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Hi everyone, I just completed replacement of practically an entire brake system on my 65. Including, master cylinder, brake lines, rotors, calipers, and pads.
After bleeding the system, the pedal feels very spongy and I have to pump it in order to stop the vehicle. There are 2 things that I suspect with bleeding that I may have missed since everything is new.
1) Bench bleeding the master cylinder - which didn't do. Is this a requirement for a single cylinder master? If yes, can I do it without removing it from the firewall, simply disconnecting the line, attaching a clear plastic tube and looping it back in the reservoir using the brake pedal to pump out any air?
2) The calipers. They are Delco re-manufactured. I read somewhere you have to bleed from 2 valves, but I didn't see 2 bleeder valves. Is this true? If yes, did I miss bleeding both sides of the caliper or are the 2 bleeders on the same side of the caliper?
I believe it is two bleeders on most rear calipers, and the fronts have one bleeder per caliper. It is possible I have this reversed, but one set of calipers has two bleeders per caliper and the other set has one bleeder per caliper. I could crawl under my car and check, but I think you already have the answer you seek.
You MUST check rotor run-out on all 4 new rotors. Rotor run-out above about 0.005 inch will cause air pumping in the calipers. Total system run-out including wheel bearing run-out must stay below 0.009 inch. Get a good dial indicator and stand and do this before going much farther. Out of spec rotors can be shimmed using special shims.
You can "bench bleed" master cylinder on the car. I would recommend you do so. For general brake bleeding you bleed at the farthest line first and work to the closest. You can either start by gravity bleeding all calipers or use a Mighty-Vac and pull a vacuum on each caliper to speed up the brake fluid flow and the time to do the job. Then get a helper and begin pumping the brakes and bleeding each caliper again to remove all air bubbles.
Some folks buy and use a Motive Pressure bleeder to make this job a one man operation as well as to provide the best result. But not everyone can afford this.
Larry
Last edited by Powershift; 08-19-2018 at 03:23 PM.
I believe it is two bleeders on most rear calipers, and the fronts have one bleeder per caliper. It is possible I have this reversed, but one set of calipers has two bleeders per caliper and the other set has one bleeder per caliper. I could crawl under my car and check, but I think you already have the answer you seek.
You MUST check rotor run-out on all 4 new rotors. Rotor run-out above about 0.005 inch will cause air pumping in the calipers. Total system run-out including wheel bearing run-out must stay below 0.009 inch. Get a good dial indicator and stand and do this before going much farther. Out of spec rotors can be shimmed using special shims.
You can "bench bleed" master cylinder on the car. I would recommend you do so. For general brake bleeding you bleed at the farthest line first and work to the closest. You can either start by gravity bleeding all calipers or use a Mighty-Vac and pull a vacuum on each caliper to speed up the brake fluid flow and the time to do the job. Then get a helper and begin pumping the brakes and bleeding each caliper again to remove all air bubbles.
Some folks buy and use a Motive Pressure bleeder to make this job a one man operation as well as to provide the best result. But not everyone can afford this.
Larry
Larry, I may try the gravity bleeding method. I believe it is the rear calipers that have two bleeders, assuming they will both have to be opened at the same time. The master cylinder is easy to remove with just 2 bolts and the brake line.
First time I drove this car in over 25 years. While I was driving it the heater core started leaking anti-freeze all over the passenger floor mat, ugh. Now I need to figure out if I want to tackle that myself.
I just did my 65. i bled the master like you said, then just used a coke bottle half full of brake fluid with a clear vinyl hose and, with someone pumping the brakes, bled every wheel, starting with the RR, then LR, RF, LF. Got great pedal! Only the rear calipers have two bleed screws.
I just did my 65. i bled the master like you said, then just used a coke bottle half full of brake fluid with a clear vinyl hose and, with someone pumping the brakes, bled every wheel, starting with the RR, then LR, RF, LF. Got great pedal! Only the rear calipers have two bleed screws.
Great. Did you perform the rotor run out measurement? Or was nothing replaced?
Just a shot, are you sure you have the calipers in the right spot - Left front, Right front, etc. I have weak eyes, but can't see the bleeder on your right front caliper in the picture. The bleeders should be at the top on all four corners. No gig intended, just asking.
I guess I have lived a charmed life with respect to bleeding the master cylinder - never had to do so to get a hard pedal. But from your post I can tell you have not bleed both halves of the rear calipers so that is probably a source of some air in the system. I think I bleed the inside half first and then the outside - but not sure it makes a lot of difference.
The biggest problem I've seen on bleeding brakes on old cars is the loose fit of the bleeder screw in the rebuilt calipers. I've tried vacuum bleeder and pressure bleeders to force fluid back to the master cylinder and both of them have been done in by air leaking around the screw threads. A Motion Bleeder would probably overcome this issue as does usually the old 2-person - press brake down - hold - open bleeder - close bleeder - let up and repeat. I've resorted to using speed bleeders on a couple cars now which have a spring loaded ball valve inside to close them off and prevent the entry of air when pedal pressure is released - makes one-man bleeding pretty simple. As an alternative on a rebuilt brake system, I think I might carefully install some thread sealer on all the bleeder screws so that air entry is cut off.
Couple of years ago I converted my 65 back to power brakes as it was from St. Louis, got changed over to non PB somewhere along its life. New booster, PB MC, same calipers and pads. Filled MC and left lid off, raised car up on the lift, (still had my shop) cracked open all 4 bleeders half turn, set bucket under each and sat down and had a coffee. Waited till all 4 calipers were dripping fluid, 15 minutes or so, climbed up on a ladder to make sure MC was close to full. Watched them drip for a short time. Closed the bleeders RR,LR,RF,LF.
Let car down topped off MC, put cap back on and stepped on brake with engine off, felt firm and high. Started engine and felt the vacuum and booster operating with a nice high firm pedal with the power assist. I guess I got lucky as I didn't have to pump and bleed at all. Just gravity bleed worked. I have been thru brake bleeding jobs before where you throw your hands up and walk away too, so I was really surprised I got it right on the first shot. Easiest brake bleeding I had ever done.
Edit, I forgot to add that I DID bench bleed the MC before installing on car.
Couple of years ago I converted my 65 back to power brakes as it was from St. Louis, got changed over to non PB somewhere along its life. New booster, PB MC, same calipers and pads. Filled MC and left lid off, raised car up on the lift, (still had my shop) cracked open all 4 bleeders half turn, set bucket under each and sat down and had a coffee. Waited till all 4 calipers were dripping fluid, 15 minutes or so, climbed up on a ladder to make sure MC was close to full. Watched them drip for a short time. Closed the bleeders RR,LR,RF,LF.
Let car down topped off MC, put cap back on and stepped on brake with engine off, felt firm and high. Started engine and felt the vacuum and booster operating with a nice high firm pedal with the power assist. I guess I got lucky as I didn't have to pump and bleed at all. Just gravity bleed worked. I have been thru brake bleeding jobs before where you throw your hands up and walk away too, so I was really surprised I got it right on the first shot. Easiest brake bleeding I had ever done.
Edit, I forgot to add that I DID bench bleed the MC before installing on car.
Air traps at the top as it rises. Bleeding the bottom bleeder won't help in my opinion. I think the rear calipers only have two bleeders so you can use them on the Left or Right side. If I am wrong I will take the correction as training.
Air traps at the top as it rises. Bleeding the bottom bleeder won't help in my opinion. I think the rear calipers only have two bleeders so you can use them on the Left or Right side. If I am wrong I will take the correction as training.
If you moved the LR caliper to the RR wouldn't that put the 2 bleeders on the bottom and one on the top? I was wondering about this also
Just a shot, are you sure you have the calipers in the right spot - Left front, Right front, etc. I have weak eyes, but can't see the bleeder on your right front caliper in the picture. The bleeders should be at the top on all four corners. No gig intended, just asking.
For a second there I thought I was losing my mind. But I just got back from the garage and did a sanity check to verify both of the front calipers are on the correct disc and bleeder valves on top. It's just hard to tell from the picture. The rear ones are almost impossible to get wrong since they connect to the bent brake tube. Thanks for suggesting. I did however, neglect to bleed both valves in the back. I don't recall even seeing a second bleeder.
Are there really 2 bleeder valves on the rear calipers?
I guess I have lived a charmed life with respect to bleeding the master cylinder - never had to do so to get a hard pedal. But from your post I can tell you have not bleed both halves of the rear calipers so that is probably a source of some air in the system. I think I bleed the inside half first and then the outside - but not sure it makes a lot of difference.
The biggest problem I've seen on bleeding brakes on old cars is the loose fit of the bleeder screw in the rebuilt calipers. I've tried vacuum bleeder and pressure bleeders to force fluid back to the master cylinder and both of them have been done in by air leaking around the screw threads. A Motion Bleeder would probably overcome this issue as does usually the old 2-person - press brake down - hold - open bleeder - close bleeder - let up and repeat. I've resorted to using speed bleeders on a couple cars now which have a spring loaded ball valve inside to close them off and prevent the entry of air when pedal pressure is released - makes one-man bleeding pretty simple. As an alternative on a rebuilt brake system, I think I might carefully install some thread sealer on all the bleeder screws so that air entry is cut off.
I'm getting speed bleeders and doing it again, looking for 2 bleeders on each caliper, and will also bleed the master cylinder just to make sure.
Couple of years ago I converted my 65 back to power brakes as it was from St. Louis, got changed over to non PB somewhere along its life. New booster, PB MC, same calipers and pads. Filled MC and left lid off, raised car up on the lift, (still had my shop) cracked open all 4 bleeders half turn, set bucket under each and sat down and had a coffee. Waited till all 4 calipers were dripping fluid, 15 minutes or so, climbed up on a ladder to make sure MC was close to full. Watched them drip for a short time. Closed the bleeders RR,LR,RF,LF.
Let car down topped off MC, put cap back on and stepped on brake with engine off, felt firm and high. Started engine and felt the vacuum and booster operating with a nice high firm pedal with the power assist. I guess I got lucky as I didn't have to pump and bleed at all. Just gravity bleed worked. I have been thru brake bleeding jobs before where you throw your hands up and walk away too, so I was really surprised I got it right on the first shot. Easiest brake bleeding I had ever done.
Edit, I forgot to add that I DID bench bleed the MC before installing on car.
Wait, I have people telling me the rear calipers have 2 bleeder valves each for a total of 4???
08-19-2018, 02:55 PM
1965 brake overhaul - Bleeding Help
