Solved my 3rd-generation 4Runner severe brake pedal pulsation at highway speeds

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You hold the Toyota manual in high regard but doesn't the manual mention warped rotors

I have only the paper versions of the factory service manual (FSM) and therefore can't easily scan it for the word 'warp'.

What I'll do is search through my FSM (and edit this post with the result) for the word 'warp' and post the results as a subsequent edit, for all to benefit.

EDIT:

OK. Since you mentioned it, I just checked pages BR-1 to BR-33 (BRAKES) in the FSM, specifically page BR-18 (INSPECTION). The factory manual suggests we measure disc thickness, disc runout, & hub bearing play; but I can find absolutely no mention of the word 'warp'.

Note: Someone with the FSM PDF might be able to help as they can do an exhaustive word search to be sure.
 
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And, as you should be aware, I wrote back saying people weren't jumping on me. I simply stated the facts. And I provided all the references. All up front in the first post.

It's really not more complicated than the first line of this thread:

  • Solving the problem requires an understanding of the cause.

You don't know the facts. You don't understand the cause. You have spent 10 minutes googling. Most of your sources are websites that are selling brake products. Your "research" wouldn't be sufficient for a high school civics paper. A source is "peer reviewed", like a paper in a scientific journal, or a published textbook. Not an online article written for the website of a retail outlet.

You think you know the facts, but you just read the top 10 hits from google. You claim to understand the problem, you don't. You have claimed that this understanding of the problem has bought you to the solution to the problem, it hasn't. You make statements like this:

"the actual word "warp" should probably be applied carefully by anyone expecting to be taken seriously unless they concomitantly provide actual distortion measurements of the rotor disassembled from the hub (keeping in mind lateral runout isn't necessarily warp; neither is disc thickness variation)."

Expect to be taken seriously? Who the hell are you to judge if someone should be taken seriously? Don't forget that you are a self proclaimed newb, so stop speaking as if you are an authority on the subject.

You misused the word concomitant. Both connotation and denotation are important. You missed both.

You don't know what lateral runout is. Unless you understand GD&T, don't try to give lessons on lateral runout. It's more complex than you know.

The fact that you were able to fix your problem is completely coincidental to your "researched" understanding of the problem. You touched on one of many causes of the problem, but have failed to comprehend the many other possible causes. And don't claim to gave that disclaimer because you added a "(for me)" in there. That is not proper disclosure.
 
Me too!

:party:

Mom, seriously, why do you come in here every couple months and write arrogant posts. Why do you write walkthrough's from the perspective of an expert in the field, taking info that you are just regurgitating from some random website you found with google, and presenting it like your own knowledge that you are bestowing upon us poor simpletons. NOBODY else does that.

You assemble some good content, but you present it as your own when it absolutely isn't, and you claim to understand systems that are way more complicated than you realize. Then you over complicate things that are really simple, like colloquial expressions in the FSM.

Stop telling us that all we have to do solve a problem is to understand it first. That is rhetorical nonsense, and it is insinuating that we havn't tried to understand it already. Stop telling us that you understand a system or an issue from reading pages on retail sites. Some of us are automotive engineers, some are mechanics, others are long time car enthusiasts. We understand alot of this stuff much better than someone who has just googled it.
 
way too much reading and sissy fits going on in here,

anyway, my vehicle was shuddering when braking from any speed above 80km/h, a few months back i almost nailed a deer and stood on the brakes really hard, mistake was i stopped right after, brakes were fine for a few weeks, then one day I was going downhill and started to feel a slight shudder, it got worse with time, ( viscious cycle mentioned in first post of this thread)

I took down my rotors this weekend, and saw i had a nice brake pad imprint on both rotors,
got some brake cleaner, and a flat plate of metal wrapped in 400 grit sandpaper, did a quick rub down evenly on both sides, and did 10-15 hard decelerations, to bed the brakes in.

rotors had a nice blue clour, on the edges.
vibration is gone, So i have to agree with the original poster in this thread based on my experience yours may be different.
thanks for the info.

just my 0.02$
 
So...back on topic

I just did this for my wife's gx470. Standard highway speed pulsation. It really was easy and fast. I was surprised how simple it was. And it worked of the first try. I might need to do a second one bc I can still detect a hint of pulsation. But overall I am very pleased.

Be warned though the brakes do start fading and acting funny. My car started pulling to the right pretty hard. But after I let it cool down my wife drove it with my and it was gtg. Thabks
 
This is rather bizarre advice - rebedding pads with warped rotors? And this:

Note 4: (Some debate whether the Tundra modification can actually reduce shudder.):
Whether the increased heat dissipation of the Tundra modification also reduces uneven pad deposition is a healthy matter of debate with much anecdotal evidence but far fewer facts.

Somebody has a very different view of brakes than I do...
 
Stop telling us that all we have to do solve a problem is to understand it first.
:)

At some point in your life, you'll find that understanding the difference between "warp" (as in potato chip) and uneven pad deposits causes an intelligent and logical thinker to come up with the same short-term solution, but different long-term solutions.

a. If the rotors truly warped (as in potato chip), the short term solution is to replace or turn them.
a. If the rotors simply had uneven pad deposition, the short-term solution is to replace or turn them.

b. If the rotors truly warped (as in potato chip), the long term solution is to prevent the heat buildup.
b. If the rotors simply had uneven pad deposition, the long-term solution is to prevent uneven pad deposits.

What throws Dunning-Kruger poster children off is that the short-term solution is the same in both cases, while the long-term solution is very different, depending on the true cause of the vibration.

Somebody has a very different view of brakes than I do...

I'm not going to try to convince you or anyone else that the term "warp" implies warp (as in a potato chip) which almost never happens in non-racing vehicles, nor that what people call warp is merely a "vibration", which can have many causes, only one of which is true warp (as in potato chip).

What happens is that intelligent and logical thinkers come up with the same short-term solution, but different long-term solutions, depending on the true cause of the vibration.

If we limit the discussion of the vibration cause to either true rotor "warp" (as in potato chip) or uneven pad deposition, the difference is absolutely meaningless in the short term; but extremely meaningful in the long term.

The fact that the short-term solution is the same for both causes is what throws the unthinking person off; they succumb to the Dunning Kruger effect, thinking they're a diagnostic genius because they solved their short-term vibration problem by replacing or turning the rotors.

But they haven't solved the long-term problem!

The reason is that, in the short term, the solution is the same whether the rotors did truly "warp" (as in potato chip) or whether the pulsation was due to some other rotor-related vibration problem (most notably uneven pad deposition).

However, in the long term, the solution is EXTREMELY DIFFERENT if the vibration was actually due to the rotors "warping" (as in a potato chip) or if the rotor-related vibration was actually due to uneven pad deposits.

What you find is that people who don't understand the difference often come back and complain that the problem "returned". Heh heh.. in the case of uneven pad deposition, their braking habits are CAUSING the problem, so, it's just natural that the pulsation would eventually return.

By focusing on repeated short-term solutions (e.g., blame the pads, blame the rotors, etc.) - they're not realizing that their long-term solutions (change the pad brand, change the rotor brand, add the Tundra brakes, etc.) are wrong.

To summarize, whether the pulsation is due to true "warp" (as in potato chip) or uneven pad deposition, the short term solution - in both cases - is to turn or replace the rotors. This "success" fools many people into believing they understand the problem because their short-term solution worked wonderfully.

However, the long-term solution is different depending on whether the rotors truly "warped" (as in potato chip, in which case the Tundra solution just might may some sense) or whether there was simply uneven pad deposition (in which case, the long term solution is to change braking habits).

Since this discussion is far too logical for most people to handle, I won't try to dissuade anyone from fantasizing that their rotors warped (as in potato chip) again! But you must permit me to feel sorry for the kid who writes that his brakes "warped again" even though he changed his pads and rotors many times.

(I am merely dismayed and sorry for these illogical people when I see them say "my brakes warped again", with emphasis on the word "again"; and then they invariably "blame" the equipment, and,worse, they advocate and instill the wrong long-term solutions simply because they were fooled by the fact that the short-term solution worked no matter whether their logic was correct or not.)
 
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b. If the rotors truly warped (as in potato chip), the long term solution is to prevent the heat buildup.

b. If the rotors simply had uneven pad deposition, the long-term solution is to prevent uneven pad deposits.

their braking habits are CAUSING the problem, so, it's just natural that the pulsation would eventually return

Yes but doesn't the Tundra brake upgrade solve the long term problem of heat based warping AND heat based brake pad buildup? The Tundra brake rotors are more resistant to the excessive heat buildup that results from lifting our trucks or towing large loads. Therefore the Tundra brake rotors rarely get hot enough to warp or to have strong enough deposits to cause a "warped rotors sensation".

Also, some people cannot change their braking habits due to the road conditions where they live, nor can they just up and move somewhere with no major hills.


BTW, do you think that your calling so many T4R people "Dunning-Kruger poster children ... illogical thinkers" is an example of you exhibiting some narcissistic personality traits?

I'm assuming it will be another 4 years before we get an answer. :beer:


Lastly,

This ...
. "The solution was effected by performing a repeating series of aggressive rebedding runs. The fact that rebedding is fast, free, and effective in some cases, indicates that others with similar issues may benefit from similar solutions."

I can agree with at least trying. Someone who's truck is exhibiting "warp like braking sensations" really has nothing to lose. Go out to a giant parking lot or the desert and try this solution out. It's free after all.

:bat:
 
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Regardless of what the paragraph challenged have to say on the subject, I ran the bed-in procedure on my Runner yesterday, and it helped tremendously in reducing the pedal pulse. I also painted the wheels and replaced a rear axle stud, (no I didn't remove the axle and press it in, so sue me), and in the process found that the rear axle had been leaking at some point, but when the PO replaced the seal, (it's no longer leaking, so I assume it's been replaced), they didn't replace the contaminated shoes, which pretty much explains the pull to the right under hard braking.

Point being that brakes are a system, and designed by some pretty damn good Japanese engineers, but if all the parts are not working as designed, you're going to get some problems. Um, brakes are important, make sure the system is 100%.
 
I've turned quite a lot of rotors/drums/flywheels in my day. If you think these things don't warp you are mistaken. Go ahead and throw some rotors on the lathe and measure the run-out if you don't believe me.
 
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