260z

please help i have 1974 260z brake problem i have just installed toy 4x4 brake caliper up front and 240sx calipers on rear can not get rear brakes to lock up at all front work fine also have adjustable proportioning valve but no installed yeat what about guting stock porportioning valve? any info on this would help thanks

ZR8ED

Not 100% sure about 260's, but I know that 280's had a pressure relief valve for the rear brakes to keep them from locking up. I tried mine when I had stock brakes and tires.. I could not lock the back tires..the fronts yes..

How does your brake pedal feel? does the car stop like you threw out an anchor?.. if so, is it just the back wheels not locking up?

Your fronts SHOULD be able to lock up. I have large sticky tires, and I could lock them up with my old stock brakes.

BTW which toyota brake swap. Calipers with stock rotors, or the larger 4 pistons with 300zx vented rotor?

I have the later, and just love the braking ability of the car!!

260z

hellow all z nuts i was talking to a buddy of mine he has done this conversion he told me to remove stock proportioning valve and install adjustable valve also have ordered a bigger master cyclinder will let all znuts know how it stops whin i finshed thanks

j260z

if you do the toyota brake swap you should also swap out the master cylinder with the 15/16" master from the 280zx. with the toyota brakes up to 88 (marked S12+8) you will see an increase in piston area of about 20%. upgrading the master cylinder from the 7/8" to the 15/16" unit will give you an increase in area of about 15%. the result is firmer pedal.