Pulsing could only be caused by a warped rotor - I can't think of any other explanation. I wonder if a floating caliper could intermittently float and not float, causing the intermittent problems? It won't hurt to put a dial indicator on the rotors and see exactly how much they're out. Maybe a sticky floating caliper would also explain the intermittent grabbing.

 

sticking floating calipers sound plausible as an explanation for the grabbing and pulsing. I am the one who installed the refurbished calipers and greased the pins. I was liberal with the grease, but maybe not liberal enough.

It doesn't explain the intermittent squeak though. Very curious.

Toyota really screwed upon on the 4runner brakes. Brake issues are extremely common on this vehicle. In fact, out of the few cars I've services (ford focus, miata, bmw z3) the Toyota brakes have always been the most problematic. With the Spyder, it's pad wear in the rear. With the 4runner, it's everything. That's why I replaced them with Tundra brakes, but alas, to no effect.

 

Since,

" I've even changed the rotors, pads, and calipers to that of a different, heavier duty Toyota, and the problem carried over to the new parts, which worked without issue for maybe two weeks before the issue returned."

It sounds like rotors, pads and calipers can be lowered on the list of things to check.

It sounded like worn pads and warped rotors at first but a second reading I almost suspect a bypassing MC from your pedal feel description. A bit rare problem but my Tacoma MC was beginning to bypass. The rear brakes don't contribute as much to stopping but I would closely inspect the rear brakes before spending any money. Rule them out completely then as cyclehead suggests check the rotors and also look for hard spots. Are the rotors and pads OEM? Nothing abnormal in the steering wheel? Warped rotors can transmit to the S wheel also.


Four wheel drive?

 

The rotors are Centric Premiums. The calipers are OEM 2005 Tundra Rotors, remanufactured and sold by Rock Auto.

I do not get any feedback at the pedal or the steering wheel, which is odd. This whole thing makes no sense to me. All together the symptoms say "uneven pad deposit" but the intermittent nature of the issue destroys that possibility.

 

Im having a very similar problem in my 97. Pulsing squeaks at the higher threshold of braking. With the exception of the brakes, 3rd gen 4runners are tanks.

 

Agreed, if not for the brakes, the 4runner would be the most reliable car I've ever owned. As it is, my Honda CBR600F4 takes that title.

Anyway, the floating caliper theory really calls to me. It makes so much sense that I'm certain it has to be it. I think it also caused uneven deposit of brake pad material. I'll pull the pins, pack them grease until the dust boots overflow, then get the rotors resurfaced.

 

I went though a similar problem three weekends ago on my Honda. When it's first driven it would be fine without much noise but a few miles down the road after repeated braking it would start pulsing after I released the brake pedal and then fade out. Being a floating caliper it was not retracting fast enough to it's resting state where it no longer makes contact with the rotor. It also had unusual loud braking/ pulsing behavior as time when on. I checked the movement of the sliding pins on the caliper and they were fine and in the end It turned out to be what I assume to be a bad piston because it was impossible to compress using the cube tool so I gave up and replace the caliper. I would check the pistons by compresing them to see if they are unusually stiff.

 

You might want to put a dial indicator on the rotors and check for runout before doing anything else.

 

Disclaimer: I am not a mechanic, please don't sue me.

I own a 2000 4runner, and it's quite normal for the drum-brakes in the rear to leak oil/grease. A friend who owns a 4runner has experienced the same problem many times.

There are a few thoughts on the subject:

* Fix it properly - this tends to be expensive, in the $1k to $2k range. However, it also tends to break down again over time.
* Clean up grease, repack, etc - This will maintain for some time, but need to be repaired again. Front brakes tend to be good enough, though you're obviously take on some risk.
* Ignore, and use front brakes - Obviously even higher risk.

If it's the front brakes that have a problem, then none of the above applies.

 

You are not a mechanic, I get that. But you are totally getting screwed if brake repairs cost that much.