avgwarhawk Posted June 28, 2017 Share Posted June 28, 2017 I'm starting this thread to talk 1960 power brakes. More specifically a power brake unit that does not release all the time. What I'm experiencing and only a recent development. Get a cup of coffee or beverage of your choice. This is the known facts: A. Entire brake system was rebuilt 3 years ago. Included the following: 1. Rebuilt master cylinder 2. Brake hoses replaced 3. Spring kits installed at all four wheels 4. New shoes at all four wheels 5. All metal plumbing replaced 6. Wheel cylinders replaced at all four wheels The car then sat and only driven 200 miles after said complete overhaul. Not much in terms of breaking in a new set of shoes. I have put about 2000 miles on the car in the past 2 months. Braking ability was ok but appeared to slowly fade. Then on a recent return trip from a show I had a panic stop where the pedal had the assist from the power unit and full braking power was applied but the pedal did not immediately return. I had enough speed to reach the side of the road while brake action was still taking place without by foot on the pedal! Within 10 seconds getting to the side of the road the pedal released and all was well. In case one is wondering...all 4 wheels are braking and it is not isolated to just one wheel or two wheels on the same axle. Getting out the trusty manual I read that it is possible the check valve assembly in the master cylinder could be blocked or having an issue. I order a new master cylinder and install. Problem still persists. Pedal is assisted by the power brake unit. All 4 wheels locked solid by the brake shoes. Only, more frequent now does the pedal stay stuck with the new master cylinder. So I rule out master cylinder as the issue. I also rule out a vacuum issue from the intake port or the reserve tank as I pulled both hoses allowing vacuum to escape. Pedal stuck to floor. Wheels locked. Reading the manual a bit closer I investigate major brake adjustment. Bear in mind the braking action and pedal feel after 2000 miles on a relatively new brake job was getting less than stellar. So, I adjust all 4 wheels as I normally do with brake drum equipped vehicles. Very little effort is required to feel braking action when driving. Car stops very well and equally(no pull). But I'm still a bit baffled and I'll explain why. Page 9-9 describes a condition where the master cylinder piston compensating holes my be plugged by dirt or covered by the piston primary cup when the brake pedal is released in the released position. The master cylinder is new and clean new fluid used. That rules out dirt in the compensating port. I note there is a spacer behind the master cylinder as indicated in the manual. I have no spacer. Second, there is tool to measure the piston on the power unit. It states to add gasket material as spacers depending on the gauge reading. If I may ask, does this adding of gasket material assist in the power unit piston to not fully push the master cylinder primary piston beyond compensating port? In other words, is it possible that full on pedal pressure is pushing the master cylinder piston past or just over the compensating port thus preventing fluid to return to the reservoir when the pedal is released? Have I some how stopped the issue by a major brake adjustment that now allows contact of the shoes sooner and the master cylinder piston does not need to move forward as far prior to the major brake adjustment? If this theory appears logical to you then perhaps a spacer behind the master cylinder extends the unit away from the power brake unit thus not allowing the master cylinder piston to require full travel of the bore this possibly covering the compensating port with the tail end of the piston. Or...the is something simply wrong with the power unit. What is your experience with spacers and power brake units? Has anyone had the magical power brake unit keep on braking and release in a few seconds or a minute later? PS. I'm happy it is actually braking. A pedal to the floor with no braking action I can do without. Link to comment Share on other sites More sharing options...
old-tank Posted June 28, 2017 Share Posted June 28, 2017 (edited) Try it with the vacuum disconnected and plugged. I had the same issue on my 55 after changing the boot --- needs to be vented. Edited June 28, 2017 by old-tank (see edit history) Link to comment Share on other sites More sharing options...
avgwarhawk Posted June 28, 2017 Author Share Posted June 28, 2017 (edited) 11 minutes ago, old-tank said: Try it with the vacuum disconnected and plugged. I had the same issue on my 55 after changing the boot --- needs to be vented. Your thoughts are an issue withing the power brake unit? I will check with the vacuum source off and the reserve tank depleted. If she sticks to the floor then I can suspect the master cylinder piston getting past the port. If that is the case a spacer should be used? Edited June 28, 2017 by avgwarhawk (see edit history) Link to comment Share on other sites More sharing options...
JoelsBuicks Posted June 28, 2017 Share Posted June 28, 2017 You might take a look at my old thread, "brakes locking up on my 60 Electra". It sounds similar to your problem. In short, it was my power booster and I recall it having a lot of brake fluid in it from a bad master cylinder that I had since fixed. The fix was was to take it apart and clean it thoroughly. I had planned to send it to Booster Dewey but after dismantling it and noticing the fluid, I figured I'd clean it up and try it. That was 23,000 miles ago and I even drove the car today! Good luck, Joel 1 Link to comment Share on other sites More sharing options...
avgwarhawk Posted June 28, 2017 Author Share Posted June 28, 2017 There was fluid noted behind the master cylinder when I removed it to install the new master. What did you use to clean up the booster? You did physically separate the booster halves as shown in the manual? Link to comment Share on other sites More sharing options...
JoelsBuicks Posted June 28, 2017 Share Posted June 28, 2017 Yes, I separated the halves and I recall an internal hose with a wire clamp that I had to remove but it was all fairly easy after a bit of beating. I cleaned it all up with soapy water and was amazed at how nice it looked. DOT 3 is glycol based and is very water soluble. I used a little stronger concentrated soap (Dawn) to help reduce friction during reassembly. I recall the whole R&R process was much easier than I expected. Hope this helps, Joel Link to comment Share on other sites More sharing options...
Beemon Posted June 28, 2017 Share Posted June 28, 2017 I think a spacer would be more like a shim between the booster and master cylinder so there isn't slop. For example, you go to put your foot on the pedal and the booster rod moves a little before contacting the master cylinder plunger. Since your braking is pretty good, I doubt you need that spacer. I would guess it's the booster, too. The master cylinder would more than likely be spring loaded and allow the rod to return easily, but the diaphragm in the booster could be stuck, or something is not allowing it to return, like how Joel noted. Also, like Willie said, there needs to be some sort of vent. On the original boot, the vent came from out of the vacuum chamber stem and flowed through the boot back to the cylinder (at least on the old units). If you have a boot on there that looks more like a cone than a cylinder, you could be restricting the flow to allow the booster to release. Cleaning the booster is probably your best bet! Willie, did you use the repro boots or the original on your rebuild? I had chucked my old one for a new one, only to find out the new one was restricting flow since it tapered at the top. The old one works without any holes cut in it. Link to comment Share on other sites More sharing options...
Smartin Posted June 28, 2017 Share Posted June 28, 2017 Go with Joel's advice. I did the same on mine. I didn't have sticking brakes, but I did tear the booster apart and cleaned it up. Not a terrible job. Since that seems to be the only thing not replaced, I would look at that first. Link to comment Share on other sites More sharing options...
avgwarhawk Posted June 28, 2017 Author Share Posted June 28, 2017 Thank you for all the tips gents! I will R&R the booster tonight. Report my findings. Link to comment Share on other sites More sharing options...
avgwarhawk Posted June 28, 2017 Author Share Posted June 28, 2017 10 hours ago, JoelsBuicks said: You might take a look at my old thread, "brakes locking up on my 60 Electra". It sounds similar to your problem. In short, it was my power booster and I recall it having a lot of brake fluid in it from a bad master cylinder that I had since fixed. The fix was was to take it apart and clean it thoroughly. I had planned to send it to Booster Dewey but after dismantling it and noticing the fluid, I figured I'd clean it up and try it. That was 23,000 miles ago and I even drove the car today! Good luck, Joel I read your thread. I have exactly the same issue. Fluid behind the master cylinder and pedal goes to full pressure and stays there. And, you are right...pressing the pedal goes fine then it looks possessed and depresses to full bore all by itself!!! Sometime it releases quickly. Other times it simply is full on braking. Car ain't moving!! Again, thanks for sharing your ills with yours and the remedy. I will let know how it goes with clean up on mine. 2 Link to comment Share on other sites More sharing options...
JoelsBuicks Posted June 28, 2017 Share Posted June 28, 2017 Just a little commentary. I was moved by the enormous response and help and back then I was new into Buicks with the 60 being the first of 19 Buicks. I knew I landed in the right spot and I vowed to myself to become a helper whenever possible. Joel 4 Link to comment Share on other sites More sharing options...
old-tank Posted June 28, 2017 Share Posted June 28, 2017 13 hours ago, avgwarhawk said: Your thoughts are an issue withing the power brake unit? I will check with the vacuum source off and the reserve tank depleted. If she sticks to the floor then I can suspect the master cylinder piston getting past the port. If that is the case a spacer should be used? yes... 7 hours ago, Beemon said: Willie, did you use the repro boots or the original on your rebuild? I had chucked my old one for a new one, only to find out the new one was restricting flow since it tapered at the top. The old one works without any holes cut in it. I used a repro boot, but clipped some holes in the bottom flutes. With it completely sealed the pedal went to the floor hard and stayed there. 1 Link to comment Share on other sites More sharing options...
Beemon Posted June 28, 2017 Share Posted June 28, 2017 1 minute ago, old-tank said: I used a repro boot, but clipped some holes in the bottom flutes. With it completely sealed the pedal went to the floor hard and stayed there. I had the same problem and did the same until I dug my original out of the trash. Link to comment Share on other sites More sharing options...
avgwarhawk Posted June 28, 2017 Author Share Posted June 28, 2017 27 minutes ago, old-tank said: yes... I used a repro boot, but clipped some holes in the bottom flutes. With it completely sealed the pedal went to the floor hard and stayed there. This is what happens with this booster. A hard stop the pedal works great....then it keeps on going to the floor applying pressure. It is possessed I tell ya! A few moments like this then I hear vacuum release. Pedal returns to rest position. Internal valve having an issue. Link to comment Share on other sites More sharing options...
60FlatTop Posted June 28, 2017 Share Posted June 28, 2017 Booster Dewey got my booster with brake fluid still in it. I didn't want him to overlook it or assume it wasn't there. 15,000 miles on mine since the brake job. I would be interested in where the hose to the torque tube was sourced. I had to have mine fabricated at a specialty shop. Take a real close look at it. Trusting it was replaced isn't as good as verifying it was replaced. On your booster, it ain't working right. I am real happy with Booster Dewey's work and it was cheaper than a bumper, grille, and headlight assemblies. Bernie Link to comment Share on other sites More sharing options...
avgwarhawk Posted June 28, 2017 Author Share Posted June 28, 2017 Bernie, I'll take a look and see if simply cleaning it up resolves the problem. If not, there are rebuild kits available. If too daunting I'll send to Booster Dewey. So, we will see. Link to comment Share on other sites More sharing options...
avgwarhawk Posted June 29, 2017 Author Share Posted June 29, 2017 Pulled the booster. Cracked it open to find a sea of old brake fluid. Some build up of junk. I cleaned all with soapy water. Reinstalled. Pedal felt totally different. Returned to resting position without issue. Drove the Buick 20 miles in stop and traffic/traffic lights etc. Vast improvement in braking. Made several very hard test stops. Performed flawlessly. I arrived back to my garage and parked just outside so I could clean up. Once done, started the car to put in the garage. Stop and put it in park. Press the pedal a few more times and she locked. This time no release. I cracked the line and pulled the vacuum source. Brakes released. Drove with no vacuum. Brakes did not lock. Looks like the booster is heading to Booster Dewey. In the mean time I have a cool 54 Buick cee-dan I can drive until my booster is returned. 5 Link to comment Share on other sites More sharing options...
JoelsBuicks Posted June 29, 2017 Share Posted June 29, 2017 Booster Dewey will likely offer you an exchange but they will also rebuild yours. I recall they also offer a "show quality" refinish. I wish the cleaning would have worked for you but glad you found that out safely. 1 Link to comment Share on other sites More sharing options...
avgwarhawk Posted June 29, 2017 Author Share Posted June 29, 2017 Worth a shot! It worked very well and braking performance was much better. So I know the booster was having issues that finally culminated in locking up. Also certain the booster is the problem. I'm ok with an exchange. This Buick is the very definition of a driver. Thank you for the help! Link to comment Share on other sites More sharing options...
Bill Stoneberg Posted June 29, 2017 Share Posted June 29, 2017 How hard is it to get it out of the vehicle ? Any issues disconnecting from the brake pedal ? Link to comment Share on other sites More sharing options...
avgwarhawk Posted June 29, 2017 Author Share Posted June 29, 2017 I had it out in about 40 minutes. I took the gas pedal out. Had to so I could get the rod off of it. Other than under dash work I'm not a fan off it is not a difficult job Link to comment Share on other sites More sharing options...
avgwarhawk Posted June 29, 2017 Author Share Posted June 29, 2017 Contacted Booster Dewey. Nice experience. I described my booster ills. Said it was full of brake fluid right? Yep. That is the issue. So, he has one on the shelf and will be sent to me today. I will send my core in the box that is used for the newly rebuilt unit. That is nice because I can still move the car around on manual brakes. I have to play musical cars when getting out my 54. It could be worse I guess! I said to him that the guys at the BCA site recommend you highly. He was appreciative! I will send pictures of the new unit when it arrives. 2 Link to comment Share on other sites More sharing options...
HuntzNSam Posted June 29, 2017 Share Posted June 29, 2017 Unless you are a fan of doing a job twice, drop the vacuum tank on the frame and drain the fluid out of it. We got nearly a quart out of ours. The master had been leaking for years, 'just top it off'. Thanks to the AACA forums and Booster Dewey, we got it fixed and it is working great. 1 Link to comment Share on other sites More sharing options...
avgwarhawk Posted June 29, 2017 Author Share Posted June 29, 2017 Awesome tip sir! Will drain it! Link to comment Share on other sites More sharing options...
avgwarhawk Posted July 7, 2017 Author Share Posted July 7, 2017 Newly rebuilt booster arrived. Thing looks like new! I will post pictures. Get this thing installed. Then stop. 1 Link to comment Share on other sites More sharing options...
Bill Stoneberg Posted July 8, 2017 Share Posted July 8, 2017 Quote Bought a 1960 because I wanted one more. Chris, Buicks are like hangers, if you leave them in an empty garage too long, they seem to multiply. This from someone who had 5 at one time. Link to comment Share on other sites More sharing options...
NTX5467 Posted July 8, 2017 Share Posted July 8, 2017 Might consider changing (or kitting) the master cylinder when ANY fluid is found in the booster, older cars or newer. Otherwise, fluid will get into the replacement booster, too. It might be that cowl-mounted boosters are more resistant as the fluid tends to only get into the inner boot rather than into the booster body itself? Just wipe/soak up the fluid accumulation in the boot and go on. NTX5467 Link to comment Share on other sites More sharing options...
avgwarhawk Posted July 10, 2017 Author Share Posted July 10, 2017 (edited) On 7/8/2017 at 0:43 PM, NTX5467 said: Might consider changing (or kitting) the master cylinder when ANY fluid is found in the booster, older cars or newer. Otherwise, fluid will get into the replacement booster, too. It might be that cowl-mounted boosters are more resistant as the fluid tends to only get into the inner boot rather than into the booster body itself? Just wipe/soak up the fluid accumulation in the boot and go on. NTX5467 This set up has a piston that projects out of the booster(male) and inserts into the master cylinder(female). The piston from the booster has 2 rubber O rings to prevent fluid from getting into the booster. The piston pushes the master cylinder piston. My original booster the O rings were worn allow fluid to get past. Newly installed. Braking ability totally different than the original booster. No doubt the booster was done for and just a matter of time for it to stop function all together. Edited July 10, 2017 by avgwarhawk (see edit history) 3 Link to comment Share on other sites More sharing options...
avgwarhawk Posted July 10, 2017 Author Share Posted July 10, 2017 By the way....thanks for the tip from those that mentioned Booster Dewey. Fast and friendly. Highly recommend. 2 Link to comment Share on other sites More sharing options...
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