Brake issue with DD

[DollyDodge]

I started having problems with the Right Front brake locking up on Dolly Dodge 6 months ago or so.  Then it would be ok for a while, but then it all of a sudden it would lock up again.  If I was light on the pedal it wouldn't complexly lock up, but if I pushed the pedal down fairly hard the brake would lock the wheel up and then release slowly.  I replaced the front brake cylinders this weekend in hopes that would help (besides they needed replacing, when I rebuilt them almost 6 years ago their was pitting on the cylinder).  After the new cylinders were in the brakes worked really great.  I probably got 50 or 60 uses on Sunday and then I could feel them start to grab, and release slowly.  Now both front brakes are grabbing, with the Right being the worst.  Is this a master cylinder issue?  It was replaced about 5 years ago with a new one.

 

[Jeff Balazs]

I would think that it is more likely to be an front brake adjustment issue. I don't have drum brakes so I can't walk you through this but I do know that there is a specific sequence the adjustments must be made in. I am sure someone with the patience for drum brakes will chime in.

Jeff

[jeffsunzeri]

First check the master cylinder actuating rod - pedal clearance. Next check for kinks in the brake lines and/or old flexible lines. Then the final suspects would be the return springs, shoe pivot cleanliness, and then the shoe minor adjustments.

 

[DollyDodge]

Thanks. 

I will try the pedal clearance.  I know there is way more free play than there should be according to the manual-I hadn't messed with that yet for fear I'd cause more problems.  It has had the same clearance for about 6 years now.  I checked the lines, and they seemed fine (flexible ones are new). The shoes seemed to move easily.  Return spring seemed fine when I took them off.  I did the minor adjustment according to the service manual. 

As a side note, when I took out the old cylinders I see they are both the same, no left or right. 

 

[MBF]

We had this problem on a friend's truck years ago.  Turns out the rear cylinders were frozen up and the front brakes were the only one's working.  If you haven't already done so, I'd replace all of the flex hoses.They wouldn't cause the brake to lock up, but they could cause a slow release    If your front cylinders were leaking, you could have fluid or if the seals are leaking grease on the shoe linings which as the shoes get hot is starting to come to the surface which could cause them to grab. Did  you clean and lube lube pivot surface and the felt washers/ on the bottom adjustment bolts?  Mike

[JBNeal]

Folks have trouble understanding when I tell them that shocks (& struts) help with braking...in short, shocks keep the nose from diving while braking, keeping the rear tires planted, which allows the rear brakes to reduce speed more.  After replacing several sets of struts and shocks on different vehicles, I immediately would find problems with brakes, primarily vibrations from warped rotors.  Once that got addressed, the improved braking performance was eye-opening:  two trucks I reworked could stop on a dime and give ya nine cents change, when their braking before was marginal and somewhat high on the pucker factor when in traffic.  These trucks are no different, with new shocks that can magnify the problems with the rear brakes.

[DollyDodge]

Ok, here is an update.  I adjusted the free pedal to 3/8 inch (as listed in the shop manual), checked the relief flow by watching the fluid it the master cylinder, check the brake lines (no damage and fluid flows through easily), checked the spring, made sure the pads moved easily on the mounts, and all seems fine.  I did the minor adjustment as well.  I sill am having troubles.  After the free pedal adjustment the brakes felt great, got a dozen or so stops and everything was fine.  Then I could feel the front brakes, both at first, then after several applications of the brake, mainly the right front.  This isn't just a drag, the brake actually locks, and releases slowly. I tried it going very slowly in granny, both forward and reverse, and it still happens.  I apply very light pedal pressure, and the brakes begin move on their own even if I release the pedal it will lock the front right.  The other thing is there is brake fluid coming out of the filler plug, until it nearly empties the reservoir after multiple stops.  The master cylinder is new, but I keep thinking that is my problem.  Any thoughts on this?

[ggdad1951]

Where would the extra fluid be coming from to come out the reservoir?  NO WAY it should empty...I can see bleeding out extra to a point, but empty?  All the brake lines are teh right size?  Propotioning block not plugged up/routed correctly?  Right wheel cyclinders?  Pedal return spring functioning right?

[Jeff Balazs]

You say the M/C is new.....did the problem begin after replacing this item?

Jeff

[DollyDodge]

See if I can answer the questions, but as clarification I replacedthe master cylyder  before the rebuild, and drove the truck for about 2 years with no brake issues, the rebuild took 5 years, and I drove the truck 18 months after the rebuild with no problems.  This just started happening.  So the mc is not brand new (almost 9 years old, but it doesn't have much use, I replaced the front cylinders when I first started have the grabbing issue and as I mentioned above, the brakes worked great for a while with the new cylinders, but then started grabbing again,  The fluid coming out of the filler plug baffles me, makes no sense, there is about 1/4 inch of fluid left in the reservoir when it looks like it  stops leaking.  It is making an awful mess. What doesn't make sense is when I had the filler plug out of the master cylinde and was checking for the relief flow the fluid doesn't spill out of the open hole, but when I put the plug in then fluid comes out of the plug.  Pedal return sping is fine.  Lines have not been changed. Not sure what the proportioning block is, but I assume that is the place where all the lines are connected. I haven't looked at it.  As I mentioned, the fluid seems to flow freely out of the lines when I bled them, the whole thing seems strange to me. 

[JBNeal]

if the master cylinder piston is starting to leak or if the piston bore has a problem such as pitting, then fluid in the lines will seep past the piston when depressed, leaking back into the reservoir when the piston returns back past the reservoir port...eventually, the "overfilled" reservoir will overflow.  I recall having this problem with my master cylinder before I sent it off to be sleeved

[Don Coatney]

Have you replaced the rubber hose lines on the front and rear brakes? Is it possible they are ballooning and filling with brake fluid. Then when they collapse the fluid returns to the master cylinder. 

[rb1949]

2¢ here. Baffled with similar R-F problem. Everything looked good. One day sprayed shoes down with brake cleaner. Stopping worked great. 4 days later problem returned. This helped confirm that although the shoes looked OK, they were contaminated with something.Replaced front shoes. Stopping power has been good ever since. Good luck chasing down all the possibilities.

[Jeff Balazs]

4 hours ago, Don Coatney said:

Have you replaced the rubber hose lines on the front and rear brakes? Is it possible they are ballooning and filling with brake fluid. Then when they collapse the fluid returns to the master cylinder. 

Also.....Are the metal lines original? or have they been replaced as well? Just trying to get a clear picture of the conditions.

Jeff

[DollyDodge]

I replaced all the rubber hoses on al 4 wheels in 2011.  All Brake shoes were replaced in 2011.  The truck has less than 1,000 miles since 2011.  The brake lines are original.  Fluid looks clear and clean when I bleed the brakes. 

BTW thanks for all the input from everyone.

[Jeff Balazs]

Not sure I would trust those old metal lines to be totally clear of debris. I don't know if it is possible?......but what would happen if some debris or metal flakes got hung up in a junction block or a wheel cylinder? Not saying this is the problem but it seems a possibility. If water ever did get into those lines it would attack them from the inside and might not show at all externally. All this is just supposition on my part. I am certain that someone more in tune with the inner workings of these particular drum brakes will come up with other ideas.

Jeff

[JBNeal]

I cut an old brake line to verify this year's ago:  if it's rusty on the outside, it will be rusty on the inside...and that's a good combination for pinholes to develop

[pflaming]

I would remove the brake line that is the easiest to remove and replace.  Then I would cut that line and see what the inside looks like. I'm no pro at this but I have yet to find a good brake line on a 50 rear old vehical. My lines are all new. Best of luck to you, problem solving is the worst.  I have discs on the front, so pleased with the results. 

[DollyDodge]

Thanks all.   I will look at the brake lines.  The thing that is amazing in this dry country is stuff just doesn't rust.  The lines on the outside have no rust.  Most were covered with dirt and grim but I cleaned that off, and they all look good.  When I did the rebuild, for the most part everything just came apart easily.  There were few rusty bolts and nuts, but not many.  I will look at that junction box next.  I agree, in my  mind, which doesn't understand a lot of mechanic stuff, it seems the flow must be blocked somewhere.  Oh well, I will keep picking away at it, until something works.

[Young Ed]

16 minutes ago, DollyDodge said:

Thanks all.   I will look at the brake lines.  The thing that is amazing in this dry country is stuff just doesn't rust.  The lines on the outside have no rust.  Most were covered with dirt and grim but I cleaned that off, and they all look good.  When I did the rebuild, for the most part everything just came apart easily.  There were few rusty bolts and nuts, but not many.  I will look at that junction box next.  I agree, in my  mind, which doesn't understand a lot of mechanic stuff, it seems the flow must be blocked somewhere.  Oh well, I will keep picking away at it, until something works.

Even though you replaced them I'd be looking at the flex lines first.

[Dodgeb4ya]

Wipe the right front shoes off with lacquer thinner thoroughly.

Drive it see if it's better.

If so a shoe lining issue.

I don't like modern day shoe lining on the old MoPars. Way too sensitive to dirt and any other contaminants... one microscopic speck of grease/ brake fluid the shoes are done. . The original asbestos linings did not have these constant ongoing issues like many many people are having these days.

I deal with it a lot in my work on the old 1934-1960 Mopars and see way too many cars with these same issues over and over again on complete re-do's..

Tired of fighting it..

[bach4660]

I know it sounds wasteful but master cylinders are only $80 I would replace. I found mine was only 1500 miles but about 5 years old and had signs of pitting inside.  But I'm also in very wet part of the world, so maybe the 300 days of rain a year contributes.

[Jeff Balazs]

On 10/14/2016 at 8:15 AM, DollyDodge said:

Thanks all.   I will look at the brake lines.  The thing that is amazing in this dry country is stuff just doesn't rust.  The lines on the outside have no rust.  Most were covered with dirt and grim but I cleaned that off, and they all look good.  When I did the rebuild, for the most part everything just came apart easily.  There were few rusty bolts and nuts, but not many.  I will look at that junction box next.  I agree, in my  mind, which doesn't understand a lot of mechanic stuff, it seems the flow must be blocked somewhere.  Oh well, I will keep picking away at it, until something works.

Not saying that you have this problem. But just because there is no rust on the outside....doesn't mean that they are not corroded or rusty on the inside. If it sat for a long time there is a possibility that there was moisture in the system......and it will work against you from the inside. Pitted wheel cylinders are one example of this. When I replaced the lines on my truck which had sat for many years I found plenty of evidence of pitting and corrosion inside the hydraulic system. It was not too rusty on the outside either. It seems to me that brake fluid actually attracts water.

Here is hoping you find the problem. Problems like this can be quite frustrating to pinpoint.

Jeff

[squirebill]

I'm trying to wrap my head around this problem but can't seem to get there from here.  I do have a few questions:  at some point you step on the brake pedal and the brake/brakes begin to lock up or do lock up.  You release pressure on the brake pedal.  Then after a period of time the brakes release.  Is this correct?  After the brakes/brakes lock up does the brake pedal return normally or does it come back slowly as the brakes release?  OK, so after the brakes lockup and release, how does the pedal feel the next time you apply the brakes?  Is it mushy/spongey like there is air in the lines or is it solid?  How "new" are the brake hoses?  Very recent or were they replaced awhile ago and just don't have many miles on them?  Is there any rust forming on the end fittings of the hoses where the hose goes into the fitting and is crimped? 

[DollyDodge]

On ‎10‎/‎18‎/‎2016 at 3:54 AM, squirebill said:

I'm trying to wrap my head around this problem but can't seem to get there from here.  I do have a few questions:  at some point you step on the brake pedal and the brake/brakes begin to lock up or do lock up.  You release pressure on the brake pedal.  Then after a period of time the brakes release.  Is this correct?  After the brakes/brakes lock up does the brake pedal return normally or does it come back slowly as the brakes release?  OK, so after the brakes lockup and release, how does the pedal feel the next time you apply the brakes?  Is it mushy/spongey like there is air in the lines or is it solid?  How "new" are the brake hoses?  Very recent or were they replaced awhile ago and just don't have many miles on them?  Is there any rust forming on the end fittings of the hoses where the hose goes into the fitting and is crimped? 

When I push the pedal down it feels normal, then I can feel the brakes start to grab, so I release the pedal and it returns to the normal position normal (goes right back-quickly), and the brakes will grab, and then release slowly and the pedal is all the way back in its normal position.  When I apply the pedal again it feels fine.

I think I will get new hoses for the front,  That recommendation has come from lots of you.  I will try the lacquer cleaner on the shoes.  I have about decided to try a new MC as well.   When I took the front cylinders out, and replaced them with new cylinders, there was surface rust around the end cups on the inside.  But everything inside looked clean.  I will keep after it, but I am really busy until December, I will get all the hoses, new MC, and try that in Dec, and let you all know.  I wish I had the tool to do the major brake adjustment but I don't.  I really don't think it is an adjustment problem, because it was fine for well over a year-but I don't understand a lot of this stuff...learning on the go