Parking brake not working

[Larryjb]

I discovered that the parking brake lever (#4) is not engaging with the tappet (#8) to spread the shoe. I've had this trouble before, but I thought I had it engaged when I last worked on it. Evidently, it hasn't engaged properly for over a year now. It does spread the shoe a little, but not enough. My parking brake pedal will go down to the floor, and this must be why. It pulls the lever back, and it goes back all the way without doing much with the shoe.

Has anyone else had trouble getting the lever to engage properly? Any tricks?

 

[Scottydoggs]

the brake shoes likely need to be adjusted. sadly you will need to take the back brakes and rotor off and then turn the star wheel and test fit the rotor drum part till you have them adjust to a very slight drag when you turn the rotors.

 

[Larryjb]

I already removed the rotor and checked. The adjustment is good.

When depressing the parking brake, it pulls back on the lever, but the shoe hardly expands. The lever is not properly engaging with the tappet.

 

[West 1]

These parking brakes are an odd design. As Scottydogs described it careful adjustment of the shoes is the only way to make these work. I owned my first Tahoe for several years with the parking brake being almost useless. We tow a boat often and this was a real issue on boat ramps. I needed a working parking brake. To get them working you need to adjust the star wheels on both rear parking brakes till the fit is tight. You may need to bump the shoes up or down slightly to get the drum to fit over the shoes. The shoes should be wire brushed clean before this fitting and the drum should be clean and free of any dirt or rust that could affect the good fit. By playing with this you can get the emergency brake to apply with the pedal at maybe 50% depressed. It takes work but there is no shortcut

If you adjust them too tight the drag will heat up your brake quickly. The brake must spin free but with near zero play.

With both E brakes adjusted and the rotors installed you can test your E brake pedal before bolting the disc brake calipers back on.

It would be great if GM left a window to adjust the star wheel with the brake assembled but they did not.
Good luck.

 

[Fless]

As @Scottydoggs noted, they need to be adjusted to have a slight drag.

Long shot, but are the backing plates in good shape?

There is also a slack adjuster for the cables, along the frame and underneath the driver's side doors. I had all four (front, intermediate, and left/right side) cables replaced due to stretched cables and no more adjustment left.

 

[Larryjb]

To be clear, the shoe is adjusted so that there is almost zero clearance between the shoe and drum. This is verified with a parking brake tool. I can see that when the parking brake is set half way, the parking brake lever is pulled 90 degrees from the backing plate. However, the shoes have hardly moved.

I’m still convinced the lever is not completely engaged with that tappet. With the shoes set the way they are, the parking brake pedal shouldn’t be going down to the floor.

Back to my main question, any hints on installing that lever so that it engages properly?

 

[swathdiver]

 

[Fless]

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I don't believe that the tension adjustment procedure (with the pedal) is applicable to the NBS parking brake systems. No auto adjust with the pedal.

 

[swathdiver]

I don't believe that the tension adjustment procedure (with the pedal) is applicable to the NBS parking brake systems. No auto adjust with the pedal.

I should have clarified that this came from my 2009s GMT900 manual, thanks.

 

[Larryjb]

Thanks Swath, I'll keep this in mind. I think Fless may be right about a lack of auto adjust with the pedal. I had to replace this a few years back.

When I set the parking brake with the wheel drum off, I would have expected to see the adjuster expand as the lever in the backing plate rotates. I did not see any such movement. My son watched the shoe and told me that the shoe barely expanded even though I depressed the parking brake pedal half way down. I used the OTC version of the J-21177 to adjust the shoe adjuster.

I had to replace the parking brake cable last summer because it was freezing and wouldn't release. I remember having difficulty getting the lever inserted properly to engage with that tappet and adjuster mechanism.

 

[West 1]

Any chance the #8 part called the tappet has fallen out on your system? If the brakes are properly adjusted and your lever is at 90* they should have applied. You are missing part of the mechanical action.

 

[Joseph Garcia]

^^^^^^x2^^^^^ My thought, as well. Something may be missing or bent/broken, so that is not engaging correctly. Have you compared it to the other side to ensure that all of the parts on the current wheel are all still there and are exactly the same in condition and position?

 

[Larryjb]

I agree there is something mechanical missing or not engaged.




Back to my main question:

Any hints on installing that lever so that it engages properly?

 

[Fless]

How's the condition of the lever? Engagement ends worn?

 

[Larryjb]

@Fless When I had it apart last year to replace the parking brake cable, I didn't notice anything unusual about the lever itself. The divot into which the tappet sits seemed fine.

What I think may be happening is that once the shoe is removed from the adjuster, there is no pressure keeping the tappet engaged with the lever. The star wheel could slide out just enough that the lever could pop out of position before I can get the shoe in place. I do add a dab of grease as shown in the manuals, but I suspect that hasn't been enough to keep things together.

 

[KC 2013 Tahoe]

Having similar issue on my bride's 2013 Tahoe. Brand new emergency brake linings installed, but didn't realize there were adjusters at the end of each tappet to zero-out the pad to inner drum surface. Will give it a shot as there's virtually no parking brake action.

FWIW - What a POS/Cheap-O way of actuating the parking brake... thanks again GM!