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Drum brake problem, parking brake failure after shoe replacement

Tiny
FISHMISER36
  • MEMBER
  • 1988 CHEVROLET 1500
  • 5.7L
  • V8
  • 2WD
  • AUTOMATIC
  • 230,000 MILES
Replaced rear drum brake shoes. Also wheel cylinders. Shoes were dragging and got smoking hot after highway driving less than 20 miles. Only driver's side rear. Pulled drum adjusted and drove highway again. Driver-side okay, now passenger side rear was smoking hot. Pulled drum and adjusted. Shoe drag/heat problem solved, but now parking brake total failure, and spongy braking. Double pump to brake full stop, and light comes on pedal close to floor. Release pedal light stays on until I give slight tap on brake pedal. Brakes do work. Truck does stop okay, but no parking brake holding power. Tried adjust automatically, then again manually, and again braking in reverse-forward-reverse multiple times. Still no parking brake. Still double pump, spongy brake. Also I did bleed brakes after wheel cylinder and shoe replacement. And again sometime after. How do I trouble shoot this?
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Monday, December 16th, 2019 AT 3:37 AM

11 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 108,336 POSTS
Hi,

First I need to determine which brake system you have. There were two used, leading/trailing and duo servo. On the Duo Servo brake system, the adjustment screw assembly is located at the bottom of the brake shoes. The other system it is at the top.

Let me know which you have. Also, what light are you referring to that is coming on? Also, as far as having to pump the brake pedal to make it solid, that is usually the result of the brake shoes not being adjusted up properly. In other words, there is too much clearance between the show and drum.

Let me know and I'll try my best to help. Additionally, here is a link that explains brake shoe replacement. See if it helps at all.

https://www.2carpros.com/articles/how-to-replace-rear-brake-shoes-and-drums

Let me know.

Joe
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Friday, April 9th, 2021 AT 2:16 PM
Tiny
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Of course. Thank you. I have the "other type", it has the adjuster/starwheel towards the top, just below the wheel cylinder. I was referring to idiot light for the parking brake/brake malfunction light in the dash.
So with drum off, I adjusted shoes out until I couldn't get it on, then backed it off till I could. I don't think I could have got it on if the brakes were pushed out anymore than they were.
I can hear brakes every tire rotation where it rubs a bit. I can also hear some not too healthy sounding creaks and groans when depressing brake pedal coming from rear. (In neutral, driver side I think). I'm starting to get pretty frustrated and am thinking about throwing in the towel and taking it to a shop. Very hard for me to do because I can and I have handled all problems that have arisen since I started driving 20 something years ago. I can usually get it figured out.
Thank you for taking the time. Please let me know if you need more info, and I will gladly give it.
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Friday, April 9th, 2021 AT 2:16 PM
Tiny
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Hi,

Try this: Adjust the brake through the backing plate until you feel a drag on the wheel when turning. Then, pump the brakes a few times (drum on) to center the shoes. Then repeat the process until you don't lose the original drag.

Or here are the directions from Alldata. The attached picture correlates with the directions.

____________________________

1988 Chevy Truck C 1500 Truck 2WD V8-350 5.7L
With Leading/Training Brakes
Vehicle Brakes and Traction Control Drum Brake System Brake Shoe Adjustments Drum Brakes With Leading/Training Brakes
WITH LEADING/TRAINING BRAKES
Exploded View Of Drum Brake Assembly.

Pic 1
Exploded View Of Adjusting Screw Assembly

Pic 2

1. Raise and support vehicle.
2. Remove wheel and tire assembly. Mark relationship of drum to axle flange.
3. Remove brake drum.
4. Using drum to brake shoe clearance gage tool No. J-21177-A or equivalent, measure brake drum inside diameter.
5. Turning the adjuster nut, adjust shoe and lining diameter to 0.254-0.508 mm (.010-.020 in), less than the inside drum diameter for each rear wheel.
6. Ensure stops on park brake levers are against the edge of the brake shoe web. If the parking brake cable is holding the stops off the edge of shoe web, loosen the parking brake cable adjustment.
7. Tighten parking brake cable at adjuster nut until the lever stops begin to move off the shoe webs. Loosen adjustment nut until the lever stops moving back, barely touching the shoe webs. There should be no more than 0.5 mm (0.019 in) clearance between stops and either web.
8. Install drums and wheels, aligning marks made previously.
9. Apply and release service brake pedal 30-35 times with normal pedal force. Pause approximately one second between pedal applications.
10. Depress parking brake six ratchet clicks. Rear wheels should not rotate.
11. Release parking brake and check for free wheel rotation.
12. Lower vehicle.

___________________

If you look at pic 3 and 4, they show how initial adjustment is done.

Fig. 7 Measuring Brake Drum Inside Diameter

Pic 3

Fig. 8 Adjusting Brake Shoes To Brake Drum Inside Diameter

Pic 4

8. Using suitable brake drum to shoe gauge, Fig. 7, measure brake drum inside diameter. Adjust brake shoes to dimension obtained on outside portion of gauge, Fig. 8.

_____________________

Let me know if any of this helps. Also, make sure there isn't excessive play in the parking brake cable. It could be stretched.

Joe
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Friday, April 9th, 2021 AT 2:16 PM
Tiny
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Thanks I will let you know how it goes. Going to work on it tomorrow.
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Friday, April 9th, 2021 AT 2:16 PM
Tiny
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You are very welcome. I will watch for your reply. Also, you mentioned there were some creaking sounds. Make sure none of the springs have broken, come disconnected, and make sure to lubricate the backing plate where the shoe sits. If you look closely, you will see areas slightly raised that the shoe sits on. Make sure it isn't rusted which can cause a squeaking noise as well as cause the brakes to not want to release.

Take care,
Joe
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Friday, April 9th, 2021 AT 2:16 PM
Tiny
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So I ordered new drums, and hardware. Supposed to get them tomorrow. I went ahead and pulled drums today. Passenger side looked okay. Driver side was malfunctioning. The pin that holds the parking brake lever in place had come undone and was jammed behind brake shoe. The spring washer and clip were gone. I assume this was the reason for no parking brake (I know it was), as well as why the brakes were not releasing properly. The pin was pretty beat up.
When the parts arrive tomorrow, I will put together and hopefully problem will be solved.
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Friday, April 9th, 2021 AT 2:16 PM
Tiny
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Hi,

Yep, you nailed it. That is the cause of all the problems. Let me know if you need help or have any questions. Here is a link you may find helpful:

https://www.2carpros.com/articles/how-to-replace-rear-brake-shoes-and-drums

Take care and if you have the chance, let me know how it works out for you. If I don't hear from you, have a great holiday.

Joe
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Friday, April 9th, 2021 AT 2:16 PM
Tiny
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Okay. I re-did everything. Parking brake is engaging now, still not like it should. Brakes themselves, well, the pedal depresses to easily when first pushed, and upon a double pump, feels better but goes to floor. It does stop but doesn't feel right. Also parking brake light in dash comes on, and stays on unless I tap brakes sharply after brake pedal hits floor and or after I come to a complete stop. Hopefully this can be attributed to and fixed by adjusting as you suggested. I will let you know if this solves the issue.
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Friday, April 9th, 2021 AT 2:16 PM
Tiny
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If the brake pedal is going to the floor, it's not an adjustment issue. The light coming on is a warning light. It sounds like the brake master cylinder is bad. Take a look through this link:

https://www.2carpros.com/articles/brake-pedal-goes-to-the-floor

Let me know if that is what is happening.

Joe
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Friday, April 9th, 2021 AT 2:16 PM
Tiny
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Before going out to get a new master cylinder, I decided to try bleeding brakes again and try to switch out/flush out old fluid from system. The fluid was pretty dark.
Well I made it around to the final tire, the driver-side front, I loosened the bleeder valve, and I had fluid coming out, but it was coming from the threads of the valve, not the hole. I noticed this when I did it the first time, but didn't really give it much thought.
Any way, this time around I pulled it all the way out, and upon close inspection, it was totally clogged up. With dirt/crud/ almost cement like. I tried to clear it out but ultimately just got a replacement from an old junked truck on the property.
I'll be damned if that wasn't the culprit. Brakes working great and no more double pump or brake failure light. The redoing of the brakes themselves have the e-brake working good, just needing a minor adjustment to get how I want it to be.
I feel pretty ignorant for overlooking this trivial seeming, but crucial aspect of the whole ordeal. Thank you for your advice and encouragement. Probably would have had to take to shop if it weren't for this awesome site. You guys are truly making a difference.
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Friday, April 9th, 2021 AT 2:16 PM
Tiny
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You are very welcome. I'm glad you got it working. Please feel free to come back anytime.

Take care and I hope you and your family has a nice holiday.

Joe
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Friday, April 9th, 2021 AT 2:16 PM

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