I came home this weekend to get my car, believing all I needed to do was permanently hook up the alternator and bolt the front seat down and I'd be in business, even though I hadn't driven it more than two feet in any direction since February... So it FIGURES that as soon as I start feeling a little better (conveniently got an ear infection...) I go do that stuff, and take it for a test drive. First problem is that the power steering doesn't wanna kick in until like 1000rpm now for some reason, which I can live with, but the main thing is that the brake booster seems to have taken a **** too. It's always done this thing where it'd only give ***ist like halfway down, so EMERGENCY stops took both feet, but otherwise there was plenty of ***ist. Now, the first few times around the block the brakes were acting funny, like it'd be no-***ist for a little bit, then ***ist, then no ***ist again. I stopped to get gas, and after I left there it was like NO ***ist at all. But the booster's doing something, I can hear it hiss like it should. As it is, I can get it to stop OK if I slam both legs on the pedal, but it's not a very good way to have it be for a 3 1/2 hour drive, obviously... Anyone have any idea? Like I said, they worked fine before I let the car sit for all this time, so I really have no idea what it might be.
if the pedal is that hard to push down, more then likely its the booster thats gone bad OR you have a leak in the vacuum hose going to it & as for the hiss, well all i can say is NONE of mine have ever done that unless it was going out, so ya may want to check or change the booster, at least thats what i would do....joe
from what i was told when I was having brake problems, you shouldn't be hearing that hiss.....I'd check all the hookups and stuff first though to make sure none of those are leaking vacuum. What car are we talking about here?
sounds like the outlet you have booster hooked to is not producing any vacuum. you shouldn't hear any noise when in use. Pull off that hose while running and see if its live. check to see that it is not soft and ****ing shut upon starting.
sounds like the booster to a ****, but measure the vacuum to it. it should have a minimum of 10" @ idle (i've also heard 15" min., but 10 sounds more reasonable). if it's ok, then check the 1 way valve, it should hold vacuum in booster. after all that is the pedal is still hard (and car is harder to stop then manual brakes) i would say booster is bye, bye......
Car's a '55 Chrysler. I suppose the vacuum hose could have cracked or something between when I parked it and now, I'll double-check that... the booster itself was TOTALLY rebuilt like 500 miles before I bought the car, though. It's had the problem where it only gives boost like 3/4 of the way down pedal travel wise, but now it's not really giving any. When I was trying to fix that 3/4-boost thing last year I took the whole thing out and looked it over, every bit of it looked brand new.
Like Kenny says, check the vacuum hose for ****ing shut on brake application. I've had a few of those on IHC trucks at work. Makes ya crazy because you can't see the hose inside. I fab'd up several pipe reducers and a "Y" to install a vacuum gauge in the hose...showed me when the inside of the hose ****ed shut.
either vacuum failure(check the hoses), or tear it apart and see if you have gotten yerself some surface rust in there,which kinda stops it. Polish the **** away,and give the sealing rubber\leather some (light)oil and tenderness. Good luck.
Tried everything else so I took it out and dis***embled it... nice two-inch rip in the diaphragm. My guess as to why it didn't stop working all at once is that there was a much smaller rip near it, too. Sigh...
I just have to rant... This brake problem was the main reason I couldn't get my car to BTT50's this weekend. I just got back a couple hours ago (took a VW JETTA) and went to work on my brake booster again. EARLY Friday morning I went to the junkyard to get a new booster diaphragm. Luckily I got one (didn't take the whole booster unit since I would've had to crawl around in rat **** under the floor of the junk car), in even better shape than my old one was before it ripped, but it was money I didn't want to spend... Got home and put the new diaphragm in the booster. The booster was now working perfectly, but for some reason the master cylinder was dumping brake fluid back into the booster (the way this thing works is the tube/rod thing the diaphragm/power valve mount to acts as the piston inside the MC). I figured I must have not put it back together right or wrecked the seal on the back of the MC or something. I didn't have any more time to deal with it anyway. When I got home today I took the booster apart again and compared the original, ripped diaphragm with the new one. Well, the reason the master cylinder was leaking out the back was because the piston/pushrod part of the new one, which came out of an IDENTICAL CAR with a visually identical MC/booster setup, was like 1/32nd of an inch smaller in diameter than the original one. I found part numbers on them and sure enough, they were different. Apparently at some point in mid 1955, Kelsey-Hayes decided it would be a good idea to start manufacturing a BARELY modified version of their ****py brake setup for no good reason I'm sure. Ugh. The third strike against this retarded thing is the brake line fitting. I managed to strip the little br*** adapter fitting on it when I was putting the line on to bench bleed the MC. "No problem" I thought, "I have some brake line that will thread into that without the fitting." Turns out that fitting is NECESSARY because the geniuses at Kelsey-Hayes didn't put anything for the brake line to seat against behind those threads. Ugh.
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