New Brake Pads = Car barely moves!!! Help please...

Some valve or some other weird problem just seems so unlikely. Did you open the bleeders when originally replacing brake pads? What’s the level of brake fluid in reservoir? Maybe you have too much fluid or your brakes need to be bled.

Replace the caliper that you now know is bad and check that pads and sliding pins can move freely on both sides. Bleed the front brakes with the way I described earlier.

 

If the driver's caliper piston is hard to move even with the bleed screw open (so no hydraulic resistance), there's a good chance you're overthinking this. I would first take the caliper apart and look for signs of why it's hard to move. Disconnect the 12 volt power and use up the boost pressure first. Just barely loosen the banjo bolt before unbolting the caliper (easier to apply loosening torque on bolt that way), then lift the caliper as high as possible (up near top of strut) before disconnecting the brake hose. You can clamp a bit of rubber around the end of the brake hose and leave it stashed up high in the spring to minimize the amount of fluid you lose while investigating the caliper.

My new policy regarding Gen 1 calipers is: always rebuild, repair, restore if possible instead of replacing with aftermarket because I found a ginormous quality gap between the Toyota caliper and an aftermarket reman: two things, namely, the reman that I bought had zero piston return, so right out of the box it dragged, and second, the reman lacked any corrosion resistance at all and was completely rust covered in a few weeks. It might be possible to just buy a better quality aftermarket reman, but the experience has turned me old-school and now I keep a spare rebuild parts kit on hand.

Now, that second point might be specific to Gen 1 calipers, which are cast iron; I think yours are aluminum and I don't know the story on corrosion resistance for those, Toyota vs. aftermarket. Maybe there's less of a difference. Toyota does not seem to sell their own reman version of the Gen 2 caliper as they do with Gen 1.

I think you also have phenolic pistons rather than metal. That's good in several ways (no rust, less transfer of heat to brake fluid) but they are vulnerable to scratching or chipping if not handled carefully (be especially careful when forcing the piston out, use thick padding). Although they don't rust, I've read that some old phenolic pistons might swell, which could be a reason to stick. Pistons aren't included in the rebuild kit, but are only about $17 each if needed.

So, I would certainly start by making sure there's a working caliper there, bleed the system well, and then see if there's still some problem.

-Chap

 

Yikes! From Village Toyota it's $28.07 here in CONUS, I guess everything must be extra expensive on the island. (The whole caliper is more like $265 here.)

Two things though ... (1) that rebuild kit has the parts for two calipers; (2) the aftermarket reman might be a lot lower than Toyota's price but, at least what I saw re: Gen 1, it still wasn't worth the step down in quality. (Maybe you ordered from a better quality reman supplier than I did, and maybe there's less of an issue with your aluminum calipers than with my cast iron ones.) If you have good repairable Toyota cores and can repair them with a $28 Toyota kit, it seems less of a gamble to me.

... but of course you don't know if one's in repairable condition until you dive in ...

-Chap

 

It will make a bigger mess. Should be ok as long as you have powered down and used up all the boost pressure, so your foot pressure is in direct control of the shove you're giving. It's pretty safe for the piston, because it will push out under a semblance of control.

That's a traditional approach, and that's where you want to be very careful (especially with a phenolic piston). Unlike brake fluid, which doesn't compress, the compressed air behind your piston will shoot it like artillery when it comes at last free. There will be a loud bang. The piston isn't likely to go very far, because the first thing it hits will be the metal far side of the caliper (assuming your fingers don't come first, which you don't want). But that's very likely to chip a phenolic piston. You should have many thick folds of rags or the like stuffed in there to pad it.

Yes, that is a mystery. While you've got the bleeders open both sides, it might be worth pumping several strokes of fluid out and replacing with new at the reservoir. (I think you can do this without complications as long as all power is off and you never let the reservoir get empty). If there was any gunk up in the hydraulics department, maybe that could help, or maybe not. What it won't do, though, is flush any of the remaining actuator passages that are only in use when the power is on. Scan tool would be needed for that.

-Chap

 

Thanks for the great pictures!

You can trial-fit the piston in the cylinder without the seal or boot installed, just to simplify the feel of the business. It looks as if yours is not far in. The clearances can be tight enough (I've found this on mine, with the metal piston) that any imperceptible angle to the piston as you are starting it into the bore can make it feel as if it absolutely won't ever go in, and then somehow after a minute or so of random jiggling you finally hit perfectly straight and shoop! it slips right in.

Naturally that's a lot harder to test when you are trying to contend with the rubber parts at the same time, so I'd recommend a trial-fit without them just so you can easily tell whether that's going to happen, or you really have a piston that won't go in at all.

I have read claims that phenolic pistons can be swollen by moisture. (I've also read claims that they aren't ... hmm ....) In the claims that they can be, usually the writer doesn't seem to be talking about random ambient moisture, but moisture that's been absorbed into the brake fluid. Or maybe the square-cut seal is now just enough harder from heat/aging/etc. that your piston hangs up on it.

I, for one, would be quite curious whether you could successfully fit a new piston into your caliper. I guess we'll only find out if (a) your replacement calipers don't come with a requirement for you to send in your cores, and (b) you're willing to invest in a piston (about $16 here in CONUS, for you $29?)

If you're allowed to hang on to your cores, you might be able to turn them back into good working spare calipers for not much money.

-Chap

 

There's a company that sells an inexpensive brake pressure gauge kit that would be one way you might be able to confirm whether that's really what's happening. (The important part of the kit is the set of adapters; the M7x1.0 is the one that fits in place of your bleed screw and lets the gauge attach. Pressure gauges you can get anywhere, I just haven't found any other inexpensive source for such an adapter.)

-Chap

 

wow, in hawaii, no less. congrats!

 

Great report! Did they want your old ones back as cores?

-Chap

 

Interesting thread and informative too. Glad to see Tommerdoo got it all sorted out.

 

Not an authority, but I have an opinion: Things you know are, you have good rotors,slide pins, pads but questionable caliper(s). If this was my car,before rebuilding calipers, I would drive carefully and allow things to "reseat". Most likely your brake job is done and you are being too analytical. The worst thing that can happen is you will ruin your calipers, but you are going to rebuild them anyway. Right?

 

I go 1.5 Toyota Prius 2009 gas padal very stiff and very havey after changing break pads and disc front and rear
After that I clean the bodythorat and tetracycline but is still the Same problem if anyone know about this so plz reply me thanx