Brake Booster Failure????

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Dec 29, 2005
Craig, CO
For the last couple of months, on occasion I have come to a stop, usaually first stop of the day, and my brake pedal falls an inch or two before any action. Slow to return also. It has been cold this winter, the 60 has many miles on it, and I'm just running her. But Thursday, on a much warmer day, it did the same thing, but did not recover. After further investigation, it has continued, and has not returned to normal operation.

When coming to a stop the pedal falls about an inch or two with no resistance or braking force. Then it begins to brake, and takes added effort. I first suspected MC failure maybe, as it is a two year old CCOT Aftermarket unit, but there has been no sign of leakage or fluid loss at all. Rear brakes seem to be working okay, although have not checked them much. Emergency brake works well, front calibers are aging, but looked good this past fall when doing knuckle job.

The one thing leading me to booster is that it is making a tad bit more hiss/whoosh sound than normal when pressing the pedal, but also makes a snorting sound when the pedal returns to neutral.

Thus far, idle and engine performace does not seem affected, good suction at nipple on intake. When disconnecting vacum, pedal just gets hard to push.

I'm suspecting that I had intermittent failure of one of the seals on the rear diaphram and now it has completely failed. I must have some assistance left, as the pedal does not feel completely dead, but the dropping before anything happens is kind of spooky, especially in an emergency situation.

Am I making the right assumptions, the hissing and snorting at the brake pedal seems to be a sign to me. Anyone try NAPA units, seem to be a fair deal, checked online, around 300 bucks. Anyone have a used booster?

Thanks, G.
just about any booster will work. When the booster fails it is like you are trying to step on a wall. The pedal hardly moves.

Most likely, your master is failing, or you have a sticking caliper.

BTW, the seals on the master can blow out one circuit at a time. It is easy to blow out the front brakes and not have the rear affected at all.

Also, commonly, the master will leak into the booster. You will never know it happened..
Still like stepping on a wall, even with the dual daiphram arrangement. Because I agree, with the hose undone, I had no assist at all, hook it back up, the pedal gets soft again.

I thought about the curcuits failing in the master. I replaced it previously due to a leak between the master and booster, obvious type of failure. Currently, the fluid level has been ver consistent.

I wonder on the sticky caliber though. I've had good brake performance since replacing the front rotors and calibers many moons ago. Did a knuckle job this past fall, pads all looked very good, even with 45,000 miles on them. However, one side of the drivers caliber had appeared to have stuck at one point in time. As one pad had more wear than all the rest. I just figured I would address it on the next wheel bearing packing, as pad wear had been very good, and it would probably last that long, then I would replace rotors and calibers. I will also say, I have had a nagging pull to the right, but intermittent also. During the knuckle job, I replaced everything of course, but also put on new tierod ends and stuff. Aligned it at home, everything looked good. But, I still get a pull to the right. Had some wheel bearing issues on that side, replaced those. Preload was all in spec, and those pads looked to have very good even wear. I have checked it for getting hot, etc... And kind of wonder if old flat springs may be the cause for the pull to the right????? But this sticky caliber idea has me thinking.

Can anyone glean anything from above. I'm still hooked on the snorting sound the booster has started making the last few days.

On a personal note, I want to upgrade to something else, but money and all that is an issue, but I have been reluctant to keep doing major overhauls to the 60, when I am going to get less and less return on it with every repair job. I keep hoping it will keep going pretty good until I find a replacement for it. But on the other hand, you can't beat a 60. Hopefully when my Ehsan top gets here I can drive my 40 a little more again, maybe decide then about selling or keeping the 60. Otherwise, I would have taken better care of it the last year or so.
brake booster

I just replaced my booster on my 1985 FJ 60 . I was able to get a rebuilt unit from Checker Auto parts. It took a day to get and I did not hve to pay any shipping. Napa wanted to charge me UPS fees. Autrozone also had one but would have taken a few days to get.
Update, rebuilt the master cylinder over the weekend. DON'T ever buy the "new" aftermarket master from CCOT. Should have gone Toyota, but it was a little cheaper, and looked good in the picture. First issue with it when I installed it a couple of years ago, was that the stock cap with level sensor does not fit the reservoir on CCOTs unit. So right off I was swapping the cup on a brand new master.

Also found that the front piston has one less seal on it in CCOTs unit than the rebuild kit I put in, and the pistons that were in my original master, although I don't know if they were original pistons in it. My rebuild kit was from NAPA, Japanese parts, Seiko??? as I recall, looked pretty good, rubber felt firmer, parts looked a little better, but were cast, and not anodized aluminum like the CCOT master had in it, and my old master. Bore was very good though.

The only failure point I found was on the rear brake curcuit, the cup that builds pressure had a small spot were part of the cup was torn/missing. I suspect this was enough to cause an intermittent failure and then complete failure resulting in the pedal dropping when applying the brakes.

I have brakes now, although my rear may need attention still, seems to be a bit spongy still. It has been awhile since I checked them back there, but the shoes still had good life left, and my ebrake works properly, and I use it pretty regular so I think they are working okay.

One thing I did do, and others may consider this. I took the proportioning valve off below the master, as I wondered if it could be causing any problems. 20 some years of gunk was quite evident in it. It contains two small plungers and return springs. Pretty simple to get apart, if you can get the stuck plungers out. They were pretty much gunked in place. No real wear or rust pitting though, which is good. I just cleaned it all out, and stuck it back together. Don't know if it made alot of difference, but I feel better. Did make bleeding the system a rea bitch though, air locked for a long time, probably because of having to push the air through the valve.

On a side note, seems Toyota hydrualic components are always best, however, a new OEM clutch master I put on my 40 failed within a year and a half. Dumped all the fluid out the back, ruined my firewall too. I suspect it may have been new old stock rubber failure. Something to think about, seems even the new parts are pretty old at times when we get them.
Everything is fine again? When I had a hiss like you described, it turned out to be the booster. Worked for a few days with the hiss and then gave out. Hard as heck to stop without a booster!:doh:
I had more of snort sound sound from the booster, but I think it was from the way the pedal was falling so far so fast. Booster seems fine now, and all the of the tests checked out, even before I got the master rebuilt, so I hope the booster is okay.

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