Ever had self adjusting brakes overtighten?

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Ken71Twister

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I recently replaced rear brake pads and brake cylinders. I have 10 inch drum brakes on a '71 Duster. I called myself adjusting the brakes to where I could barely detect a drag during wheel rotation. Yesterday- I took the car out and, after a 15 mile highway drive, I detected the smell of hot brakes. The wheel wasn't much more than warm - so I headed home about an hour later. I sensed a drag after a few miles on the highway - so I pulled off and found the left rear brakes smoking hot. I jacked up the car, pulled the wheel, and backed the adjuster off all way to drive home. No problem on the way home (except maybe no brakes on back).

Question 1 - Anyone ever have the self adjusters cause the brakes to overtighten?

I'm considering disabling the automatic adjuster and manually adjusting the rear brakes. I don't put a lot of miles on my car and I'd prefer to manually adjust them a time or two each year than to have another episode like yesterday.

Question 2 - Is the brake adjustment likely to remain in place without the pressure of the self adjuster against the notched wheel?
 
Could you have mixed up the adjusters side to side? Or put the secondary shoe on the primary side? The adjusters are only supposed to adjust up when braking in reverse.
 
Agree with toolmanmike. Probably the adjusters are switched from side to side. Ken, I learned about that when the same thing happened to me after my first home brake job way back in my rookie years.
 
The brakes were replaced one side at a time - so the adjusters were not swapped. As for secondary shoe on primary side....please educate me on which is primary and which is secondary. I called myself putting new shoes on the same way the old shoes were setup. I'll need to pull the wheel and look to verify the primary vs secondary shoe location. I'm looking at a picture in the service manual of the left rear wheel/brakes. I recall looking in the manual for guidance on which shoe went where and only found the picture for the left rear. I almost hope I screwed up - that might explain why the parking brake wasn't holding well enough on a steep hill.
 
The brakes were replaced one side at a time - so the adjusters were not swapped. As for secondary shoe on primary side....please educate me on which is primary and which is secondary. I called myself putting new shoes on the same way the old shoes were setup. I'll need to pull the wheel and look to verify the primary vs secondary shoe location. I'm looking at a picture in the service manual of the left rear wheel/brakes. I recall looking in the manual for guidance on which shoe went where and only found the picture for the left rear. I almost hope I screwed up - that might explain why the parking brake wasn't holding well enough on a steep hill.
The primary shoe is always on the front position and is the shorter of the two shoes. Note the shorter shoes on the outside.

brake shoes.jpg
 
after you assemble the brake shoes and hdwe on the backing plate, as a check I always pull on the adjusting cable several times to make sure the adjusting pawl is engaging the teeth of the adjusting wheel correctly, and advancing the screw, and returning to the next tooth correctly.
There is always the possibility of a frozen emergency cable, also. When the cable is pulled and then released, the cable may not retract fully in the sheath, therefore applying undue pressure on the brake shoes. A little extra pressure can be enough for unwanted brake drag, and extra heat.
 
I'm headed out to pull wheels and check. Based on info I've just looked up - the leading/primary shoe should be the shorter shoe. Agree?
 
after you assemble the brake shoes and hdwe on the backing plate, as a check I always pull on the adjusting cable several times to make sure the adjusting pawl is engaging the teeth of the adjusting wheel correctly, and advancing the screw, and returning to the next tooth correctly.
There is always the possibility of a frozen emergency cable, also. When the cable is pulled and then released, the cable may not retract fully in the sheath, therefore applying undue pressure on the brake shoes. A little extra pressure can be enough for unwanted brake drag, and extra heat.
Yes, did you apply the E brake and then the tight brakes happened? Had you test driven it and it worked fine until you tried the E brake?
 
I'm headed out to pull wheels and check. Based on info I've just looked up - the leading/primary shoe should be the shorter shoe. Agree?
shorter brake shoe is always on the front side of each backing plate.
I use my hand to advance the wheel until each drum just slides on easily with little or no drag. You have to slap each side of the shoe assembly to make sure it is free and pivoting around the top anchor post AND to center the assembly on the backing plate (and thus centered in the drum).
After you bolt the wheels on, drive someplace vacant and safe, and backup straight at 5 or so mph, and step firmly on brake pedal. You don't want to skid the tires, but still a rather abrupt stop. This will hopefully advance the self adjuster properly and you will get minimum shoe clearance without brake drag.
 
For the record - I posted my question in #7 before the #5 post appeared - which answered my question about which shoe faced forward.

I just pulled the left and right wheels off and the shoes are in the proper location. I also checked the adjusters by pulling the adjusting cable and the adjusters are moving in the right direction.

To answer an earlier question - I’ve driven the car several times since the brakes were installed and I’ve used the E-brake several times with nothing to make me think the brakes were hanging up. I did find that the E-brake wasn’t holding as well as I thought it should and I jacked the car up and played with the manual adjustment to make sure it was right and all seemed to be okay. The E-brake seemed to fully release the brakes and then seemed to engage the brake early in the stroke - so I didn’t change the adjustment in the E-brake cable.
 
If you press on brake with e-brake applied its possible to over-adjust brakes. Sticking emergency brake cable or wheel cylinder.
 
First photo is left rear and second photo is the right rear. I’m going to back off the adjustment on both sides and let the self adjusters do their thing and see if I have a repeat of the issue. I’ll also check the E-cable vs release a couple of times before I button things up. I’m still left with the head scratcher that the E-brake doesn’t hold well on a steep hill. I was counting on this to improve as the brakes tightened. They were still loose enough to that I could back the car with the E-brake on. I always noticed right away when going forward. If the brake gets too tight again and if no one tells me I shouldn’t - I figure my next step will be to disable the automatic adjusters.
 
If you press on brake with e-brake applied its possible to over-adjust brakes. Sticking emergency brake cable or wheel cylinder.
Interesting but makes sense the the e-brake could mess up automatic adjustment. Hmmm. I do sometimes back up before I notice that the E-brake is still engaged. I wonder....
 
e- brake is ALWAYS weaker in reverse gear.
the short shoe/long shoe, single wheel cylinder "modern" design is also called "self energizing" because it utilizes the forward rotation of the drum to add leverage to the brake shoes. In reverse, you don't get that effect. It's not usually a problem because you're not usually driving 35mph in reverse.
 
you might want to back off on the e-brake completely to take that variable out of the equation. Once you get the brakes working correctly, then you can worry about the e-brake. is the car an automatic or a stick?
 
Remember “BOB”. Big on back. I always remove the self adjusting stuff, has caused me more trouble than it is worth. It’s not hard to check them a couple times a year. Replace your rubber flex hose too, those will cause your brake shoes to not fully return home.
 
Several other things come to mind;
1) the wheel cylinder pistons could be sticking
2) the fluid may not be returning to the M/C
3) the fluid is boiling.

check that the shoes are properly parked on the anchors and that they return smoothly after application.
If you have water in the w/c and it boils, the resulting gas pressure could apply the brake, if it can't blow the fluid back into the M/C; ie if the compensating port is restricted ,plugged, or blocked by the piston.
 
Top picture, short shoe. Its seperating. The lining is coming off. And looks like lead shoe on other side may be coming apart too. Whether its a result or cause, im not sure.
 
When i do brake jobs, im diligent to check e-brake is fully released. Especially before adjusting. I pry e brake lever to see that its fully returned.
 
I keep going back and looking at pics. Top one looks like e-brake is partially on.
 
Top picture, short shoe. Its seperating. The lining is coming off. And looks like lead shoe on other side may be coming apart too. Whether its a result or cause, im not sure.
I can't tell if that is the case or not, but he brings up a good point. Unless the linings are glued AND riveted, if they get hot enough the glue can melt and the lining can slide out of position on the shoe.
 
Update... With adjusters backed off and self-adjusters still intact.. I went out and went thru the ritual of backing up and applying brakes ...over 50 cycles. This started with a very spongy brake pedal and ended with a nice solid brake pedal. I then jacked the car - one side at a time - and the rear wheels are too tight. I can turn them but way too much drag on both sides. I must also amend my previous statement that the E-brake doesn’t need adjustment. With the brakes so tight the E-brake is still relatively ineffective and I can pull the handle to the stop. When this is over with the brake adjusters - I’ll adjust the E-brake handle to tighten things up. If I don’t get any great solutions - I’ll go back to plan A and manually adjust the brakes and disable the automatic adjuster. I’d rather find a rationale and correctable solution to the automatic adjusters that have worked fine for 48 years.
 
I keep going back and looking at pics. Top one looks like e-brake is partially on.
I can’t guarantee .... but I can’t imagine why I’d have the E-brake on since that would have made it very difficult to pull off the drums.
 
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