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Brakes just won't bleed out?????

3535 Views 17 Replies 11 Participants Last post by  palladin
Hey all,
The 76, after 10 years of work is almost back together. The engine, rebuilt 5 years ago was started last month and has 5 hours of static break in on it. And then came the **** brakes............ The fronts are Toyota double pucks and the rears are Maxima calipers on new discs, the m/c is new. No matter how many times I bleed these darn things they are spongy for the first 2-3 pumps before they firm up. So, all 4 calipers are new, the m/c is new, the fluid is synthetic, all 4 calipers are installed correctly with the bleeders screws on the high side (yes, I have made THAT mistake once before, LOL). They have been bled from the drivers rear to passengers rear to passengers front to drivers front 5 or 6 times. No air comes out just pure fluid and yet still the spongy feel. Any ideas?? I have checked past posts and while there are a few novel ways of bleeding the system I am not seeing anything new. I am wondering if the rear discs are not compatible with the stock, but new, m/c. Even if it isn't I should have a hard peddle. Any guesses will be appreciated.
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Did you bleed the master cylinder? There is most likely air trapped in it.
What color was the fluid when blead?
Jas - I bled the m/c first thing and then a second time.

Jaket- fluid was perfectly clear. I have pumped darn near an entire quart thru the system at this point.

The annoying part is that i have bled brakes since I was 12 (I am 56 now) and have never come across one this stubborn even on other Zs. I am ready to hang the front clip and start wrapping this project up but will hold off till I get these brakes straightened out.
Close all bleeders and push on the brake to see if it holds...if not, the brake master may be suspect or you have a leak. Pound on the pedal..if it holds for a second and fades,,,it's a faulty master.. provided no lines have let go.
Also check to ensure the vacumn booster is working or the hoses have not failed. Remeber the brakes are vacumn assisted.
Are you sure that BOTH sides of the M/C have solid fluid coming out? Norm K.
All great ideas, hehehe, that have been done I hate to say. The brakes have been both pressure bled and two person bled. Last night I got a hard peddle and then jammed a stick between the seat support and the peddle overnight, came back to everything the way i had left it, no leaks or leak downs.
Now, I did notice something last night when I was setting up the stick on the peddle. When i first set it all the wheels locked up expect the drivers rear. I pushed the peddle harder jammed the stick in and that one locked as well. Also, on the intial filling of fluid that same caliper was slow getting fluid to it. I think, but am not sure, that the problem is somewhere in that caliper so i will act like the U.S. government--I will throw money at it and buy a reman. caliper from Rock Auto, change it out and see what happens. meanwhile any other suggestions are appreciated.

Thanks Guys
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When I swapped mine w/ the same set up as yours, I also encountered the same issue. Check the distance of the rod from the booster to M/C... there should be enough clearance between both when not pressed. One trick I did was I pulled the MC forward and gently pushed it back into the booster. If you see air bubbles coming out from the reservoir, adjust the rod until you see none. Its a lot easier to do this if you remove the booster and the M/C all together... kinda like bench bleeding. When done, put it back and bleed all 4 sides until mo more air and is visible and/or pressure is back.
Hmm, that sounds different. I will look at the illustrated breakdown of the system in my factory shop manual when i get home because for the life of me I cannot remember what the interface between the booster and the m/c looks like inside. In fact, I did not even realize it was adjustable. Hey worth a try, LOL. This is really holding me up as I am not going to put the front clip on the car until I have this straightened out. Once that clip is on the car is done except for final Weber tuning which is pretty close as it is. Thanks for the tip.
Different brand has different angle/vertex on the cone.... you will want that MC to be completely on rest position prior to bleeding when connected to the booster. As you can feel when you step on the pedal, there should be a little 'free' distance before the brakes actually engage. Common mistakes are either the rod is too extended or too far from the M/C. Good luck and hope that helps...
What master cylinder did you put back on? You should have put a master for both frt and rear calipers. If you put a master on that is for a disc/drum setup,you may have to change masters.
zeeyah, when I got home I pulled out the shop manual and darn if there is not an adjustment there, I never noticed one before, guess ya learn something new every day. I will pull it apart tomorrow after work and see if it needs to be adjusted.

coolhand, I have known other people who have used the standard Z m/c with a 4 wheel disc setup. Besides, you should be able to get a firm peddle anyway. The four wheel disc m/c may work better but either one should be able to achieve a firm, spongy free feel to it. Usually the problem involves the bias between the front and rear after you ad read discs which is solved by adding a proportioning valve to adjust the pressure going to the rears.
;) were all still in a learning process.

@coolhand... You are completely wrong. I have installed the 'old' M/C with same set up on my buddy's car before and works out perfectly. The newer M/C have a bigger volume capacity and somewhat 'its better to have it in there'...
How am I "completely wrong"? I did not say it would not work. But,you yourself said "the new M/C have bigger volume capacity and somewhat it's better to have it in there". There is a reason they make different masters for disc/drum and disc/disc setups. The same goes for proporitioning valves. But you seem to be the master here. Since I am completely wrong,you tell us why he is having these problems.
Be sure the reaction disc is in there between the booster and the master cylinder.
As for Rockauto. On the ZX it is about the same money to get one from Autozone/O'reilly/Advance and are guaranteed for life.
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