Stuck Caliper?

Does this sound like a bad caliper and is it normally hard to find parts?

It sounds like a "sticking" caliper - as in it is not releasing after you let off the brake pedal. Have you done a "brake job" before? It isn't that hard - and, NO - the parts should not be that hard to get - the Internet is a great tool

 

welcome! is it front or rear? when you turn the wheel by hand, is there more drag? i would check with parts.com for a caliper, or, it may just need to have the slide pins lubed. all the best!

 

You might not want the caliper the shop was going to put on, anyway.

It does sound like that brake is dragging, which can always be caused by slide pins not sliding easily, or the piston not retracting properly; in addition, for a Prius rear, there's the third possibility of the parking linkage binding somehow. These are all things you can check and probably correct while keeping the caliper you have. (Slide pins are the part you can attend to without disturbing the hydraulics; delving any deeper will require the ability to bleed air from the brake when you're done.)

Shops these days avoid spending any more time than it takes to bolt in a reman caliper and send your old one away to be cheaply remanufactured itself.

I just recently learned a lot about quality in reman calipers ... the hard way.

Two things about Toyota's calipers: (1) there's a shocking price difference compared to generic remans, so it would take a shocking quality difference to persuade me they're worth it ... and ... (2) I am persuaded. I'm now on the same page with the classic Porsche restorer dude: "... adamant about getting the proper caliper on your car. There's a good chance those are the calipers you have on your car..." (assuming, of course, those are original, and not already replaced with something else).

Now that I've seen what I've seen, my first choice (if your caliper casting looks sound and undamaged and is still keeping corrosion at bay) would be to go totally old-school and get the rebuild kit for it. Even from Toyota that's just $25 for all the stuff do to both sides, even down to a little packet of the proper rubber grease. You could spend still less than that on 3rd-party rebuild kits, but ... dude.

Then just sit down with any of the online howtos and videos and restore the proper function of the caliper you've got.

One caution: at least going by the illustration, the kit does not include new seals for where the parking linkage goes through, so if that ever leaks, it might be necessary to replace the caliper. (Or maybe if you buy the kit, you'll find it really does have those seals too, just left out of the illustration.) But other than that, you'll end up with the dragging problem fixed, little money spent, and original-quality parts still on your car.

I strongly recommend testing the caliper after rebuilding—or any replacement caliper, even right out of the box—for proper piston retraction, as I described in my other thread I linked to above. It's an easy test (doesn't require shop air, a bike pump should be adequate) and calipers I've tested from Toyota return by a good 0.3 mm or so when you release the air; it's visible to the naked eye. The (non-Toyota) reman I first bought would have failed that test right away, and saved me the trouble of installing it and driving around for weeks wondering why it still seemed like my brake was dragging.

-Chap

Edit: just to be clear, your Gen 3 caliper is probably aluminum, so the exact details in my other post about the finish used on the cast iron obviously won't apply, but the other points should stand.

 

What you definitely want is to make sure both calipers work:

• they clamp when you brake
• they unclamp (by about 0.3 mm) when you release brakes
• they slide freely on their pins
• they don't leak fluid

As long as you can say those things are all true on both sides, the calipers are as they need to be. And in almost every case if those things aren't all true, you can make them true simply by servicing the calipers you have. Replacing a caliper unnecessarily is expensive if you use a $200 real Toyota part as the replacement, and cheapens the car if you don't. (Ok, that's a personal opinion of mine, but it's one I didn't have before I had the need to compare up close.) Keeping the originals in good shape with the $25 servicing kit, when you can, is a good value-conserving move. If the other caliper is passing all the function tests with flying colors and you don't feel like fussing with it, just hang onto the other half of the parts in the kit until you do.

Cases where you might have no option but to replace the caliper could include real, deforming, physical damage (as in a crash), or severe corrosion. (On my calipers, the piston is metal, and could get rusty if the rubber boot tears and lets salt water in. I think your pistons might be phenolic and might not even be damaged in that case.)

Examples of changes you do want to always make on both sides simultaneously would be anything changing the friction surfaces. New pads, new rotors, lathing the rotors, hand sanding to take off surface glaze ... any of those things you'd want to avoid doing to just one side, or the friction properties wouldn't be matched.

As for the calipers themselves, their jobs are simple enough that as long as they both work (per the four points above) it's fine. If one is working fine and one isn't, and you fix the one that isn't, then they both work, and it's fine.

-Chap

 

I have a 2010 with 85,000 miles. Recently replaced the front wheel bearings but have since come across a thump sound. Thought I installed the bearings incorrectly; after putting a second set of front bearings on, new struts, ball joints, and tie rod ends...still thumped. Thought the rear bearings were going, replaced those...still thumped. Finally found a frozen caliper pin on the rear right and thought I found the problem. Replaced both calipers, new pins, etc, still thumping. FINALLY thought to just feel the rotors after driving, the left rear is hot, other three are cool. So I’m dragging a rear left brake but can’t find the problem. I bled the system without issue and the parking cable looks fine. When I find the answer I’ll post a follow up.

 

@A_P when putting the rear brakes back together, make sure the piston caliper is oriented like this:



The shaded areas are raised "spokes", and it's important that the stubby pin on the pad backing plate is in between the spokes. It locks the piston, prevents it from turning when the parking brake is applied. If the pin is not in between the spokes, or manages to slip and ride up onto a spoke, the brakes WILL drag, be hot, wear the pads unevenly, score the rotors, and on and on.

If the inside face of the rotor is about 50% rusty, that's very likely what's happening. If the rear end's raised and the wheels spun by hand, they should go a revolution or two after you let go.

The key is to get the caliper piston orientation right when reassembling, then tromp the brake pedal multiple times, to get it seated.

Then hook up the 12 volt negative cable (best to disconnect at the outset), do a test drive.

When you get back, apply/release the parking brake brake a few times, raise the rear, and check the wheel spin. If they're spinning relatively freely you're out of the woods.