I think my brakes are trying to kill me

[DZNUTS]

When driving over undulating blacktop and applying the brakes with firm but no where near emergency stop pressure, the ABS seems to kick in for a split second and the pedal looses all sense of felt connection to the brakes. Upon releasing the brake pedal and depressing it again (not in a panic) there still appears to be little impact on braking yet the ABS activates and slows the truck down.

After almost coming to a complete stop, a release and reapplication of brake pedal pressure provides a very grabby brake feeling.

The front calipers were replaced prior to purchasing the truck a year and a half ago. Pads and rotors have been replaced less than 9 months ago.

Removal of the front sway bar(for a separate purpose) seems to have positively effected the initial braking issues.

The past couple of days, I have now noticed that the pedal is not squishy or soft, just not as effective as it should be upon initial bite. However, when releasing the brake pedal and depressing it again, it firms up and feels like it used to.

Any thoughts??


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[riceandpho]

might want to flush out the brake fluid? could be air ? might need to do a zero point calibration.

 

[81runner]

Is the brake fluid dark? If it is, its old and contaminated. Dirty fluid = no compression, which results in poor braking. Just went thru this on my brother's truck. Not to say that it couldn't be something else, but I always start with basics and work my way up from there. Just a good troubleshooting practice in my experience.

 

[Keros]

The issues I had were significantly more subtle... I had all the calipers, pads and rotors (and added stainless lines) and the brakes are normal.

Symptoms I had were unusual initial bite (sometimes firm, sometimes non-existent, sometimes grabby, with no correlation). ABS would do strange things when it kicked in.

In any case, most of the calipers had one or more jammed up piston(s). All rotors were good and front pads had alot of meat; but the front calipers were 13 months old so I was certainly surprised that they were reported as jammed by the mechanic; inboard pistons, both sides.

 

[81runner]

The issues I had were significantly more subtle... I had all the calipers, pads and rotors (and added stainless lines) and the brakes are normal.

Symptoms I had were unusual initial bite (sometimes firm, sometimes non-existent, sometimes grabby, with no correlation). ABS would do strange things when it kicked in.

In any case, most of the calipers had one or more jammed up piston(s). All rotors were good and front pads had alot of meat; but the front calipers were 13 months old so I was certainly surprised that they were reported as jammed by the mechanic; inboard pistons, both sides.

So, I've read alot about the brake system in these trucks lurking this forum in the past year, and two things became obvious to me: 1. The majority of individuals reporting frozen pistons were lax in the upkeep of brake fluid, which is hydroscopic and absorbs moisture over time which will rust internals out,
2. Of the pics I could find where these trucks were having problems, they were all standard rotors. Now, that may seem inconsequential, but consider for a second how much heat is generated by ABS, or ATRAC when off roading. Now consider how that affects wear on the the moving parts of the system, and now add moisture into the mix.

My 07 SR5 had drilled and slotted rotors on it when I bought it in March of 2017. Carfax showed brake fluids being flushed regularly, fluid is a nice color. Tire man told me pads were thin, being on a budget I just slapped some pads on it and scuffed the rotors up a bit. Pistons moved fine, no issues. That was about a year ago. Brakes still feel fine.
Now, this is just my 2 cents, but it seems like having drilled and slotted rotors to help keep the system cool makes a difference. Living in socal, lots of stop and go, and having to slam on brakes for people texting when they should be driving [emoji34]. I also off road my rig. Like, a lot. And with all the abuse I subject my now 11 year old truck to every day, my brakes still feel fine.

Coming full circle, while your problems may be related to mechanical or sensor failures, remember its the fluid that comes in contact with all of those things to make it all work. And with the cost of parts and labor to repair, its the old "ounce of prevention vs. Pound of cure" discussion. Just food for thought. Hope it helps, sorry it took so long lol.

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[DZNUTS]

So, I've read alot about the brake system in these trucks lurking this forum in the past year, and two things became obvious to me: 1. The majority of individuals reporting frozen pistons were lax in the upkeep of brake fluid, which is hydroscopic and absorbs moisture over time which will rust internals out,
2. Of the pics I could find where these trucks were having problems, they were all standard rotors. Now, that may seem inconsequential, but consider for a second how much heat is generated by ABS, or ATRAC when off roading. Now consider how that affects wear on the the moving parts of the system, and now add moisture into the mix.

My 07 SR5 had drilled and slotted rotors on it when I bought it in March of 2017. Carfax showed brake fluids being flushed regularly, fluid is a nice color. Tire man told me pads were thin, being on a budget I just slapped some pads on it and scuffed the rotors up a bit. Pistons moved fine, no issues. That was about a year ago. Brakes still feel fine.
Now, this is just my 2 cents, but it seems like having drilled and slotted rotors to help keep the system cool makes a difference. Living in socal, lots of stop and go, and having to slam on brakes for people texting when they should be driving [emoji34]. I also off road my rig. Like, a lot. And with all the abuse I subject my now 11 year old truck to every day, my brakes still feel fine.

Coming full circle, while your problems may be related to mechanical or sensor failures, remember its the fluid that comes in contact with all of those things to make it all work. And with the cost of parts and labor to repair, its the old "ounce of prevention vs. Pound of cure" discussion. Just food for thought. Hope it helps, sorry it took so long lol.

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Thank for the reply, I’m not convinced that it’s brake fluid yet. I know I need to replace ALL of my front ball joints as they are shot. I’m going to check my wheel bearings soon as well.

I was hoping someone else may have had the same or similar issue.


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[Mike07SE]

Thank for the reply, I’m not convinced that it’s brake fluid yet. I know I need to replace ALL of my front ball joints as they are shot. I’m going to check my wheel bearings soon as well.

I was hoping someone else may have had the same or similar issue.


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I myself have experienced what you have described from time to time. The symptoms you describe have nothing to do with the fluids or brake caliber hardware, but that of our ABS and traction control system. There are certain road conditions when the system can get overactive and induce a situation that is very undesirable either putting you in a situation of a panic stop or where you try to let go of the brake pedal to modulate the situation you're in and leaves no braking assist as well. It is disconcerting and I only hope nobody is near me when this happens as it tends to leave you feeling like you've lost control of your vehicle.

 

[Monkey Wrench]

My '08 4Runner does the same thing- there is one pot hole on my commute that will cause this "oh crap my brakes aren't working" feeling. I think its from the wheel being in the air for a split second.

My brand new Tacoma would do the exact same thing in the same spot.

It must be the ABS/traction control freaking out. Small consolation, but at least its "normal" for Toyota brakes. At the same time, double-check your fluid (bleed/flush if its been more than 2 years) and your pads and rotors.

 

[blind squirrel]

I vote re-bleed the breaks.