brakes lock up

[ronald B.]

Rebuilt the entire brake system on my '71 n600. Every time i push down on the pedal, front discs lock up and wont release. If I open the bleed screw at the caliper, it releases and they turn just fine, until i step on the pedal again. Anybody heard of this before?
Sent from my iPhone,Dr Ron

[Eric Geiger]

I think I've heard this mentioned before and it's a check valve issue in the master cylinder.
------------------------------------------
Eric Geiger
PRG-Nocturne
XXX-XXX-XXXX
Egeiger@...

On Apr 9, 2014, at 7:44 PM, "ronald B." wrote:
Rebuilt the entire brake system on my '71 n600. Every time i push down on the pedal, front discs lock up and wont release. If I open the bleed screw at the caliper, it releases and they turn just fine, until i step on the pedal again. Anybody heard of this before?
Sent from my iPhone,Dr Ron

[Mark P Hatten]

or the return port is plugged ..
The 2014 National Microcar Show is at www.gpnwmme.com and is sponsored by www.mphspecialties.com
To: 2cylinderhondas@yahoogroups.com From: egeiger@...
Date: Thu, 10 Apr 2014 00:46:45 +0000 Subject: Re: [2cylinderhondas] Re:brakes lock up
I think I've heard this mentioned before and it's a check valve issue in the master cylinder.
------------------------------------------
Eric Geiger
PRG-Nocturne
XXX-XXX-XXXX
Egeiger@...

On Apr 9, 2014, at 7:44 PM, "ronald B." wrote:
Rebuilt the entire brake system on my '71 n600. Every time i push down on the pedal, front discs lock up and wont release. If I open the bleed screw at the caliper, it releases and they turn just fine, until i step on the pedal again. Anybody heard of this before?
Sent from my iPhone,Dr Ron

[Charles Gould]

Or the flexible hoses have collapsed internally, causing the hose to act like a one way check valve. Replace the hoses and you should be fine.
Sent from my iPad

On Apr 9, 2014, at 9:10 PM, Mark P Hatten wrote:
or the return port is plugged ..
The 2014 National Microcar Show is at
www.gpnwmme.com
and is sponsored by
www.mphspecialties.com
To:
2cylinderhondas@yahoogroups.com
From:
egeiger@...
Date: Thu, 10 Apr 2014 00:46:45 +0000
Subject: Re: [2cylinderhondas] Re:brakes lock up
I think I've heard this mentioned before and it's a check valve issue in the master cylinder.
------------------------------------------
Eric Geiger
PRG-Nocturne
XXX-XXX-XXXX
Egeiger@...
On Apr 9, 2014, at 7:44 PM, "ronald B." wrote:
> Rebuilt the entire brake system on my '71 n600. Every time i push down on the pedal, front discs lock up and wont release. If I open the bleed screw at the caliper, it releases and they turn just fine, until i step on the pedal again. Anybody heard of this > before?
> Sent from my iPhone,Dr Ron

[Bill]

Ron;
    It sounds like your master cylinder.  Both front and rear have bleed back holes in the fluid supply ports going to/from the brake fluid reservoir.
There are two holes in each port the small one is plugged with crystallized DOT-3 brake fluid. See the information in the Sedan shop manual page 11-10 Fig.
11C-14, it doesn’t look like your master cylinder but the compensating ports are the same and it shows where they are.
This plugged hole is preventing the fluid to release your front brakes.
If you look at the side of the master cylinder there will be a F for front and R for rear, open up the front port and using a drill bit the size of a pin or needle see if it will go through.  Caution: make sure the wheels are turning and the pedal is all the way up off the master cylinder (which would mean the piston cylinder is all the way back, or in the none applied position).   Because the opening in the master cylinder has to be beyond the piston seals to allow fluid to pass back into the reservoir.
You don't want to put a hole in the master cylinder piston seal while trying to open the bleed back hole.
Bill

[feltonminicycle]

Did you rebuild the brake booster? It's usually the 10mm piston in the reaction port getting stuck.
Miles

[ronald B.]

I took the booster apart but did not have a kit yet so had to clean it up and put it back together.
Thank all of you for your suggestions, car is in Oregon, i am in Hawaii, i work on it when i come over to see my mom. Need to fix the brakes before i sell it. I'm sure it is one of the things mentioned, will go through it step by step. I have a new master cyl and kit i will put on, and watch for a used booster to rebuild before i return again. Thanks again,
Aloha, Ron
Sent from my iPhone,Dr Ron