twinturbos Posted May 5, 2008 Share Posted May 5, 2008 Hi guys, while performing an overhaul of my Z's susepsnion and bushings, i decided to upgrade to stainless steel lines and toyota 4 piston calipers. during the process i allowed my brake master cylinder to dry out for 2 weeks(i know stupid me:shifty:). I bought a new brake master cylinder, bench bled it, then bled my brake lines. i then bled the master cylinder while it was attached to the brake booster and the brake lines again. i repeated this process for 3 days straight, 3-4hours each of those days, took a day off and restarted the process for another 2 days. the brake pedal has finally improved last night. But i was wondering if something else could be the cause of the spongey brakes. anyone else with similar issues? At this junction, my brake pedals are still mushy as hell, but since bleeding it again last night "for the 20th or so time" it has regained a lil pressure. Quote Link to comment Share on other sites More sharing options...
twinturbos Posted May 5, 2008 Author Share Posted May 5, 2008 by the way. i unbolted the brake master cylinder from the brake booster, but i kept the lines attached. I had my buddy press down the brakes while i forced the brake master cylinder into the brake booster to see if there was any bubbles. there was none. Quote Link to comment Share on other sites More sharing options...
twinturbos Posted May 5, 2008 Author Share Posted May 5, 2008 also like to add that i bled the brakes and brake master cylinder while the car was off and on. Quote Link to comment Share on other sites More sharing options...
intuitdriver Posted May 5, 2008 Share Posted May 5, 2008 bleed in proper sequence and make sure that the master stays topped off. Also use dot 3 fluid. Bleed the hell outta that master too but you need to bleed everything including the master in the proper order. the entire bleed process should take 10mins with 2 people, one pumping and one bleeding. I think you are doing the sequence wrong. 15 mins if you are using a pres bleeder only because it can take time to hookup. Quote Link to comment Share on other sites More sharing options...
twinturbos Posted May 5, 2008 Author Share Posted May 5, 2008 yea, i constantly topped it off and used dot 3. I bled the master cylinder, then i bled the brake lines starting with the rear passenger, then rear driver, then front passenger and ending with front driver. it would take us 15min initially but as of late we've been going above and beyond, bleeding the hell out of each part. Quote Link to comment Share on other sites More sharing options...
twinturbos Posted May 5, 2008 Author Share Posted May 5, 2008 my setup is the 280zx master cylinder(15/16) with the larger and smaller reservoirs bolted to the stock brake booster. i dont think the brake booster has anything to do with the issue at hand. i drove the car around before i did the upgrades and the brake pedals felt fine. i dont think i misplaced the reservoirs(the larger for the front and smaller for the rear). with the car off, the brakes would feel fine, but when i turn the car on, the brake pedal would submerge and get spongey. I also broke in the brake pads with bout 10+ stops at 30mph. Quote Link to comment Share on other sites More sharing options...
intuitdriver Posted May 5, 2008 Share Posted May 5, 2008 and did you bleed in the proper sequence? also back the master off of the brake booster and check for fluid leak. sounds like bad master Quote Link to comment Share on other sites More sharing options...
twinturbos Posted May 6, 2008 Author Share Posted May 6, 2008 one of the things i checked for when i did the test to see if there was bubbles in the brake master cylinder was a leak, i did not see any. what do you consider is the proper bleed sequence? Quote Link to comment Share on other sites More sharing options...
intuitdriver Posted May 6, 2008 Share Posted May 6, 2008 I don't have my bleeder book with me. I suspect i know what the sequence is and ill check in a little bit... but what is the sequence you have been bleeding in so far? Also, bubbles in the master is the easy symptom to look for but you wont always see bubbles. Separate the master from the booster and tell me if it is wet between the two... (just back it off the bolts, no need to remove it completely) If it is dry, pump the brakes up really good and inspect EVERY brake line connection, bleeder screw, and caliper (around the piston boots) for moisture. Your problem either lies with a bad master, or air in the lines. In the mean time do the checks, and ill get you a bleed sequence within an hour or so. Quote Link to comment Share on other sites More sharing options...
intuitdriver Posted May 6, 2008 Share Posted May 6, 2008 This process does no good if the master is bad so check that first bleed sequence is this: master cylinder first: start bleeding the line closest to firewall and then the one closest to you. Do this repeatedly until the fluid flows and doesn't foam or spit airy fluid. Open back, then front, back then front... brakes: RR, LR, RF, LF (standard Z bleed) tell your buddy to pump it up 1.pump pedal 5 times and hold it 2. open bleeder and have him tell you when the pedal hits the floor -make sure when the pedal goes to the floor he holds it until you close the bleeder 3. repeat until there is no air in that caliper 4. check the master to make sure it has plenty of fluid 5. move to next caliper Repeat that process until all the brakes are bleed. This process does no good if the master is bad so check that first Quote Link to comment Share on other sites More sharing options...
intuitdriver Posted May 6, 2008 Share Posted May 6, 2008 i forgot to mention. if the system is functioning properly, when you start the car the pedal will drop a short ways and stay solid. This is normal of most every car. Also check to make sure the vac line on your brake booster -> intake manifold is nice and tight with little to no wear on the hose. Don't want you loosing brake booster pressure. another tip, be easy on those bleeder screws. they only need to be hand tight + a little more with the wrench. they are fragile and don't need much torque anyway. Ensure that your brake lines are properly routed as well as to not get caught OR KINKED. Those are my best tips for doing proper brake line work. Take those to heart, I used to be a brake and underbody specialist. Quote Link to comment Share on other sites More sharing options...
twinturbos Posted May 6, 2008 Author Share Posted May 6, 2008 thanks intuit. i did already did all of the above. i initially pumped the pedal 5 times, than decided to pump it 10+ times. master cylinder is in good condition. no leaks. however, i did came across this article http://forums.hybridz.org/showthread.php?t=113035&highlight=brake+issues&page=2 ima probably try the method of flippin the calipers upside down and bleeding it that way. if that doesnt work, then trying to adjust the MC. if that doesnt work, ima probably go back to a stock 280z MC and see if taht does the trick. Quote Link to comment Share on other sites More sharing options...
intuitdriver Posted May 6, 2008 Share Posted May 6, 2008 try running the car while you bleed. its what we do for some ABS systems, who knows it may work if it don't work, gravity bleed it for about half a day. just pop all the calipers open and let em drip for about 6hrs Quote Link to comment Share on other sites More sharing options...
twinturbos Posted May 8, 2008 Author Share Posted May 8, 2008 Last night, i bled the calipers while it was layin on its back cause i couldnt bend the lines to bleed it upside down with the nipples up. I noticed an improvement there. But i havent made enough progress to where i feel at least 80 or 100% confident in the brakes. 2 last thing I am going to do is check to see if my MC is adjustable and fool around with it. If I cant make that work, then go back to the original 280z MC. Quote Link to comment Share on other sites More sharing options...
intuitdriver Posted May 8, 2008 Share Posted May 8, 2008 remember if your brakes fail, you still got about 5 deteriorating braking stops using the pressure built up in the booster. Of course if you got no brakes, its probably a bad idea to go out on the road, but if you do have brakes and they suddenly go out, you still got some stopping left with the booster. When you start the car, pump your brakes really good about 30 times and lift and drop the ebrake about 30 times before you drive. Then get the car rolling and make sure those brakes work before you really drive. Alot of safety systems in a brake system so don't worry to much. Quote Link to comment Share on other sites More sharing options...
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