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So nearing the point of getting my Z back on the road and I am having severe brake bleeding issues.

Its a 73 240z w/ Toyota S12+ (non vented), '85ish Maxima rear brakes with DatsunPartsLLC brackets, and 15/16 Master Cylinder, and braided lines front and rear.

 

Calipers and master cylinder were good prior to install.

 

In a hurry (because I was moving) I put the master cylinder, bled the system and actually had pressure throughout the system, it was loaded onto a flatbed and towed to where I'm at now. I finished installing the e-brake, ran the car and I have squishy pedal, no pressure or brakes until I pump the brake pedal 3 times.

 

I pulled the Z back in the garage and noticed upon the 3rd or 4th brake pedal pump and on it would "hiss" at the last inch of pushing the pedal.

 

I bench bled the MC, re-bled the system, and still the same story, no pressure until I pump the brakes in rapid sequence and on the 3rd or 4th press. Also I'm noticing when I bleed the rear brakes I'm barely getting any fluid coming out, or at least no where as near as much as I do in the front. I have no signs of leaking anywhere (lines, brakes, distribution blocks, MC, booster), and I am at a loss.

 

I'm considering taking it to a brake shop and have them bleed it with a brake flusher (so it bleeds all 4 corners at the same time). But I'm on a budget and would rather save the $$.

 

Any ideas?

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Check bleed valve orientation.

 

as in how tight/deep are the bleeder valves?

 

So you just installed the master? Reaction disk or master pushrod adjustment are my guesses if that's the case.

 

Its been installed before moving, and I had pressure, then I bled the system, test drove, bench bled the master, then bled the system, then test drove again.

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as in how tight/deep are the bleeder valves?

Some of the popular brake swaps end up with the bleed bolt at a position other than the very top, where the air is.  The bleeder needs to be where the air is, otherwise fluid flows past but doesn't take the air with it.  You might have to remove a caliper mounting bolt to rotate the bleeder to the top for bleeding then put it back for use.

 

Just something to check, I'm not familiar with the details of your swap.

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I have a similar setup except I have a 1" Wilwood master. I have bled the hell out of the lines. Vacuum bled, gravity bled, set up a recirculating line back to my M/C with a check valve at the bleeder and finally last night set up a pressure bleeder using a garden sprayer, clear hose and an old M/C cap. I have 7 one quart bottles of fluid in my garage and at least one of them has been emptied on the floor for various reasons! It looks like the fronts are firm but in the back the master starts to empty as I pump the pedal and then fills back up slowly after pumping, to me that means I still have air trapped in the back lines. I am going to pressure bleed the backs again, after getting the 8th bottle of fluid (2 gallons total!). I think I will try to pressurize the system and open both bleeders at once to see if I can flow any more air out.

 

I did check the reaction disc and blocked off the outlets to the M/C to make sure it's not leaking through, it builds pressure instantly and doesn't fall off. I'm not 100% sure my M/C push rod is set correctly but if anything it is set a little short so I would think that if all the lines are free of air I would have a solid pedal, just a little lower than expected.

I have about 30 hrs into trying to get my brakes working and I am getting more than a little frustrated. I think I have tried everything that I have seen on the interweb, does anyone have any suggestions if the pressure bleed doesn't work tonight?

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With Maxima and 240SX calipers I found that I had to unbolt the caliper from the bracket and bleed it while shaking, tapping and moving the caliper in various orientations to get the air out. Unless you have a pressure bleeder you have to block the piston with something so it doesn't push out. I use a caliper piston tool (Harber Freight $30) turned all the way in to hold the piston while pumping the pedal.  Use Earls Solo Speed Bleeders or other brands of bleeders that have a check valve built into them on the calipers and master cylinder.

Edited by Miles

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I had some GM calipers with parking brakes on a different car that I had to remove from the brackets and turn all around while tapping with a rubber mallet to get the air out of them. This was gravity bleeding with a clear tube going into a bottle of fluid. It was ridiculous how moving it all around and tapping, shaking and everything else then the tiniest bubble would come out. They sucked so badly but for some reason all the hot rod guys love them.

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Amen, Miles. Dave, it is super easy to swap out fluid once the air is out. If I have a super higher temp experience, I swap from one color fluid to another and it only takes a second to know that I'm flushed. I did have a line-lock solenoid o-ring failure recently and I'm wondering if one fluid or another made it brittle(?). I got speed bleeders last year and I can't say enough about them.

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Well the pressure bleed with removing the calipers and rotating and tapping did the trick.
I pulled the calipers while gravity bleeding and it didn't help. It seems like there may be a little room for improvement but the pedal doesn't hit the floor with the engine running. A few more good hours and I'll be terrorizing the neighborhood!

Edited by Naptown Dave

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Some of the popular brake swaps end up with the bleed bolt at a position other than the very top, where the air is.  The bleeder needs to be where the air is, otherwise fluid flows past but doesn't take the air with it.  You might have to remove a caliper mounting bolt to rotate the bleeder to the top for bleeding then put it back for use.

 

Just something to check, I'm not familiar with the details of your swap.

 

 

Everything is oriented correctly, I made this mistake the first time I put on my Toyota calipers

 

 

Too many people never follow up with a solution.  Be sure to post your solution(s)  once you are able to get a firm pedal.

 

I'm gonna rebelled everything twice over and let you know

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I would check the master to make sure it didn't go bad . You can remove the brake lines then plug the holes ( at master ) , press the pedal ( slowly ) down to see if it's firm and holds pressure . You could have a master that's bleeding through .

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I would check the master to make sure it didn't go bad . You can remove the brake lines then plug the holes ( at master ) , press the pedal ( slowly ) down to see if it's firm and holds pressure . You could have a master that's bleeding through .

 

As in bleeding through into the booster? If its not bleeding through it (the pedal) shouldn't move at all right?

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Daphur, sorry to threadjack earlier! Have you made any progress? One thing I noticed that helped me isolate my problem (air in the caliper) was my fluid level dropping in my rear master as I pumped the brake and then slowly returning as the trapped air pushed the fluid back ti the m/c. Like I said above I ended up using a homemade pressure bleeder and removing the calipers from thethe mounts so I could get all the air out of them. Basically turning them so the bleed screw was at the highest point. If you don't have much flow to th back that may make getting a good bleed tough. There have been some posts about the safety switch on the drivers side inner fender going bad and not allowing fluid flow to both the front and back, you may want to look into that as well.

I'm no expert but do have some recent experience!

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No progress, I let the pressure bleeder go to town on the calipers and I still have to pump up 3-4x to get pressure.

 

Could this braided line orientation be causing some issues?

 

image.jpg

 

With the way the line is above the bleeder?

Edited by Daphur280

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I think your flex line is ok as long as the bleeder screw is above the flex line inlet on the caliper. I would bet a stack you have air trapped in the calipers. Remove the calipers and turn them so the bleed screw is the highest point and bleed again. I got a bunch of air out of mine even after doing the same thing while gravity bleeding, mine needed the flow of the pressure bleeder to push out the air. Take the caps off the master and watch the fluid level as you pump up the brakes, you'll see the level drop in the master if you have air in either the front or back systems. Mine only needed the back but it was enough to have a soft pedal.

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I think your flex line is ok as long as the bleeder screw is above the flex line inlet on the caliper. I would bet a stack you have air trapped in the calipers. Remove the calipers and turn them so the bleed screw is the highest point and bleed again. I got a bunch of air out of mine even after doing the same thing while gravity bleeding, mine needed the flow of the pressure bleeder to push out the air. Take the caps off the master and watch the fluid level as you pump up the brakes, you'll see the level drop in the master if you have air in either the front or back systems. Mine only needed the back but it was enough to have a soft pedal.

 

So you're saying I should vacuum/pressure bleed the calipers unmounted from the rotors?

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Could this braided line orientation be causing some issues?

 

 

One thing I noticed that helped me isolate my problem (air in the caliper) was my fluid level dropping in my rear master as I pumped the brake and then slowly returning as the trapped air pushed the fluid back ti the m/c.

 

It's possible for the front and rear to leak to each other. If you have this situation and pump the pedal a lot you'll see the front master reservoir filling up and the rear going empty. It could also pump fluid into the booster.

You'll make a lot more progress if you get methodical and test each potential problem area individually.  There's three areas right here, above.  Test each one -

 

1.  Eyeball the hose while someone pumps the brakes.  Does the line expand like it's collecting fluid?  It's probably not orientation but it could be a bad hose.  I've not seen any red brake hose, where did it come from?

 

2.  Watch the reservoirs as someone pumps the brakes.  Which reservoir is moving more fluid?  That's the system that has air in it.  Unless... 

 

3.  Watch the fluid.  Does it transfer from one reservoir to another?  If so, your master cylinder is messed up.  Does it drop and never come back?  If so, you have a leak, either internal or external.

 

You have enough clues now to focus on exactly where the source of the problem is.  You just have to pick one area at a time and dig in to each one.

Edited by NewZed

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You'll make a lot more progress if you get methodical and test each potential problem area individually.  There's three areas right here, above.  Test each one -

 

1.  Eyeball the hose while someone pumps the brakes.  Does the line expand like it's collecting fluid?  It's probably not orientation but it could be a bad hose.  I've not seen any red brake hose, where did it come from?

 

2.  Watch the reservoirs as someone pumps the brakes.  Which reservoir is moving more fluid?  That's the system that has air in it.  Unless... 

 

3.  Watch the fluid.  Does it transfer from one reservoir to another?  If so, your master cylinder is messed up.  Does it drop and never come back?  If so, you have a leak, either internal or external.

 

You have enough clues now to focus on exactly where the source of the problem is.  You just have to pick one area at a time and dig in to each one.

 

1. I doubt they expand, at least on the driver side from what I can see, the lines were custom made as are the fronts from a local tube n hose shop.

 

2 & 3. I am unfortunately on my own. So I don't have anyone unless I ask a neighbor. I'll try tomorrow.

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Set up a mirror so that you can in the reservoir.  Put a little boat in there with a flag on it that you can see moving up and down.  Something.  I have a broken shovel handle that is perfect length for actuating the clutch and brake pedals.  I use it all the time for bleeding.

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