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Brake lockup


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I am the Master Editor of the Hornets Nest Region, AACA and write a tech article each month. Replys and the web site will be used in a new article.<P>My problem: I have restored the brakes on my 1957 Dodge Royal Lancer (no power brakes)and have used silicone brake fluid. All wheel cylinders as well as master cylinder where replaced new from NAPA. All rubber hoses have been replaced including hose from master cylinder to brake lines. All shoes were relined.<P>The problem: A wheel locks up when brakes applied when moving forward after backing out of my garage. It had been the driver front wheel where there are two cylinders, I replaced one of the cylinders that was locking up. Then the back driver wheel (one cylinder) locked up. I could move forward on slight incline and apply brakes and the locked up wheel would prevent the car from moving just as if I applied the hand brake. I rebuilt the rear driver cylinder, now the front driver brake locks up again!<P>One of our members has told me that the possible older rubber in the new NAPA cylinders is not compatible with the new silicone fluid or newer brake fluids and may be causing the problem.<P>This may be correct in that the front driver locking cylinder was "free" for a while. Now it locks up again. I may see that the driver rear wheel cylinder I just worked on may lock up again after it has been in a while.<P>I need help on this from some of you pros out there to solve this problem. As I said, I want to write an article on this issueand reference this site with hopeful solution to this problem.<P>I have restored many cars over the years and never had this experience before. But this is the first time I have used silicone fluid.<P>Help!<P>3/6/01 UPDATE!!!!!!!<P>I have studied the parts manual for the brake cylinders (Mopar Parts List Book 1955-1958) and have noticed the brake cylinder inner core components consist from center inside outward 1)Inner spring, 2) EXPANDER*, 3)Rubber Cup, 4) Piston. The piston forces the plunger outward to push the brake shoe against the drum.<P>The rear single brake cylinder that I took apart and honed out and replaced inner parts (inner spring nad cup) did not have the EXPANDER -- either with the kit on inside the brake cylinder that was new when installed. I have never taken the NAPA brake cylinders apart that were originally installed 2 years ago, and it might be that none of them had the EXPANDER in them. *The EXPANDER is shown as similar to a pie pan with peferations which houses neatly into the back of the rubber cup.<P>Without an EXPANDER, could this be the cause of brake locking? Anybody know.<P>I can e-mail a parts detail picture showing the barke cylinder. <P>[This message has been edited by Brooke Davis (edited 03-06-2001).]<P>March 14 UPDATE:<P>I have adjusted the master cylinder push rod to what I believe are the correct specs. This seems to solve the rear left wheel tightening after driving.<BR>Also, and this was a surprise, I took off the left front brake shoes, put them on the bench and wanted to be sure they were the same dimensions, etc. and same surface area of brake lining. Upon close inspection I discovered that the two shoes were the same brake shoe area, length, width, etc., etc. BUT the 90 degree rib differed between the two shoes in a very subtle way. The profile of the "hook" protrusion where the brake cylinder forces the shoe against the drum differed. Also, one shoe had a large round opening on the face at one end. Puzzeled, I looked at the MOPAR parts book which listed all 8 shoes as the same part number and in the service manual no reference was made to anything different. I looked at the right front wheel and reversed the shoes on the left to match the right front wheel (since the right wheel had been ok all along.<P>Now my only problem wth the brake system is a lock of the front or rear left brake when I start to drive the car after sitting over night or for a long period the same day. It is the type "lock" that goes away after driving a few blocks, but it will definitely lock up the first 4-5 times brakes are applied.<P>Any suggestions out there?<p>[This message has been edited by Brooke Davis (edited 03-14-2001).]

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I have never heard of silicone fluid causing lock ups. And I can't think of a plausible mechanism for it to happen. I'd look at some other stuff... I assume you were careful installing the shoes and so will not consider contamination on the shoes.<P>Is the master cylinder new or rebuilt too? Is brake pedal linkage adjusted so that the pressure relief port in the master cylinder is exposed when the pedal is released? I've had that lock up brakes on me.<P>On many Chrysler products of that vintage, with the two front cylinders, you need to put the shoe with the shorter lining in front. Failure to do that will cause the front brakes to lock up. (Should not affect the rear brakes though.)<P>Just a couple of ideas that I hope will help.<P>Tod

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I would agree with Tod about the leading and trailing shoes being in the proper position. Also, you should check to make sure you have the proper return springs. Some brake mfg.'s spec different strength springs for each shoe. The incorrect spring tension or incorrect spring will cause exactly what you are describing.<P>Preaching time: Anytime you are dealing with a vintage car, remember that spring has been under tension pulling back those shoes long past its expected life span. New springs are a cheap enough investment and should be part of any brake overhaul.<p>[This message has been edited by Chris NJ (edited 03-05-2001).]

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Thoughts and comments welcomed. But, a wheel decides to lock up after working fine for a time. Front wheel fine after new cylinder, but locks up weeks later. Leads me to believe rubber/brake fluid compatibility as best source of problem.<P>There is a definite rotation of wheel to use when adjusting brakes which I've followed.<P>I'll check the leading and trailing brake shoes, but in position that they are in, they work, then they don't! Springs: have several replacements (can't find new) and that doesn't help.<P>Manyu thanks!<P><BR> <BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by Chris NJ:<BR><B>I would agree with Tod about the leading and trailing shoes being in the proper position. Also, you should check to make sure you have the proper return springs. Some brake mfg.'s spec different strength springs for each shoe. The incorrect spring tension or incorrect spring will cause exactly what you are describing.<P>Preaching time: Anytime you are dealing with a vintage car, remember that spring has been under tension pulling back those shoes long past its expected life span. New springs are a cheap enough investment and should be part of any brake overhaul.<P>[This message has been edited by Chris NJ (edited 03-05-2001).]</B><HR></BLOCKQUOTE><P>

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I,m not sure if NAPA master cylinder is rebuilt or new, assume rebuilt. I,ve had the problem on a 57 Chrysler of relief valve which locked up back right wheel! Blew the tire from the heat.<P>Shoe are clean. Have you ever heard of the rubber in the cylinders not being compatabile with newer brake fluids. One clun member thinks this is the problem.<P><BR> <BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by TodFitch:<BR><B>I have never heard of silicone fluid causing lock ups. And I can't think of a plausible mechanism for it to happen. I'd look at some other stuff... I assume you were careful installing the shoes and so will not consider contamination on the shoes.<P>Is the master cylinder new or rebuilt too? Is brake pedal linkage adjusted so that the pressure relief port in the master cylinder is exposed when the pedal is released? I've had that lock up brakes on me.<P>On many Chrysler products of that vintage, with the two front cylinders, you need to put the shoe with the shorter lining in front. Failure to do that will cause the front brakes to lock up. (Should not affect the rear brakes though.)<P>Just a couple of ideas that I hope will help.<P>Tod</B><HR></BLOCKQUOTE><P>

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Okay Brooke, lets look at this. The master cylinder pushes fluid into the piston pushing out the brake shoes. Release the pedal and the springs return the shoes. Unless there is evidence of leakage, the fluid is not the problem. <P>I did think about something else. Is the anchor pin eccentric and held in place by a lock nut from the backing plate? On some brake applications this is used to center the shoes. If the locknut isn't holding the pin in position it could move throwing off the shoe position. I am not familiar with the 57 Dodge design but this was a common feature of brakes in the 40's and 50's.

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Brooke,<BR> Tod Fitch in the silicone brake fluid thread comments that air entrainment while bleeding brakes with silicone fluid is quite possible. If your system has significant air in it, since the air is compressible combined with weak springs might the strange effects you describe possibly occur? Just an idea.<P>jnp

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John Packard ~~ I would think that air in the lines would simply cause a soft pedal and fading during prolonged braking. I don't see how it would cause a lock up.<P>Brooke ~~ If I recall correctly, the expander is simply to keep the edge of the rubber cup (seal) firmly against the cylinder wall when there is no pressure in the system.<P>In master cylinders there is may be a check valve that maintains a small amount of presssure in the system when the foot is off the pedal. On those systems, the residual pressure keeps the seals in the wheel cylinders pressed against the cylinder walls.<P>If the master cylinder does not have this check valve, then there is no pressure and you need an expander on the wheel cylinder seal to guard against leaks when the foot is off the brakes. Typically disc brakes cannot have this residual pressure and thus the rear drum brake cylinders have expanders. In a all drum system, the master cylinder often has this check valve and needs no expanders.<P>Thus the expander should keep the cylinder from leaking. It should not have an effect on locking up the brakes.<P>I don't think expanders would ever hurt, even in a system with a check valve. The only problem would be a slight increase in cost of manufacturing.<P>I still think your most likely suspect is the adjustment of the linkage from the brake pedal to the master cylinder.

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<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by TodFitch:<BR><B>John Packard ~~ I would think that air in the lines would simply cause a soft pedal and fading during prolonged braking. I don't see how it would cause a lock up.<P>Brooke ~~ If I recall correctly, the expander is simply to keep the edge of the rubber cup (seal) firmly against the cylinder wall when there is no pressure in the system.<P>In master cylinders there is may be a check valve that maintains a small amount of presssure in the system when the foot is off the pedal. On those systems, the residual pressure keeps the seals in the wheel cylinders pressed against the cylinder walls.<P>If the master cylinder does not have this check valve, then there is no pressure and you need an expander on the wheel cylinder seal to guard against leaks when the foot is off the brakes. Typically disc brakes cannot have this residual pressure and thus the rear drum brake cylinders have expanders. In a all drum system, the master cylinder often has this check valve and needs no expanders.<P>Thus the expander should keep the cylinder from leaking. It should not have an effect on locking up the brakes.<P>I don't think expanders would ever hurt, even in a system with a check valve. The only problem would be a slight increase in cost of manufacturing.<P>I still think your most likely suspect is the adjustment of the linkage from the brake pedal to the master cylinder.</B><HR></BLOCKQUOTE><P>3-7 from Brooke: I will look into the linkage situation on the master cylinder. I did adjust this some time ago when I was experiencing other problems (hard rubber hose off master cylinder to main lines). But I'm not sure where we're going here. Just waht does the linkage adjustment have to do with the brake lockup problem?<P>

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I had <I> exactly </I> the same thing happen to me under <I> exactly </I> the same circumstances with my 1960 Buick about 4-5 weeks after I bought it. Only for me it occurred first about 100 miles from home on a tour with some friends of mine with the Corvair club here in Pittsburgh. <P>The right rear brake on my car started smoking on a 2-lane state highway north of Pittsburgh. After the guys flashed their lights and stopped me, I discovered that that brake was locked up.<P>Here's the lucky part, I happened to pull over directly in front of a guy's house who was restoring a 1933 Plymouth. I was able to work on the car out of the rain in his (huge) garage, and with his tools. I misplaced his name or I'd thank him publicly here.<P>The brake was locked hydraulically, with new hoses and cylinders (the shoes had been done before I bought the car). I tried to bleed the frozen brake. At first I only got a few drops, then nothing. Standing on the brake pedal with as much force as I could muster, with the engine running (power brakes), and the line disconnected and free still yielded no fluid. I backed the shoes off manually and plugged the line at the fitting, finishing the tour with three wheel brakes.<P>As it turned out, there was 35 years worth of crud inside the steel lines on the car. Bleeding the brakes and using the car extensively (100 miles is probably further than that car had ben driven in 20 years) had freed up that crud. It sloshed back and forth inside the lines until it formed a one-way check valve, trapping pressure inside the right rear cylinder and eventually seizing the brakes.<P>I replaced the lines with stainless, pre-formed lines from Classic Tube (I've also used Inline Tube and been very satisfied with both). I've since (6 years) not had the slightest hint of the problem returning. <P>If everything is in place on your Dodge and the problem persists, try bleeding the brakes. If there seems to be a diminished flow of fluid out of the bleeder, try the line itself. If you notice <I> anything </I> out of whack, replace all of the lines. Don't chance this happening next month or next year on some other wheel.<P>Good luck! smile.gif

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Dave@Moon ~~ Ya gotta love those people with 1933 Plymouths smile.gif<P>Brooke ~~ If the linkage from the pedal to the master cylinder is adjusted too long, then the piston in the master cylinder will not retract to the pressure relief port. Result: Brakes lock up. This has happened to me. On my 1933 Plymouth smile.gif

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<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by TodFitch:<BR><B>Dave@Moon ~~ Ya gotta love those people with 1933 Plymouths smile.gif<P>Brooke ~~ If the linkage from the pedal to the master cylinder is adjusted too long, then the piston in the master cylinder will not retract to the pressure relief port. Result: Brakes lock up. This has happened to me. On my 1933 Plymouth smile.gif</B><HR></BLOCKQUOTE><P>Thanks for replys. I am going to adjust the barke pedal this weekend. It has a travel of more thatn 1 1/2" to resistance. A Chilton book I looked at last night said to adjust to 1/4" to 1/2" before resistance. A 1957 Chrysler I restored 10 years ago had a faukty master cylinder and pressure built up in the right rear wheel (farthest from master cylinder) and enought heat was generated that the tubeless tire actually blew with a big bang after I reached home. This was the fault of the pressure relief valve and the buildup point was the wheel farthest away from the master cylinder. As for crud in the brake lines, I've replaced all meatl lines except from master cylinder to front wheels and fron rear axel to right rear wheel. Sticking has occurred on the left front and left rear recently. Never the front right and one a while back on the right rear. Meatl lines still a possible. Many thanks for input from everyone. Keep them coming. I'm determined to solve this perplexing problem!

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  • 3 weeks later...

Brooke, the answer is to buy a Model T! Actually, were very familiar with this problem - happened once to my wife's MG and the problem was a NOS brake hose that was collapsing internally. It looked fine from the outside, and we knew it had been replaced so no way that it could be the problem, but we eliminated everything else and then removed it, and sure enough, it was coming apart from the inside. Recently went to a car show and listened to a good friend with a Natl Senior 56 Chevy tell us about how he has started to really enjoy driving his car, except that he had this terrible brake lock-up problem and in an effort to solve it had replaced everything - except the brake hoses, which were NOS when he installed them two years ago. Well, Sue told him about her problem and after replacing those hoses everything was fine. Im no expert but this was our solution. <BR>Terry

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Lots of good ideas here. I had a 54 Ply with the same brake setup that had lockup and grabby brakes after I replaced the shoes with the new non asbestos friction lining material...found some NORS shoes with asbestos linings and solved the problem!<P>Willie

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Brooke,<P> One thing about working on brakes, every problem could have a number of causes. First, if you have an old "junk" drum, cut out the center, mount it on the car and watch what happens. You may have a notch on the backing plate and the shoe catches. You may have that side adjusted just a hair tighter than the other and it locks up. You may have a blocked line and it doesn't allow the fluid to return(when it locks up, try opening the bleeder and see if that frees it).You may have dirt in the line as stated earlier. You may have a crimped flex hose(take it off and blow through it BOTH ways). It could be separating inside permiting it to flow one way, but usually that would be a constant problem. I stress usually. Have you bled all the air out of the system? It sounds like you have an upper and lower cylinder on each wheel. Make sure you've bled them in the proper sequence. Don't forget, your blocked lines may be on the opposite side of the car not allowing fluid to the other side. How are the drums? Are they egg-shaped? You may be hitting a high and low spot. <P><BR>Sometimes you have to start from scratch and check everything. Usually it turns out to be some stupid thing you never suspect. That's why you may have to start from the beginning. That means disconnecting steel lines, blowing them out, making sure there is free flow. Did it move from the front wheel to the rear wheel or did I misunderstand that? If it's just the rear wheel, and I assume the emergency brake cables go to the back wheels, make sure the cable isn't hanging up. It doesn't take much to keep that brake applied. Make sure the cables work freely.<P><BR>Try not to focus on one thing like the fluid. If you had to, you could use almost any fluid in the system for a short time. Finally, if you changed the master cylinder, I've seen the wrong length pushrods used because the cylinder was slightly different from the original. It was actually meant for a different application, but looked similar to the original. Now thats really reaching for a solution.<P>

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  • 2 months later...

Sorry I haven't replied sooner - I've been without PC for several months.<P>I have 59 Dodge Royal Lancer which had exactly this problem. Reversed OK but catches when going forwards.<P>My local mechanic solved it...<P>Wrong size brake shoes!!!!<BR>Apparently there is a fractional difference in size between the original brake shoes, and newer editions.<P>Solution is to change your brake shoes but be sure to replace with original specifications.

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I'd find out if you have a hydraulic or mechanical problem. When that wheel locks up again, be prepared to crack a bleeder screw to see if there is any pressure in the line, (should be under 15 PSI,should be some as the result of the residual pressure valve). If there isn't significant pressure, then it's a mechanical fault, such as mentioned; incorrectly installed shoes, shoes not properly arced to drum, no relief at heel and toe of shoe, notched or worn shoe ledge(s) on backing plate, etc.

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