Brake issue... HELP NEEDED. PLEASE

[learning fj62]

Okay, to begin.

I was on a wheeling trip up to Clayton OK, and on the last day my brake booster failed. My brakes were in manual mode, I was able to drive it home, just the brakes wouldn't do squat unless I pushed the pedal down to the ground with all my strength (Not saying too much though). I made it home, and went on to replace the booster, and according to the FSM, i was suppose to syringe out brake fluid from the master cylinder in order to remove the brake booster, when looking back at this it seems unnecessary. All in all the booster is replaced, master cylinder bled, all calipers bled, and the brakes are still squishy as can be. Now, the brakes do work, but are squishy as can be, but i bled all the bubbles out. I know my pads are worn to death, but this couldn't be causing this because it worked on the drive home when the booster was out, or could it? Any ideas on why they are squishy even though i have the new booster and the brakes are bled? The only other thing i can think of is that i installed a brand new booster from toyota that was for an 80 series because the fj62 series are discontinued. I read that the booster was suppose to be flipped and the pushrod had to be adjusted. I adjusted the pushrod, and i actually installed it non upside down because that is the only way it fit. ANY ideas are greatly Appreciated and if someone can figure it out for me, i owe you a case of beer

 

[gregnash]

If the pedal is going to the ground then your brake MASTER has gone. if the pedal is high and hard no matter what then the booster is gone.

Also, if you are installing an "upgraded" booster then you are changing the effects of the braking combo. By going with a 80 booster (or something that is larger bore than the standard FJ60) you will substitute feel for braking power. Many threads on this out there so do some reading. While the T100, 4runner, 80 series boosters are direct FITS they are not direct SWAPS as they change the braking efficiency.

So basically, if you stay with the 80 series brake booster, FJ60 brake master, and FJ60 calipers you will end up with a somewhat squishy pedal. Only true remedy is to get a 60 series booster to replace it (used of course) or look at upgrading the master and calipers while you are at it.

There is also a chance you still have air in your lines, I know you bled them but many guys say that you need to bleed them multiple times to get ALL the bubbles out. By removing the M/C you will get air in the lines pretty much no matter what.

Good luck with the fix, I went through the same issue (PO told me the booster was gone when the it was the master) and I am still chasing brake demons months later.

 

[snowbound1975]

Did you bench bleed prior to re-install?

 

[learning fj62]

What do you mean by bench bleed may I ask? I'm assuming I did not because of the previous question. It feels like their is just a large amount of air right in the master because the brake is very squishy, but when you do apply them all the way down, it does stop. I followed the manual to bleed the master, but it seems weird. What symptoms are normal for a bad master? Could this all be because the booster is from an 80, I heard from others that 80 series boosters have been a great upgrade, but now I'm hearing it makes brakes a little looser?

 

[Trapper50cal]

Did you follow the bleed procedure of bleeding the furthest point from the master first? i.e. passenger rear, then driver rear, then pass. front then driver front? I don't know the procedure for bench bleeding the master but it seems really important as well.

 

[ashack2004]

X2 on the Bench Bleeding, on some of the older Brake systems it can make a world of difference.

 

[gregnash]

What do you mean by bench bleed may I ask? I'm assuming I did not because of the previous question. It feels like their is just a large amount of air right in the master because the brake is very squishy, but when you do apply them all the way down, it does stop. I followed the manual to bleed the master, but it seems weird. What symptoms are normal for a bad master? Could this all be because the booster is from an 80, I heard from others that 80 series boosters have been a great upgrade, but now I'm hearing it makes brakes a little looser?

Bench Bleeding is when the M/C is off the truck and you literally bleed it while it is on a bench vise. Two lines go from the side ports and into the cup and you slowly press the master cylinder in so that it is in essence pushing the air out through the short tubes. This must be done SLOWLY otherwise you will run into more air in the lines from the bubbles being sucked back in.

Now this can be done while installed on the truck, just with the temp lines installed into the cup and using the brake pedal to push the cylinder.

Proper bleeding technique for the brakes is:
FJ60 - LR, RR, LF, RF
FJ62 - LR, RR, LSPV, LF, RF (if I remember correctly)

Normally a failed M/C feels like what you are describing, pedal goes all the way or nearly to the floor before braking is experienced. Squishy/Spongy pedal can be air in the lines, or failing component elsewhere (i.e. leaky calipers like I have).

Again, the bleed process is not a quick one and should be done multiple times all the way around to ensure you are getting clean, new fluid with no air bubbles in it. Also be sure that you bottle that the fluid is going into has the interior tube in a small amount of fluid, you don't want to do all that work to have it pull air back up the line.