Booster Issue? (1 Viewer)

[Boaf 32]

LC members,

Searched through all the Brake Booster threads I could and not sure if I found the answer to this problem.

Replaced all Pads on 1972 (10/71) LC Bled Master Cylinder, Front and Rear brakes (roughly 2 pints) and adjusted the shoes to a nice rub. I step on the brake when driving and it's firm at first, then fades to the Brake travel stop point. When stepping on the brake, I hear a below type noise; not a his but a moan type noise.

1. Took the Vacuum hose off at the Manifold, tried to blow into the booster and could not (is that right?)
   
2. took the hose off at the booster end and of course was easily able to blow through into the manifold.

I cannot drive it so it's stuck. The booster looks good, no rust. I can adjust the pedal travel (need to find out how), but not sure if that's the issue.

Any help is greatly appreciated.

Boaf.

 

[shawnfj40]

1 = yes that's right.
2 = Yes that's right too.
3 = Sounds like your booster is fine. You either have air still in the system or more likely your Master is shot.

Pump up your brakes with the engine off, while holding the peddle down start the engine. If the pedal pulls down more, the booster is working.

 

[Boaf 32]

Shawnfj40, Thanks, I will check it out shortly and let you know. Appreciate it!

 

[Boaf 32]

Tested and the booster works as advertised. Will bleed the Master and brakes one more time to be sure. Thanks.

 

[brian]

where at in PA?

 

[Boaf 32]

North of Philly.

 

[Boaf 32]

Replaced the Master cylinder, Bled all the wheels, purged the air from the master cylinder and still not great braking. Stepping on the brake, the pedal travels, and then stops, and cannot be pressed any further. I've read about pedal travel adjustment. How is the adjustment done and can it be done with the Master cylinder in place???

Boaf

 

[BeeJii]

To me it sounds like you might still have air in your system, or a leak somewhere?
Have you checked for leaks? Maybe broken hose, or tube? Might be leaking brake sylinder in one of the wheels too?
I dont mean to question your expertise, but have to ask to be sure, have you bled brakes before and are sure you do it the correct way. There was one time i had to go help a friend who was sure hes brakes were busted and actually he just bleed the brakes incorrectly.

 

[Boaf 32]

It's a fair question, you never know if the person is experienced or not. Yes, been "Braking" for 30+ years now. I bled the fronts, the rears and the master trough a bleeder valve on the side of the master with the assistance of a pedal pusher partner.

Now, I press the brake, it travels to the stop point and the red light indicator comes on. Guess that is correct because there is a brake problem somewhere.

I've been through 3 full cups of brake fluid in the front and the rear chambers. There has to be some air somewhere, and I see no leaks, no fluid anywhere. New brake cylinders in the rear.

Thoughts???

 

[BeeJii]

I guess 30 years makes you qualified brake bleeder!
Have you looked the brakehoses while someone keeps pressure on the brakepedal? Might be hose that has broken "fibers"(not sure what it called in english?) inside the rubber, and rubber just bubbles up when you push on the pedal. Ive seen this happen couple of times, and it feels just like air in the brakes. It can be seen clearly, when pushed on the pedal and looking in the right spot at the same time.

 

[JohnnyC]

Drums not adjusted yet... Or... Cylinders issue

There has been quite a few CCOT issues of the cylinders not fully bleeding and having to disassemble on truck ... Remove top cap on cylinder ... Top off and reassemble

Toyota drums can be a PITA to adjust correctly ... Not a your a nubbie thing ... IMHO ... They are just a pain to get correctly adjusted

Remember they are not self adjusting... You can't get them close and be done ... You need to get them spot on

 

[peiserg]

This doesn't help you directly....but i went to disks after years of shady adjust ment issues. Much Better!

 

[honk]

Drums not adjusted yet... Or... Cylinders issue

Toyota drums can be a PITA to adjust correctly ... Not a your a nubbie thing ... IMHO ... They are just a pain to get correctly adjusted

Remember they are not self adjusting... You can't get them close and be done ... You need to get them spot on

+1 ^^; the rear drums need adjustment at both cylinders - there are two per side so you have to adjust each brake shoe individually. Getting them right is quite a PITA and is probably one of the main driving forces for conversion to rear disc brakes.

The way you described the pedal you get is a spot- on indication that the rear shoes are not adjusted correctly.

BTW, you don't have to pump tons of fluid when bleeding. YOU'RE DOING THE THING TO REMOVE AIR ONLY! Not fluid.
So have someone pump and then hold, You crack the bleeder. If it sputters that's air.
If it's quiet with a nice little stream close it up as soon as you can tell the difference and you're done with that one.
Start bleeding at the right rear and NEVER let either master cylinder chamber get low. Check it after each wheel. If one side or both run out while bleeding it'll be pumping air into the system and you get to start all over again.

 

[tls3601]

It is possible you have a small leak in one of your cyclinders................I have seen this before even with brand new cylinders!!!

 

[Boaf 32]

Thanks all. I definitely had to bleed the a larger volume of fluid to get the dirt and garbage fluid out. It had been sitting for 2 years. Working on the rear's tomorrow and adjust all 4 rear cylinders again...Let you know.

Yep, disc's...may be...

 

[Boaf 32]

There is not one single thing about this LC that is not a PITA. Everything is a dic^%#^ to adjust. I've had performance cars that were more enjoyable to work on than this POS.

That rant out of the system, sometimes you just need a vent to start thinking clearer!!! All shoes are adjusted to the point that the wheels are hard to turn by hand. I still hit the hard spot when pressing the brakes. Almost feels like stepping on an under-inflated balloon on the floor that won't pop. I believe if I adjust the pedal push rod (into the Master Cylinder) that still will not solve the problem.

The rubber brake hoses look in good nit and I do not see any bubbling or expansion when an assistant presses the brakes. I am going to replace them anyhow starting with the rear, then move to the front.

This is becoming a moneypit and it's not even on the road yet after 4 months ..

 

[srgould41]

What happens when the engine is off and you press and hold the brake pedal down? Does it eventually continue to go down until it bottoms out or does it stay firm?

When I first got my '71 I replaced the master with a rebuilt that felt great. I found that my rear slaves were all frozen. Once I replaced those I found the brake pedal would sink to the floor when held. The rear circuit in the master was failing. The rebuilt master had to be replaced. Poor quality parts and work I guess. The second master worked well then I went and did a 4 wheel disk swap. 6 years later and I am almost done with that particular upgrade

 

[Boaf 32]

Hi SRGould41

Answer your first question, yes to the floor and bottoms out. I put the car axle on jack stands at the rear ran it in 2WD and put it in gear. Got the tires spinning and mashed the brakes...crappola, no instant stop. Eventually stopped spinning due to the drag on the shoes.

Replaced the master cylinder with a new one, and yep, same thing. I find it hard to believe that both are bad so there is something else. Yes, disc swap's are a pain...

Lastly, replacing the rear hose first, and see what happens. What a pain in the neck this project is...I am a patient person but man, getting on my last nerve!

Boaf

 

[srgould41]

Boaf,

What you just described sure sounds like the rear slaves are not adjusted right. I read lots of negative posts about aftermarket cylinders so I rebuilt my stock ones. I had to make a chart showing me which way to turn the adjusters to tighten or loosen them from the back side. You might take the drums off and work on the adjustments so that you can barely put the drum back on, first on the lowers then the uppers or vice versa. That was how I did it to get them close then I would adjust one cylinder at a time to lock the drum, then back it off until the drum barely turned. I did that back and forth upper/lower since adjusting one threw the other off a little bit. I did finally get mine adjusted then came out one day and found a large puddle of brake fluid under a rear drum. That was my last straw.

Steve

Hi SRGould41

Answer your first question, yes to the floor and bottoms out. I put the car axle on jack stands at the rear ran it in 2WD and put it in gear. Got the tires spinning and mashed the brakes...crappola, no instant stop. Eventually stopped spinning due to the drag on the shoes.

Replaced the master cylinder with a new one, and yep, same thing. I find it hard to believe that both are bad so there is something else. Yes, disc swap's are a pain...

Lastly, replacing the rear hose first, and see what happens. What a pain in the neck this project is...I am a patient person but man, getting on my last nerve!

Boaf

 

[Boaf 32]

Hi Steve, thanks, yep that is exactly what I did. Took off the drums, tightened each wheel cylinder equally until I could barely get it back on. That has to be the issue, nothing can be this silly, or can it??