Brake Caliper/piston Locking On Slightly. Only Sometimes. Causing Stee

[Mace1979]

As per the title, my (I believe) Front caliper/piston locks on slightly, randomly and I can unlock it usually by stamping on the brake a couple of times.

It's more of an annoyance as it makes the steering wheel shudder.

There is no shudder as I brake. NONE. So it isn't the rotors being warped.

I upgraded from the stock brakes more than 6 months ago. The problem has been around since probably 3 months ago.

The brakes are the PBR upgrade 322mm from I believe the XR8.

These are second hand. They had been painted yellow so the mechanic cleaned this off with a bead blaster.

They have DBA 4000 slotted rotors which were machined nice and flat.

The mechanic serviced the calipers and I also doublechecked myself recently that the caliper sliders had good grease.

I had new front and rear pads fitted at the time.

I'm wondering if the (maybe) twin pistons need lubrication.

Anybody ever dealt with this?

Could the shudder be actually coming from the rears?

[Fastaxi]

Had the same issue in a ba xr6t, the brakes would creep on sometimes and cause a shudder that made you pull over and stop. I could fix it by turning the car off and pumping the brakes. Ended up replacing the brake booster with a new one and solved the problem. I've had a bf mk2 with the bigger brakes and now a g6et mk2 and never had the issue again so must be a teething problem with the early falcons.