Great write-up!! Nice job circling the various components too. Are you using Photoshop?

The shim kit is the way to go (greasing the kit lightly will help keep it from corroding) I bought the kit which also comes with new pins. The brakes sure take a beatin!! It ranks number one in my book as far as maintenance is concerned.

The original inner shims were bent, because of the frozen and stuck piston, and rusted where it seperated from the pad surface. I'll take your hint about lightly greasing the open face. Turns out this 2 part shim kit is an upgrade due to earlier noise issues (found this in a service bulletin, BR004-06, attached.)

Overall, I'm pleased with the T4R 4 piston system and brake life but I'm disappointed with the "high" maintenance aspect. Need to keep a closer eye on them. My prior GM needed brakes more often but you definitely needed to lube the slide pins (just like the Toy rears.) I guess it's a wash in the comparison.




(Just using Microsoft Paint to edit the pics.)

Attached Images

br004t06.pdf (60.3 KB, 1650 views)

Bump for Colemanfu

Changed out the winter wheels and did the semi-annual brake maintenance as per my lessons learned earlier above in this thread.

Found the lower inner piston on the passenger side, that was suspect before, was now frozen solid. Caught this in time before there was any noticeable uneven pad wear or damage to the shims. Got my parts together and did the caliper replacement this weekend. Noticed that this reman replacement didn't have the piston boot retainer spring clips like the previous one so I'll be going back to Carquest and see if they can order them.

No other issues and as good as new.

I was under the impression that Toyota has a fix for this now? Kmreveter, are you getting new calipers?

I'm out of warranty, even if it potentially applied, so I'm not using brand new parts that are overpriced big $$$.

I installed remanufactured replacements. Maybe there are some internal piston or seal changes I can't see. The only difference I noticed compared to stock was the driver's side caliper that I did last year had an extra retainer spring-ring around the base of each piston dust cover boot. I plan to source these and install them on the passenger side caliper I just did.

Bump for trishalk.

Those pins are a real pain to get out once they are rusted in place. I mentioned it in a post a while back and also suggest greasing them every time you rotate your tires(twice a year).
I went with the reman calipers because they were a hell of a lot cheaper and in stock. Yes the lower pistons on the inside were frozen on both calipers.

where do you guys recommend getting the remand calipers, or is there a good set of aftermarket ones you could recommend

Try an auto parts trade counter. Got mine at NAPA and CarQuest. Someone mentioned Rockauto.

Did the spring ritual driveline service and summer tire change. Followed my lessons learned below.

So guess what? Déjà Vu.

I have a frozen inner lower piston on the driver's side caliper. That's what started this thread almost 2 years ago. There was no indication of a stuck or even slightly tight piston when I did the last tire rotation. I got almost 64,000 Km (39,500 miles) and almost 1320 hours on this reman NAPA unit.

It's definitely not caused by sitting (it's my DD) or bad fluid (I bled the entire brake fluid last spring.) The 4 piston caliper is good for braking power but the pistons must be a poor design or material.

I caught it early enough that there isn't any uneven pad wear or shim damage. I'm not sure whether I'll go with another reman, Toyota OEM or get a rebuild kit to do a teardown and look at the piston design/material. I have some access to a machine shop and am thinking of custom pistons.

I'm not looking forward to doing alternating calipers every spring.

That is unreal. I'd be hugely disappointed if it was me.

Wonder what the heck can be causing it.

What kind of condition are the slide pins in? I only ask because I replaced mine last fall and lubed them good but this spring when I removed them, they were totally corroded and crusty again. (Calipers were fine though.)

Yeah, it bl@w$.
Slide pins are fine. Mine also always rust but I wire brush them off and grease the holes to keep them loose.

Got the chance to replace the caliper with another reman unit. NAPA was out of stock (probably because they have the best price.) The Carquest 13WL reman lists at C$211 but I got it for C$194 + tax (13WL casting.) I passed on the 13WH from APC which is a gold coloured Cardone reman that lists for C$263 but costs C$214 + tax.

Followed Ducman's hint about greasing the face or leading edge area of the pistons. Also regreased the shims because they were "dry".

I also saw a reference in another thread about the design allowing the fluid to "pool" in the lower half. This makes sense because the brake line and bleeder are in the top half. I'm going to increase my brake bleeding to include actually removing the calipers and draining the old fluid once a year. I'm going to do this to the passenger side now since I have to bleed the system anyway. It's a pain but it will only cost my time instead of a whole caliper. I'll see how it works. Ideally, there should be a "drain" in the closed bottom bleeder location. I may drill and tap a hole.

A note about casting numbers. As far as I can tell all the remans use OEM castings. Three options show up in every supply shop listing. I didn't see the 13WG but I'm guessing it's for the larger Sport brakes (actually 13WH; see Edit below.) The only difference between the other 2 is the shape or angle of the threaded brake line fitting hole. The 13WH (actually 13WG; see Edit below) is the original casting with the horizontal angle. The 13WL has the vertical angle. That's what I've been using because it's 20 bucks cheaper and Carquest includes new pins and spring. All you have to do is put a slightly different bend in the brake line.

Edit: I may have the 13WG and 13WH mixed up. Clarification: the 13WH is definitely for the larger Sport brakes; 13WG is OEM for non-Sport & 16" wheels; 13WL is an alternative for non-Sport & 16" wheels.

Did the light greasing on the caliper face help mitigate corrosion? I just put on a reman'd caliper 2 weeks ago and it's already corroding quite noticably (the other 3 pre-existing ones are fine, though).

This caliper situation that Toyota has created is quite vexing. I started a thread about my attempt to think outside the box on it and may eventually have to do something like this. In the end I can't imagine the price difference being that substantial - $150 every two years for a new caliper or twice that for a single purchase and never worry about it again? Before I do that I'm going to just try something simple and try spraying Rustoleum on the surface, the kind that converts the rust to a paintable surface and see if that helps.