Brake wind back tool
I have had issues with a 'soft' brake pedal with a feeling of still some air in the system. Despite numerous attempts at bleeding the brakes I couldn't get any improvement. I found one obscure reference on the internet suggesting that air can become trapped in the Sierra rear brake callipers. I removed each rear calliper and wound the piston back with a wind back tool. I then bleed the rear brakes with the tool in place to stop the piston moving out. After some aggressive pumping of the brake pedal I did get some air out of the offside calliper. The brake feel is now much better.