4th Gen Front brake caliper rebuild for stuck piston

[eliask08]

Ahhh, corrosive winters with defective design!

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.

 

[ChuckJ]

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

 

[volcom440]

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.

 

[Kmvreter]

Found time for a short update to this thread due to my winter tire rotation.
I did my caliper check by extending and depressing the pistons (one set at a time multiplied by 4 sets.) It's only been since last spring but no stuck or dragging pistons yet.
I'll do another check and on-vehicle piston lube in the spring.

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.

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.

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.

 

[Riseagainst]

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!

 

[SureShot516]

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

 

[737AMT]

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?

 

[M1911]

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).

 

[ExpeditionBill]

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

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.
http://www.toyota-4runner.org/4th-gen-t4rs/196236-5th-gen-calipers.html

 

[earthrealm]

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

 

[barakuder]

Quick Question: What if I did press the brake pedal while the caliper was off? How can I get the piston back into the bore? I've put all my torque strength into a C-clamp and it's not going in.

Appreciate any tips.

 

[CoastDog]

Knowlegable and well researched

Thanks for the great write up with pics. Im new to 4Runner group. Love the gen4 4Runner i just bought, but of course had a brake issue right away.
No sweat, I researched here and ordered the correct parts to install. Very knowledgeable well researched posts are much appreciated.
I opted for the reman calipers this time around. I have rebuilt '80s 911 brake calipers, just as illustrated here. Messy with brake fluid, but very straight forward. Pistons can be grief to extract! lol.
Thanks again for write up.

 

[2UZ-FE]

Both the fronts seized on my 03 for the first time last winter when I was doing the brakes. Didn’t know it was a common problem so I didn’t have a clue what was wrong when the pistons didn’t retract enough to get the new pads in. I thought the new pads were too thick or something. Owned lots of Japanese vehicles with 20+ years on the original calipers and none of them have ever seized.

Got a pair of reman Napa ones, I read on some other threads here that they are lifetime warranty and guys have had them exchanged when they seize up again. If the 4runner was my only vehicle I would have no problem exercising the pistons every year but having to take care of all the vehicles in the family, it isn’t something i’m too keen about.

 

[Benny123]

Nice thread guys. Are you able to remove the piston with vice grips, before it seizes? Planning on rebuilding the rear calipers before it happens.

 

[ilovesingletrac]

Same / similar for the rears?

I have dragging rear calipers and I'm wondering if anyone has done this process for the rears with any success??
Any part no's for the rear piston and seal kit??
Thanks in advance

 

[2cast]

2015 4runner same problem

Thanks for posting. Very helpful post and pictures.
Seems front lower inside caliper piston boot has a build up of dirt, snow, salt and any other crap causing mine piston to be froze. As with most vehicles I have own the driver side always catches the extra winter mixture produced by the oncoming vehicles. I am looking at the Power Stop S6278 caliper replacements for both front brakes. 98,000 miles and towing a boat, it seems to be a good time for this.

 

[DrRobot]

Brilliant idea. I wonder if this has eliminated the stuck piston problem for the OP, it has been several years since.

 

[SeanWN86]

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.

@Kmveter how have the calipers held up with your maintenance plan?

 

[catrains]

@Kmveter how have the calipers held up with your maintenance plan?

I use silicone brake lube . compatible with brake caliper rubber components, I never had any issues with my GM/Toyota brakes. I keep them over 10 yrs. my 1996 chev sedan no brake issues. had to replace the rotors ... still have the OEM factory calipers on that 96 sedan .

do not use any petroleum based lube on the rubber seals pins etc...causes the rubber parts to swell and break down.

just rotated my 2016 4 runner tires . 26K miles pads all look perfect..
I put that silicone based brake lube on my runner when I purchased it .
rotors look like a mirror .. 10% wear on pads.