300ZX 4-PISTON Caliper Upgrade problem...

[REC]

I recently upgraded the calipers on my 90 Q45 with the 4 piston 300zx calipers. My brakes were working fine before but i wanted the increased performance. A member here named Wes told me that i could use the stock brake lines I just needed to shorten the brake line bolt to fit the caliper. After cutting off the heat shield and shortening the bolt me and a friend began to bleed the brakes and everything went as planned until i started the car. When the car isnt running there is plenty of pressure on the brake petal but as soon as the car is running the pedal is mushy and goes to the floor and doens't get any stiffer after pumping it several times. Obviously when driving around the parking lot there is literally no brakes at all as the pedal goes to the floor. I'm basically stuck and have no idea what the problem is. Has anyone experienced this before with this upgrade?

[Bwana]

Not with my Q, but the brakes on my MG were the same way. Turned out to just be more air in the lines and took forever to get it all out. Brakes felt fine with no vacuum to the booster, but as soon as I started it up they would turn to mush.

[elwesso]

double posting=

zerothread/251553

[Bwana]