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PostPosted: Wed Aug 20, 2014 9:21 am 
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Joined: Sat Jun 01, 2013 5:38 pm
Posts: 539
Location: Orange, CT
I finally got around to installing the speed bleeders last night and if you have any inkling of bleeding your brakes get a set!
Anyway I did the fronts, check.
I went to the rear, right side, check.
Got to the left and wait, what the..
Some knuckehead had broken the bleed screw clean off.
OK so now I have to disassemble the drum/piston assembly and fix this.
However after doing the fronts I started it up and tried the brakes.
Still very soft and I still have a lot of hissing noise coming from my rebuilt vac booster when the pedal is applied.
The vac lines are new and clamps are tight and the check valve is in the right way.
I have a feeling that after I get the rear back together I will still have soft brakes.
Could the proportion valve be bad?

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PostPosted: Wed Aug 20, 2014 9:48 am 
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Joined: Wed Apr 09, 2008 5:53 pm
Posts: 12882
Location: CT
I don't have my manual in front of me at the moment, but in yours you should look up the progression sequence for bleeding the brakes. It's important to bleed them in the correct order, like tightening head bolts. They get bled in order, determined by their individual distance from the master cylinder. You can't do much until you replace that broken nipple, tho. Also read the manual about bench-bleeding the components.

The Z employs a two-wheel split safety brake system; if one pair of brakes fails, the other two wheels still work. Back in the day I used to be 100% confident this was a staggered-wheel system (l/f and r/r, r/f and l/r), but today I guess I was wrong and they are front/rear systems?

After my car runs and I shut it off, applying the brakes a few times gives me a hiss too, but it decreases in volume each time and only lasts a few pumps.

The MasterVac interior diaphragm should hold some vacuum inside the canister for awhile after you shut the engine off. If there's a rupture or leak in the diaphragm, you might hear the hiss of air without touching the brake. If you decide to replace your MasterVac, ensure you buy the same year part. They had slight modifications over the years and the actuating rod is longer or shorter on different models.

["now I have to disassemble the drum/piston assembly and fix this"]. This is not such a big deal, did it myself many times over the years. The biggest problem I ever encountered (aside from stupidly rubbing brake fluid in my eye) was the occasional stubborn removal of the brake drum. Because the brake drum and center hub are dissimilar metals, they sometimes become attracted to each other and are unwilling to stop hugging. Believe it or not, the remedy was to smack the drum face all around with a hammer until the bond broke. A Datsun dealer in New Bern NC once shattered my drum doing that and gave me a new one free. Not a likely scenario but it can happen. Some good PB Blaster or penetrating oil around the center hub might help loosen it up, but not much. :lol: Make sure you adjust the brake shoes inward, well away from the drum before trying to pull the drum off. No progress will be made if your drums are extended outward in the 'deployed' position against the drum.

Rebuild kits for the brake cylinders are cheap and should be used at any opportunity. As long as you are in there, you might as well give yrslf another 10,000 miles of good brake service.

HINT: Make sure you understand the handbrake before messing with the rear brakes. You can drive yrslf craZy trying to loosen the brake shoes if you don't release the brake cable first. Again, don't ask me how I know that. :oops:

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PostPosted: Thu Aug 21, 2014 6:30 am 
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Joined: Sat Jun 01, 2013 5:38 pm
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Location: Orange, CT
I got it apart and took the cylinder out. It was fairly easy other than deforming a few fins on the drum. As it turns out the old bleed screw was fused in so I drilled it out but the drill went a littlt off center as I expected.
I did get it out and it holds fluid but I'm going to replace it anyway.
You're right the general bleeding procedure on any vehicle is to do the farthest to closest from the master cylinder.
I still have a very long pedal travel and the brakes are still soft.
I need to bleed the master itself then move to the booster.

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PostPosted: Thu Aug 21, 2014 8:47 am 
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Joined: Thu Oct 30, 2008 9:34 pm
Posts: 105
Location: Torrington
Just some general tips from my experience in bleeding brakes. Not a mechanic but have done it countless times.

If the master cylinder was changed I would bleed it 1st, if it was not changed then I wouldn't bother. I go from farthest to closest as you state, and often make a few laps around the car if I am having trouble reducing pedal travel. (I have much, much better luck pushing the fluid in the bleeding process with the brake pedal rather than trying to suck it through with a Mityvac.)

If I have gone around the car much more than three times with the pedal still going to the floor, I usually leave the car for a few nights and come back to find that the brakes now feel firm with the pedal nice and high; my theory is that the last few elusive bubbles often find their way out to the fluid reservoir.

On my 53 Chevy I changed all four wheel cylinders and must have done 10 laps around that car. The brakes would only grab with the pedal nearly to the firewall no matter what I did. The Bel sat for the winter and when I pulled it out in the spring; beautiful solid brake pressure high on the pedal; it was like magic.

I think Keebler Elves work on my cars when I sleep.


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PostPosted: Thu Aug 21, 2014 9:33 am 
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Joined: Wed Apr 09, 2008 5:53 pm
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Location: CT
["I think Keebler Elves work on my cars when I sleep"].

:lol:

I think those same elves drain my bank accounts while I sleep. Maybe they're using my money to fix your car?!!

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PostPosted: Sat Sep 06, 2014 8:19 am 
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Joined: Wed Jul 23, 2008 2:38 pm
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Location: rhode island
Best way is to bench bleed the master before installing, running tubes from the ports back into the reservoir....but you can do this on the vehicle as well, ...pump until air bubbles are gone. Hook up lines, pump pedal slowly a few times, hold onto floor with a stick or other implement, now crack master lines and make sure no air bubbles. Repeat if so. Now start with furthest, and use a Bottle half filled with brake fluid. Crack bleeder....hook hose to bleeder and submerge in fluid. Pump until you see NO air bubbles. Without fluid, you can't see AIR. This is the fool proof way. You also have to make sure rears are adjusted, then there is pedal adjustment, then there is the rod adjustment from the booster to master. and hopefully you didn't drop the ring in the booster. (I don't think you did from the sounds of it)


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PostPosted: Sat Sep 06, 2014 11:05 am 
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Joined: Sat Jun 01, 2013 5:38 pm
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Location: Orange, CT
Thanks Paul I had it installed already so I just bled the master again and it solved the problem. I'd still like to get a rebuild kit for the booster but I don't know if they still make them. If so I'd have two boosters.

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PostPosted: Wed Jul 27, 2016 11:03 pm 
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Joined: Sat Jun 01, 2013 5:38 pm
Posts: 539
Location: Orange, CT
Late reply but I eneded up getting a rebuilt A1 Cardone booster and I HAVE BRAKES!
I had to paint it black and installed it twice due to forgetting the fork that goes on the pedal but man I can stop on a quarter now. I'd say a dime but the brakes still arent' like modern cars.
I'm now 89% safe.

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PostPosted: Thu Jul 28, 2016 6:47 am 
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Location: CT
You sure didn't look as if you had any problems at Lime Rock last week. :thumbs_up:

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PostPosted: Thu Jul 28, 2016 4:18 pm 
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Location: Orange, CT
Well I try to stay off them as much as possible.
If I had to do an emergency stop it just wouldn't happen.
Braking was a well planned event.

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