "lets's go get a beer".... we came back three hours later, he closed the bleeders and turned the adjusters in about 1/8 of a turn each.... best pedal feel I ever had in that thing.....

 

My 1st choice is to gravity bleed the furthest from the master to the closest.
Sometimes on a old system it needs a little push to get it started {blow out the mud daubers & what not}

2 nd choice is my mighty vac I had one bust on me so I use 2 of the containers in line to catch if the 1st fills up before I get back .sucks it pretty quick.

Some will say to do it again in a week or 2 cause air will generate In new parts ?

I never re use the brake fluid I'm saving it for paint removal :evil:

I need to work on my double flair techniques.

Chances are if you can't Gravity bleed a typical set up there is some kind of restriction & a future problem.



R :thumbup:

 

Here is a twist on bleeding brakes: vacuum / pressure. I would have trouble alot of times with under the floor M/C cars even with the pressure bleeder and one day after I charged up a new AC system, I thought why not do brakes the same. I put an extra line on my pressure bleeder adapter plate with an inline valve. I purge all of the fluid out of the system. hook a vacuum pump and vacuum jar to the extra line. Evacuate the system down to 20 to 25" vacuum. shut the vacuum valve. The pressure bleeder is hooked to the standard fitting on the adapter plate. I open the pressure bleeder valve slowly and fluid is drawn in to the system, filling the vacuum. I pump the pedal once or twice to seat the pads and I'm done. I don't even open the bleeders. Works great, doesn't waste any fluid if you are doing a brand new system and that pedal is harder than chinese algebra the first time. An added benefit is that you don't take the chance of getting fluid all over a newly painted caliper or suspension part. I have done a few 4 wheel disc cars but no disc/ drum setups yet. I'm not sure that the wheel cylinder seals will seal when I put the vacuum to them. If anyone has any opinion about this, let me know. thanks for reading this,mikey

That's the way the factory fills the brakes, AC and powersteering systems. Evac and fill.

 

That's the way the factory fills the brakes, AC and powersteering systems. Evac and fill.

Thank you sir :thumbup: welcome to the board!
Have you had experience with doing it this way also?
I never knew that anyone else did it that way.


I wondered if anyone would ever read that post of mine and take it seriously. I had made my own master cylinder adapter plate and fluid seperation chamber that I use with my pressure bleeder and AC vacuum pump.

It works extremely well for me as most of the systems I do are not easy to bleed by conventional methods.
Later, mikey

 

Bleeding brakes

I have used all three methods and usually end up using a combination of vacuum and gravity.
I like the pressure system because you can see any leaks right away, but the pressure plate has to be centered both ways on the master cylinder to work, or you end up with brake fluid all over the place. Some master cylinders don't have the clearance required to get the plate centered.
I am converting to Dot 5 on all my cars because it is not supposed to eat the paint and it does not absorb water (I live in Florida). It also has a high boiling point. Dot 3 will boil if the lines get too hot (close to manifold etc) and the brakes will fail as happened to my wife in our 57 bird just after I installed disk brakes with braided stainless lines. She was not a happy camper!!
When converting to Dot 5, I use a new mater cylinder and drain as much as possible out of the system and then starting from the longest line (usually right rear), I take the bleeder screw out and insert the rubber nozzle that comes with the system and start pumping. You need clear plastic tubing (I get 3/8" from home depot). You can see the residual dot 3 drain out and the new Dot 5 (purple) come in. It take a while to get all the old stuff out so be patient. I then replace the bleeder screw and vacuum a little more, but I always seem to get air from around the screw unless it is the speed bleeder type (the treads are coated).
I then let the system gravity drain for 30 min.
Thanks to hotrodders for all the tips

 

bleeding

After reading all the ways to bleed brakes, my MCyl. is just about 4 inches above the wheel cyl height.. and has residual valves in both lines,, and rear has the prop-valve too.. should I have it wide open, and try gravity first.?

 

Gravity bleeding question

Old post but still relevant. If you introduce a bunch of air into the system by replacing hose/caliper/mc, etc. can you still use the gravity method? Do you fill the lines with the bleeders closed first? Or just open them and start filling the master (and waiting)?

 

Thats about the only way you can bleed most Corvettes. Its the only way I can get all of the air out of my streetrod too.

Hi Henry
Just going through the power brakes on my 67 Mustang after it hit the road yesterday. It has new 4 wheel discs fitted and the problem i am having is with a spongy pedal which it did not have before i pulled the car into a thousand pieces and rebuilt it. I put a seal kit through the tandem master and bled the brakes from rear to front using a power bleeder the first time and my son in the seat the second time using the pump pedal /bleed valve release method. I am at a loss to get rid of this spongy pedal. The car stops okay with single piston calipers, could be better though.
My question is if i
open the bleed valves for an hour and let the fluid trickle out through a clear hose can i expect the air to disappear, if it is air that is my problem.
Cheers Al.

 

It's the only method I have used for years. But you sure don't leave the bleeders open for an hour. I also sometimes lightly pump the pedal with my hand, maybe stroke it about 1/2 inch or so by feel. That usually gets the fluid flowing and you can watch for bubbles and close the bleeder(s) when there are no more bubbles in the stream. It obviously won't work with a master cylinder lower than the wheel cylinders/calipers.

 

It's the only method I have used for years. But you sure don't leave the bleeders open for an hour. I also sometimes lightly pump the pedal with my hand, maybe stroke it about 1/2 inch or so by feel. That usually gets the fluid flowing and you can watch for bubbles and close the bleeder(s) when there are no more bubbles in the stream. It obviously won't work with a master cylinder lower than the wheel cylinders/calipers.

Thanks for that. I will give it a go shortly. I have just been to town to buy more brake fluid and the brake guy said to pin point the problem area, pinch the brake fluid supply at the flex lines at each wheel in turn to cut the supply off to each caliper and see if the pedal rises up. I keep thinking there is something i have overlooked but i have double checked all connections and there is not a leak anywhere. The brake guy also said that new discs and pads will give the effect of a spongy pedal until the mating surfaces are bedded in and to be patient.
So i will have a go at pinching the lines to see if i can locate a problem caliper with trapped air and then as you suggest open the bleed screws and look for air.
Thanks.
Al.

 

Pinching the rubber lines isn't a good idea, you can damage them, especially if you are pumping the brakes with one pinched off. New pads do need burnished in, especially the metallic ones. Do this by making several aggressive stops in short succession.

 

Pinching the rubber lines isn't a good idea, you can damage them, especially if you are pumping the brakes with one pinched off. New pads do need burnished in, especially the metallic ones. Do this by making several aggressive stops in short succession.

Hi willow billy.
Yeah the guy at the brake service shop said to use line clips or flat faced clamps with a protective shield around the flex pipe.
Yeah you ae right about bedding the brakes as i stopped it dead on the road after a 80 mph burst coming home from a wheel alignment. As it is not inspected/registered yet i am not game to go out again as the 347 has some noise with it. I would like to do that three or four times.
I found a tip on here about testing a Master by jamming a piece of wood on the pedal and the other end on the drivers seat and leave it overnight for a leak down check. I have just done this and will wait until the morning and see if i have lost cylinder pressure. After ten minutes it has not moved at all.