Need brake help!!

JNYD401

JNYD401

New member
Hey all, Here's the problem: Since I replaced my rear axle seal, my brake pedal goes to the floor....sometimes. I have new front pads/rotors/calipers. I have new rear hardware. I have new master cylinder. I have bled the shit out of it. I have adjusted rear adjuster. I have replaced rear pads and had drum turned. I have had my mechanic look at it, and bleed system. He thinks it must be booster (nothing else left to eliminate?) but I don't think so, it would be a hard pedal. Anyone have any experience or thoughts on this??? I can't figure it out and it's sketchy as hell to drive!!

You are my only hope Obi-wan(s)!!!
 
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JNYD401 said:
Hey all, Here's the problem: Since I replaced my rear axle seal, my brake pedal goes to the floor....sometimes. I have new front pads/rotors/calipers. I have new rear hardware. I have new master cylinder. I have bled the shit out of it. I have adjusted rear adjuster. I have replaced rear pads and had drum turned. I have had my mechanic look at it, and bleed system. He thinks it must be booster (nothing else left to eliminate?) but I don't think so, it would be a hard pedal. Anyone have any experience or thoughts on this??? I can't figure it out and it's sketchy as hell to drive!!

You are my only hope Obi-wan(s)!!!
Click to expand...

Was your master cylinder properly benched bled before installed? Was this issue happening before your rear axle leak, or only after?
 
Air bubbles

Probably Air bubbles hiding somewhere in the system/
You may have to force fluid through the whole system...
 
I'm interested in what you find too. I just did my brakes because my master cylinder was bad but my pedal is still pretty soft. I bled all the old fluid and air out of the system too but I still don't think it's right.
 
Air in the system would give you a spongy pedal. You say it is sinking all the way to the floor, but only sometimes. Is it firm when it doesn't sink? If so, is the pedal travel about right or is it too far? I assume that your fluid level in the master cylinder is not dropping and you are not leaking fluid anywhere, right? Given that it is going to the floor, it sounds like the master cylinder is bypassing.

Buckaroo
 
You guys are bleeding it with the engine ON, right? Makes a difference.

As a bonus, here's how to bleed the brakes (including the booster), per the FSM:

(a) Turn the ignition switch OFF, depress the brake pedal more than 40 times.
HINT:
When a pressure in power supply system is released, reaction force becomes heavy and stroke becomes shorter.
(b) Turn the ignition switch ON, check that the pump stops after approx. 30 to 40 sec.
NOTICE:
When the pump does not stop, repeat step (a) and (b) again.
(c) With the ignition switch remained ON, depress the brake pedal more than 20 times.
(d) Observe the procedure in step 4 and bleed the right and left front brake caliper.
(e) Holding the brake pedal depressed, bleed the right and left rear brake caliper.
HINT:
It is not necessary to depress the pedal continuously, as brake fluid flows out by first depressing.

I disagree with that last hint, but it might work for some.
 
I have a 1997 base model with ABS. I have bled the brakes till I taste brake fluid in my breakfast. Mechanic has too. Did the 40 pump thing too Gamefreak. I bench bled first MC, mechanic did 2nd. when it works, feels good, right amount of pedal.but then every 3rd to 5th time you hit brakes, to the floor until you pump it a bit. No fluid loss noticed on ground or MC. I have also spoken to 2 toyota dealer mechanic friends. No clue. is there a proportioning valve that could be screwed up? Buckaroo, i'm with you, sounds and feels like a bad MC but i've replaced it twice. Run for fun, only started AFTER new pads and drum turning done after axle seal. Stumped.
 
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I was able to figure my 97 out today. Maybe something I did will help the O.P.

After replacing the MC, rear wheel cylinders, shoes, drums, front pads, a bleeding for over an hour; I still had a soft, sinking pedal. I finally took it to "Brake Masters", and they inspected it. After trouble shooting it for about a half hour, the tech somehow isolated the front from the rear brake circuit. Rear checked fine. But the front showed a "leak" somewhere down stream of the MC.

Upon further inspection, it was found that my front calipers needed to be replaced. The front caliper(s) were bypassing internally, causing the sinking pedal.

Front calipers were replaced and now I have a firm pedal.

Hope this helps you. Best of luck!
 
JNYD401 said:
I have a 1997 base model with ABS. I have bled the brakes till I taste brake fluid in my breakfast. Mechanic has too. Did the 40 pump thing too Gamefreak. I bench bled first MC, mechanic did 2nd. when it works, feels good, right amount of pedal.but then every 3rd to 5th time you hit brakes, to the floor until you pump it a bit. No fluid loss noticed on ground or MC. I have also spoken to 2 toyota dealer mechanic friends. No clue. is there a proportioning valve that could be screwed up? Buckaroo, i'm with you, sounds and feels like a bad MC but i've replaced it twice. Run for fun, only started AFTER new pads and drum turning done after axle seal. Stumped.
Click to expand...

Very strange, and I assume the rear brake cylinders checked out fine? I just did rear brakes and had the same feeling, but mine still had air in the lines after I bled it twice. Keep us posted if you figure it out.
 
Run 4 Fun said:
Very strange, and I assume the rear brake cylinders checked out fine? I just did rear brakes and had the same feeling, but mine still had air in the lines after I bled it twice. Keep us posted if you figure it out.
Click to expand...

Y'know, mechanic said it all checked out but I'm thinking it has to be the problem. Or cheap enough to try it. I'll post any changes.
 
I just replaced the front calipers and the rear brake line on my 96 T4R. Both front calipers bled out well but I can't even get fluid at the rear.???

I'll have to look at my FSM. I did the 40 pump thing to release the pressure on the booster bu didn't turn the ignition back to "On" when I finished. Going to get back on it tomorrow.

Have a good pedal.

Following...
 
Mine is all fixed and have good brakes. I guess I'm just stupid but when I read the FSM and the procedure says "turn the ignition to "on"", it doesn't occur to me that the engine should be running. I can turn my ignition to "on" without starting the engine or am I wrong?
After several (very many) attempts to bleed the rear brakes with no luck.....and almost no fluid visible, I started the engine and very easily bled the brakes.

Hmmm.... I guess THAT is the proper procedure but the FSM should say....."With the engine running....."

Got great brakes now!!!! Tundra....
 
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OK, so, I put in a brand new (not reman) master cyl with a new reservoir. Still had trouble. Took rear drum off to look again and saw that it came right off. Adjusted it and brakes are fine. Not sure if last master was bad but rear adj needed to be done again.
 
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