C6 parking brakes lock up when rolling

[JustJohn]

I put a request into Tobin who sent me some help and diagrams but thought I'd ask in advance of taking the rear brakes apart again...

Finished installing rear C6 brakes with parking brake, bled, test drove etc with everything seeming to be fine. Installed the Lokar parking brake cables and everything seemed to work off the ground.
On the ground, the car backed up a few feet and locked up the parking brakes. Loosed the cables, tried again, and got the same result. Unhooked the parking brake cables and all is well with the brakes.

I probably have something backwards.

Anyone else had this happen?

[dontlifttoshift]

Where are you doing this work? On jack stands or a lift? Is the rear axle supported?

The rear axle swings backwards from full droop to ride height and that can be enough to take all of the slack out of your cable system.

[icemanrd19]

Seems simple. Issue isn’t there when the. Take cables are disconnected. Sounds like your cables are putting too much pressure on the plate. Where did you loosen the brakes? I hope st the cable by the front subframe

[modular93fox]

Do you have the correct backing plate installed on the correct side. I think they are side specific if I remember correctly.