Caliper Sticking - Tried my best to figure it out

Hey gang!

Long time listener first time caller.

I hate asking for help when others have had similar issues on this forum, but the answer still alludes me.

My front passenger caliper has been slow/hard to release after brakes are engaged. Really only feel it at very slow speeds, moving either forward or backwards from a full stop. Most extreme when turning right, but that might just be my imagination.

Symptoms:
- Rubbing/vibration from full stop, more intense when in reverse or turning right
- Hard to rotate tire when vehicle is on jacks, all other tires no issue
- Grooves are deeper and signs of high heat on that rotor
- Stiff caliper pistons when no brake pressure applied
- Vehicle has a slight pull to the right even after alignment

Attempts to fix/isolate issue:
- Remaned the brake caliper using Toyota kit
- Replaced the caliper after reman did not work with NAPA reman unit (ceramic coated and feels great)
- Replaced wheel bearings on both sides
- Replaced rotors and pads
- Replaced soft brake lines on both sides with OEM lines
- Bled brakes 4 times now after all my tinkering with DOT 3/4 synthetic fluid
- Inspected hard lines and found no kinks
- Took to Les Schwab, they have no idea
- Called my local Toyota Service department and they don’t know either but will gladly drain my bank look for the issue using this as last resort

Vehicle Specs:
2008 Tacoma PreRunner 4.0L Automatic

I’m currently unemployed so repairing on a budget but try to use as much OEM as possible. Any help would be so so appreciated.

You guys are my collective hero’s and I appreciate all you do!

Cheers,
Brad

 

I'm honestly not sure what your issue may be, but it doesn't seem like you've done anything to rule out the master cylinder? Maybe the problem could be up there?

 

Thanks for the response Darth!

I haven’t fussed with that yet, not something I’ve had experience with. I wasn’t sure if the issue being isolated to only one brake would be a symptom of the master cylinder, but I will certainly look up some posts on it now. Thanks for the push in that direction.

 

frankly I'm not sure either, but its something I didn't see you mention, so thought that might be something to check. I do know the master cylinder does some amount of proportioning/distribution of the brake force to each wheel (though I couldn't say how exactly, or how to go about troubleshooting it off the top of my head), so I wouldn't be too surprised if there was issue up there.

 

I suppose you could test the fluid pressure at the caliper.
I don’t know what the pressure should be, but if you compare it to a known good caliper, you should see a difference.

Something like this kit.
https://leedbrakes.com/i-23439488-b...MIwLS9wu716gIVCr3ACh3rSA61EAQYASABEgJ1xfD_BwE

 

So from what I gathered reading your OP, you've rebuilt the right brake caliper which didn't fix the issue so you went and replaced the whole caliper with a new one? Are we talking the whole caliper or just the piston and associated seals/boots? I'm just trying to get the whole picture here. You rebuilt your OEM brakes calipers with a rebuild kit and this kit came with all necessary seals. When you replaced your pads, did you open the bleed port when you compressed your pistons or did you squeeze the brake fluid back into the lines? When you had your brakes apart when you replaced the hardline from your brake caliper how did hydraulic connection that connects your brake line to your piston look (see brake, tube and clamp link below item 47317) Given the age of your vehicle and the possibility of rust and corrosion, the connection I mentioned may be rusted or partially rusted closed restricting hydraulic fluid from applicating your brake piston. If you did what you said above, that's where I would point my finger. If that's not the issue, you would need to pull your caliper off your truck and do a full bench rebuild with new pistons, new seals/gaskets and new boots. When you're rebuilding your calipers, ensure that you use a schmear of brake fluid on your new piston seals prior to installing them as they should be lubricated as to not dry out and crack. Another place to look would be at your caliper guide pins. Pull them out and check to see if they have sufficient brake grease on them. When you install them they should move freely when you push on them and spring back to their original position smoothly, they should've been lightly coated with brake caliper grease. This is what I use.

Brake, Disk
Brake, Tube and clamp

-J

 

this is actually a good point. OP, did you reuse any parts when rebuilding or replacing the calipers? if parts are sticking that might explain it, at least in part.

 

Wasn't there a poster a long while ago that had issues with the brakes and the final result was a worn out wheel bearing.

I bring this up as you stated that the issue is "Most extreme when turning right,".

 

i had an issue with an f150 that would make all my calipers lock up starting with the front then the rear started as well till the truck would barely move under hard throttle and brake fluid boiled out of the master cylinder. mine was a little different in that i didnt have issues driving normally but when towing my 5k lbs trailer they would lock up. i only had the truck a few weeks and drove it as my daily driver to try to make sure i didnt have issues before using it for work. which it didnt till i added the heavy trailer.

i replaced the brake both front brake calipers, bled the system completely and the same issue happened 2 days later. all brakes literally smoking and too hot to even touch the wheel.

i replaced the master cylinder and it happened again

read about how it may be a collapsed line when hot which started at one caliper then affected the rest but this wasnt my issue

looking around and had the master cylinder disconnected from the brake booster ready to take it apart again. noticed a flat head screw between the master cylinder and the booster, i cant remember which one had it, but i used blue wall sticky tack on the end of the plunger piece and bolted the master cylinder back on the brake booster to check the gap. the sticky tack pinched all the way through. i took it back apart and adjusted the screw to create a larger gap. i did this a few times till i thought there was a decent gap, by measuring my sticky tack, and drove the truck. the pedal throw was extremely long and i didnt like it, almost to the floor long. took it apart one last time and made the gap a little smaller and bolted back together. pedal throw was still longer than original but i never had issues again.

these were small adjustments the made a huge pedal throw difference, just a few turns in or out. also i have no idea why it became an issue.

 

If you jackup the tires does it feel like its dragging? If you crack open the bleeder screw does fluid squirt out and the tire spins more freely? Just asking

 

Thanks you for the super thorough response it means a lot that you guys are willing to help out.

- when I rebuilt the right OEM caliper all I replaced were the seals, all 4, and cleaned the hell out of the pistons and the housing, pulled it in half, and replaced the seals between the housing. All but one piston looked great, so I was sort of pre-planning that I might just want to replace the whole unit.

- after that didn’t solve the issue, I got a reman assembled unit from NAPA, with new seals but I assume cleaned and reused pistons. It moved freely and the sliding pin was also replaced and I put a little clean brake fluid on the outside of the seals.

- new pads were installed then, and I did NOT open the bleeder valve on the caliper when I put them in, though since it was new it didn’t fight be at all putting it on the rotor, there was plenty of clearance. I did not open the bleeder valve on the other side either, just compressed, and now I’m thinking that may have forced extra fluid into the system?

- sorry if I misspoke, but I only replaced the soft lines, not the hard lines. When I took the hard lines out from the caliper, it did take some knuckle smashing and liquid wrench, but the connectors looked okaaay, no rust to speak of but certainly not new. Fluild drained freely from the hard line coming from the truck while I changed the soft line, and with some force like a cut vein, it blew off every attempted cover I could put on the line. I’ll replace the hard lines next thank you for the idea.

- I did put brake fluid on the piston seals as on both the reman and the rebuild ones, but I did NOT use brake grease on the guide, I’ll do that as well thanks for the suggestion.

apologies if my format is off I’m on my phone and this is my first series of posts!!

 

I reused the pistons and the housing, but the seals were replaced. This unit has been removed and replaced with a fully remaned unit though, both exhibiting the same symptoms after installation and use though.

 

super interesting ok this reinforces getting into the master cylinder and getting to know what/where restriction could be occurring. I’ll dive into this tomorrow thanks for sharing your fix I do appreciate it!

 

YES! This is exactly what happens! Hoping to all that is holy this is the tee-up to an easy solution

 

Well good, now we are getting somewhere. when did this problem start. all of a sudden or after you did something/what? to the truck?

 

Ok, after all that work you did to your front end, I find it hard to say definitively that it is your brake. You mentioned that you changed your wheel bearing, was this prior to you tearing into calipers? Did you get a pre-assembled bearing or did you press out/in a new hub/bearing? When you get some available time, check your wheel bearings by lifting the tire off the ground and safely supporting the vehicle. Then grab the 12 o'clock and 6 o'clock position on the tire and push/pull with all your might. Do not put anything under the tire that you are willing to loose in the event that you pull the vehicle off the jacks. There should be no play in the wheel when you do this. If there is play, your suspect will be your wheel bearing (or your UBJ/LBJ). For shits and giggles, grab the 3 o'clock and 9 o'clock and do the same thing. If there's play, your tie rods and connecting linkages might be shot.

On to your hard line, you shouldn't have to replace the hardline since you noted that brake fluid flowed freely from it when you pulled the caliper off, no sense in throwing money at that part regardless of the price. Also, you mentioned that you didn't open the bleed port when compressing your pistons. I was trained to open the bleed port prior to compressing the pistons as rusty/water infused brake fluid moving backwards into the master cylinder may induce problems with the ABS system. I don't believe that your 08 has the same computer driven hydraulic brake booster as my 12 so I don't think it's that big of a deal so I wouldn't worry about it especially if you bled your brakes prior to putting everything to bed. Did you bleed all 4 or just the passenger?

This is a tough one to diagnose without actually putting hands on as it sounds like it's not one definitive answer but a combination of small things. When you installed the new brake pads, did you use the new pad return spring that's included with the pads or did you reuse the old spring (part number 47748)? These types of fixes tend to be the easiest before we elevate to something more substantial.

Another thing to try would be to take the passenger tire off again, have someone else apply the brakes and you watch what the pistons are doing when they actuate your brakes. That would be the next step in my troubleshooting process. You should be able to watch both pistons moving equally and return to the relaxed position when they come off the brakes. Your new pads will drag on the disks brakes but something out of the ordinary may stand out to you.

After you've done all of that and exhausted all options prior to purchasing a complete new caliper assembly with all new hardware, I would try your hand at another bench rebuild. (04479 and 2 ea 47731) A complete rebuild kit would set you back around 130$ so now you have a decision point. What would a complete aftermarket brake caliper set you back? We're here to help so keep us posted.

-J

 

A caliper that won’t release is usually caused by a collapsed flex line. Have seen it a number of times where the fluid will go in the direction of the caliper but not the other way hence the caliper sticking on or slow to release. Worth a shot replacing it.

 

@Beertopia stated in their OP that they replaced the flexlines with OEM.

-J

 

Does the book, call for synthetic brake fluid? How long have you been using synthetic? Did the problem start before or after it’s use?