C6 MOT Handbrake issue

[mach2andy]

I recently put my 2008 auto in for MOT. It had only failed on one previous occasion; a blown number plate lamp some years ago. This time it failed, the reason being the handbrake was only working on one side. I never use the handbrake ever, and it didn't even occur to me to check it. However, I'm not really sure what a check would have revealed as the one side that was working may well have held the car OK? The handbrake design [which I think was carried over from the C5] is quite basic and is not self adjusting. Adjustment involves removing the calliper and the disc to access the adjuster unlike other cars I have worked on whereby there is a hole to access the adjuster without removing the disc. So it's a matter of adjusting it a bit, putting the disc back on and trying it. I probably did this 4 or 5 times. I was advised by another Sussex member to be careful not to adjust it too much. I got it to the point where the disc rotated quite freely with the handbrake off, but with the handbrake on the disc wouldn't budge at all. The MOT retest was fine and in fact the LH & RH readings were virtually identical, but this was I think more down to luck than judgement.

 

[teamzr1]

For future need,
GM Process

You have to pull the wheel, remove the caliper and bracket assembly and then the rotor.
Adjust the shoes, so there is a very slight drag on the drum when you reinstall it.
WARNING! If you get the drum too tight, you will NOT get it off again until the brake shoes wear down further!:

Park Brake Adjustment
Tools Required
J 21177-A Drum to Brake Shoe Clearance Gauge

Important
Park brake adjustment is not necessary after replacing the park brake lever or park brake cables.
The park brake cables are tensioned automatically by cycling the park brake lever three times.

Important
Do not operate the park brake lever with the rear disc brake rotor removed.
Place the inside measurement contacts of the J 21177-A at the widest point of the drum portion of the brake rotor (1).
Tighten the set screw on the tool in order to ensure the proper measurement when removing the tool from the drum.
Position the outside measurement contacts of the J 21177-A over the park brake shoe (1) at the widest point.

Important

If the gap between the adjuster nut and the adjuster screw exceeds 5 mm (0.25 in) during the adjustment procedure, the park brake shoe must be replaced.
Adjust the park brake shoe-to-drum clearance by rotating the adjustment nut on the park brake actuator. Specification
0.38 mm (0.015 in)
Install the rear brake rotors. Refer to Brake Rotor Replacement - Rear in Disc Brakes.

Install the rear tire and wheel assemblies.
Apply and release the park brake lever three times.
Apply the park brake lever. Inspect the rotation of the rear wheels:
The wheels should not rotate forward.
The wheels should drag or not rotate rearward.
If the rear tire and wheel assemblies rotate forward or do not exhibit drag rearward, repeat the adjustment procedure.

Release the parking lever. Verify that the wheels rotate freely

Lower the vehicle
Now that the Emergency Brake has been adjusted, test for tension (grab of the brakes shoes on the rotor).
If there is no tension, then the issue may just be the following problem in the brake handle assembly.

Take out the passenger seat and the rear portion of the center console to expose the Emergency Brake handle assembly.
Lubricate all areas near the lever and check for correct movement of the brake lever and ratchet system

Reassemble and test