JMortensen Posted February 4, 2009 Share Posted February 4, 2009 I'm betting reaction disk. Quote Link to comment Share on other sites More sharing options...
240hoke Posted February 5, 2009 Author Share Posted February 5, 2009 Thanks for all the input guys I have a lot of things to mess with now when I get back to the car this weekend... Timz - As far as bleeding the master I will definitely give it a shot Ill have to rebleed everything to check the reaction disc anyway. I bleed the old master before I swapped it just ot be sure and it didnt change anything so i didnt bother with the new one with the way Im bleeding it is shoudl flush the air out. Cygnusx1 - Thats definitly something to think about Im going to check this out for sure, it woudl be a easy fix to throw a residual valve in line... Right now this looks like my plan: - Bleed master to double check - Inspect reaction disc / rebleed - Check for piston retraction Hopefully a combo of one or all of those will fix it...ill update as soon as i figure it out. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted February 5, 2009 Share Posted February 5, 2009 You should be able to pull the master out of the booster far enough to check the reaction disk without disconnecting the lines. If you're more comfortable disconnecting the lines go for it, but I don't think it's strictly necessary. Quote Link to comment Share on other sites More sharing options...
240hoke Posted February 5, 2009 Author Share Posted February 5, 2009 It is the way Ive run my lines..my front line actually goes straight down through the fender. While Ive got the thing out I should prolly add some "service loops" in to prevent having to remove the lines though. I want to add to this thread that Motive brake bleeders are AWESOME before I would cringe at having to rebleed the system...but its cake now to do myself and i can totally flush the system in no time. http://store.motiveproducts.com/shared/StoreFront/default.asp?CS=motive&StoreType=BtoC&Count1=210323512&Count2=127463936 Quote Link to comment Share on other sites More sharing options...
drmiller100 Posted February 5, 2009 Share Posted February 5, 2009 bleed it the old fashioned way with two guys to at least make sure your master cylinder is pumping fluid. if the master cylinder is pumping fluid, then bleeding it again won't help. Quote Link to comment Share on other sites More sharing options...
aziza z Posted February 5, 2009 Share Posted February 5, 2009 It is the way Ive run my lines..my front line actually goes straight down through the fender. While Ive got the thing out I should prolly add some "service loops" in to prevent having to remove the lines though. I want to add to this thread that Motive brake bleeders are AWESOME before I would cringe at having to rebleed the system...but its cake now to do myself and i can totally flush the system in no time. http://store.motiveproducts.com/shared/StoreFront/default.asp?CS=motive&StoreType=BtoC&Count1=210323512&Count2=127463936 Been looking for a bleeder lately. Mind if I ask which one you bought? Was it the Round Universal Bleeder 0101 Quote Link to comment Share on other sites More sharing options...
240hoke Posted February 5, 2009 Author Share Posted February 5, 2009 Drmiller - Master cylinder definitely works, car is drivable just mushy pedal at the top. I can say with 99.9% confidence there is no air in the system. Aziza Z - I bought the universal one and then I got the Tilton adapters for use with my reservoirs...its really works awesome. Quote Link to comment Share on other sites More sharing options...
aziza z Posted February 5, 2009 Share Posted February 5, 2009 Awesome. Ill order mine soon. Do they have adapters for 280zx master cyl? Didnt see it on there. Maybe im blind (btw sorry to hijack your thread a little). Kinda on topic though. Quote Link to comment Share on other sites More sharing options...
240hoke Posted February 5, 2009 Author Share Posted February 5, 2009 Just call them Im sure they will be able to help you out..I think they have and adapter for almost anything. Quote Link to comment Share on other sites More sharing options...
drmiller100 Posted February 7, 2009 Share Posted February 7, 2009 Drmiller - Master cylinder definitely works, car is drivable just mushy pedal at the top. I can say with 99.9% confidence there is no air in the system. . If everything works, and you have no air, then why do your brakes suck???? Does your master cylinder pump fluid in the first 1/3 inch of travel? Quote Link to comment Share on other sites More sharing options...
Forrest Posted February 14, 2009 Share Posted February 14, 2009 This is why my car has been off the road for over 3 years instead of 6 months. I have been fighting the exact same problem and I refuse to drive the car until it's solved. I have the AZC front and rear, 4 brand new 15/16 280zx masters, brand new booster. I've bled using pressure, vacuum, and every manual way possible. Reaction disc was the first thing I checked, and it was in place. I wasn't originally using the wilwood porp valve because I was told by several people, including Dave at AZC, that it wouldn't cause this problem. I didn't want to cut into the brake lines and potentially add another point of failure until I worked it out, but after a while of no success, I added it in and it made a huge difference - now the pedal feels perfect after you push it down 1/3 of the way, but zero resistance until then. I've already adjusted the booster rod out farther than I should have, and it didn't help, so I'm not sure what more I can do. I did discover something about the AZC rears that I had, the calipers were not correctly centered on the rotors with the brackets I got. I think I read that the newer brackets corrected this, but I had to use washers to space them correctly. I have been doing a ton of other stuff that's kept me from being able to test the brakes, but I'll be getting back to it in a week or two. We may have the same problem, I'm not sure. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted February 14, 2009 Share Posted February 14, 2009 I have the AZC front and rear, 4 brand new 15/16 280zx masters, brand new booster. I've bled using pressure, vacuum, and every manual way possible. Reaction disc was the first thing I checked, and it was in place. Is it possible that the reaction disc isn't sealing to it's little hole in the booster? After all that, I'd probably try another booster, since you've already tried 4 masters. Quote Link to comment Share on other sites More sharing options...
240hoke Posted February 16, 2009 Author Share Posted February 16, 2009 Forrest -- It sounds like we very well may have the same problem, I have a 1/3 pedal of mush travel and then it feels normal. I have the same brackets as you, my calipers are spaced out with the two washers AZC supplied, never liked that much at all...but anyway I didnt get much time to work on the brakes this weekend since I was messing with the engine but I did get started. I took the plunger out and the reaction disc was in place to my dismay. I went ahead and removed the master and the 280z booster. I got a pile of parts with the 72 240z I just bought and to my delight there was a rebuilt 240z booster in with them. Im going to trow it in there, and add a 2psi residual valve in the front line for safe measures...while Im at it Im also going to add some service loops in at the MC to make all this easier next time I need to mess with the booster or anything. Hopefully next weekend Ill get it all back together and have some results. Quote Link to comment Share on other sites More sharing options...
240hoke Posted March 5, 2009 Author Share Posted March 5, 2009 I finally got everything back together on my car. I ended up replacing the 280z booster with a remanufactured 240z unit and thoroughly bleed the system. It is a night and day difference, the pedal is much firmer and feels like it should! It seems crazy to me and I dont understand how a bad booster could make the pedal spongy but it did....maybe it was just the size I dunno. Regardless Im happy Quote Link to comment Share on other sites More sharing options...
blue72 Posted March 5, 2009 Share Posted March 5, 2009 Congratulations on figuring it out. Restores my confidence in the AZC big brake setup. Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted March 5, 2009 Share Posted March 5, 2009 Hmmm...weird. Glad you sorted it out. Solid brakes are mandatory. I can't explain that one though. Now go perform a bed-in procedure and feel those brakes pop your eyeballs out when they get up to temperature! Amazing. Quote Link to comment Share on other sites More sharing options...
Forrest Posted April 5, 2009 Share Posted April 5, 2009 Hmmm...weird. Glad you sorted it out. Solid brakes are mandatory. I can't explain that one though. Now go perform a bed-in procedure and feel those brakes pop your eyeballs out when they get up to temperature! Amazing. I just re-read your old post about your brake setup on my previous troubleshooting thread. Thanks for posting that. Sometimes I really need to hear that someone else with this setup has gotten it working. You're using the 280Z M75 booster, right? Did you adjust the booster rod to stock spec when you installed all this stuff? Or did you have to run it out further? Austin, your post is making me wonder if my only problem is pedal feel. Changing the booster should only change pedal effort, not travel distance, right? So, even with the firm pedal, do you have to push just as far as when it was lighter to lock them up? Unless you also changed the rod length as a result of switching the booster, I don't see how it could have solved your problem....and I -really- want to solve mine. I can lock my tires up no problem, but it feels like too much travel and the pedal goes down way too easily, regardless. Quote Link to comment Share on other sites More sharing options...
240hoke Posted April 5, 2009 Author Share Posted April 5, 2009 It may very well have just been pedal feel. Whatever it was it was too mushy to be anywhere near acceptable for me. I was using the 280z booster, I just used the rod that came with it and adjusted it so it barely contacted the MC it was bolted on.... I switched to a rebuilt 240z unit which is much smaller, and I thought would make the pedal feel better anyway. Once again I double checked the rod and whatnot. I also slightly preloaded the pedal which may have also helped. Other then that I just bleed everything like normal and bam they felt nice. Quote Link to comment Share on other sites More sharing options...
DCZ Posted April 6, 2009 Share Posted April 6, 2009 I think it may just be the booster. My 71 has the smaller booster and is instantly hard as a rock. My 73 has the larger booster and it feels softer, especially at the top of its travel, like you describe but is still solid. This is with stock calipers/rotors and aftermarket pads on both. I agree that I like the feel of the 71 better. Just not enough to go changing boosters. Quote Link to comment Share on other sites More sharing options...
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