E stop or footbrake?
I have seen alot of issues with cars with rear disks in the uk at our MOT test. they are very fussy about the %.
They can be divided into 3 groups and are common for caliper ebrake type indicated by these symptoms. basic hydraulics says if the rears are not working well then something is sapping the force.
1/dragging / low efficiency. The pads and slides should be checked. The slides should be free ( no pads and caliper assembled) only light finger pressure should be required to slide the caliper back and forth. 2nd check. without the caliper carrier arrached the pads should slide through very easily with the ratle shims in. In the uk with the salt and the rain we have to abrade the hard black corrosion on the sides of the pad ears, in the pad slides and in the pin slides. typically I use a m8 or m10 tap in the slide holes as a file to clean them out and a file on the caliper carriers.
2/Caliper piston seal binding. again due to the salt and damp I do this alot and it never tails. Pop the piston out, lift out the dust seal and the main seal. sctape out thedust seal groove till you get to proper metal, the very small land of the bore between the main seal and the dust seal, also make a corner tool and scrape the outside of the seal groove and the od of the seal groove. You can reuse the dust seal and main seal if there are no nicks or tears. I think i've only ever replaced dust seals.
3/Ebrake cable saddle is not balanced, the caliper mechs were not seated at the same time. Wind both calipers back in fully and with ebrake cable disconnected and both brakes assembled stand on the brake pedal. once this is done connect the cables and re-adjust the slack the saddle should be level.
Follow the order above, and if the pads are reasonable and the disks are ok and it'll pass. you'll be surprised of the effect and you should get sub 10% difference. mind cos its a filthy days graft though.
Rich
