So i'm having an odd brake issue, I am dealing with a 96 4 runner v6 2wd and the brake pedal have gotten really spongy, the pedal will sink to the floor while braking and the truck will hardly stop. while doing the self check from the hanes manual I think I determined that the booster checks good. so i replace the master,bench bleed it and then bleed the whole system twice. and the pedal has gotten a little better but the brakes are still working like before.

 

I find if you don't have the rear drum set perfectly and everything bled perfectly, your brake pedal will feel spongy/excess pedal travel. I also replaced my front flex line to Braided SS lines and noticed a immediate increase in pedal stiffness, still hoping to replace the other single rear flex line as I'm sure it contributes to the spongy pedal feel although my 99' feels like new now, all factory original calipers.

 

A sinking pedal could be a couple of things. Either a bad leak somewhere or the ABS system 'falsing' and not working correctly. Is there any buzzing sound or vibration feel in the brake pedal when this is happening? Is it using brake fluid?

If the rear drums are waaaay out of adjustment as Malcolm mentions, then pulling the handbrake lever should make it a bit better - not saying you should drive around like that, but it that makes the pedal feel better, then taking the rear drums off and looking at the adjusting mechanism is in order. It's not too unusual for them to get stuck with age and rust.

 

I have checked the flex lines and I dont see any leaks or swelling. No vibration or buzzing from the abs. Abs will work while doing brake checks on gravel. I will double check the rears adjustment.

 

Alright update, still chasing a soft pedal. Swapped the master cylinder out again(just in case it was bad from stock) rebled. Still no help. New calipers up front. No help. Rear brakes adjusted. No help. Still have a soft pedal and wont stop the truck. Flex lines are not swelling and no brake lines are leaking. What am I missing?

 

How are you bleeding the system? I use a Motive Power Bleeder (dry).



Andreas

 

I have used a vaccum bleeder and the old fashioned way. Leg power

 

I had the same issue after I replaced a break booster. The breaks were very spongy. The peddle went almost all the way to the floor before the car would stop. I looked for evidence of leaking break fluid but found none. It turned out that I didn't fully bleed the breaks. Here is a great video on bleeding the brakes...