brake conversion problem

[D0DGEE]

i got a ke30 just fitted mazda rx7 series 4 front and rear brakes to my car and the brake pedal is crap the pedal just goes to the ground when pushed. cars has a line lock on the rear and when turned on the pedal is good and the rear is not used. have spent ages bleeding the air out and replaced calipers from my other car and still having problems thinking the master cylinder isnt big enough just seeing if anyone else had this problem

[Rick]

So whats the line lock for?

Are you using the factory rear brake proportional valve?

[strx7]

S4 rear calipers have 2 bleed nipples on them, you need to bleed BOTH of them otherwise you get that symptom. I had the same issue when i used S4 calipers on the front and rear of my SE104. pump the pedal up and it'd be sweet, give it about 10 seconds and try it again and it'd go to the floor, ended up having to pull the calipers off to bleed both nipples and then hey presto, mint brakes.

If you have already done that, what size master cylinder do you have?

[CelicaGT8]

You have the calipers on the right side?

[mjrstar]

had the same problem with rx7 rears.. i spent a LOT of time bleeding. the solution was to pump the pistons nearly all the way out( used a thin bit of wood to stop them coming right out), bleed them cycle them back in, bleed again. then repeat till the pedal came right.

man i spent ages getting them to work properly, i tried numerous preportioning valves, master cylinders etc...

[D0DGEE]

calipers on the right side. got a 7/8th bore so i was told when i got it. ok ill try re bleed brakes like that tomoro no proportioning valve i think in the car the line lock in on the rear brakes to dis connect them so i can do skids without the brakes coming on. brakes were fine before changing the brakes

[strx7]

7/8th will be sweet provided there is enough travel length in them, sure sounds like air trapped in the rears to me.