Brake bleeding (again!)
Le Mans Master
Joined: Oct 2004
Posts: 5,269
Likes: 54
From: Orlando Florida
St. Jude Donor '05
Originally Posted by bobs77vet
great job!!! i love it thks...
Next time that i bleed brakes I'll add a pressure gage... my curiosity....
Thread Starter
Drifting
Joined: Feb 2002
Posts: 1,906
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From: Berlin
Sorry to dredge this up again, but my brakes still don't work! I tried a pressure bleeder today. The pedal feels minimally better now, but is still terrible. If it means anything, I couldn't maintain more than 6 psi or so of pressure at the MC. Even getting the adapter to seal that well required spilling almost half a liter of fluid.
I actually tried bleeding twice today. I went through a total of 3 liters of fluid. I'm not getting any air anymore, so I don't know what the problem is. I know on my other car, there is a warning that the seals in the MC can be damaged by pushing the pedal to the floor (eg when bleeding). Is this true for vettes? I've bottomed out the pedal a bunch of times when taking test drives.
Also, how would I know if one of the new calipers I put on isn't sealing properly?
I actually tried bleeding twice today. I went through a total of 3 liters of fluid. I'm not getting any air anymore, so I don't know what the problem is. I know on my other car, there is a warning that the seals in the MC can be damaged by pushing the pedal to the floor (eg when bleeding). Is this true for vettes? I've bottomed out the pedal a bunch of times when taking test drives.
Also, how would I know if one of the new calipers I put on isn't sealing properly?
Le Mans Master
Joined: Mar 2004
Posts: 7,465
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From: Little Rock AR
I bought one of those pressure bleeders and it required an extra piece of wood on top of the adapter with a big C-clamp on top to seal properly. The best way to do it is to first pump it up with air to see if the pressure holds. If it does, then drop the pressure in the resevoir and then add the fluid. This way you know you have a good seal before you add fluid. This prevents a lot of messy leaks.
Another problem I had was wet brake pads. They did not work well when wet. I replaced them and all is well now.
As for leaks, you know they are leaking if you have a puddle of fluid under the caliper. If you see fluid, wipe the caliper off directly above the puddle, then pump the brakes hard a few times. If the caliper is wet again in the same place, you have a leak. Be sure to use 2 copper washers at the hose connection. They can leak there too. I had fluid bubbles from the dust boots on one of my calipers. Had to go through a few before I got a good one.
If you have power brakes, you should pull the hose and check valve out of the booster before you begin bleeding. This is to insure the master cylinder is fully zeroed out.
Hope this helps.
-Mark.
Another problem I had was wet brake pads. They did not work well when wet. I replaced them and all is well now.
As for leaks, you know they are leaking if you have a puddle of fluid under the caliper. If you see fluid, wipe the caliper off directly above the puddle, then pump the brakes hard a few times. If the caliper is wet again in the same place, you have a leak. Be sure to use 2 copper washers at the hose connection. They can leak there too. I had fluid bubbles from the dust boots on one of my calipers. Had to go through a few before I got a good one.
If you have power brakes, you should pull the hose and check valve out of the booster before you begin bleeding. This is to insure the master cylinder is fully zeroed out.
Hope this helps.
-Mark.
Race Director
Joined: Sep 2004
Posts: 11,874
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From: Arlington Va Current ride 04 vert, previous vettes: 69 vert, 77 resto mod
Originally Posted by aharte
. The pedal feels minimally better now, but is still terrible.
2. when you bleed the rear brakes are you putting the back end of the car up high?
3.did you open all of the rear bleeders?
Safety Car
Joined: Oct 2004
Posts: 4,512
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From: Self-Governing
Also make sure that you keep the master cylinder full with fluid during bleeding. The last thing you want is for the MC to pull in air. 
It will prolong the bleeding process 10 fold. If at any point the MC was empty when you checked it, you will need to begin the entire process again. I did this to my daily driver and it took hours to repair even with someone pumping the breaks for me.
If you use an assistant make sure he or she can take direction well, you need to coordinate every step together to make this work.
I have always found to bleed the calipers furthest away from the MC first then work back toward the MC. rear pass, rear driver, front pass, front driver, etc.
Jack up only the corner you are bleeding leave the remaining on the ground. Small bubbles can get trapped in tubing and allow clear looking fluid to pass.
Those check valves sound like a great idea, I think I will get some for my next caliper replacement.
It will prolong the bleeding process 10 fold. If at any point the MC was empty when you checked it, you will need to begin the entire process again. I did this to my daily driver and it took hours to repair even with someone pumping the breaks for me.
If you use an assistant make sure he or she can take direction well, you need to coordinate every step together to make this work.
I have always found to bleed the calipers furthest away from the MC first then work back toward the MC. rear pass, rear driver, front pass, front driver, etc.
Jack up only the corner you are bleeding leave the remaining on the ground. Small bubbles can get trapped in tubing and allow clear looking fluid to pass.
Those check valves sound like a great idea, I think I will get some for my next caliper replacement.
Race Director
Joined: Sep 2002
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From: San Diego - Deep Within The State of CONFUSION!
Originally Posted by aharte
For these pressurized brake bleeding tools, does it matter whether it's adding positive pressure to MC or negative pressure at the bleeder? I found something that does the latter at the local parts store.
Hook up the air hose, turn the suction on, hook up to a bleeder and then open the bleeder .... very simple, no mess.
Race Director
Joined: Sep 2004
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From: Arlington Va Current ride 04 vert, previous vettes: 69 vert, 77 resto mod
Originally Posted by SanDiegoPaul
Mine is a vacuum bleeder. An air hose supplies the power ... venturi effect siphons the fluid out of whatever you put the tube into. Great for draining power steering pumps, etc. Second set of hoses are for brake bleeders and they have different tips for different bleeders.
Hook up the air hose, turn the suction on, hook up to a bleeder and then open the bleeder .... very simple, no mess.
Hook up the air hose, turn the suction on, hook up to a bleeder and then open the bleeder .... very simple, no mess.
these some times don't work on the vette calipers especially if the calipers have lip seals because they pull air in from around the lips of the piston seal, instead of pulling the brake fluid down from the MC. I have used my mity vac to bleed every brake system on all the cars that i have restored and it worked fine until the vette.....
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Thread Starter
Drifting
Joined: Feb 2002
Posts: 1,906
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From: Berlin
If you have power brakes, you should pull the hose and check valve out of the booster before you begin bleeding. This is to insure the master cylinder is fully zeroed out.
1.ok lets look at the rubber brake lines.... when you press onthe brakes have someone see if they are bulging...
2. when you bleed the rear brakes are you putting the back end of the car up high?
3.did you open all of the rear bleeders?
2. when you bleed the rear brakes are you putting the back end of the car up high?
3.did you open all of the rear bleeders?
How high is high? I jack up one side at a time, and have it so that the tire is maybe 2-3 inches off the ground before I take the wheel off.
I did open all of the rear bleeders sequentially. Are you saying to open both at once on a given caliper?
Another thing is that the pedal is fairly solid with the car off. Once the booster gets vacuum, though, there's nothing there. I know all cars have a lot more play with the power assist on, but it seems like the difference is a little excessive.
Race Director
Joined: Sep 2004
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From: Arlington Va Current ride 04 vert, previous vettes: 69 vert, 77 resto mod
Originally Posted by aharte
How high is high? I jack up one side at a time, and have it so that the tire is maybe 2-3 inches off the ground before I take the wheel off.
Thread Starter
Drifting
Joined: Feb 2002
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From: Berlin
Originally Posted by bobs77vet
thats not enough!!!! get the entire rear of the car up as high as you can get it....... look at the caliper, the idea is that the top of the circle that the piston is in has to be lower then the bleeder valve or the air will simply stay at the top of the piston bore....i do my car at the max height of my floor jack. this will fix your problem....or your money back
Race Director
Joined: Sep 2004
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From: Arlington Va Current ride 04 vert, previous vettes: 69 vert, 77 resto mod
Originally Posted by aharte
I'm not understanding what you mean. I assume that you're talking about the pistons in the caliper. If so, the bleeder is always higher, and jacking up the car doesn't change that.
edit: in fact some guys even tap on the top of the calipers to help the air bubbles get released...
Last edited by bobs77vet; Nov 7, 2004 at 11:56 PM.
Thread Starter
Drifting
Joined: Feb 2002
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From: Berlin
I just looked at a picture, and the bleeder actually looks slightly higher than the piston bore, but maybe that's just the perspective playing tricks on me.
Even if you raise the rear, though, the caliper has a fixed shape. If anything, the bleeder gets lower relative to the piston as the rear of car is angled higher.
I did tap on the calipers while the fluid was draining out.
Even if you raise the rear, though, the caliper has a fixed shape. If anything, the bleeder gets lower relative to the piston as the rear of car is angled higher.
I did tap on the calipers while the fluid was draining out.
Burning Brakes
Joined: Aug 2004
Posts: 914
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From: Longview Texas
well, i'm curious on this one ....... just replaced front calipers and m/c and went through h*ll geting any pedal .. used a vacuum pump and it worked ok, but won't use it again ..... just open the bleed screws and grab some beers and watch/ fill/ watch/ fill etc 
...... probably will do this next weekend due to the fact the brake light went on today (fluid is fine so I figure it is just some air from the caliper(s) working it's way up the line and has found the proportioning valve)
Race Director
Joined: Sep 2004
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From: Arlington Va Current ride 04 vert, previous vettes: 69 vert, 77 resto mod
Originally Posted by aharte
I just looked at a picture, and the bleeder actually looks slightly higher than the piston bore, but maybe that's just the perspective playing tricks on me.
Even if you raise the rear, though, the caliper has a fixed shape. If anything, the bleeder gets lower relative to the piston as the rear of car is angled higher.
I did tap on the calipers while the fluid was draining out.
Even if you raise the rear, though, the caliper has a fixed shape. If anything, the bleeder gets lower relative to the piston as the rear of car is angled higher.
I did tap on the calipers while the fluid was draining out.
no....is this a picture of it when its on the car? when its mounted on the car the very top of the piston bore is just above the bleeder valve, raising the rear of the car elevates the bleeder valve above this spot... this works, try it....
Last edited by bobs77vet; Nov 8, 2004 at 07:40 AM.
Le Mans Master
Joined: Jan 2001
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Pressure bleeder w/ solid aluminum plate
I have used both a specific master cylinder cap modified to accept the pressure bleeder and a solid aluminum plate. The solid aluming plate clamped on with a c-clamp and homemade rubber seal works better than the specific m.c. cap.
I added a pressure gauge to the garden sprayer tygon and usually pressurize it to ~15 psig.
Once you have the system pressurized, bleed away at all 4 corners, you can even pump the brakes if desired....the master cylinder refills on it's own from the pressurized garden sprayer canister. Works like a dream.
I added a pressure gauge to the garden sprayer tygon and usually pressurize it to ~15 psig.
Once you have the system pressurized, bleed away at all 4 corners, you can even pump the brakes if desired....the master cylinder refills on it's own from the pressurized garden sprayer canister. Works like a dream.
