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Hello , first time posting not sure if it is the right place but here goes. My 2007 cruiser was acting strange going down the road , including when I brake the brakes would like , pulsate, or grab? But I couldnt feel it in the pedal. Took it to a shop and found my front drivers side caliper was siezed. They wanted way too much to fix it so I ended up taking it to a private garage so to speak. He fixed the caliper and said he "turned" the rotor and everything was fine. But slowly the pulsating has come back and seems to be getting worse , but the other issues I had are still gone. Ive read alot on this site about "pulsating" brakes but almost all of them talk about feeling it through the pedal and I have not read anything on a siezed caliper causing this. Any suggestions on what this might be and if I might be able to fix it myself? I am reasonably mechanically inclined. Thanks for your time.
 

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I was going to say check the calipers but as you’ve done that the most likely is that the sticking calliper has caused uneven wear on the pads and that may have distorted (warped) the rotors. I’d swap out pads and rotors. It would also be worth getting an alignment check. Also when was the fluid last changed?
 

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Just an idea: did the mechanic replace/rebuild the calipers or simply free up the stuck pins? I suppose it is possible the freed up pins re-stuck themselves (underlying cause was only temporarily improved, not solved).
 

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Rotors are cheap and easy to replace. I would also make sure your mechanic replaced the calipers and not just cleaned them :)
 

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These are your brakes and nothing to mess around with.

Rotors do not warp. They can wear unevenly and give the pulsating feeling. Uneven is referring to the inner and outer side of the rotor are no longer running true parallel to each other. Uneven wear can be cause by excessive pad deposits (organic pads deposit more than semi-metallic) a dragging caliper (seized), incorrect torque on lugs nuts. To truly check the runout on your rotor you need 2 dial gauges - one for the outside face and one for the inside face. This will tell you how the 2 faces are running in relation to each other. High spots on the rotor face will generally be 180deg high on the other face. Turning rotors is also a pretty poor practice since most people have a vauge idea of what they are doing will hog off way more material than is needed. To truly true the faces of a rotor you should have them run on a surface grinder where the faces can be ground parallel, with minimal material loss and tight tolerances.

I'm going to guess your caliper is still sticking or seized again starting the cycle all over again. I would check out this kit from RockAuto - there are quite a few members running this kit (myself included ) and have had good success with it.

 

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Not trying to confuse the issue, but let's clear up a few possible misconceptions first:
1. "did the mechanic replace/rebuild the calipers or simply free up the stuck pins?"
The FJ does NOT use floating calipers, so there are no sliding pins to stick or seize, which is a common problem with floating calipers. The FJ's calipers are fixed, bolted directly to the spindles.

2. "Rotors do not warp"
Rotors DO "warp" or distort, usually from overheating, which is frequently caused by a stuck or binding piston in the caliper creating a lot of heat on only one side of a rotor. Cheap imported non-OEM rotors seem to have a much greater tendency to warp than OEM or high-quality aftermarket parts.

All you need to do is watch someone turning rotors on a brake lathe to see that many are clearly "potato-chipped" with one or more high spots on each side that make contact with the cutter first. Almost invariably, the HIGH spot on one side will be directly opposite the LOW spot on the opposite side. Even a very small amount of rotor runout will generate an easily felt pulsation while braking.


Very likely your mechanic was able to temporarily free up a stuck piston in the caliper, but it then started sticking again, and your problem has returned. If you have an infrared non-contact thermometer, you can take a temperature reading of both front rotors immediately after a 15 minute highway run, after coasting to a stop. The temperature of BOTH rotors should be very similar. If one is distinctly hotter, it likely has a binding piston in one caliper that is keeping the brake pad in firm contact with the rotor.

Seriously, the only real solution to return your braking system to original performance is to replace rotors, calipers and pads with OEM or OEM-quality parts, and with all new hardware (shims, pad retaining pins, anti-squeal springs, etc.). The entire brake system MUST be purged to eliminate moisture-contaminated fluid that likely was the root cause of the binding piston in the first place. Every surface that Toyota specifies as requiring lubrication must be lubricated with the correct lubricant. Then, the pads and rotors must be correctly bedded per the pad manufacturer's recommendation.

After the front braking system has been brought up to spec, you need to do the same with the rear. As the front brakes handle ~80% of braking loads, the rears last longer and are generally in better shape, as long as you do not live in the rust belt. Regardless, rotors must run true, pads must be in good shape, and all caliper pistons and seals be perfect.

At the end, if everything was done correctly, you will be able to perform a hands-off-the-wheel, dead-straight, panic stop from 80-0 MPH (on flat, dry pavement), while modulating braking power just shy of triggering the ABS, without any drama.
 

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Some light reading re "warped" rotors:
 

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Some light reading re "warped" rotors:
Sure enough, if you cruise the web you'll find many "opinions" about what causes brake judder on disk-brake vehicles. Some will tell you that it's absolutely IMPOSSIBLE for a rotor to warp or distort, and that any brake judder you may feel is caused by non-uniform transfer of pad material to rotors, or phase-of-moon effects.

Regardless, spend a few minutes watching a few rotors being resurfaced on a brake lathe, and it will immediately become OBVIOUS that the rotors ARE warped, and that the faces are no longer flat.

Rather than just reading someone's "opinion", let's actually WATCH a warped rotor getting machined on a brake lathe, and see how the cutter initially only contacts the "high" spots on the warped rotor. To take it one step further, let's watch a rotor being machined using an "on the vehicle" brake lathe, which supports the rotor on the actual wheel bearings the rotor will spin on, and mounts the rotor on the actual hub face that it will operate on, thereby eliminating some sources of rotor runout that could be introduced by machining the rotors on an off-the-vehicle brake lathe.

At about the 1-minute and 20 seconds mark, the cutting tool starts to contact the rotor. Notice (visually and audibly) that the cutter is just touching the high point on the rotor. This is now cutting iron, not just scraping off a micron-thin film deposit of pad material:


As for the some of the explanations that "rotors can't warp", just a little common sense shows they are not logical. In the first link, it is stated:

"Rotors are cast in extreme heat — three to five times greater than the most aggressive braking situation. Physically “warping” a rotor would require a similar application of extreme heat, which is impossible."

This is a ridiculous statement ... we all know that cast-iron cylinder heads can warp, sometime spontaneously, and sometimes as a result of serious engine overheating. And that the maximum head temperature in a serious engine overheating incident is thousands of degrees less than the melting point of iron, yes?

Right?

Rotors can warp because:
1. Cast-in stress due to non-uniform cooling during the casting process;
2. Lack of perfect symmetry in the sand cores used to produce the central cooling passages;
3. Lack of perfect homogeneity of the molten iron at the time the casting is poured (gas, slag, displaced sand from the core, etc.);
4. Non-symmetrical heat input from a dragging brake pad caused by a binding caliper piston or a binding floating caliper;
5. Non-symmetrical cooling from a hot rotor suddenly exposed to a deluge of water;
6. Mounting problems like improperly torqued lug nuts, debris or corrosion on the rotor, hub or wheel mounting surfaces, etc.

True?
 

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OK apologies...warped is a simplistic term with which to describe them as not a perfect flat surface due to uneven contact bythe pads or from other causes... point remains the same...
"Warped" is commonly used terminology. More technically correct would be "axial runout" of the rotor's friction faces, referenced to the rotor's mounting surface.
 

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I'm with mikey on this one. Anyone who has ran an actual lathe, CNC or not, knows that it is always impossible to center the part perfectly. FJTest have you ever put a rotor in the machine and had it contact perfectly all the way around?

Another question, how come my brakes while being used hard during a week long road trip pulse during the last few days? But a week later they are perfectly fine? Do you think the rotors became "warped"? Then straightened themselves back out?

I think 90+% of the time its uneven pad material causing this.
 

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I'm with mikey on this one. Anyone who has ran an actual lathe, CNC or not, knows that it is always impossible to center the part perfectly. FJTest have you ever put a rotor in the machine and had it contact perfectly all the way around?

Another question, how come my brakes while being used hard during a week long road trip pulse during the last few days? But a week later they are perfectly fine? Do you think the rotors became "warped"? Then straightened themselves back out?

I think 90+% of the time its uneven pad material causing this.
It is absolutely possible to perfectly center a brake rotor, just as it is possible to perfectly center a tire and wheel for computer balancing. If it werent, we wouldn't spend many thousands of dollars to invest in machines that are engineered to true these components down to the thousandth of an inch or fraction of an ounce, etc. Warped rotors are not a myth, regardless of what wive's tales exist.

If a person here wants to spend a few hours in my shop, I'll be happy to give them a free education in machining and trueing rotational matter. I also have a metal lathe and mill for building components based on numerical control if they would like to get even more precise than standard cast components.

Don't just believe every Yayhoo on the Internet when it comes to this stuff. Safety is our liability in this industry.
 

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I'm with mikey on this one. Anyone who has ran an actual lathe, CNC or not, knows that it is always impossible to center the part perfectly. FJTest have you ever put a rotor in the machine and had it contact perfectly all the way around?

Another question, how come my brakes while being used hard during a week long road trip pulse during the last few days? But a week later they are perfectly fine? Do you think the rotors became "warped"? Then straightened themselves back out?

I think 90+% of the time its uneven pad material causing this.
If we want to talk about technical topics, we need to use the correct terminology.

Any "centering" error of a rotor on any kind of spindle, brake lathe, or conventional machine-tool lathe will result in RADIAL runout ... which has no effect on the brake pulsation we are discussing here. It would, potentially, have an affect on the rotor's dynamic balance.

We are talking about AXIAL runout ... the runout of the FACE of the rotor, that would apply a cyclical load against the brake pad, causing pulsations in brake fluid pressure.

And it's "always impossible" to center a part in a lathe? It's only limited by the precision of your lathe's spindle bearings, the quality of your lathe's chuck, the resolution of your runout measuring instrument, and your patience.

Using a 50-millionths of an inch dial indicator and a 4-jaw chuck will allow you to get the OD of the part pretty close to zero measurable runout.

In my day job, we hold tolerances on some optical system components to less than +/- 5 microns (~0.0002"), so I'm no stranger to tight tolerances and the special equipment and techniques needed to reliably measure parts to these tolerances.
 

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