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Discussion Starter #1
I have a 1992 C3500HD dually with the NV4500 and the driveshaft parking brake.

The parking brake pedal and system as a whole doesn't really work right. When I first got the truck the pedal was on the floor and pulling the brake release didn't bring it up, but the brakes weren't engaged. Looking at the pedal area I found the cable wasn't attached but it was too long on that end to attach properly; it wouldn't stay put.

So I went to the other side and tried pulling as much slack out on the drum side as I could and re-adjusted the end link (literally threading it down all the way) and attached it all back together, but it hasn't really helped much. The pedal will at least operate the brake now, but on release it only comes up about halfway, and not with the gusto I usually expect a parking brake to release with.

I also noticed when I was down at the drum side that the brake doesn't have a lot of movement; from where the shoes would be just barely contacting the drum to where I am putting as much force on it by hand as I can, there's only about 1/2" of movement on the lever arm and therefore not much movement of the brake cable.

So, I have some questions.

Does the parking brake disengage entirely by the force of the spring inside the brake drum? I had always assumed there was a spring as part of the pedal assembly but I'm not seeing one or a place that I'm missing one.

If it is, does this mean that my parking brake is somehow broken because it doesn't have as much play as it should?

Or is my cable just stretched and a new cable will cure this? That doesn't seem quite right because even a new cable won't end up with more movement between disengaged and fully engaged.

Thanks in advance for any help or guidance you fine folks can give me.
 

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I have a 1992 C3500HD dually with the NV4500 and the driveshaft parking brake.

The parking brake pedal and system as a whole doesn't really work right. When I first got the truck the pedal was on the floor and pulling the brake release didn't bring it up, but the brakes weren't engaged. Looking at the pedal area I found the cable wasn't attached but it was too long on that end to attach properly; it wouldn't stay put.

So I went to the other side and tried pulling as much slack out on the drum side as I could and re-adjusted the end link (literally threading it down all the way) and attached it all back together, but it hasn't really helped much. The pedal will at least operate the brake now, but on release it only comes up about halfway, and not with the gusto I usually expect a parking brake to release with.

I also noticed when I was down at the drum side that the brake doesn't have a lot of movement; from where the shoes would be just barely contacting the drum to where I am putting as much force on it by hand as I can, there's only about 1/2" of movement on the lever arm and therefore not much movement of the brake cable.

So, I have some questions.

Does the parking brake disengage entirely by the force of the spring inside the brake drum? I had always assumed there was a spring as part of the pedal assembly but I'm not seeing one or a place that I'm missing one.

If it is, does this mean that my parking brake is somehow broken because it doesn't have as much play as it should?

Or is my cable just stretched and a new cable will cure this? That doesn't seem quite right because even a new cable won't end up with more movement between disengaged and fully engaged.

Thanks in advance for any help or guidance you fine folks can give me.
Look in the 6.5L FAQ page. If you search towards the bottom of the link you will see some info on the 91/92 brake system that may help you::

manual.png
 

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Discussion Starter #3
Thanks @OkDually but that TSB only updates the torque used on the drum bolts, which doesn't really affect the parking brake cable or actuation assembly at all.

I did some more research and it looks like I'm missing a spring, number 31 in this diagram from the FSM:

636020


If I had that spring I'd have all the force I need to pop the brake pedal back up. Since I don't have it, I'm considering just running a spring to the frame rail on the passenger's side; it would need a length of steel cable to reach that far but it would perform the same job, if look a little hack-y.
 
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