michaelqasem Posted February 13, 2009 Share Posted February 13, 2009 Hi. Ok, I am currently working on restoring my 78 280z all stock. I have recently finnished repairing my brake system. New calapers, master cylinder, brake booster, and all new lines and hoses. The booster is buildin up the vacuum and in turn slowley locking up my brakes, causing me to burn my clutch. This usually happens after running on the highway, or after driving around for about half an houre. If I release the vacuum from the booster, the brakes return to normal. I have not looked to far into this problem, so any advice is helpful. Thank You. Quote Link to comment Share on other sites More sharing options...
jeffer949 Posted February 13, 2009 Share Posted February 13, 2009 Do you have the check valve in place?? Quote Link to comment Share on other sites More sharing options...
michaelqasem Posted February 13, 2009 Author Share Posted February 13, 2009 Yes the valve is in place, but i have not checked it to make sure its workin right. Quote Link to comment Share on other sites More sharing options...
woldson Posted February 13, 2009 Share Posted February 13, 2009 The check valve only helps to keep vacuume in the can, correct? Quote Link to comment Share on other sites More sharing options...
deja Posted February 13, 2009 Share Posted February 13, 2009 Have you made sure the peddle play is adjusted right? When I put my car back together I had the peddle play set too tight and the brakes would not release properly after applying the brakes at speed. Quote Link to comment Share on other sites More sharing options...
jeffer949 Posted February 13, 2009 Share Posted February 13, 2009 It was just a guess. But if it was installed backwards wouldnt this have negative effects?? Quote Link to comment Share on other sites More sharing options...
woldson Posted February 13, 2009 Share Posted February 13, 2009 Yes, no assist. No vacuum would be drawn on the diaphragm. Quote Link to comment Share on other sites More sharing options...
Administrators BRAAP Posted February 13, 2009 Administrators Share Posted February 13, 2009 It was just a guess. But if it was installed backwards wouldnt this have negative effects?? If it were installed backwards the pedal would be difficult to push down, like pinching the hose, and if it was sealing correctly, would have no vacuum help a tall. Quote Link to comment Share on other sites More sharing options...
Administrators BRAAP Posted February 13, 2009 Administrators Share Posted February 13, 2009 Hi. I have not looked to far into this problem, so any advice is helpful. Thank You. 1) Do you have a shop manual or a Haynes manual for your car? If not, GET ONE! 2) Searching prior to posting a query, some/most of the time answers the question. 3) Obviously a problem in your brake booster. Gut reaction says it’s the Reaction Disk. Search this forum for this word "Reaction disk" Hope that helps, Paul Quote Link to comment Share on other sites More sharing options...
KunoZ Posted February 15, 2009 Share Posted February 15, 2009 Had the EXACT same problem with my car. And I mean exact. It puzzled me for a few days. Brakes slowly locked up as the car warmed up and what do you know pulled the line from the brake booster to releave the vacuum in it and BAM!! the brakes released. First I thought it may have been the check valve myself but the check valve only goes one way and lets in vacuum and holds it for the booster to allow more stopping power and figured if it was inop. at first before I thought that but if it was the check vavle it would actually just release my brakes after the engine was off. So what is left?? Something internally was wrong with the brake booster. I think it may have been becuase my master cylinder was leaking and just leaked into the booster and may have destroyed the diaphram in it but not 100% sure. May have just busted/jammed with age, but my point is to solving my problem is that I replaced my brake booster and NEVER had it happen again. I would also check your master cylinder too at the back, where the push rod engages the cylinder to see if it is leaking and consider a replacement, besides a reman unit is pretty cheap. Hope I helped. Quote Link to comment Share on other sites More sharing options...
michaelqasem Posted February 16, 2009 Author Share Posted February 16, 2009 Ok. I checked my valves. no problems there. I do have a haynes manual, but that is useless. I already know what it has to say. And Thank you "ZXturbo11". I am leaning towards a bad brake booster myself. I am going to adjust it a little bit as "deja" said, see if that helps any. but if not i will replace it again. Ive already replaced it twice. Got them from autozone. I think they half assed them. and i put a reman master on about 3/4 months ago. Havent checked it since for leaks, but the reservoirs are full. Thanks for the help. Ill keep you posted. Quote Link to comment Share on other sites More sharing options...
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