rear brakes adjusting to tight

[Nekkedbob]

When I bought my truck about 8 or 9 years ago the rear brakes had been over heated and would shudder when the rear drums got hot. I  have replaced the shoes and drums once and had 3 different shops do rear brakes including drums , shoes, Ebrake cables hardware and had them check everything that go with it.  The last time was in Oregon ( I live in Wi.) when I was in vacation in Oct. when they overheated on the way there and again they have self adjusted back to the point that they drag and the pedal has moved up to the top of the travel.  I have 2 question. 1 Can anyone think what else to check. 2 What components do I have to remove to get rid of the self adjusting and just make it manual adjust like they were years ago.       

[Mopar1973Man]

The only thing I can think of is the cable is too short maybe and causing the auto-adjuster to pull the shoe too tight. 

[Royal Squire]

If e-brake cable is too tight, could that cause it?

[Nekkedbob]

When I and the shops did the adjustment everything looks to be set right but as i said the adjustment creeps up ( it takes months ) to the point they drag which they didn't when first installed.

[Mopar1973Man]

2 hours ago, Royal Squire said:

If e-brake cable is too tight, could that cause it?

 

Possible if the parking brake cable doesn't have enough slack to drag the brakes but that would be the other way around tight at first then lighten up later. 

[Nekkedbob]

After more research I think that I can install both bottom spring and the adjuster backwards it may solve my problem. I would have to use the other adjustment hole but I don't mind.

After I did the first brake job I thought that I my have done something wrong and couldn't tell what it was so I sent it to my trusted local shop and he went through it and adjusted it a little tight but I couldn't tell when I left. 50 miles later that day the brakes are dragging and smoking. He came out (50 miles to his credit) and backed them off and when I got it back to his shop neither he or me could find anything done wrong so he put it back together with the brakes adjusted loose.Lasted just over3 years almost 4 and overheated on a trip again. I then found a local shop that only did diesel pickups and had them do the brakes again and I told him to adjust them loose. 3 years later in a trip they overheat again in Wy. Buy the time I caught it the drums were warped so I backed them off and went the rest of the way to Or. The shop in Or. did the 4th brake job and I asked them to go completely through it again to see if they could find the problem. New drums, shoes, hardware. parking brake cables and here I am again. Im old enough to have owned many cars without self-adjusting brakes that I don't mind crawling under it once a year to adjust them.

[Mopar1973Man]

Going by memory... 

 

If I remember correctly the cable typically is ran on the front shoe and down to the ratchet arm. The adjuster can only go one way being if you install it backwards then the adjuster will add slack every time you hit the brakes. But I've not done drum brakes on a Dodge in a long time.

[Tractorman]

On 12/25/2021 at 9:17 AM, Nekkedbob said:

When I bought my truck about 8 or 9 years ago the rear brakes had been over heated and would shudder when the rear drums got hot.

 

On 12/25/2021 at 9:17 AM, Nekkedbob said:

The last time was in Oregon ( I live in Wi.) when I was in vacation in Oct. when they overheated on the way there and again they have self adjusted back to the point that they drag and the pedal has moved up to the top of the travel

 

In the first quote you mention "brakes" as in plural.  In the second quote you mention "they", which indicates plural again.  So, I am understanding that both brakes on the rear axles are overheating.  It is highly unlikely that a self-adjuster will cause this - especially in both drums simultaneously.  By nature, a self-adjuster can only move the adjuster when there is enough movement in the brake shoes.  Even if the brakes are initially adjusted too tight, the self-adjuster cannot grab a tooth on the star wheel until the brake lining has worn enough to allow for enough brake shoe travel for the self-adjuster to grab the next tooth on the star wheel.  

 

On 12/25/2021 at 9:17 AM, Nekkedbob said:

What components do I have to remove to get rid of the self adjusting and just make it manual adjust like they were years ago.

15 hours ago, Nekkedbob said:

After more research I think that I can install both bottom spring and the adjuster backwards it may solve my problem. I would have to use the other adjustment hole but I don't mind.

 

I highly recommend to not do this.  There is something wrong with the brake system.  The problem needs to be resolved, not skirted around.  When I have situations that are very difficult to resolve, I go back to fundamentals to help arrive at good conclusions.  I seek help from people who understand and can explain the fundamentals well.  Unfortunately, there are fewer and fewer people around who know drum brake systems well, since the drum brake system is becoming obsolete. 

 

That being said, the thing that I see being repeated in your posts is that both rear brakes are overheating at the same time.  You also mentioned, "and the pedal has moved up to the top of the travel".   This could indicate a hydraulic problem - specifically, brake fluid is not making its way back to the reservoir when the brake pedal is released.  A possible source could be brake master cylinder.  The first 1/8" forward movement of the dual piston in the master cylinder covers up the compensating port of each piston bore.  These compensating ports allow for thermal expansion and contraction of brake fluid when brakes are not applied.  If the pistons do not return to their home positions, then brake fluid can be trapped in the brake lines which would not allow for the full return travel of the brake shoes.  Over time the brake shoes creep toward the drum surfaces and finally begin to drag.  

 

If the hydroboost unit has been replaced at some point in the past, then the pushrod length adjustment could cause this anomaly.  Also, there should be some sort of a proportioning valve in the rear brake hydraulic system as well as the anti-lock brakes for the rear axle.   These are potential sources of the problem.

 

I am not saying that these things are the cause of your problem, but a possible hydraulic lock would match the symptoms you are having, including the inconsistent time intervals between events.  Backing off the brake adjustment and starting over would just mask the problem.

 

- John

 

 

[IBMobile]

27 minutes ago, Tractorman said:

I am not saying that these things are the cause of your problem, but a possible hydraulic lock would match the symptoms you are having, including the inconsistent time intervals between events.

To test if one of those things is causing a hydraulic problem, opening the bleeder screw at one of the rear wheel brake cylinders will release any pressure and increased brake fluid volume in the rear braking system.  This would allow the springs to return the brake shoes to a retracted position.  If there is an increase in pressure you may see brake fluid squirt out, not dribble out when the bleeder screw is opened.

[Tractorman]

1 hour ago, IBMobile said:

To test if one of those things is causing a hydraulic problem, opening the bleeder screw at one of the rear wheel brake cylinders will release any pressure and increased brake fluid volume in the rear braking system. 

 

This is an excellent idea and an easy step that will have informative results.  I was going write that in my original post, but I forgot to do so.  I seems that I forget many things, but I don't worry too much because shortly I will forget that I forgot.

 

- John

[Nekkedbob]

Just a FYI I have been doing brake jobs since the 60s and lost count many years ago. When I said brakes overheated both me and the other mechanics could not visibly see which one or if both did it.  When I bought my truck I could not tell that they had been overheated because I live in a fairly flat area. On at 400 mile trip I had to use the brakes more then I like and when they got hot I had a bad shudder ( steep down hill in a panic stop from 60 MPH with 600 pounds on the bed) that would go away when they cooled off.  I was taught on drum brake (note when I said I started doing brake jobs) and just in case I missed something I have made use of and asked and bothered many other mechanics. And yes it has been checked for residual  pressure and none has been found. Maybe I am wrong but if it is a hydraulic problem I would think it would rear it ugly head a little more often then mine has. I did have this problem on a 68 ford in the 70s and took the self adjusters out. That was the cable and pawl that MPM mentioned and the problem went away. Mine has a rod, lever and a pawl that I did not want to remove until I could confirm that it was the problem. I also want to say I was taught to drive with the motor and transmission and only use the brakes minimally. I also have spent most of my working life looking through a windshield of cars, pickups ( on site field service ) and big rigs (owner/operator )  and because I owned them I learned to drive to make them last because I had to fix them when the broke or wore out.

[wil440]

After reading over the responses I can see where tractorman is coming from with a hydraulic problem but there is also one other thing that could cause both rear brakes to drag and that is the primary E brake cable from the cab or the E brake lever seizing or at least sticking, my lever does sometimes not quite come off

[Haggar]

By chance do you have the Mechanical load system on the rear axle of your truck?  (some had it.  trying to find a picture)  SOme had it in the combination valve.  (so you could have an issue in your combination valve... )

This was a mechanical way to prevent the rear wheels from locking up, when the axle stayed stationary and the bed lifted.  It would also do the reverse, allow more flow to the rear brakes when the bed moved down relative to the axle.... (pulling a trailer,  weight in the bed etc.)

anyway, that is one thought.  The other you mention changing all kinds of things EXCEPT the hose/hoses in the rear brake system.   IF you don't have the mechanical rear anti-lock there is only one hose.   If you have the mechanical anti lock  there may be 2 hoses.   Dodge brake hoses have been NOTORIOUS for failure on the inside limiting/preventing fluid returning to the master cylinder.  (a tsb uses the 2 hoses to remove the mechanical valve.)

 

Next time you think they have approached their too tight adjustment,  loosen the bleeder on one side or the other.  If you get any squirting of fluid from the brake system, you have yourself your own pressure accumulator somewhere, and I bet it is a hose but it could be the combination valve if it has the proportioning valve internal or the external proportioning valve.

 

Merry Christmas and Happy New year!

 

Hag

 

 

[Nekkedbob]

I do have that valve on the rear and I lowered the rear for my 5th wheel and that valve sets at it max but I only did that 4 years ago. I have cracked the bleeder and it has on pressure after brakes have been applied and released.  My trailer is small and only has 800 pounds tongue weigh.   

Edited December 29, 2021 by Nekkedbob

[Haggar]

Your description is that it only happens over time.  So I would check for pressure when they seem to have self adjusted too far. 

 

It seems so strange that properly applied self adjusters would over tighten over time.   I can't believe you back up that much!  The system is looking at the reverse motion of the brake shoes relative to the backing plate.  If there is no looseness (the brakes are adjusted pretty tightly) there is no movement of the shoe relative to the backing plate to allow the arm to tighten the adjuster.  So it really can't over tighten.

 

 

Good luck!   I hope you find the issue.  That is no fun at all.

 

You can just remove the cable from the lever if you like to disable the function.  (make sure the lever can't rotate too far or something with the cable gone.)

 

I would double or triple check that the adjuster rotation is proper.  I think if someone swapped them, they may tighten during forward stopping action.  (not sure, not enough coffee for mental models to work properly yet....)

 

HTH

Hag

[Tractorman]

1 hour ago, Haggar said:

You can just remove the cable from the lever if you like to disable the function.

 

If the cable is removed, there nothing to stop the adjuster from backing off and reducing brake performance.  A manual brake adjuster should be used.  It has a much coarser, rounded tooth pattern with a spring clip that locks the adjuster in place.

 

1 hour ago, Haggar said:

It seems so strange that properly applied self adjusters would over tighten over time. 

 

I agree.  Personally, I don't think it is a self-adjuster issue, but I could be wrong.  If it was my truck, I would figure out what is actually causing the problem before making an assumption it is the self-adjusters and then modifying the braking system based on that assumption.  I would start by adjusting the rear brakes in a normal manner.  Then I would just drive the truck.  I would frequently check the brake drum temperature carefully by hand so that I would be aware of the heating of the brake drum / drums before it got out of hand.  

 

- John

[Nekkedbob]

I agree that this should not happen. I have owned many cars and pickups since the 70s and most of them have had self adjusting brakes with no problems. My thought was to disable them and see if the problem reoccurs without removing the parts ( I tend to miss place things and then have to replace things only to find them far to late ) . My first thought was I did something wrong and that is why it has been done by other shops with full history when done. Looking at pictures and diagrams it appears that if I reverse the lower spring ( this keeps the pawl from moving) and adjuster should do it. Per two different shop all hardware has been replaced including parking brake cables and adjusted correctly.

[Tractorman]

@Nekkedbob, it seems that you have a unique situation.  I don't think anyone here is challenging your knowledge - I know that I'm not.  But, I also know that when very unusual problems occur, sometimes I have to sit back and rethink things, kind of start over.  By starting over, I mean set the brake adjustment as it should be.  Then monitor the performance regularly as I mentioned in my previous post.   At least then you should be able to find out which is the problem side (if it is only one side).  If it turns out to be both sides happening simultaneously, that will be good information to know. 

 

 

On 12/26/2021 at 6:50 PM, Nekkedbob said:

When I said brakes overheated both me and the other mechanics could not visibly see which one or if both did it.

 

This would be another strong reason to start over with diagnosing without changing anything first.  You need to know which brake assembly is the problem or if both brake assemblies are having the problem at the same time.  That information alone would be of great help to move ahead diagnosing the problem.

 

You have provided a lot of information, but you haven't given much detail.  For example, you said, "And yes it has been checked for residual  pressure and none has been found."  What were the conditions when this residual pressure check was done?   If the check was done when the brakes were hanging up, the results of the check would have value.  If the check was done hours or days later, then the check would have absolutely no value.

 

Like you, I have done a countless number of rear drum brake repair work.  One of the most overlooked things I have observed (even by qualified brake specialists) is the parking brake actuator not being backed off enough to allow both brake shoes on both sides to set firmly against the anchor pin.  They may mount the brake shoes correctly on one side, but when the brake shoes are installed and compressed to set on the anchor pin on the other side, energy is transferred through the park brake equalizer, consequently energizing the park brake lever on the previous side which will promptly move the brakes shoes away from the anchor pin.  That action usually does not get observed.  The park brake cables must be relaxed considerably for this not to happen.  I don't think this is contributing to your problem, but it is still worthy of mention.

 

I am really interested to hear what the final fix is going to be.

 

- John

 

 

 

Edited January 4, 2022 by Tractorman

[Mopar1973Man]

As for your brakes I would double check everything. Assembly, cables, you can actually look at the way things work in the drum by having a partner slow and lightly pressing on the brake pedal and watch the shoes slowly expand past the point, it should pull the cable tight and ratchet up the star wheel. I wonder if the ID of the drum is TOO wide and constantly wheeling up the shoes because the shoes are just traveling too far every stroke. I would suggest checking the ID of the drum for size. 

Edited January 4, 2022 by Mopar1973Man

[Nekkedbob]

When I checked the residual pressure I had drove about 25 miles total in town and parked in the driveway which is flat and let it idle when I got the wrench. I did check everything in the parking brake system and went so far as to even install a helper spring on the equalizer just encase the parking brake pedal was not releasing the cable. Yes MPM my only next thing is to find one in a junk yard and start to compare measurements. I would not be surprised if I find that a replacement component out of spec . One other thought was does any body know where I can  find a parts breakdown or assembly instruction for the parking brake pedal assembly as that is one thing that I nor any of the other shops did not take apart because it appeared to work fine.  My truck is now put away for the winter because they are now salting and deicing the roads and would really hate to need to buy another one before I die.