J240ZTurbo Posted August 20, 2011 Share Posted August 20, 2011 Hi, I installed new wildwood brakes on my car few months ago and also a new 15/16 brake master all was working fine until today, I began to feel the break pedal getting hard and also when I press the brakes the RPM jumps to an extra 8-10 more has anyone had this problem? Quote Link to comment Share on other sites More sharing options...
rossman Posted August 20, 2011 Share Posted August 20, 2011 Sounds like you got a bad brake booster. 1 Quote Link to comment Share on other sites More sharing options...
jhm Posted August 20, 2011 Share Posted August 20, 2011 (edited) Yep. A leak in the booster system (booster, hose, one-way valve) equals a leak in your intake vacuum, which will increase your idle revs. It's a double whammy, because your engine is revving up at the same time that you're trying to brake (which is harder to do because you're losing the brake power benefit of the booster). Before buying any new parts, inspect the entire system, beginning with the booster vacuum line connection to your intake. One easy trick to help zero in on the problem is to reverse the one-way check valve in the vacuum line between your intake and the booster. If it solves the high idle problem, then the problem should be between the valve and the booster; if it doesn't solve the problem, then your leak is probably between the intake and the valve. I had a similar problem with my booster a couple years ago, and it turned out to be a small crack in the hose connection on the booster (below the master cylinder). Was able to easily fix it with gasket sealer. If it does indeed turn out to be a bad booster, I think Centrix is the cheapest remanufactured replacement unit. Here's one for roughly $80: http://www.partsgeek.com/gbproducts/DC/6634-05121002.html?utm_source=google&utm_medium=ff&utm_term=1975-1978+Nissan+280Z+Brake+Booster+Centric+75-78+Nissan+Brake+Booster+77+76&utm_content=DN&utm_campaign=PartsGeek+Google+Base Good luck. Edited August 20, 2011 by jhm Quote Link to comment Share on other sites More sharing options...
J240ZTurbo Posted August 21, 2011 Author Share Posted August 21, 2011 ok reverse the valve and no more high idle, but i still got hard brake problems and the car is hard to stop. Quote Link to comment Share on other sites More sharing options...
rags Posted August 21, 2011 Share Posted August 21, 2011 Reversing the valve is only for testing . What you did was to show that there is a vacuum leak somewhere after the valve, probably the booster itself. Reversing the valve plugged the leak which fixed the high idle. Quote Link to comment Share on other sites More sharing options...
J240ZTurbo Posted August 22, 2011 Author Share Posted August 22, 2011 so looks like Ill be buying a new booster soon, I see they sell a 8 1/2" and a 10" diameter what will be better for my 240z as I already got wilwood brakes on there? Quote Link to comment Share on other sites More sharing options...
jhm Posted August 22, 2011 Share Posted August 22, 2011 I would stick w/ the 8.5" (I'm assuming that's what you've got in there now). Will fit better, and should provide plenty of brake assist. The 10" may give you more brake assist than you want. All depends on your personal preference and intended usage. Some guys are running their cars w/ no assist at all. Good luck and be sure to post your results! Quote Link to comment Share on other sites More sharing options...
rossman Posted August 22, 2011 Share Posted August 22, 2011 The larger one may be a later model booster with a different bolt pattern. Quote Link to comment Share on other sites More sharing options...
J240ZTurbo Posted August 26, 2011 Author Share Posted August 26, 2011 Guys I need your help again, I finally found a new rebuilt 8.5 booster,new 15/16 master cylinder and still no brakes, all was working fine until my brake booster wen't bad last week, so today I installed a new 8.5 brake booster, and I had no good reaction from this, I adjusted the rod lenght and even, re-bleeded my entire brake system, and still my brakes are no safe for me to say lets hit the road, any ideas what could be wrong, maybe the new rebuilt booster I got is damaged from factory? scratching my head on this one. thanks, J. Quote Link to comment Share on other sites More sharing options...
tyler031734 Posted October 4, 2011 Share Posted October 4, 2011 (edited) ok reverse the valve and no more high idle, but i still got hard brake problems and the car is hard to stop. Is that valve still reversed? Edited October 4, 2011 by tyler031734 Quote Link to comment Share on other sites More sharing options...
J240ZTurbo Posted October 5, 2011 Author Share Posted October 5, 2011 delete. Quote Link to comment Share on other sites More sharing options...
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