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At My Wits End With 52 Special Brakes Need Sum Help!!


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Ok, I have a 52 special that I just bought. The car basically had no brakes. If you pushed the pedal all the way to the floor it would slowly roll to a stop. So I have rebuilt the entire brake system. Put a rebuild kit in master cylinder, 4 new wheel cylinders, new rubber hoses, new shoes, and new springs. I have taken all of the junction/distributor blocks off and cleaned them as well. I have bled the brakes what seems like 100 times. I have adjusted the shoes out til they rub lightly on the drums. I have adjusted the pedal linkage. I also cleaned the master cylinder cap as I read somwhere that the vent holes being clogged could lead to bad brakes. There are no fluid leaks that I can see. All this and I am STILL at square one. The brakes are the same as they were before I started all of this! The pedal is soft and goes all the way to the floor before the brakes lightly kick in. I just don't get it! I really don't want to send her to a mechanic but I just don't know what else could be wrong. I just read in the buick service manual that there is a gasket that goes on the screw-in cap for the master cylinder. Mine does not have a gasket. Is this little gasket that important? Does anyone else have a similar master cylinder that does have this gasket? Any help or suggestions would be appreciated. I just want to drive(and stop) my Buick!!:)

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77, sure sounds like a bleeding problem. How did you bleed the brakes? Pumping with a helper? Vacuum? Pressure? This is a pretty simple system. I just recently installed a rebuilt MC on my '50. Using an inexpensive vacuum bleeder from Harbor Freight, I was able to bleed them sucsessfully. Just had to be alert and not draw down the MC level and draw air back in.

Good luck.

Ben

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Well I've tried two methods. I did the pump with a helper and then tried the method where you put a piece of clear tubing on the bleeder screw put the other end in a bottle with some fluid in it and slowly pump til there are no bubbles in the tube. I've lost count of how many bleeding sessions I've done. I might have to look into that harbor freight bleeder. Just out of curiosity, does your mc have the gasket on the filler cap that it shows in the service manual?

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My vote on the MC being the culprit, made the same error on my 65 single cyl. Car blew a line, replaced it but never got full pedal, bled my brains out. Finally pulled down the master to find a piece of crud blocking an inlet for the fluid. Cleaned my master, put new rubber in, end of problem.

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I too feel your master is the problem. You might have the wrong kit or you might have a worn master which needs sleeved back to original dimensions plus a correct kit or you might have a blocked port in the master.

Martin Lum

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What order did you bleed the brakes? I learned to start from the furthest wheel fromthe cylinder and work to the closest. On left hand drive cars this would be the right rear, left rear, right front, left front.

If you had pressure at the wheel cylinders then I would not think the MC is the problem unless it is sucking air when you release the pedal. Did you eventually get bubble free bleeds when using the tube into the jar of brake fluid? I would check and re snug all fittings.

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Had a similar problem with my 1950 Special last year. Did all the steps you mentioned and finally found out that the compensating port (which is under the master cylinder) was clogged with dirt. Cleaned it out and the brakes are fine. Hope this helps

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Had a similar problem with my 1950 Special last year. Did all the steps you mentioned and finally found out that the compensating port (which is under the master cylinder) was clogged with dirt. Cleaned it out and the brakes are fine. Hope this helps

Ok. just got back from another unsuccessful round with these brakes. Took the MC off, took it apart and cleaned it out til you could eat out of it. Vent holes in filler cap are clear as are the two holes inside the reservoir(one tiny the other bigger). I double checked internal components to make sure I put them back in correctly and they are fitting snugly in the bore. I bench bled it and put it back on the car and bled all wheels til there was no air......nothing. No change at all. So, where is this compensating port? By "under the master cylinder" do u mean its actually outside of the MC? If you are referring to one of the two holes inside the reservoir those r clean. Arrrrgggghhh.

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What order did you bleed the brakes? I learned to start from the furthest wheel fromthe cylinder and work to the closest. On left hand drive cars this would be the right rear, left rear, right front, left front.

If you had pressure at the wheel cylinders then I would not think the MC is the problem unless it is sucking air when you release the pedal. Did you eventually get bubble free bleeds when using the tube into the jar of brake fluid? I would check and re snug all fittings.

Well, the order you describe is also what I was taught but in the 52 buick service manual it tells you to do the exact opposite and start with the wheel closest to the MC. I didn't believe it at first but I read it over and over and that's what it says so that's how I've been doing it. And I've got plenty of pressure at the wheel cylinders while bleeding.

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I'd go back and adjust the shoes till they drag heavilly, then try your brake. If the pedal is up then readjust the shoes till you find the sweet spot. If the pedal is still down BUT stop the car, then I'd look for something missing in the mechanism between the brake pedal and the MC. Perhaps a push rod of some sort?

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When you bench-bled the master cylinder, was the stream of fluid coming from the cylinder strong and solid, or otherwise? Did, by chance, you also put a block-off plug in the line (during the bench bleeding process, after the air was gone) and see how solid the pedal might be? Granted, this is not something that's normally done, but in this case, might be interesting to know. Reason is that just because the cylinder's output line has no air bubbles in it, that just means the piston's cup is moving fluid, but not that it'll hold pressure and have a firm pedal (at the normal pedal height).

If, per chance, the cup was put on the piston's plunger backward, it might well move fluid against no resistance, but would let the piston would easily "bypass" once the fluid was moved in the line but not let pressure build-up happen. Even if the cylinder bore had some wear, I would think that the pump cup would expand to significantly seal the cylinder and not let very much fluid by-pass under normal use. On many newer "new" cylinders, if you stand on the brake pedal, they CAN bypass in that mode a little, with extended continuous pressure . . . but would act normal in normal situations and use.

Just some thoughts about an extreme situation . . .

Keep us posted on what you find, please.

NTX5467

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Lots of good suggestions so far....

If everything is working properly and there is only air in the system, the pedal should come up after rapidly pumping 3-4 times. If not suspect the master cylinder. If the pedal does come up after pumping, try bleeding again while pressure is in the system.

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This whole string of messages could describe the problems I have had with bleeding the brakes on my 1954 Special 2-dr. sedan over the past four weeks. Have rebuilt the M/C and all of the wheel cylinders. I have good pressure at each bleeder screw when bleeding the brakes. Have done it what seems like 100 times. "Shadetree77" I totally sympathize with you. After all of this work, nothing is any different. Pedal goes nearly to the floor but can be pumped up rather quickly after 3 or 4 pumps of my foot. It's the same @#(%*%)$_(*#@ situation as before I started ANY of these repairs. No, there are no leaks and no puddles of fluid at any of the wheels. Aren't old cars "fun"?! AUUUGHHHHHH!!!!

Pete Phillips, BCA #7338

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When you bench-bled the master cylinder, was the stream of fluid coming from the cylinder strong and solid, or otherwise? Did, by chance, you also put a block-off plug in the line (during the bench bleeding process, after the air was gone) and see how solid the pedal might be?

NTX5467

The stream of fluid looked to be plenty strong and continuous while bench bleeding. I didn't put a block-off plug in it but that might be something I'll try eventually as I read that you can do that while the MC is on the car and use the pedal to check it. Also, you mentioned that the primary cup might be on backwards but I checked it and compared it to the service manual pictures several times and it is in the right position. Everything seems to be in order with the MC(all parts in right positions and all ports clean and clear)but still no brakes. Ahhh well, the fight continues tomorrow. Gonna bleed and adjust some more and hope for a miracle! Thanks for all the suggestions and I'll keep everyone updated. If anyone has more suggestions please feel free to chime in. Any and all help is much appreciated.

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It sounds like you have eliminated the hydraulics and need to look elsewhere.

Just a few thoughts, does the '52 have the same type of backing plate as a "39 ??

If so it has an anchor pin with a big nut on the back that can move up and down.

If it sits low, when the shoes are adjusted only the very bottom of the shoes will drag on the drums but leave a lot of travel for the wheel cylinder pistons to move in and out at the top. The little master cylinder bore dispersed over the 4 wheel cylinders (times 2 pistons each) equals a lot of pedal travel. You could try moving the pins up a little and check to see if you can get a bit more adjustment. A few extra clicks on each wheel can make a difference.

Something else to consider is to check that that drums aren't over sized for the linings as that too will affect the pedal travel. (or linings undersized for the drums)

When I had my drums machined, I had over-sized linings fitted that were then ground to match the new diameter of the drum. I only have about 1/2" travel on my brake pedal till a very full and firm pedal.

Just a few thoughts that helped me out with my beasty.

Danny

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Ok, I have a 52 special that I just bought. The car basically had no brakes.

Just my 2 cents:

are you sure the right MC is in the car?; it seems the former owner already had breaking issues and maybe he changed the original MC for the wrong one (which you rebuild).

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On my '51, the MC has an adjustable pushrod. I understand that setting this up, as described in the service manual, is a critical step. If the rod is set too long, the piston won't return all the way in the bore and it won't uncover the port in the rear allowing the pressure to equalize. I think this condition leads to the brakes locking up. But maybe if the rod is too short, the stroke of the piston won't be long enough to engage the brakes fully? Just a conjecture.

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A couple of people touched on this and now its got me wondering. You got the car with bad brakes, did a bunch of work and still have bad brakes. I am beginning to wonder if there is a defective part or a wrong part in the system. Maybe get a couple of plugs, bleed it at the MC and see if you can get a solid pedal, backtrack so to speak. Just a thought.

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Even with a little air in the lines, the pedal wouldn't go all the way to the floor with no resistance. I vote for something placed incorrectly in the MC rebuild. (no offense)

If the bore was bad, it would leak from the front. Thirdly, yes you need the gasket for the filler lid...before you put the carpet back down and drive it. It isn't the cause of your problem. You can make a gasket if your kit didn't come with one.

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If so it has an anchor pin with a big nut on the back that can move up and down.

If it sits low, when the shoes are adjusted only the very bottom of the shoes will drag on the drums but leave a lot of travel for the wheel cylinder pistons to move in and out at the top. The little master cylinder bore dispersed over the 4 wheel cylinders (times 2 pistons each) equals a lot of pedal travel. You could try moving the pins up a little and check to see if you can get a bit more adjustment. A few extra clicks on each wheel can make a difference.

So I was messing around with these brakes again today and I decided to pull the old shoes out that came off the car and check them out. They are worn pretty unevenly. They are worn a lot more at the top than they are at the bottom. Could this indicate a problem with my anchor pins as discussed above? I've included a pic of the old shoes so everyone can see the uneven wear. Would an anchor pin problem cause my pedal to go all the way to the floor and not pump up though? I cannot get the pedal to pump up at all no matter how fast I pump it. Also, several members have mentioned that there might be a mistake in the MC rebuild. I have included a picture of the internal components exactly how I have installed them on the MC. I pulled them out and took a picture just as they came out. If anybody sees a mistake please let me know. Next step is to plug the outlet on the MC and see if the pedal pumps up. After that, its off to a mechanic because I am absolutely out of ideas!!!

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post-75106-143138533571_thumb.jpg

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Here is a long shot for you.

Disconnect the park brake cable and make sure that the cable returns fully to the off position. Then readjust the back brakes as normal and reconnect and adjust the park brake.

If that does not work then purchase a pair of brake hose clamps from your local auto store. To isolate the problem clamp the hose to the rear brakes and test the pedal travel. Clamp the hose at each front wheel and test.

Good Luck.

Koala

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Wow !! The mystery deepens. The shoe wear looks normal enough and even with under adjusted brake shoes and way off anchor pins, you should still be able to get a near enough full pedal by pumping it several times and holding it. It does seem that the master cylinder is the culprit. At least plugging it you would confirm or deny it as such.

Curiouser and curiouser :confused:.

Danny

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Here's my thought.....

Your pic of the brake shoes noted that the bottoms of the shoe linings are

thicker than the tops meaning.....the very bottom adjusting screw with a wheel, nut, and socket needs to be spread out more.....and the top anchor pin and shoe guide needs to be checked for any slop or excessive wear.

Just my $.02 worth.

Al Mack

"500 Miles West of Flint"

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Just what ya need here, is another what if, but here goes. If ya block off the master, with plugs and have full pedal, that means MC is fine. Still does not explain pedal travel, with no fluid leaking. What if the original owner replaced the wheel cylinders or a set with the wrong ones, causing too much travel before brakes???

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If the master checks out OK, the wheel cylinders might be too large. They'll bleed just fine, but won't grab very well. When I did the brakes on my Dodge pickup the parts store gave me the wrong wheel cylinders, and after several days of chasing problems, I finally took them out and replaced them with a different set, and voila! Problem solved.

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If the master checks out OK, the wheel cylinders might be too large. They'll bleed just fine, but won't grab very well. When I did the brakes on my Dodge pickup the parts store gave me the wrong wheel cylinders, and after several days of chasing problems, I finally took them out and replaced them with a different set, and voila! Problem solved.

Mechanical leverage comes from the differing piston sizes between the master cylinder and the wheel cylinder pistons. Usually, the diameter of the wheel cylinder pistons are cast into the rubber "cups". Sometimes, the size will be different between the front and rear wheel cylinders, too. All of these things need to be matched "as designed" for things to work correctly.

All things considered, it might be good to get the complete master cylinder and wheel cylinder specs for the vehicle, from a reliable source, and check them against what's now on the vehicle. Just one more thing to check, but then after you do it, you'll know what's really there.

Thanks for mentioning that situation, Matt.

Enjoy!

NTX5467

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Another update from my battle with the Buick! Over the weekend I tried the MC test where you plug the outlet and check it with the pedal. Pedal was firm and high.....for about 10 seconds before it began to fade all the way to the floor. Soooooo....I've ordered another MC rebuild kit from a place that should have better knowledge of what I need than the place I ordered the first kit from(especially seeing as how this first place also sent me the wrong brake shoes the first time through). Someone earlier on in this thread suggested that I might have gotten the wrong rebuild kit and, while the kit I got seemed to fit in the bore snugly, maybe its slightly off causing the MC to bypass fluid. So it will take a few days to get here and at that point I'll remove the master cylinder for about the 4th time I think and rebuild it for the 3rd time. At least I have finally narrowed my problem down to the MC. If this doesn't work I guess I'll spend the $135.00 on a new one. In the meantime, keep the suggestions coming as I'm willing to give just about anything a try to get these brakes working! Thanks again to everyone who has offered up some insight. DING DING DING!!! ROUND 27!!!:P

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I really can't believe you are having this much trouble, old cars are always so easy to work on ;)

I would bet at this point your MC needs to be resleeved. I had mine done at Hagens Auto in Oregon. (253) 845-7020

Good luck. At least you will be really good at brakes after this.

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Another update from my battle with the Buick! Over the weekend I tried the MC test where you plug the outlet and check it with the pedal. Pedal was firm and high.....for about 10 seconds before it began to fade all the way to the floor. Soooooo....I've ordered another MC rebuild kit from a place that should have better knowledge of what I need than the place I ordered the first kit from(especially seeing as how this first place also sent me the wrong brake shoes the first time through). Someone earlier on in this thread suggested that I might have gotten the wrong rebuild kit and, while the kit I got seemed to fit in the bore snugly, maybe its slightly off causing the MC to bypass fluid. So it will take a few days to get here and at that point I'll remove the master cylinder for about the 4th time I think and rebuild it for the 3rd time. At least I have finally narrowed my problem down to the MC. If this doesn't work I guess I'll spend the $135.00 on a new one. In the meantime, keep the suggestions coming as I'm willing to give just about anything a try to get these brakes working! Thanks again to everyone who has offered up some insight. DING DING DING!!! ROUND 27!!!:P

Some sort of victory at last!! Glad to hear it. Do you have access to a micrometer and the I.D. dimensions of that cyl? Reason I ask is at this point rather than taking a fresh kit and finding out it won't work because the cylinder is worn out, ya might have it micrometered out to see if its out of round or worn beyond specs. Then if its worn, you can decide to fix or get anther. Just a thought.

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My quick research shows the bore of the master cylinder is one (1) inch; the bore of the rear wheel cylinders is one (1) inch and the bore of the front wheel cylinders is one and 1/8 inches. If this matches your parts, great. Now send the master cylinder to be resleeved with stainless steel and that should be a lifetime repair. New master cylinders have a very thin hardened layer on the bore surface, which wears with use and is depleted when honing for a rebuild. Most cylinders can be rebuilt once, more than that you will get limited service. There is a good chance that original cylinders on cars of this era have been rebuilt many times and cannot and should not be rebuilt again.

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  • 2 weeks later...

Ok, sorry for the long delay but it took an incredibly long time to get my new rebuild kit in the mail. Anyway, so today I rebuilt the master cylinder with my new kit and bench bled it. I put it back on the car and did the test where you plug the outlet again. This time the pedal was firm and high and did NOT fade at all. So the MC is fine and is officially ruled out as the problem. I put everything back together and bled all the lines. I got good pressure at all cylinders and I bled and bled way past the point where I stopped getting air. I also jacked the car up and followed EVERY single line from MC to wheel cylinders checking for leaks/holes and tightening and double checking every hose and fitting along the way. No leaks. Also checked the adjustment on the wheels. When I turn the wheels by hand I can hear the brakes lightly rubbing drums. I put the car down and checked the brakes....not much of an improvement.:mad: The brakes still go down way too far for comfort before they begin to catch. I'd say somewhere between 1/2 and 3/4 of the way down. I'm really at a loss here. I did notice something kind of strange today though. I had my dad get in the car and press the brake pedal(wheels off the ground) while I tried to turn the tires by hand. The tires had a bit of play in them even with the brake pedal pushed. I could maybe turn them about an inch in either direction before they caught and would not move. The thing is, when they reached the point where they caught my dad says the brake pedal dropped a good inch or so. ????? I've never heard of this happening. Could this be a symptom of some kind of problem? Should I have any play at all in the wheels when the brake pedal is pushed? By the way, this also happens when you put the car in gear. When the trans. kicks into gear it jerks the car a bit and I guess that moves the wheel a little and the brake pedal drops just as described above. Anybody ever heard of this?

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The brake pedal will drop when you put the car in gear on any car with drum brakes, so that's normal. I didn't go through the whole thread, but are you sure that every brake is adjusted so that you can hear the shoes just rubbing the drum as you spin the wheel? I had one that I forgot to adjust up once and it ruined my pedal. Even when they're working well, it seems like the pedal travel on old Buicks isn't like newer cars...mine has more pedal travel than my 60s cars, and I've been through the whole system too.

Edited by Aaron65 (see edit history)
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SOME of what you're feeling when the vehicle is put into gear is the "servo action" of the brakes themselves. This means that as the brake drum turns forward, when the brake linings touch the inner drum's contact surface, the action of the drum turning helps apply the forward (leading) brake shoe, which then helps stop the vehicle with less brake pedal input. Still, though, such servo action would NOT result in the amount the pedal drop mentioned as the vehicle tries to move forward, with the foot brake firmly applied, when the trans is put into "D". What does it do when the trans is put into "R"??? Or when once you apply the foot brakes, put the trans in "D" and THEN into "R"???

It's been a while since this thread started, so I don[t recall specifically if the rubber lines were replaced in this whole affair. Sometimes, they will delaminate internally and block brake fluid flow through them. To me, this is one reason and place where NOS parts should not be sought out and used! Such delamination is not too common, but can and does happen, even on newer (1980s+) vehicles as they age.

Adjusting the brake pedal's master cylinder push rod might help with the pedal height, but all that will be changed is the height at which the pedal "works" rather than the actual travel inside of the master cylinder that makes everything happen.

Have you checked the brake lining adjustment with an "inside-outside brake adjustment caliper"?? This might be an interesting investigation! Basically, with the brake shoes adjusted as they are, you compare that "diameter" with the inner diameter of the brake drum . . . at the same time. The center of the brake lining diameter is checked, not the area at their pivot points, which might indicate that not enough brake lining is actually contacting the inner drum surface as the brakes are applied. You might have to look for one of these calipers, but they should still be around and available.

A related issue migiht be the particular lining material itself, being too hard and requiring more pressure (and resultant pedal travel) to make them work. Old-Tank has mentioned his experiences with his Buicks and 5563 might also have this information too, as to brands that work best. Similarly, having the "leading" and "trailing" shoes reversed on the backing plate (IF this might apply), due to potential differences in lining material.

As I mentioned, the servo action in the brake system is what's making the pedal drop when the foot brakes are firmly applied and the vehicle is put into a forward gear. Usually, though, this "drop" is more like the help which the servo action gives resulting in less pedal pressure being needed to apply the brakes. BUT it should not be anywhere near what is mentioned. As crazy as it might sound, that might indicate (to me) that the wheel cylinders might have pistons that are too tight, but for them to be THAT tight, they'd probably be galling themselves inside of their respective piston bores! OR, they are too small for what they should be (smaller bore diameter = more more travel for the same fluid displacement as a larger diameter bore diameter), which could also affect pedal travel just as wheel cylinder push rods, which transfer hydraulic pressure to the brake shoes themselves)). This puts us back to wheel cylinder issues. IF the wheel cylinders don't have short push rods which are held in place by the piston cups, then whatever brake shoe/wheel cylinder interface might be having some issues. Contact surface wear, incorrect push rods or unnoticed wear, incorrect size wheel cylinder bore diameter . . . or combinations thereof.

I will admit that my experiences with that era Buick brakes is limited, but if the brakes on a '50s GM 1/2 ton pickup can be adjusted to where the pedal travel is "at or near the top", then I would suspect that Buick brakes can be adjusted similarly. Perhaps that's an incorrect presumption?

Keep us posted, please!

NTX5467

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The brake pedal will drop when you put the car in gear on any car with drum brakes, so that's normal. I didn't go through the whole thread, but are you sure that every brake is adjusted so that you can hear the shoes just rubbing the drum as you spin the wheel? I had one that I forgot to adjust up once and it ruined my pedal. Even when they're working well, it seems like the pedal travel on old Buicks isn't like newer cars...mine has more pedal travel than my 60s cars, and I've been through the whole system too.

I had this happen on an all drum Chrysler, only one was so out of adjustment it created a lot of travel, times that by 4 thats alot. Drum brakes should drag a little when first adjusted, you will hear em, but ya have to do this to seat the shoes a bit.

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