curious if I was to do this lubing as a maintenance would i need to replaced the boot and springs? Also, you just used the permatex caliper lube for the maintenance stuff? I dont currently have an issue but I was going to be installing stainless steel lines soon and painting my caliper so I want to service them while I am there. thanks

No, you would not need to replace the boots and springs as a maintenance item (I did because I bought the kit basically for the new piston seals.)
Yes, just used the Permatex lube.
Let us know how you make out.

thank you I will let you know

It looks like RockAuto has similar rebuild kits and pistons. Since I'm not particularly impressed by the OEM build quality I'm pondering using those aftermarket parts. Anybody have thoughts about that?

I just wanted to warn anyone doing this that if you are not going to take out the pistons then the pictures in post #2 is too far concerning the amount that the piston can extend safely. at the point the piston is millimeters away from going out of the groove. More than likely the piston will leak and you will have a hard time pushing the piston back into the caliper. Stop just short of post #2's length.

Great writeup

I'm heading out to Napa tonight pick up a replacement set of WH calipers as I am doing a yet another replacement (thats four calipers within five years). In all cases, the inner lower piston is seized, just as what happened to you. Absolutely frustrated that this design is so prone to rust and seizure. I know that the sets I've had up to this point did not have a ring on the boot, so I do hope that the Napa ones do or I will be doing this again in two years.

I just put my first set on last week, same problem as you Eliask08,.. picked up NAPA rotors, pads, calipers.. I guess I'm lucky I made it 80k on the originals..I knew the rotors were warped from the stopping vibration I had but coincidentally the car started shaking like hell at after I got new tires and got it to highway speed (which I very rarely do)...thought my new tires were way out of balance..nope, calipers were'nt releasing..both sides, both lower pistons... smooth as silk now, hopefully the NAPA parts will work out for both of us...good luck

Nice write up, I had my front passenger piston stick a few months ago. I wanted to do a rebuild but was deploying in a few days and didn't have the time to do it. Just bought a new one so the wife could still drive while I'm away.

Did my spring brake maintenance. Found the passenger side lower inner piston was dragging but not completely stuck.
Went ahead and tried the on-vehicle piston lubing. I didn't extend the pistons any further than normal. Removed the brake hardware (pins, springs, pads.) Removed the brake line mounting and caliper mounting bolts to free the caliper to work on it but didn't disconnect the brake hose. Removed the spring rings and piston boots. Proceeded to grease the pistons at the joint and reinstall the boots. Paid special attention to remove as much rust as possible at the bottom of the lower pistons; the notorious tight spot.
This isn't the best way to work on them so see below.

I stand corrected about the boots. I needed to replace them because I couldn't get a good seal on the piston and under the spring ring with the old boots. Luckily I had the spare set that came in the original kit (see earlier in this thread.)

It was a real pain to work on the calipers while on the vehicle. It's hard to give them a good cleaning and you are flipping them back and forth many times trying to lube the pistons and redo the boots. In the future I'll just remove them entirely to work on them on the bench. Thought I would give this a try to avoid the brake bleeding step but it's actually easier to remove, reinstall and bleed the calipers than it is to work on them like I did.

Sorry, no pics this time.

That's awesome, I have a entire brake service(new powerstop rotors and pads) to do on Wednesday and i'll certainly be stepping up and taking care of this at the same time. Hopefully this is the reason for my OEM rotors warping and not my wife driving like a mad lady lol Could be the reason why my work trucks (f250&350's) are having the same sized rotors as well thanks!

just went thru my 4th caliper in 100,000 miles

I have become accustomed to resorting to rockauto.com and buying the centric calipers for $52 as opposed to $85 at autozone

Is it possible this is more of a problem for vehicles in northern climates? Looking at where some of you live, I'm wondering if this issue is related to the corrosive effects of road salt?

I'm sure this is related to the corrosive effects of road salt.

That said, I've lived in the snowbelt for most of my life and my 4Runner is the only vehicle that I have ever had to replace brake calipers. I've replaced pads and rotors on all previous cars, but never a caliper.

In other words, there is something unique (that is, uniquely bad) about the 4th gen 4Runner calipers).

From what I read on this forum and what a local Toyota dealership told me.
4th Gen Calipers suck

I'm upgrading to 5th Gen (Caliper, Rotors, Brakes) that do not get stuck pistons so far. Also got Centric from Rockauto.

Read up on it here.
5th Gen Calipers

what of the rears, can a 5th gen rear caliper work on a 4th gen rear?

my rear calipers are shot, considering rebuilding or buying a new one

edit: wrong thread, didnt know how i posted this here, lol