Brake problems after tundra brake upgrade

[TXRick]

Before I did the Tundra brake upgrade my brakes were soft but still stoppable. After the brake upgrade they were still soft so I bled the brakes. Then started getting brick brake so I checked the booster check valve. It was fine, no leaks and opening/closing properly. Test drive mostly mushy pedal to floor. Every once in a while get a hard pedal and have to pump it. Bled brakes again. Sucked all the fluid out of my master cylinder. Bled MC with brake lines from junk yard. Got it "working" like it was before. Can drive it at this point but wouldn't trust it in stop and go traffic. Brakes slowly disappeared so bled again. Now I have hard brakes, the pedal actually feels normal but the brakes don't engage...

I've read to replace the booster check valve but that things working fine.
Replace master cylinder? Brake booster? What should I check next? Any advice?

 

[Freb_mc]

If the check valve seems ok, have you checked the vacuum lines to the booster to see if it's cracked or leaking? If it's a small crack it may flex and open up a bit as you drive causing your intermittent issues. But soft pedal also points more to the master cylinder in my experience. You may have a couple issues presenting at once.

 

[nc-grayson]

when was the last time the rear's got some love? Adjust them, and keep bleeding.

 

[SilverRidgeRunner1]

Cleaning and adjust the real will make that brake pedal so responsive u will be surprised

 

[98 ltd Anthracite]

Cleaning and adjust the real will make that brake pedal so responsive u will be surprised

Correct! needs cleaning

 

[TXRick]

Thanks! Ok, I'll check the lines and look at the rears. It was in the shop for alignment and tires a couple of months ago and I had them adjust the rears. They said they adjusted them and they looked ok.

Compared to my 01 the brake pressure feels similar except the 01 stops fine...

My pedal isn't mushy or soft anymore. It's pretty stiff, can get it to the floor but no or very little response from brakes .

 

[fourfive]

Thanks! Ok, I'll check the lines and look at the rears. It was in the shop for alignment and tires a couple of months ago and I had them adjust the rears. They said they adjusted them and they looked ok.

Compared to my 01 the brake pressure feels similar except the 01 stops fine...

My pedal isn't mushy or soft anymore. It's pretty stiff, can get it to the floor but no or very little response from brakes .

As mentioned in a couple previous posts about the rear brakes, my brake pedal feel, braking response, & parking brake function improved after adjusting my rear brakes. I've read different methods on adjusting the rear brakes...

The way I adjusted my rear brakes: This is after bleeding my brakes using a mityvac hand pump. I have noticed that doing the 2 person brake pedal method on a friends 4runner seemed more effective.

1. Lift rear on jack stands & removed wheels & drum.
2. Adjusted star/adjuster wheel to expand the diameter of the brake shoes until I could barely slide the drum back on. Did this on driver & passenger side.
3. Once I could barely slide the drum back on, I removed the drum & adjusted the star wheel several clicks, to slightly decrease the diameter of the brake shoes, until I could put the drum back on without as much resistance compared to step 2, a good snug fit.
4. With the drum on, I put the heels of my hands in the 9 & 3 o'clock position on the drum with moderate pressure. Then with moderate force, spun the drum/wheel assembly (in the direction of the vehicle moving forward) so that it would make one full revolution. I readjusted the star wheel as needed until the drum/wheel assembly would make one full revolution.
5. Once the driver & passenger side rear brakes were adjusted to make one revolution, I slowly pulled up on the parking brake to make sure it took 7-8 clicks to fully engage the parking brake. If it took more then 7-8 clicks, I adjusted the star wheel a little more on both sides to expand the brake shoes until I was at 7-8 clicks for full parking brake engagement.
6. Put wheels back on and removed jack stands.
7. Checked parking brake function by finding a small incline/hill & engaged parking brake, put 4runner in neutral to see if it would hold. I also tested by engaging the parking brake on a level surface and putting my 4runner in drive D to see if it would hold.

*Before adjusting my rear brakes, I would get around 10-11 clicks before my parking brake was fully engaged & it wouldn't hold my 4runner in place if I was in drive on level surface or in neutral on an incline. After adjusting the rears, the parking brake functions 100%.

 

[TXRick]

Hell yeah. Best Father's Day gift so far. I'll try that out tomorrow...today...beer.

 

[jeremyc74]

Are you following the brake bleeding procedure from the FSM? If not, that's probably the problem. You have to pump the brakes a bunch of times to get the ABS to cooperate.

 

[nissanh]

Yeah!

Cleaning and adjust the real will make that brake pedal so responsive u will be surprised

I'll remove the rear brake drums and then remove all its hardware if not been removed in the past few years. Make sure not to mix the hardware between the left and right sides.

Give a good cleaning on the adjuster (star wheel) mechanism. Clean the threads with a wire brush so they can turn with the help of the park brake lever (toyota has auto adjusting rear brake shoes, with the park break). Apply some high temperature grease into the unit, but not on the threads. Assemble all and adjust the brake shoe manually.

 

[TXRick]

Are you following the brake bleeding procedure from the FSM? If not, that's probably the problem. You have to pump the brakes a bunch of times to get the ABS to cooperate.

I've been bleeding per instructions here, start at passenger back etc. I read abs needs to be engaged to prime it. When I bleed them, my partner pumps the brakes and I work the valve until no bubbles...what's the fsm say?

 

[jeremyc74]

I've been bleeding per instructions here, start at passenger back etc. I read abs needs to be engaged to prime it. When I bleed them, my partner pumps the brakes and I work the valve until no bubbles...what's the fsm say?

Easier for me to just quote from another thread than to write it up:

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'm a little late but there is an important fact here that everybody in this thread is missing. The older systems like my '99 bleed the rear brakes first. If you don't bleed the rears first, you can't bleed the front. See this excerpt from my '99 paper FSM:

On the other hand, the later systems bleed the front brakes first, specifically front right, front left, then the rears. See this link to the 2002 FSM:

http://tacoma.site40.net/4Runner_96-02_Repair&Wiring/techinfo.toyota.com/ileaf/02toyrm/02toypdf/02rmsour/2002/024runne/br/braflu/blee.pdf

 

[TXRick]

That's awesome! Thank you.

 

[TXRick]

The rears were way out of whack so I adjusted them properly...still no stop.

More reading and decided I'd replace the brake booster. A quick trip to the junkyard and $41 later...success!

She still needs a little tweaking but stops almost perfect