Ive just finished fitting a refurbed rear axle with mk4 calipers on the mk2. I didnt have a brake bias valve before so that was also fitted. This valve came with the second hand axle from the donor car. Ive bled the brakes using the many guides on here. I closed the pivoting bracket towards the ground and put something into the holes that line up to lock it into position I did get fluid running to the rear calipers and they seem to clamp onto the discs fine but the pedal seems abit spongey still Once the car was back on the ground I went to tighten up the spring into position by taking the slack out and this positioned the spring right at the end of the slot on the bracket. The car is lowered but not silly But before this I checked to see if the lever/arm on the valve would push against the valve body as there was now fluid inside the valve but it didnt move with the resistance of the fluid. It seemed to stay full open (in the position when its clamped towards the ground) with no resistance when the spring wasnt attached and I could move the arm freely with it having no affect to the valve operation Surely the valve should push against the lever arm and only close towards the ground when the spring pulls it? Does this sound like a shot bias valve? If so, whats a good replacement as I couldnt seem to find a an ATE branded one This photo shows the lever/arm in the "clamped" position where I held it in place with a screw in the holes that lines up This photo shows the spring position once tightened up to take out the slack
You can adjust the valve with the nut and screw on the end. Newer valves don’t have this so the only adjustment is at the spring. We had terrible trouble get a firm pedal but it improved considerably with a couple of hundred miles running. Tristan will tell you that you should tighten the rear calipers by getting the pads as close to the discs as you can to the disc before refitting them. This will definitely help get a firm pedal but the pads still need to bed in properly all round. Best thing to do is find a safe space and give the brake a good shove. If the rears don’t lock up you have nothing to worry about
So the thread on the nut and screw is worn out and only tightens up right up towards the end because rust had gotten to it when it was on the donor car But surely the valve should press up on it and push the lever the other way (unloaded car) when I disconnect the spring from it?
