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busted240

73 240z rear drums won't bleed.

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So a while back a piece of the wheel cylinder failed and broke off inside the drum damaging everything during a short drive. Now, I replaced the drum(scoring), wheel cylinder(broken and leaking fluid), hard lines(nut stripped) and brake shoes.

After endlessly bleeding the brakes with my brother helping, I still can not get them to bleed. The front are fine, perfect in fact, but the rear is like it has air no matter how much I bleed it. When pressing the pedal while driving I usually have to pump 2 or 3 times before it catches and it normally just goes to the floor with the brake light in the dash coming on if I don't pump it. The car stops fine after that, but feels like the rear is not working.

Is there something I am missing? I am bleeding from passenger rear to driver rear and while doing so the fluid just comes out dripping not the normal solid gush that it use to.

Any help or tips would be appreciated greatly.

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Are you sure the fronts are good? How can you tell that they're perfect if the pedal goes to the floor? Did you do any work on them while you were working on the backs?

The rear brakes can be weak for a while until the shoes get seated in the drums. You might have weak back brakes because they're new, with air in the front calipers causing the pump-up problem.

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When I bleed all four corners, fluid comes out the fronts in a steady stream like they should, while the backs only barley run out like a slow drip. That is what I was referring to since I can not tell with the peddle issue. Front brakes were not touched other then bleeding them to check for air in the lines.

While they are "seating" would this cause there to be little fluid coming out during the bleeding process?

Edited by busted240

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While they are "seating" would this cause there to be little fluid coming out during the bleeding process?

No.

I'm with AxtellZ. Sounds like a master cylinder issue. Sounds like it needs to be primed. That, or it coincidently failed at the same time as your rear cylinder.

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Good points about the master cylinder. Did the fluid level ever drop to the bottom of the reservoir during bleeding? That could have introduced a bubble in the master cylinder. You have to keep the fluid level off the bottom of the reservoir during the whole process, once you start.

Also, apparently, the master cylinder seals can be damaged by the bleeding process if they run over crud at the bottom of the bore. But if they pump up, it's more likely air n the system.

The brake light in the dash turns on because of the pressure imbalance between front and back. It's a warning light that something's wrong. Pumping the brakes balances the pressure.

Good luck, brakes can be time-consuming to get right.

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bleed the master for the rears first, then rebleed at the back.
I'll give that a shot tomorrow.
Good points about the master cylinder. Did the fluid level ever drop to the bottom of the reservoir during bleeding? That could have introduced a bubble in the master cylinder. You have to keep the fluid level off the bottom of the reservoir during the whole process, once you start.

Also, apparently, the master cylinder seals can be damaged by the bleeding process if they run over crud at the bottom of the bore. But if they pump up, it's more likely air n the system.

The brake light in the dash turns on because of the pressure imbalance between front and back. It's a warning light that something's wrong. Pumping the brakes balances the pressure.

Good luck, brakes can be time-consuming to get right.

The bowl never went dry, other then when everything was off and the lines were being replaced. I don't think there was any gunk or crud in the lines, they were fully drained and filled with new fluid while the brake lines were being replaced. Hopefully bleeding the master will solve the problem, I never had to bleed the master before, even when I first got the car and there was no fluid in the lines at all. Maybe that was just lucky, I'll find out tomorrow.

Thanks guys.

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Also, make sure the brake shoes are adjusted to be close to the drums. You should be able to detect a little drag here and there as you turn the drums by hand. If they are too loose it will cause a low pedal.

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Bleed both front and rear at the master and then at the brakes. Solid flow like it should but still have to pump the brakes once to get them solid.

Also, make sure the brake shoes are adjusted to be close to the drums. You should be able to detect a little drag here and there as you turn the drums by hand. If they are too loose it will cause a low pedal.
I adjusted the wheel cylinders out as far as I could and it still has no drag on either side. Am I missing something? These are brand new pads with only a few miles on them. Oh, and in case it matters the emergency brake has not worked since the wheel cylinder failed. It is hooked up properly and the cable works but it does not stop the car at all, assuming this is hand in hand with the rears not working. Edited by busted240

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Silly question, but are you turning the adjuster for the rear brakes the right way. If its all the way out you should not be able to turn the drum. Just another thought, perhaps the brake shoes are not the correct ones. Do they look to be the same diameter as the origionals. Another thought. Can you mesure the ID of the replacement brake drum. It may be way oversize, or it may be cracked. It could then expand as you applied the brakes.

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Silly question, but are you turning the adjuster for the rear brakes the right way. If its all the way out you should not be able to turn the drum. Just another thought, perhaps the brake shoes are not the correct ones. Do they look to be the same diameter as the origionals. Another thought. Can you mesure the ID of the replacement brake drum. It may be way oversize, or it may be cracked. It could then expand as you applied the brakes.
Yes, the adjuster is pushing the shoes outward towards the drum. The brake shoes are from MSA and match the removed ones identically. I did not measure the replacement drum but I got it from a buddy who parts out z cars, and it seemed to match my original one and has no cracks what so ever, looks very clean in fact.

How far out does the adjuster go? I turned them until it felt very hard and stopped, but it did not seem to rub the drum at all still. I was afraid to go any further and risk breaking the wheel cylinder again.

Edited by busted240

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You should be able to lock up the rear drums with the adjuster, and the adjuster wheel should not be difficult to turn until that happens.

It's been a while since I've been in that deep into the pre-77 brakes, but I believe if you keep turning, and turning, and turning... And if by some weird set of improper circumstances occurs the shoes don't contact the drums... You'll eventually wind the adjuster stalk completely out of the cylinder. I don't remember any stops on that thing anywhere.

You know that the two sides adjusters rotate opposite directions, right? "Bottom to top" should tighten the shoes.

Can you hear the adjuster lever clicking over the teeth in the wheel as you turn it?

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You should be able to lock up the rear drums with the adjuster, and the adjuster wheel should not be difficult to turn until that happens.

It's been a while since I've been in that deep into the pre-77 brakes, but I believe if you keep turning, and turning, and turning... And if by some weird set of improper circumstances occurs the shoes don't contact the drums... You'll eventually wind the adjuster stalk completely out of the cylinder. I don't remember any stops on that thing anywhere.

You know that the two sides adjusters rotate opposite directions, right? "Bottom to top" should tighten the shoes.

Can you hear the adjuster lever clicking over the teeth in the wheel as you turn it?

It's possible I am not adjusting them all the way out then. I will have to check them tomorrow, and try going further and see what happens. I can feel it clicking, as well as see the shoe's moving out ever so slightly.

Now, since the shoes are not contacting the drums enough yet, would that make for the emergency brake not working as well? I can't find any reason why it stopped working since everything on that end looks good.

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Have you had the adjuster out of the wheel cylinder to clean and lube the threads? Perhaps it is full of dirt, rust, or other foriegn matter that is binding the threads. If not, do so. When you put if back together leave the adjuster out near last few threads so the shoes are at the maximum diameter. If you can still put the drum on you have a problem with the parts or assembly.

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To me this sounds like a master cylinder issue. I had similar symptoms, tried to bleed and bleed with no good results. Got a new master cyl, bleeded, and works like a charm.

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To me this sounds like a master cylinder issue. I had similar symptoms, tried to bleed and bleed with no good results. Got a new master cyl, bleeded, and works like a charm.

Regardless of the master cylinder, the adjuster should still be able to lock the drum when screwed out.

Seems to me he has two problems here. Problem at the drum and problem at the master cylinder or the wheel cylinder.

Unscrew the adjuster fully out and wirebrush the threads.

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I agree. Sounds like more than one issue at play here. Let me recap to make sure we know where you are at now...

Originally you had brakes that went to the floor and took 2-3 pumps to get any pedal at all, and even after you got some pedal, it seems the braking was happening only on the front axle. In addition, you couldn't get fluid out of the rear cylinders when bleeding.

Then... You bled right at the master, and again at the corners. After that bleeding, there is now a strong bubble-free stream of fluid out of both front and rear corners when bleeding, but you still have brakes that go to the floor on the first hit and require pumping once to get firm pedal.

Is that where you are now?

As for the rear adjusters, I really don't think there are any stops on that adjuster wheel. You're doing the adjusting with the drum off? If you keep turning it and watching the shoes spread, you will eventually reach the point where the adjuster stalk completely unthreads from the cylinder. From memory, I believe the threaded stalk is about an inch long, so you should be able to screw that adjuster wheel out about that much, and there is NO WAY you should be able to get the drum back on with the shoes adjusted out that far. If you can, then there is something seriously wrong somewhere.

Edited by Captain Obvious

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I agree. Sounds like more than one issue at play here. Let me recap to make sure we know where you are at now...

Originally you had brakes that went to the floor and took 2-3 pumps to get any pedal at all, and even after you got some pedal, it seems the braking was happening only on the front axle. In addition, you couldn't get fluid out of the rear cylinders when bleeding.

Then... You bled right at the master, and again at the corners. After that bleeding, there is now a strong bubble-free stream of fluid out of both front and rear corners when bleeding, but you still have brakes that go to the floor on the first hit and require pumping once to get firm pedal.

Is that where you are now?

As for the rear adjusters, I really don't think there are any stops on that adjuster wheel. You're doing the adjusting with the drum off? If you keep turning it and watching the shoes spread, you will eventually reach the point where the adjuster stalk completely unthreads from the cylinder. From memory, I believe the threaded stalk is about an inch long, so you should be able to screw that adjuster wheel out about that much, and there is NO WAY you should be able to get the drum back on with the shoes adjusted out that far. If you can, then there is something seriously wrong somewhere.

Correct.

One wheel cylinder is brand new, clean and lubed. The other I removed and cleaned up a bit and put some new lube on the end of the adjuster but did not un thread the screw to check it.

I am doing it with the drums off, and the adjuster did not extend out an inch so I will be checking tonight to see what's keeping it from going any further.

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Haha! Don't quote me on that one inch. It's been years since I've messed with the adjuster in detail. Let's say "around" an inch, OK?

But... Now that I'm thinking about it... Is this on the brand new wheel cylinder, or on the old one? Seems very odd that a brand new, clean one would have any issues spinning the adjuster gear. If it's the old one, then I suspect you've got grunge in the threads on the hidden side of the adjuster wheel.

If it's the brand new one... :confused:

Hey... At least now you have a strong bubble-free stream to the rears now! :beer:

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Yes, %50 victory alright. The brake light no longer comes on, but I didn't get a chance to try and adjust out out anymore today. It feels like that is probably it, the brakes do work fine even though they nearly reach the floor still, and just get a firmer pedal if I pump it.

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the brakes do work fine even though they nearly reach the floor still, and just get a firmer pedal if I pump it.

Wait a minute... Do you mean "firmer" or "higher" pedal when you pump it?

"Higher" after you pump it would be too much travel in your rear brakes.

"Firmer" after you pump it would be air bubbles still hiding in the system somewhere.

Here's what I think you're talking about: You hit the brakes and the pedal goes closer to the floor than what would be considered "normal" before it reaches end of travel. But once it does reach end of travel, the brakes work fine and the pedal feels firm and won't travel much more than that point. In other words, the pedal stops abruptly at end of travel... It's just that the end of travel is too close to the floor.

Then if you let the pedal up and then hit it again quickly, the pedal still stops abruptly and feels firm, but now stops higher off the floor than it did the first time you hit it.

Is that what's going on?

Also, are you were having the adjuster sticking issues on the new side, the old side, or both?

I apologize for asking so many questions. I just want to make sure we're chasing the right demon.

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If it is a low pedal from too much travel on the rear shows, it might be fixed by setting and releasing the parking brake multiple times. Each pull ratchets the shoes a little wider, if it's working right. Worth a shot, if you don't want to take things apart again, plus it's a good test of the mechanism.

And it will tell you how loose the back shoes are. If the shoes are loose, the lever will come way up. When they get close to proper tightness, it will only come up a couple of inches.

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Wait a minute... Do you mean "firmer" or "higher" pedal when you pump it?

"Higher" after you pump it would be too much travel in your rear brakes.

"Firmer" after you pump it would be air bubbles still hiding in the system somewhere.

...

Also, are you were having the adjuster sticking issues on the new side, the old side, or both?

I apologize for asking so many questions. I just want to make sure we're chasing the right demon.

I guess I would clarify it as higher pedal, it was always firm. The adjuster was sticking on the old one, took it out and cleaned it real good and now it doesn't.

I adjusted them pretty far out, till they finally rub'd a bit on the drums and now the brake pedal is solid and the e-brake is working again. Thanks for all the help guys! :D

And it will tell you how loose the back shoes are. If the shoes are loose, the lever will come way up. When they get close to proper tightness, it will only come up a couple of inches.
My e-brake always goes all the way up, even before the brake problems. It does work perfectly though so I don't know what that means.

It's kinda nice this happened in a way, now I got all new hardware and new lines in the back not to worry about LOL.

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