zapata Posted February 16, 2009 Share #1 Posted February 16, 2009 So, here's my situation... I have a 71Z, stock brake set-up, no idea how old the components are. My MasterVac is disconnected b/c lack of funds/credit to fix, so it's blocked off with caps until I can replace it. No brake problems to speak of. So the other day I have to make an emergency stop in traffic, I'd say from 30-35 mph to stop as fast as I could. At the first stoplight after that, a faint grinding comes from the rear passenger side. It's a little worse at the next stoplight, a good bit worse at the next, and at the fourth stop, its a horrible, loud metal on metal grinding that makes my heart stop, and I drive home (through the neighborhoods, thank god) with good downshifting and the e-brake. The grinding is only on one side, and only when the brakes are applied in motion. No noise when rolling, none when pressing the brakes sitting still. Stripped a shoe? Whacked out something else? What do you guys think?Thanks. Link to comment Share on other sites More sharing options...
Arne Posted February 16, 2009 Share #2 Posted February 16, 2009 Yeah, I'd guess that the lining came loose on one shoe. Easy enough to find out, jack it up and pull the drum and look. Link to comment Share on other sites More sharing options...
Zs-ondabrain Posted February 16, 2009 Share #3 Posted February 16, 2009 Yeah, I'd guess that the lining came loose on one shoe. Easy enough to find out, jack it up and pull the drum and look.Easier said then done on some Z's. I had to destroy the drum on the 260Z to get it off. But you're right, sounds like a shoe slipped off or something.Dave Link to comment Share on other sites More sharing options...
zapata Posted February 17, 2009 Author Share #4 Posted February 17, 2009 Here's a somewhat related question. Are there any potential problems that could arise from having the servo disconnected? Link to comment Share on other sites More sharing options...
Nissanman Posted February 18, 2009 Share #5 Posted February 18, 2009 Pedal effort will be greater since you no longer have that additional 14.7Lbs/sq" assisting you.As long as the vacuum line to the inlet manifold is securely sealed so air cannot enter the engine, all is well for a temporary fix. Link to comment Share on other sites More sharing options...
ktm Posted February 18, 2009 Share #6 Posted February 18, 2009 The master vac does not have 14.7 psi of vacuum. At best it is 22 to 24 in. Hg. or around 11 to 12 psi of vacuum. Just saying. Your master vac only has teh vacuum it pulls from the balance tube or intake manifold. The most vacuum it sees is from high RPM deceleration with your foot completely off the gas. At that point you'll pull around 22 to 24 in. Hg. This is why large cam'd vehicles have brake booster issues. Link to comment Share on other sites More sharing options...
Nissanman Posted February 18, 2009 Share #7 Posted February 18, 2009 I'm referring to the pressure of the atmosphere aiding your foot since the vacuum is applied on the engine side of the booster diaphragm. Link to comment Share on other sites More sharing options...
ktm Posted February 18, 2009 Share #8 Posted February 18, 2009 (edited) It is not the pressure of the atmosphere but rather the differential pressure across the diaphragm. Now stay with me here. The engine applies a vacuum that is not a true full vacuum, therefore the differential pressure across the diaphragm is not going to be 14.7 psi but rather 11 or so psi.http://auto.howstuffworks.com/auto-parts/brakes/brake-types/power-brake2.htmIf the engine did not create a vacuum, or creates a low vacuum at idle like on a radically cam'd engine, then the differential pressure is going to be minute. Edited February 18, 2009 by ktm Link to comment Share on other sites More sharing options...
zapata Posted March 10, 2009 Author Share #9 Posted March 10, 2009 Man was I off... I went back and tried to pinpoint the origin of the noise, and find that it is not the back at all, but the front brakes! I pull the wheel and do a quick visual, and find that the passenger caliper is very screwy. Somehow, the outer half (toward the wheel) is dragging on the rotor. So the caliper itself is grinding down the upper 1/4 inche of the rotor! Anyone else had this happen? Link to comment Share on other sites More sharing options...
ktm Posted March 10, 2009 Share #10 Posted March 10, 2009 The only way for that to happen is for the caliper itself to be loose. The 240z/280z caliper is a one-piece unit that is attached via two bolts. Maybe one of the bolts snapped/backed out and the caliper rotated forward/backward? Link to comment Share on other sites More sharing options...
Weasel73240Z Posted March 10, 2009 Share #11 Posted March 10, 2009 Definitely sounds like one of the 2 caliper mounting bolts snapped off or backed out. Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now