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97 Chevy Blazer rear drum brake issues (grabbing)

Home Forums Stay Dirty Lounge Service and Repair Questions Answered Here 97 Chevy Blazer rear drum brake issues (grabbing)

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  • #528890
    Daniel DominBlazerguy1983
    Participant

      I own a 1997 Chevy Blazer 2-door base model with the 4.3L and rear drum brakes. I have been having issues with the rear drum brakes grabbing and hanging up since about 6 months after I purchased it used two years ago. The issue occurs about 50 miles of driving after cleaning the dust out of the rear drum brakes. The brakes will make a high pitch squeal from the driver rear wheel when stopping from a low speed or a drift and the rear wheels skid/lock up at first until the ABS kicks in and then you can feel the ABS counter acting the locked up wheel. Sometimes the feel like the stick on when I go to pull away from a traffic light and make a clunk when the release. The brakes feel grabby and it’s hard to make a quick stop when they are acting up like this because of the ABS kicking in to counter act the wheels locking up. Also feels like the one side (rear driver side) grabs more and release last when letting go of the brake pedal from a stop. The vehicle feels like and uneven release of the brakes.

      So far I have replaced with brake spring hardware, brake shoes with a higher quality pair from Napa, drums, wheel cylinders, cleaned and smoothed the backing plate, A new ¼” brake line from the ABS module by the master cylinder back to the hose at the axle and new 3/16” lines across the axle, new brake hose, new brake fluid, the rear axle seals where replaced and are NOT leaking and adjusted the e-brake cable. Yes the shoes are installed properly, the bigger shoe on the back side. I have not replaced the self adjusters but they spin freely and are clean.
      I am at a loss of what to do. The issue has gotten me really annoyed. I feel that someone out there should have come across this. If you clean the brakes to remove brake dust the issue goes away for about 50 miles of driving. I have even tried to adjust the shoes in away from the drums a bit per a mechanic I know and the issue still came back one brake dust accumulates. Seems like too much stopping from rear? Someone mentioned a proportioning valve. Where is it located and what kind of cost am I looking at for this now? Thank you in advance!

      I have checked and re-checked everything is installed properly. Here is a picture of what my configuration looks like. This is not an actual picture of my brakes but a picture I found online. Thanks.

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    Viewing 15 replies - 1 through 15 (of 16 total)
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    • #528892
      davedave
      Participant

        I am not specifically familiar with your vehicle, but here are some things to consider:

        • does your vehicle have a height-sensing proportioning valve (common on trucks and pick-ups)
        • does your vehicle have a residual pressure check valve for the rear brakes?
        • does your vehicle have any metering valves in the brake lines?
        • are the drum diameters within .020″ of each other?
        • are the shoe resting clearances set correctly?
        • are the shoe bosses lubricated?
        • are you using the correct shoes on the corrects sides of the vehicle, in their correct spots?
        • are the the star wheel adjusters located on the correct sides of the vehicle and do they operate normally?
        • do the wheel cylinders operate normally? are they leaking excessively?
        • is your parking brake frozen or in need of adjustment?

        Q: could you take off both wheels and post pictures of both sides of your drum brakes so we can see your shoe and spring configuration?

        Extra Bonus: Could you post a short video of drum brake actuation for both sides?

        #528895
        Daniel DominBlazerguy1983
        Participant

          this is an older base modle Blazer. I am unsure of any special sensors. I know when I changed the brake lines there wasn’t any valves in them, just brake lines all the way back form the factory. The shoes and hardare are installed proerly. I checked and re-checked and have had two mechanics check. Everything is new including the drums. The issue occured with the old brakes too before I changed everything out. I cannot take a video at the moment but, I attached a picute of my setup from a source online. This all happened around the time I had a real seal leak that I fixed and even after replacing practily everything regarding the drum brakes this still keeps happening.

          #528897
          davedave
          Participant

            In the mean time while I’m scratching my head over this, here are three TSB’s that may be applicable:

            #528899
            davedave
            Participant

              Based on all the information, I believe that the wheel speed sensor gaps are out of spec, causing your rear wheels to actuate ABS at low speeds. Therefore, your brakes and drums never get ‘broke in’ and therefore causing the noises and lock-ups that you are experiencing.

              #528901
              Daniel DominBlazerguy1983
              Participant

                Brake 1 – The wheel cylinders habe both been replace, Brake 2 – the dront ABS sensors that are attached to the dust sheilds, then entire dust sheild and ABS sensors have been replaced on front. Dorman makes an aftermarket part for this. Brake 3 – drums are new but feel out of round now because of all these issues. Feels like too much stopping n rear and over heating drums now I think they are out of shape again. I am kind of thinking the backing plates. I did pry some on them when I first service the brakes for this issue when it stated. The drum was really stuck on. they look fine, they are clean and I used a grinder to smooth out any grooves that could be causing the shoes to get hung up. I applied some anti-seize to the areas thare are raised to where the shoes meet up to the backing plate. Didn’t help my issue either. I have no ABS lights on and no codes. This is a very very base modle. I don’t even know where the ABS sensor is for the back wheels. I aussume on the transmission or trasfercase someonewhere because there are no sensors anywhere on the rear end. How hard is it to comvert to DISC brakes? haha

                #528906
                davedave
                Participant

                  The backing plate could definately cause drum brakes to grab and lock-up.. but then I referred to your original post:

                  So far I have replaced with brake spring hardware, brake shoes with a higher quality pair from Napa, drums, wheel cylinders, cleaned and smoothed the backing plate

                  Through the process of elimination I felt that more attention should be focused on proper ABS system operation, especially since it is part of your complaint… and no one thus far has “ruled-out” or examined wheel speed sensor output; specifically, the sensor air gap.

                  I could be over thinking this. Perhaps it could be something simple, but it seems that you have already covered the fundamental basis of your drum brake operation.

                  #528941
                  college mancollege man
                  Moderator

                    what I could suggest is have someone push the brake
                    pedal down while you open the wheel cylinder bleed screw.
                    see if fluid shoots out on both. if it does not or is weak
                    I would suggest your proportioning valve is weak.

                    #529005
                    DanielDaniel
                    Participant

                      If your brake or abs light is on, go get the codes pulled. It kinda sounds to me like you may have a bad tome wheel or sensor. If either of those is bad there should be a code for it. Also if you have a bad wheel bearing (which is common on those) it can cause or mimic a bad sensor or tone wheel.

                      #529019
                      BillBill
                      Participant

                        The first thing i would like to know are the parking brake levers returning fully? They should be almost invisable behind the brake shoe and resting on the shoe. Make sure there are no grooves worn into the backing plates where the shoes rest. Grooves there can make the shoes bind if deep enough.

                        I have had problems with locking,noisy brakes on several GM vehicles and i’m getting to a point where i won’t use anything but Delco shoes on them.

                        I would want to be sure of these things before condeming anything else.

                        #529030
                        davedave
                        Participant

                          as a caveat to wysetech’s comment about the brand of shoe, it is also important that you get the correct shoe that corresponds to the diameter of your drum; a 12″ drum for example will take different shoes than 13″ drums.

                          It is possible to have varying drum sizes for the same make/model of vehicle. VIN number information becomes very important in this case. Make sure your parts guy makes this important distinction if applicable. If nothing else, bring a drum into the store and measure it right there on the counter.

                          As with any part, make sure your new drums match the old drums and your new shoes match the old shoes.

                          #606694
                          Daniel DominBlazerguy1983
                          Participant

                            I wanted to bring an old topic to life! I have resolved the mystery of my drum brakes sticking, crabbing and hanging up. Watch my YouTube video! Thanks everyone for all your constant support and information. Eric, I love your videos and your Eric the car guy site!!!

                            #606731
                            Lorrin BarthLorrin Barth
                            Participant

                              Very informative video. It should be in the how-to section.

                              #607024
                              EricTheCarGuy 1EricTheCarGuy
                              Keymaster

                                [quote=”barneyb” post=104824]Very informative video. I should be in the how-to section.[/quote]

                                +1

                                #612153
                                Daniel DominBlazerguy1983
                                Participant

                                  I wanted to update everyone and let you know I solved the issue! I made a YouTube explaining. After adjusting the drum brakes with a slight drag on the self adjuster, I backed the shoes in by 3-4 clicks on the self adjuster. This also works on Cavalier’s and other GM’s with this drum brake platform. Hope this helps someone else out. I have driven for over a month and the drum brakes are still working great after doing this.

                                  #612174
                                  college mancollege man
                                  Moderator

                                    Thanks for the seminar. 🙂

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