MaTTSuN Posted January 19, 2009 Share Posted January 19, 2009 took my booster off today i have a 78 280z the problem ive been trying to fix is my brake pedal is way to light the brakes seem to work fine but there is not much resistance when i push on the brakes it used to be allot worse befor i put my rear disks on more of a reaction disk symptom no brakes then all brakes looking at my booster it is pretty rusty, looking on the inside i can see the spring looking scaly white not sure where to go from here - maybe the booster is getting o much vacuum assist? - some of the rust isnt letting the booster seal....then the brakes might be hard? -master cylinder needs a rebuild? or upgrade ? i just want brakes that feel like they should grrr 'Matt Quote Link to comment Share on other sites More sharing options...
zzzzed Posted January 19, 2009 Share Posted January 19, 2009 i think i know what your problem is, I had the same thing. There should be a rubber bush on the inside of your booster, it sits between the master cylinder rod and the booster plunger. If you cant see it it has fallen out. Shake your booster to see if you can hear it rattling around. Good luck getting it out it took me a while to retrieve mine Quote Link to comment Share on other sites More sharing options...
MaTTSuN Posted January 19, 2009 Author Share Posted January 19, 2009 that is called the "reaction disk" and it is in there, the plunger and the disk is stuck in the housing i shook the booster around and there is nothing loose save for some rust ;-P Quote Link to comment Share on other sites More sharing options...
batou Posted January 20, 2009 Share Posted January 20, 2009 probably not the problem, but is that spring that holds the pedal back in good shape and not wore out? Quote Link to comment Share on other sites More sharing options...
MaTTSuN Posted January 20, 2009 Author Share Posted January 20, 2009 the spring look fugly but it still has a fair bit of pressure when i depress the booster out of the car it may be a bleeding issue im going to put it all back together and bleed the balls off it and go from there may even rebuild the booster for fun since i messed up the retainer clip and rubber thingy under it Quote Link to comment Share on other sites More sharing options...
batou Posted January 21, 2009 Share Posted January 21, 2009 I don't mean the spring in the booster, on my 76 280z I have a spring that goes from the pedal to a mount on the pedal box. It adds a good bit of resistance to the brake pedal. IE if you pull your booster out (which by your prev. post you have) and the pedal can just swing back and forth, you are definitely missing that spring, or it just fell off, or they didn't add it in 78 (which would be odd). Quote Link to comment Share on other sites More sharing options...
MaTTSuN Posted January 21, 2009 Author Share Posted January 21, 2009 oh ill look into that... shouldnt the master cylinder build pressure and thats what give the pedal its feel? Quote Link to comment Share on other sites More sharing options...
batou Posted January 22, 2009 Share Posted January 22, 2009 I would think the master cylinder would build a decent amount of pressure to the pedal, giving it a good bit of feel when you press it down, but that spring would add a good bit of resistance too, I would check both. Spring is easy to check, master cylinder is harder. I always check the easy things first Also I ReRead your initial post, did not catch that you put in rear disks. I have read on this forum that depending on which calipers you use you might want to swap over to a 15/16ths master cylinder to regain pedal feel due to the increase in required fluid to actuate them. You can pull that from the 1979-1981 ZX's I believe (the ones with the dual reservoirs). It is pretty much a bolt on part, just need to adjust the brake lines and I think also (cant remember the name of the part) the threaded rod that goes between the master and booster(or pedal and booster) I would look at the brake sticky to be sure. Also It very well could be a bleeding issue. If it were me I would check for the spring and if its there switch over to the 15/16ths master cylinder(if necessary) and then bleed the crap out of it. The master cylinder would probably be an easy junk yard find, but I would buy the rebuild kit (about 8-10$ at your auto store) You very well could use a rebuild on your current master cylinder if you keep it being that you have the white oxidation and whatnot inside of it. I'm gonna add I'm no professional with Z's as most of my Z knowledge is from browsing this forum. I haven't been able to work on my Z in a while. Maybe one of the more experienced could chime in? I would love to have somebody say I'm right (or wrong, I like learning new things but I would hate to find out I am wrong after you go and follow my advice.) Lol man I just wrote a nice long one huh? try not to fall asleep readin all of it. Quote Link to comment Share on other sites More sharing options...
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