Brake pedal low after Tundra Brake Upgrade

[ultimatt]

First let me say I have searched to forums and this is not an uncommon problem, but there seems to be a wide variety of explanations out there for the remedy.

I have a 2000 3.4 limited 4x4 that I put the larger (231mm?) Tundra rotors and calipers on w while back. The rotors were new and the calipers were rebuilt units. When I did it I bled the entire system starting with the back pass wheel, then back driver, front pass and then front driver.

I immediately noticed 2 things, the pedal was low (about half travel before the brakes kicked in) and there seemed to be too much effort involved once you started braking (seemed like you would really need to stomp it in an emergency).

The brake system on the car was all original, the master cyl nor anything else had every been replaced except for pads.

The hoses looked bad so I figured since I was going to bleed it again I would replaced all 3 hoses...and so I did.

The 2nd bleed along with the hoses made it maybe 10% better, but it is not where it should be. Some of the forums suggested the following -

replace master cyl
adjust rear brakes
Bleed the whole system 4-5 times

Anyone have this problem recently want to chime in on what worked for them?

Thanks.

 

[Squirt]

We just had a similar problem with one that came through the shop. Had to bleed the entire system at least 4 times before pedal travel/resistance was correct. After that it would throw you through the windshield it would stop so well!

 

[ultimatt]

Any idea what would cause that and why 4 complete bleeds would fix it?

 

[Squirt]

When you open the lines it sucks air into the lines which is the reason you would have to bleed.. The longer you have the lines open the more the air bubbles travel through the system. sometimes when that happens it requires more than one bleed. At least that's the way it was explained to me.

 

[ultimatt]

mmm...since it looks like I'm in for another bleed I think I might order some speedbleeders for the job

 

[Squirt]

Speed bleeders awesome. definitely cuts time from the job...

 

[cashmoney]

Motive Products #1 Selling DIY Brake Bleeder

Makes bleeding so much easier.

 

[s20004runner]

https://www.youtube.com/watch?v=dRaYaytYkIY

according to speedy, if you get air in the master cylinder you have to go to dealer and need a special tool to get it bled.

If you had the brake fluid in the reservoir low enough, that's one possibility and maybe the reason for 4 bleeding.

Also, I upgraded to synthetic brake fluids and upgraded to all steel brake lines.

I followed Speedy and made my own brake bleeder, worked like a charm and cheap.

good luck.

 

[Konkordmusk]

The larger bore of the tundra calipers require more brake fluid. In order to compensate, one would need a smaller bore master cylinder to account for the larger bore "slaves". No one does this, so lets move on.
Another way to compensate is to adjust the throw rod, connecting the brake pedal to the master cylinder piston. Adjust this so its longer.
Lastly, adjust your rear brakes, if you haven't already. The less the shoes have to travel to adequately brake, the less fluid you will need and therefore, the pedal will be higher.

I believe people get a normal pedal feeling after many brake flushes and bleeds because there was air and moisture in the system prior to the upgrade. Worn out brakes and bad fluid can make the tundra brake upgrade seem MUCH better than it is, due to the contrast in feeling.

 

[LittleCaesar]

Were there any bubbles in the fluid when you bled the lines?

Try and find a dirt road or two to activate the ABS to purge the air that has gotten trapped in there. Then go back and bleed them again. The dealer would do the same thing, but use a scan tool to activate the ABS system to open and close the valves, then bleed the lines.

 

[ultimatt]

I made real sure the master stayed full during the process...

 

[gamefreakgc]

1. Did you bleed with the engine on? That's key.

2. Try this for bleeding the brake booster before bleeding the brakes (worked wonders for me):

(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.

Then bleed as normal:
(a) Connect the vinyl tube to the brake caliper.
(b) Depress the brake pedal several times, then loosen the
bleeder plug with the pedal held down.
(c) At the point when fluid stops coming out, tighten the
bleeder plug, then release the brake pedal.
(d) Repeat (b) and (c) until all the air in the fluid has been bled
out.
(e) Repeat the above procedure to bleed the brake line for
each wheel.

3. Try this if it's the pedal that has too much "play" and not the brake lines themselves:

(a) Stop the engine and depress the brake pedal several
times until there is no more pressure left in the booster.
(b) Push in the pedal by hand until the beginning of the second
resistance is felt. Measure the distance.
Pedal freeplay: 1 - 6 mm (0.12 - 0.24 in.)

If it has play, do this:

(b) Disconnect the connector from the stop light switch.
(c) Loosen the stop light switch lock nut and remove the stop
light switch.
(d) Loosen the clevis lock nut.
(e) Adjust the pedal height by turning the pedal push rod.
(f) Tighten the clevis lock nut.
Torque: 25 N·m (260 kgf·cm, 19 ft·lbf)
(g) Install the stop light switch.
(h) Connect the connector to the stop light switch.

 

[jeremyc74]

I followed the procedure above for mine and they feel fine.

It's important to note that Toyota tells you to start with the front, and then do the back. That's opposite of what I was always told, but I'm not going to argue with the manufacturer about something like this.

 

[Ula'Tek]

I just did the Tundra brake upgrade myself a couple days ago and had the same problem. Pedal right to the floor.


Solution: bleed the entire system 4 times, around and around, which really made my wife happy since it's insanely hot out and she was working the pedals
:rockthrow:

 

[jhfleet]

1. Did you bleed with the engine on? That's key.

2. Try this for bleeding the brake booster before bleeding the brakes (worked wonders for me):

(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.

Then bleed as normal:
(a) Connect the vinyl tube to the brake caliper.
(b) Depress the brake pedal several times, then loosen the
bleeder plug with the pedal held down.
(c) At the point when fluid stops coming out, tighten the
bleeder plug, then release the brake pedal.
(d) Repeat (b) and (c) until all the air in the fluid has been bled
out.
(e) Repeat the above procedure to bleed the brake line for
each wheel.

3. Try this if it's the pedal that has too much "play" and not the brake lines themselves:

(a) Stop the engine and depress the brake pedal several
times until there is no more pressure left in the booster.
(b) Push in the pedal by hand until the beginning of the second
resistance is felt. Measure the distance.
Pedal freeplay: 1 - 6 mm (0.12 - 0.24 in.)

If it has play, do this:

(b) Disconnect the connector from the stop light switch.
(c) Loosen the stop light switch lock nut and remove the stop
light switch.
(d) Loosen the clevis lock nut.
(e) Adjust the pedal height by turning the pedal push rod.
(f) Tighten the clevis lock nut.
Torque: 25 N·m (260 kgf·cm, 19 ft·lbf)
(g) Install the stop light switch.
(h) Connect the connector to the stop light switch.

I'm confused, which isn't all that unusual:

What motor runs for 30-40 seconds when the key is turned on after depressing the brake 40 times?

What is the purpose of bleeding the brake booster and what is bled from it?

Which component in the brake system contains pressure that is released by pumping the brakes?


Thanks