Idea on brake squeal

[Hacksaw]

I don't yet have the squeal but it's probably just a matter of time.
TRD Jon has the brake squeal:


and he loves to spend money on modifications and accessories for the benefit of the owner community, but most of them are beyond the budget of many owners.

If someone knows him, maybe you could persuade him that it would be valuable for 6th gen owners (and him too, since he has the squeal issue) and also one of the least expensive mods if he tried out a few aftermarket pads to see if any of them fix the issue and don't compromise 60-0 brake performance much.

If he agreed to this, I'd suggest he do the pad swap at an actual brake shop, not a dealership. Since they are brake experts, they could probably also opine on who makes the factory pads and what material they're made of, and maybe even suggest aftermarket pads to try. The only issue may be that there aren't yet many aftermarket pads available for the 6th gen. But I did find this one that says it's for the 2025 4runner but I don't know who makes the pads: https://brakeperformance.com/product/premium-ceramic-brake-pads/2025/toyota/4runner

What do you think? Anyone know Jon and could ask him?

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[FoozGrind]

I mean, the fix is right here.... For other models .

 

[Hacksaw]

I mean, the fix is right here.... For other models .

Huh? There are youtube videos to fix squeal on various other cars. How is that useful? If an owner plans to wait for Toyota to agree to replace the pads and rotors on 4runners, if it happens at all, it's probably a year away. Besides, how do you know that pads alone (a relatively cheap fix, especially if you have a bad case of squeal and are fed up with it) won't fix it?

 

[FoozGrind]

That fix above is for the same issue we have. It’s probably be what we need also from Toyota. I am not saying what you recommend won’t work. I am sure if it was just a simple pad fix this would be easy for Toyota to do. I mean whatever at this point I want the noise to go away. I’ve asked the service person I am friends with 15 years now same dealership I’ve purchased my other 4Runners. I asked him toss grease on it do something. His words were it will come back….. so I dunno man

 

[Chicane]

Huh? There are youtube videos to fix squeal on various other cars. How is that useful? If an owner plans to wait for Toyota to agree to replace the pads and rotors on 4runners, if it happens at all, it's probably a year away. Besides, how do you know that pads alone (a relatively cheap fix, especially if you have a bad case of squeal and are fed up with it) won't fix it?

Yep, the first step should be, install new pads and clean the rotors with acetone. No different than when my hydraulic brakes on my mountain bike get dirty or contaminated and start howling like a mother F, just on a smaller scale.

 

[3gto6g]

My ORP has just got off the boat not in my hands yet. This is just an idea for though. Could the setting or return travel of the parking break function be the possible dragging? I wonder how many of the people who have experienced this problem been in a heavy breaking situation?…. I am crossing my fingers for mine not developing this issue..

 

[Van Solo]

Shave the edge of the pads, the old dirty trick.

 

[bkw777]

I don't see how any of the things in the video can do much for this chatter. All of it looks like things that only affects how hard the pads drag on the rotor when *not* braking.

The 4runner brake squeal only happens when applying light, but still active positive brake pressure.

And it only happens in reverse.

It's a geometry problem not a grease/clip/shim problem. But a geometry problem is expensive to fix.

It means changing the placement of the ultimate mount points relative to the force between the rotor and pad. That could mean a whole new caliper assembly, or possibly even a whole new front knuckle. They ain't doing that except in the form of subsequent model year updates.

If they can't figure out a cheap fix like a new pad design that fits in the existing calipers, then they will fix it the even cheaper way, by fixing the documentation to simply say "The brakes will make a noise under X conditions, this is normal." Fixed! I'll make vp by 35 easy.

Imagine scraping a vertical stick along the ground,
always dragging the stick from right to left, holding it from the top.
Tilt the stick left, vertical, right.
Put oil on the ground.
Replace the stick and your hand with a heavy steel shovel on a tractor.
Wrap the stick in dynomat.

 

[FoozGrind]

Every one of us that have this problem that is on the extreme side like mine we basically are F'ed.

 

[ugahairydawgs]

I don't see how any of the things in the video can do much for this chatter. All of it looks like things that only affects how hard the pads drag on the rotor when *not* braking.

The 4runner brake squeal only happens when applying light, but still active positive brake pressure.

And it only happens in reverse.

It's a geometry problem not a grease/clip/shim problem. But a geometry problem is expensive to fix.

It means changing the placement of the ultimate mount points relative to the force between the rotor and pad. That could mean a whole new caliper assembly, or possibly even a whole new front knuckle. They ain't doing that except in the form of subsequent model year updates.

If they can't figure out a cheap fix like a new pad design that fits in the existing calipers, then they will fix it the even cheaper way, by fixing the documentation to simply say "The brakes will make a noise under X conditions, this is normal." Fixed! I'll make vp by 35 easy.

Imagine scraping a vertical stick along the ground,
always dragging the stick from right to left, holding it from the top.
Tilt the stick left, vertical, right.
Put oil on the ground.
Replace the stick and your hand with a heavy steel shovel on a tractor.
Wrap the stick in dynomat.

I am legitimately asking here because I don't know....for something that goes through an assembly line like this with mass manufactured parts, how do you end up with a geometry problem that isn't universal among owners?

 

[kekecarioca]

The reverse brake squeal is so moody! It's present 4 out of 5 reverses and not always at the same pitch...
I really think it's outside temperature/ moisture at this point.

 

[bkw777]

I am legitimately asking here because I don't know....for something that goes through an assembly line like this with mass manufactured parts, how do you end up with a geometry problem that isn't universal among owners?

It is universal. It's just marginal.

Chatter requires setting up a resonance. That can be a finnicky slightly random thing that comes and goes. Obviously they tried to design to avoid any resonances in general, and so even though they failed, they still did at least come close, so it's marginal. A slight difference in temperature changes the rigidity and the frequency that some part resonates at. A slight difference in humidity changes the friction between the pads and rotor

And by friction I mean not just static simple constant friction, but the difference in friction between when it's grabbing and when it's snapping forward.

Like how you need water to make a glass ring by rubbing it. When you ring a glass your finger is sometimes grabbing the glass hard and deforming your skin, and sometimes hydroplaning forward with no friction at all. The water both cleans away oils to provide more grip, yet also hydroplanes removing all grip. And the rubberyness of your skin provides the means for it to grab>skip>grab>skip repeatedly. And the glass being almost perfectly rigid but having some flex that basically returns almost all energy put into it (like a good spring, and the opposite of a shock absorber) allows the initial vibration to sync up with the glass resonating and build a stronger viilbration.

But like the "0 degrees" part of my drawing, the design is marginal. It's neither robustly chattering and resonating, nor robustly avoiding it. It's a weak design that *can* chatter if several conditions are just right. Just like a small change in temp or humidity or speed or brake pressure all breaks up the chain of things needed to get it to resonate, so too a small change in manufacturing tolerances can make it better or worse. One casting could have a slightly different seam or a weld could be slightly different and that throws off the way the whole part resonates.

 

[ugahairydawgs]

It is universal. It's just marginal.

Chatter requires setting up a resonance. That can be a finnicky slightly random thing that comes and goes. Obviously they tried to design to avoid any resonances in general, and so even though they failed, they still did at least come close, so it's marginal. A slight difference in temperature changes the rigidity and the frequency that some part resonates at. A slight difference in humidity changes the friction between the pads and rotor

And by friction I mean not just static simple constant friction, but the difference in friction between when it's grabbing and when it's snapping forward.

Like how you need water to make a glass ring by rubbing it. When you ring a glass your finger is sometimes grabbing the glass hard and deforming your skin, and sometimes hydroplaning forward with no friction at all. The water both cleans away oils to provide more grip, yet also hydroplanes removing all grip. And the rubberyness of your skin provides the means for it to grab>skip>grab>skip repeatedly. And the glass being almost perfectly rigid but having some flex that basically returns almost all energy put into it (like a good spring, and the opposite of a shock absorber) allows the initial vibration to sync up with the glass resonating and build a stronger viilbration.

But like the "0 degrees" part of my drawing, the design is marginal. It's neither robustly chattering and resonating, nor robustly avoiding it. It's a weak design that *can* chatter if several conditions are just right. Just like a small change in temp or humidity or speed or brake pressure all breaks up the chain of things needed to get it to resonate, so too a small change in manufacturing tolerances can make it better or worse. One casting could have a slightly different seam or a weld could be slightly different and that throws off the way the whole part resonates.

How significant of a redesign would it take to the brake assembly in order to eliminate this in future year models? Seems like this has been present in Tacomas and Tundras as well with no fix, so I’m guessing this isn’t something we should hold our breath on.

 

[bkw777]

Since the volume requires a resonance, and that is easy to disrupt even if you can't change any other variables, by absorbing the initial input vibration energy as it's being created so it can't sync up and amplify (ex like putting dynomat in your doors) I bet one possible cheap fix is just stick some tire balancing weights almost anywhere on the caliper. Or possibly the pads if there is any place it could fit.

I mean chamfering the edge of the pads is even simpler if it really works, and bonus they can just start making the pads already like that in the first place. It's hands down a good practical solution, problem solved, as long as it turns out to actually work.

I'm curious to see if simply chamfering the pad keeps working after the pads wear down. If you make sure the bevel goes all the way to the plate then I guess it should keep working through the whole life of the pad.

 

[bkw777]

How significant of a redesign would it take to the brake assembly in order to eliminate this in future year models? Seems like this has been present in Tacomas and Tundras as well with no fix, so I’m guessing this isn’t something we should hold our breath on.

In my drawing, the stick is basically everthing in a chain from the rotor surface, through the pad, to several different contact points all around the pad to the caliper, to the knuckle. And ultimately to the frame but I'm just going to assume that the knuckle is more or less solid and it's either the caliper or maybe even just the pads, or just the rotor vibrating.

If it's the rotor that's resonating, then it should be dead simple to change that any number of different ways.

If it's the caliper, Imagine your hand holding the top of the stick, that's the mounting bolts where the caliper bolts to the knuckle. The angle of the stick is the relationship between the exact position of the bolts and the contact point where the pad meets the rotor. To change that means a whole new casting for either the calper or the knuckle or both, and probably replacing every single part or the front brakes. Way non-trivial.

No way they are going to do it. But I WOULD have thought they would at least update the design so that future vehicles don't have the problem even if they don't fix existing vehicles. But apparently the problem has already been known for a while before the 4runner and they still haven't, which I don't understand.

It's not like car brakes are some exotic new tech. Every manufacturer including Toyota has been doing them just fine for 100 years. It's completely boggling for this to be a thing for more than one small initial run on one model immediately addressed.

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