510 280zx Front Brake Setup....New 7/8" Master....No Fluid Getting to Calipers

Suspension, including wheel, tire and brake.
Cable
Posts: 6
Joined: 18 Feb 2017 06:58
Location: Jackson, Ca

510 280zx Front Brake Setup....New 7/8" Master....No Fluid Getting to Calipers

Postby Cable » 18 Mar 2017 22:37

Hey guys, been messing with my 1970 Goon. Put a 280zx front strut assemblies and brakes. New pads, new (not reman) 7/8" master cylinder bench bled using the bleeder screws on the side of the master cylinder.

Started bleeding brakes on the rear using some tubing into a jar of brake fluid, went great. Moved onto the front and can't get any air or even fluid moving to the calipers. Left both the bleeders open overnight, still nothing.

I can pump the pedal and it gets firmer, but still not a drop of fluid out of the caliper bleeders, just the master cylinder bleeders.

The calipers still move around by hand since the pistons haven't taken up the slack between the rotors and pads.

So now what? The calipers came from a recently running 280zx. The pistons moved fine when I used a c-clamp to push them to fit the new pads, so they aren't frozen or leaking.


Thanks!! 
Cable
-1970 Datsun 510 Wagon: L20B, Weber DGV, 4 speed, 280zx struts/brakes/coilovers, 15x7 Konig Rewinds, Nitto 205/50/15
-1974 Chevrolet K5 2wd, Full Convertible, LSx 6.0 swap, turbo, etc

datzenmike
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Joined: 24 May 2006 12:40
Location: Van. Isle.

Re: 510 280zx Front Brake Setup....New 7/8" Master....No Fluid Getting to Calipers

Postby datzenmike » 19 Mar 2017 12:48

Even if the caliper pistons were seized, fluid would still come out the bleeders.

As both calipers/flex lines or both front individual lines are unlikely to cause an identical problem at the same time, problem is towards the master.


Unscrew the front brake line from the master (that's the one towards the rear of the master marked F) and try. Got fluid?

No... problem is in the master.
Residual valve blocked/stuck. Cheap made in China casting not drilled out. Seal in master torn. Never full stroke a master to bench bleed as it will travel well past where it would normally stop under hydraulic pressure.

Yes... problem between here and caliper.
Kinked/blocked line or blockage in the ft/rear proportioning valve or pressure differential warning light switch.
"Nissan 'shit the bed' when they made these, plain and simple." McShagger510 on flattop SUs


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