Braking issue...Help!!

[justaZcarguy]

I must have pissed off the Z Godz this week, between my '74 and my series 1 '71 I am going thru the ringer here!!

Anyway, the brakes in the series 1 '71 have allways been crappy with only the front brakes working and nuthin' to the rear. Figuring that it was the master cylinder I replaced that and fixed nothing. Matter of fact, things are worse. (how nice)

In reviewing past posts, I decided to check the check valve on the firewall, it seemed preety sticky so I replaced it with one that was in my '73 parts Z. Now I've gone from brakes going to the floor to brakes being stiff as a rock and having to lay into 'em hard to even think about stopping the car. And still, no fluid travel to the rear brakes even with the bleeder all the way out / removed completely. And yes, I've bled the Master Cylinder several times...

I thought that I maybe put the check valve in backwards and turned it around to wich the brakes have zero pressure but oddly enough seem to stop the car a bit better but also kinda sporaticlly. Right now the "bevel" in the check valve is towards the booster.

This is driving me craZy not to mention dangerous.

Suggestions???

Thanks all!

[carguyinok]

With the brakes being hard I would look at the (power booster\ Master Vac) BUT with the bleeders out from the back and no fluid leaking. Sorry I dont know:stupid: . Maybe a pluged or pinched line. I would start with getting someone to push the brake while you look for fluid or air moving in the master cylinder.

PLEASE PLEASE PLEASE park it untill its fixed. The loss of the Z would be bad enough but you may hurt or kill :dead: yourself or worst of all someone else. :dead:

[LanceM]

First off since you changed the master cylinder and still have no fluid out of the rear you have not fully bled the system and have air in in now, so the brakes are worse than before. I would say that with air still in the master cylinder brakeing would be erratic on the side that was bled too.

Here's what I would do, first you need to find out where the fluid is stopping on it way to the back brakes.

I'm not sure which way the check valve goes in off hand but you probably know going by the clean side dirty side method of how it was mounted.

I would loosen a fitting one at a time starting at the master cylinder and have someone pump the brakes while looking for fluid, if fluid comes out move backwards until you find where the fluid stops.

You may have a clogged line, frozen wheel cylinders, clogged bleaders.

Got to get them fixed right, stopping is not an option

[justaZcarguy]

If the wheel cylinders were froze, I would still be getting fluid to the rear at the bleeders, right?

Thanks

~Brian

[2ManyZs]

If the brake cylinders are seized, you wouldn't get any fluid out of the bleeders. The question I have is, does the parking brake work? If it does, then the cylinders can't be seized.... work the handle and see if the arm works correclty on the cylinders... if the hand brake doesn't work, then the cylinders definately could be siezed.

What I would do is take the lines loose from the rear cylinders and blow them out with compressed air, just to see if there is something keeping the fluid from reaching the rear brakes.

Then, if you get good pressure out of the hard lines, pull the cylinders and make sure they are in working order.

Third, hook everything back up, and bleed the master cylinder first and repeatedly... it could be that there is air still trapped in the master at the end of the cylinder under the rear brake reservoir that is causing all the trouble to begin with.

However, if you don't get any air out of the hard lines, take hard lines apart at the "T" fitting that is mounted on the floor pan just above and a little behind the diff and blow through the lines again, it could be something such as rust or sludge form moisture that is clogging up the T fitting.

I'm also in agreement that if the brake pedal is very hard, it sounds like you might have a vacuum leak, stuck check valve( are you sure you mounted it in the line correctly with the arrow pointing to the Master Vac?), or a bad Master Vac.

[justaZcarguy]

Thank you 2Many and nice to hear from you sir...

The Parking brake Never worked in this car, I thought that it was sized cables, but now that you bring back memories, I am starting to think that the rear brakes are sized. The car did sit for a year or so before I got it....

I was under the impression that even IF the rear calipers are sized you will still get fluid to the bleeders.

I have seen no "arrow" on the check valve, but I will look again, I just followed the vacumn flow I figured if I could get air thru it with suction that was the side that went towards the booster, it would draw vacumn and the check valve would allow no "bleed back" of air.

Thanks all you have been a great help...

Soon to come - the mystery miss with the '74 - stay tuned

It's driving me crazy....

Opps I mean cra Z.

~B

[2ManyZs]

Well, the brake cylinders could be the problem, but at the same time, there are quite a few things that would make the hand brake inoperative besides seized cylinders. Seized cables, stretched cables, or the arm could be off the ratchet assembly on the brake cylinder......

Before you do anything more, try bleeding the master cylinder a couple more times, you'd be surprised how many times it can be just trapped air in the master cylinder.

If you don't get any fluid to the rear after another good bleeding, then take the hard lines apart and blow them out... it never hurts to do this once in a while anyways...

The only way to check the brake cylinders would be to pull the drum and try to manually move the piston in the cylinder, that is unless you suddenly start getting fluid back there so you can visually see the piston moving. Then you can inspect the hand brake mechanism on the cylinder and see why that isn't working.... my guess would be the cables are either stretched or seized... there is an adjustment in the tunnel... but it's a PITA to get to unless you drop the driveshaft......:tapemouth

[justaZcarguy]

Been there done that, the cables are out of the car as we speak, the cables once it was out did seem sized and I have not put them back in due to the fact that I have been either working a bunch or just plain lazy...

I do plan on checking the calipers...

And you are right the cable was a PITA.

Thanks again..

~B

[Daniel]

I fought a similiar demon on a 71 years ago.The problem was the brake booster.I had been told that if it failed the results would be you would just have no power assist for the brakes.That is not true..I tried the same things you did,with no success.They would not bleed.Sometimes hard,then soft.I took apart that front /rear valve.It was a ball and a spring.Your problem seems very similar

[justaZcarguy]

Great Info...

So, did you replace the booster or just fix?

I looked into a replacement and they are pretty proud of that part...

Let me know and Thanks!

Brian

[Daniel]

Back then you could still find good unit in the boneyard.

[justaZcarguy]

Ouch, our boneyard just shut down taking a bunch of cars with them...

Ouch..

I guess that I will begin the search....

Anyone in the Portland area got one??????

And yes it's a series one Z (early 1971)

thanks!!!

Brian