Psych0matt Posted February 4, 2012 Report Share Posted February 4, 2012 So my brakes in the sedan are annoying the crap out of me. A few weeks ago they seemed to be getting worse as it was getting colder, and didn't think too much of it because of the age, and temps. Well, it started getting to where I felt it unsafe, so I topped it off because it was a bit low, and it was fine for like a day. Both before I topped it off and after, it seems as though my brakes barely work, unless I pump them a few times coming up to where I need to brake, and if I do so they seem fine, but then next time I have to stop I have to do it again. Maybe I sucked air in and need to bleed them? any other thoughts? Quote Link to comment Share on other sites More sharing options...
Addicted To Boost Posted February 4, 2012 Report Share Posted February 4, 2012 Booster going bad? Quote Link to comment Share on other sites More sharing options...
Psych0matt Posted February 4, 2012 Author Report Share Posted February 4, 2012 ahh, that could be too! I've never done any brake work up by the booster, so I don't know what kind of symptoms I'd have. Quote Link to comment Share on other sites More sharing options...
AL Posted February 4, 2012 Report Share Posted February 4, 2012 The booster usually makes for a really hard pedal... Like braking when the car is off... If your fluid was low, it may be leaking out somewhere and thats where you are losing your pressure Quote Link to comment Share on other sites More sharing options...
94 olds vert Posted February 4, 2012 Report Share Posted February 4, 2012 That's how my brakes felt before I swapped them. I thought they were supposed to feel like that. Quote Link to comment Share on other sites More sharing options...
urbex Posted February 4, 2012 Report Share Posted February 4, 2012 I know whenever I have to move the car it feels like I'm going to crash into something because I have to push the brakes so hard and it doesn't do shit... Quote Link to comment Share on other sites More sharing options...
kinger_13 Posted February 4, 2012 Report Share Posted February 4, 2012 It sound like your Master cylinder is on its way out. I had this problem on an older vehicle once. If you pump the brake pedal and hold it, is there pressure first and then it goes down? If so I'd say Master cylinder. Quote Link to comment Share on other sites More sharing options...
Cutlass350 Posted February 4, 2012 Report Share Posted February 4, 2012 Did you loose any brake fluid after you topped it off? If not, it's the Master Cylinder. If you lost fluid, check the calipers, hoses, and brake lines for leaks. A bad booster makes the brakes hard. Make sure you use a good flare wrench on the fittings on the brake lines. Otherwise, you can round off the fittings. A cheap flare wrench can also round off fittings. For really tough fittings, I carefully use the vise grips made specifically for use on nuts. Good Luck! Quote Link to comment Share on other sites More sharing options...
Brian P Posted February 4, 2012 Report Share Posted February 4, 2012 x2 on checking the calipers first, including the sliders/pins too since that could create a similar effect. Given your sedan is a '91 I'd check the rears before anything else. Quote Link to comment Share on other sites More sharing options...
Schurkey Posted February 5, 2012 Report Share Posted February 5, 2012 Poor braking power with Low, squishy pedal = hydraulic problems especially air in the hydraulic system, but could be defective seals in the master cylinder. High, hard pedal = defective booster or seized calipers. Possible ABS problems, but not as likely. Both my '92 and my '93 had defective boosters. Neither has had defective calipers in the time I've owned them (bought '92 in November, '92; bought '93 about 5 years and 40,000 miles ago. I think the reputation for seized rear calipers is exaggerated--but I acknowledge that my sample size is pretty small. Quote Link to comment Share on other sites More sharing options...
Cutlass350 Posted February 5, 2012 Report Share Posted February 5, 2012 (edited) Both my '92 and my '93 had defective boosters. Neither has had defective calipers in the time I've owned them (bought '92 in November, '92; bought '93 about 5 years and 40,000 miles ago. I think the reputation for seized rear calipers is exaggerated--but I acknowledge that my sample size is pretty small. Plus, it's easy to verify a bad booster. Remove the vacuum line at the check valve, plug the vacuum line with a bolt to prevent a vacuum leak, and see if there's any difference in the brakes. On my Intrigue, when the booster went, it also caused cylinder misfires because of the vacuum leak. BTW, when I plugged booster vacuum to verify a bad booster, it also got rid of the cylinder misfires. For my Intrigue, doing a booster R&R means fully removing the ABS/TC unit. Old Booster removed, ABS removed, EGR valve removed: New Booster, ABS (right), EGR valve(left) installed: Edited February 5, 2012 by Cutlass350 Quote Link to comment Share on other sites More sharing options...
Psych0matt Posted February 6, 2012 Author Report Share Posted February 6, 2012 I'll have to check some things out tomorrow, maybe I can convince Eric to help me out. Food is a good negotiating tool It seems to hold pressure just fine when stopped, but I have to pump it again shortly after if stopping again. I do have a rotor or caliper messing up as well, but I don't think it's really related, just time to replace it anyways Quote Link to comment Share on other sites More sharing options...
Schurkey Posted February 6, 2012 Report Share Posted February 6, 2012 Plus, it's easy to verify a bad booster. Remove the vacuum line at the check valve, plug the vacuum line with a bolt to prevent a vacuum leak, and see if there's any difference in the brakes. On my Intrigue, when the booster went, it also caused cylinder misfires because of the vacuum leak. BTW, when I plugged booster vacuum to verify a bad booster, it also got rid of the cylinder misfires. Neither of my boosters leaked vacuum or caused misfire. Both boosters had "some" assist--the '92 had a bit more than the '93, but neither had PROPER, FULL assist. Truth is, I didn't know a booster could fail that way--to simply have reduced power assist without vacuum problems--but I'm two-for-two. Quote Link to comment Share on other sites More sharing options...
AL Posted February 6, 2012 Report Share Posted February 6, 2012 It sounds like a bad master cylinder because its not sending the proper pressure to the wheels Quote Link to comment Share on other sites More sharing options...
brake Posted February 7, 2012 Report Share Posted February 7, 2012 Did you bleed the brakes or just dump new fluid in ontop of the old stuff? Quote Link to comment Share on other sites More sharing options...
Psych0matt Posted February 7, 2012 Author Report Share Posted February 7, 2012 Did you bleed the brakes or just dump new fluid in ontop of the old stuff? I topped it off a bit, but there should be no air in the brakes, I haven't had them apart for over a year, and I don't lose pressure once it's built up (or fluid so far that I can tell), until I let off again. I'm betting master cyl as well Quote Link to comment Share on other sites More sharing options...
BXX Posted February 7, 2012 Report Share Posted February 7, 2012 Its not a master, or a booster. Plain and simple, its his rear calipers or brakes. Your calipers are old and shitty, your brakes are prolly worn, the caliper isn't adjusting up, so you gotta do the quick double pump to get them to where they actually are pressing the pad on the rotor. Im sure the slides are sticking and not doing a very good job either. Slap on some new rear calipers, pads, and rotors. Make sure your parking brake cables aren't froze. You parking brake mechanism is what keep the rear calipers adjusted properly and 'in range' Why do you think I went ahead and replace the calipers on my Euro when I did rear brakes a few weeks ago? I have a nice firm pedal after a few hundred miles of everything braking in and seating, and use my parking brake as well. It's the first parking brake I've ever had work on a W-body and also the firmest pedal I've ever had on one of them as well. Quote Link to comment Share on other sites More sharing options...
Psych0matt Posted February 7, 2012 Author Report Share Posted February 7, 2012 I'm supposed to have an Ebrake? Quote Link to comment Share on other sites More sharing options...
Night Fury Posted February 7, 2012 Report Share Posted February 7, 2012 Quote Link to comment Share on other sites More sharing options...
Psych0matt Posted February 7, 2012 Author Report Share Posted February 7, 2012 (This car has never had a working ebrake since long before I owned it) Quote Link to comment Share on other sites More sharing options...
Cutlass350 Posted February 8, 2012 Report Share Posted February 8, 2012 (edited) You parking brake mechanism is what keep the rear calipers adjusted properly and 'in range' On a GM with rear calipers?? Unless it's a non-GM made car, as far as I know, for rear calipers, for the ebrake mechanism, GM uses an inside drum&shoes assembly that do not have anything to do with the rear caliper adjustment. Other manufactures may have a ratcheting mechanism inside the piston of the rear caliper - Ford does that. I know that my W-body uses the a drum and shoes inside the rear rotor for the ebrake on my 4-wheel disk setup on my Intrigue. The F-bodies and Vette are the same way. Below is a picture of the rear of my Intrigue, showing one of the new calipers, new hubs, new pads, new rotors, new hoses, etc. You can see how huge the inside hub portion is. That's because the inside is also an "old fashion" drum/shoe setup for the ebrake. Edited February 8, 2012 by Cutlass350 Quote Link to comment Share on other sites More sharing options...
Schurkey Posted February 8, 2012 Report Share Posted February 8, 2012 GM uses an inside drum&shoes assembly that do not have anything to do with the rear caliper adjustment. First-gen W-body rear calipers are kept in adjustment by the park brake. Park brake gets fucked up, brake pedal goes low and has to be pumped. Why the original poster didn't mention prior brake issues is beyond me. Could have saved a lot of time. Why I didn't think to ask is also pissing me off. BXX nailed it. Quote Link to comment Share on other sites More sharing options...
white4d96 Posted February 8, 2012 Report Share Posted February 8, 2012 Random: would a fucked-up parking brake cause the idiot light on the dash to light up? I have fluid, ebrake pedal comes up all the way, but I unhooked it to one side because it kept sticking. Quote Link to comment Share on other sites More sharing options...
Psych0matt Posted February 8, 2012 Author Report Share Posted February 8, 2012 Yes, that would cause the idiot light to be on. Mine has been on for the two years (plus) that I've owned it, and the parking brake has never worked, and it has never caused any problems previous (and I'm pretty sure it didn't work a few years before I got it either). Quote Link to comment Share on other sites More sharing options...
AL Posted February 8, 2012 Report Share Posted February 8, 2012 On a GM with rear calipers??Unless it's a non-GM made car, as far as I know, for rear calipers, for the ebrake mechanism, GM uses an inside drum&shoes assembly that do not have anything to do with the rear caliper adjustment. Other manufactures may have a ratcheting mechanism inside the piston of the rear caliper - Ford does that. I know that my W-body uses the a drum and shoes inside the rear rotor for the ebrake on my 4-wheel disk setup on my Intrigue. The F-bodies and Vette are the same way. Below is a picture of the rear of my Intrigue, showing one of the new calipers, new hubs, new pads, new rotors, new hoses, etc. You can see how huge the inside hub portion is. That's because the inside is also an "old fashion" drum/shoe setup for the ebrake. Second gens, yes, First gens have a cable that hooks to the back of the caliper and engages the caliper Quote Link to comment Share on other sites More sharing options...
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