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Hi everyone,  Got a brake question.


Since getting my 1973 240z on the road and running after an intensive tear down and rebuild, all has been good except for the brakes.

For some reason, with even the slight amount of pressure, the brakes grab really hard. So when I drive I have to barely feather the pedal to brake normally. 
When I pull the vaccum line off of the booster, the opposite happens, the brakes take a LOT of effort to decelerate normally.
So I am thinking the booster may be providing too much assistance.
Wondering if you guys have ever experienced something like this in your builds?
Brake system "brake-down"
-240z Original booster (tested and working)
-Aftermarket check valve installed in vacuum line (the correct direction)
-Vacuum line connected to the crossover tube on the intake manifold (SU carbs). OEM has the vacuum connection on one of the runners.
-1981 280zx master cylinder 15/16"
-wilwood proportioning valve (for rear brakes) with built in splitter for front brakes L and R.
-toyota  4-piston front calipers with vented Z31 rotors
-maxima rear disc brake conversion
-All new hard lines and brake hoses.
Any feedback is welcome. I will be repairing a very minor leak in one of the inverted flare hard line connections soon and can use the opportunity to try to solve this issue.
Thank you!
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Edit:  Perhaps he didn't lengthen the push rod as required for the 280ZX MC swap which would act like a missing reaction disk. He should check that the measurement  first and if that doesn't fix the problem go looking for the reaction disk.


When I lost my reaction disk I made a new one from a rubber stopper and used JB Weld to fix it to the push rod base permanently.


Push rod length per the picture below is 0.53 inch or 13.462 mm from the flange.


Note: you do not have to remove the brake pipes to adjust the push rod. Just pull the MC back and push it aside.




Push rod adjustment




Edited by Miles
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