The reaction is normal. When you push the piston back, it displaces brake fluid. It needs to go somewhere, in this case the fluid pushes the other piston back.
Either compress both pistons at the same time so the fluid goes back to the master or open a bleeder and let it come out.
I'm guessing you have not worked on many cars. Get a car guy to come over to help you. This is pretty basic stuff. It is also normal to have the rear of a rear wheel drive with discs to have drag. They will never freewheel. You are trying to turn axles and if you have a clutch style differential it's also turning other side or the driveshaft.
Pry the piston back so the caliper is floating. Clearance between pads and rotor. Still drags?
Okay i realize that there will always be drag. The question was how much is normal. I know the wheels wont just free spin…there have been some minor issues with this kit, somewhat bizarre issues so the kit is obviously cheap quality…. i thought maybe this is a popular swap and someone on the board may have had similar issues..
As stated above the pads touch the rotors, meaning both inner and outer pad at rest, makes contact with the rotor, to which i cannot see how any amount of shimming, bleeding, removing flex hoses, or swapping out proportioning valves will fix. I expected pushing piston in would send fluid back to the master, so yes it was a surprise to me to see the opposite piston move. Bolts were “uncomfortably” close to the rotor which i will know if they are part of the problem tomorrow. After grinding all the zinc off i am now waiting for paint to dry. The kit instructions are generic but talk about pedal ratio, which nobody here mentioned. I honestly think the pads are too thick but again was looking to you guys or someone who has used these g body disc swap kits. Ive never had to compress two calipers at the same time, and my thought is after doing so and applying brake pedal i will be back at square one but it is not an issue and i will give it a shot tomorrow.
