Disc brake with 4 pistons

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NH
I'm 99% sure that this means that I need new calipers... both fronts on my Tundra have some sort of damage to these pistons. Or at the very least a rebuild. From what I can tell, the pistons are amazingly still free though, so I'm tempted to buy a rebuild kit. However I've never worked on a 4 piston caliper--do you just open the bleeder and push down on the piston, and just that piston will move? It's been a couple of years since I messed with those bleeders, and I didn't think to see if they were loose yesterday. Alternatively, is there a downside to leaving it alone? I'm guessing if it seizes, it'll just be like a single piston caliper, and cause a dragging brake when it goes. [Linked Image] [Linked Image] [Linked Image]
 

JHZR2

Staff member
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New Jersey
Wow, doesn't look good. Frankly, given the amount of rust, I'd be looking for replacements, at least rebuild some junkyard pulls from someplace else... Ive done two piston calipers, and the key is to have a block of wood and/or a clamp to allow only one piston to come out at a time. It can be a pain, especially if one is more difficult, or after you get some of them out and they're moving well. It just takes patience. Use low pressure air, as it doesn't always take a ton, if stuck, use a bit more pressure. Think about what the piston will crash into when it pops out with force and speed. Wood is good. A poorly located clamp can be crashed into and nic or bend a portion of the piston face. At minimum, to get started I'd put the old pads in there, and use sequentially smaller pieces of wood between them to try to get all of the pistons further and further out together. Then it's just a matter of smaller shims to walk them all out. Ultimately you might clamp one side in entirely and blow out the other side, or something else. I believe Toyota has a special glycol grease for brake assembly. I used brake fluid, but other products may be better.
 
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25,174
Location
Upstate NY
You either need to rebuild the caliper or replace it. If you rebuild you may need new pistons also. If metal they need to be pristine looking when wiped off. No rust or pitting. Don't wirebrush, replace if rusty.
 
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4,922
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VA
I'd probably go new if I had the money and I planned on keeping the truck. One thing I didn't learn until later in life was the importance of lubing the caliper pins. If I had plenty of money, I'd at least "consider" the rotors as well. Just do them all at once. IF I had PLENTY of money. Toyota makes 3 different lubes for brakes. 1. Anywhere metal touches rubber 08887-01206 (Rubber Grease) 2. Ears of pads 08887-80609 (Brake Caliper Grease) 3. Back of pads between shims and back. Comes with pads or Molykote AS-880-N Very expensive if you go OEM lubes.
 
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7,985
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Michigan
Yeah, get new calipers. You're truck is 10 years old, so the creeping crud has invaded. But it only has 158k miles, so it seems like there is a lot of life left in it.
 

supton

Thread starter
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NH
Those rotors are nearly new--less than 3 years and less than 20kmiles. Sounds like I need to look into rebuilding or replacing. At least I have warning, I guess.
 
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25,174
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Upstate NY
Originally Posted by Gebo
I'd probably go new if I had the money and I planned on keeping the truck. One thing I didn't learn until later in life was the importance of lubing the caliper pins. If I had plenty of money, I'd at least "consider" the rotors as well. Just do them all at once. IF I had PLENTY of money. Toyota makes 3 different lubes for brakes. 1. Anywhere metal touches rubber 08887-01206 (Rubber Grease) 2. Ears of pads 08887-80609 (Brake Caliper Grease) 3. Back of pads between shims and back. Comes with pads or Molykote AS-880-N Very expensive if you go OEM lubes.
I am not sure lubing of the caliper pins is necessary on a regular basis but certainly inspection is. I have yet to find a caliper pin that was not lubed or had dirt/water inside the boot. But I only do my own brakes. Not in business as a mechanic. But if you are going to inspect then lubing is not that big a deal.
 
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VA
Originally Posted by Donald
Originally Posted by Gebo
I'd probably go new if I had the money and I planned on keeping the truck. One thing I didn't learn until later in life was the importance of lubing the caliper pins. If I had plenty of money, I'd at least "consider" the rotors as well. Just do them all at once. IF I had PLENTY of money. Toyota makes 3 different lubes for brakes. 1. Anywhere metal touches rubber 08887-01206 (Rubber Grease) 2. Ears of pads 08887-80609 (Brake Caliper Grease) 3. Back of pads between shims and back. Comes with pads or Molykote AS-880-N Very expensive if you go OEM lubes.
I am not sure lubing of the caliper pins is necessary on a regular basis but certainly inspection is. I have yet to find a caliper pin that was not lubed or had dirt/water inside the boot. But I only do my own brakes. Not in business as a mechanic. But if you are going to inspect then lubing is not that big a deal.
For clarification, I only lube caliper pins when changing pads. Every 3-5 years. But before the last 5 years, I never lubed them.
 
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601
Location
Earth
In my opinion those are shot and I'd second Slacktide_bitog's suggestion on the replacement brand recommendation, those are excellent for the price. I had to do the rears on my G37x in February when one started to stick and they both had similar levels of deterioration to yours. Brakes are important, if they fail somewhere inconvenient you are likely going to spend a lot more money getting out of that jam then you will to use better parts to do the job from the start.
 

supton

Thread starter
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16,939
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NH
Why do people say they are shot? Is the rust impeding heat transfer? The pistons still move freely, once free the pads do not rattle about. I haven't tested the bleeder in a while. so that might condemn them I guess. If it wasn't for the torn boots I wouldn't think twice about running them longer (and TBH all the pistons that have seized on me had perfectly good rubber boots so... what good are they for?). These are a really long ways from somehow breaking in half or otherwise falling off. shrug
 
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ON, Canada
I have the same truck, but a little older. If the pistons move freely, you should be okay. I agree, the rust shouldn't be a problem for function. However the boots definitely need to be changed. They will allow moisture inside which could cause piston corrosion and failure. And if you haven't loosened the bleeder, that might be challenging to get loose without some heat to keep it from breaking. The other issue is if you take it apart to rebuild the pistons might already be corroded. So then you get into replacing all four pistons plus a seal kit back into rusty caliper. It might not be too much more to get a new or rebuilt unit (Raybestos makes new that are zinc coated). I am in the same boat with truck. The front brakes will need to be done soon. I have at least one front caliper with bad boot but they still seem to be working okay. I was going to fix it but I may just order new calipers and save the time.
 
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Under the hood
The outer boot(s) has ruptured, so at the very least, like you said, they need to be rebuilt. Given the amount of external corrosion, and the odd penchant for some here to neglect brake fluid changes, chances are that there will be damage to the pistons and/or bores found after they've been disassembled. For many, by the time the seal kit, new pistons, etc. is factored in, it's just easier to replace them. It appears that they've lead a rough life, and both sides have been compromised. A dragging or seized piston will generate extra heat and increase the risk of the fluid boiling, especially if it hasn't been maintained. In that situation, even only one affected caliper will affect the rest of the system, and it goes downhill fast from there. I've experienced it. The pedal goes straight to the floor. With things like this, the value assigned to one's own life isn't the only factor; others' lives are at risk as well. Some will obsess over wavy filter pleats or UOA numbers, things that matter not one bit to others, but will blithely, even proudly, proclaim that they neglect their brakes. The incongruity is puzzling.
 

supton

Thread starter
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NH
I don't see the correlation between brake fluid changes and system lifespan--I've done fluid changes every 2-3 years and still had calipers go bad. I still do it, if nothing else to keep the bleeders free. But I no longer think it quite the necessity it was. Calipers still go bad--maybe fluid changes are good for the lines, but I'm not convinced any more about it lengthening caliper lifespan. I've had the pedal go to the floor. Pads still had 3/4 of the lining, but rust got behind a pad and it came off one day. I forget, must have been 6 years old, something like 175k, but the other 3 pads were still at 3/4 the lining--so why would I change them? Today, after 2 or 3 years I inspect the pads annually, looking for rust jacking; 5 years or 100k is about the max I push now, there's something to condemn them at that point. No brakes is no fun. These pads have certainly seized a couple of times, but I don't recall ever having a dragging brake--no hot brake smell. Just the sense the brakes aren't right. Sure enough, I'll find the works seized up. I'm starting to think this design is somehow deficient, it's been needing the most attention of any brake system I've owned. I am hesitant to remove these calipers--they have a hard line behind them, and I'm hesitant to twist that off in the driveway. I've done conventional calipers, those I feel comfortable with, but these give me pause. I'm sure this would be a grand at a shop.
 
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Lakeside CA
I don't see any piston damage, just some corrosion transfer from the pads, and damaged seals. They can be rebuilt, or replaced if you prefer. Rebuilding is not easy at first, takes practice, and knowledge of a few tricks is very helpful, but after a while it just becomes what you do instead of replacing. If you have never rebuilt one, would be worth it to have someone show you the first time or watch a few videos. Edit: Just watched "Eric the car guy" video....DO NOT DO WHAT HE DOES! So much is wrong with his procedure it shouldn't be followed.
 
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Under the hood
Originally Posted by supton
I don't see the correlation between brake fluid changes and system lifespan--I've done fluid changes every 2-3 years and still had calipers go bad. I still do it, if nothing else to keep the bleeders free. But I no longer think it quite the necessity it was. Calipers still go bad--maybe fluid changes are good for the lines, but I'm not convinced any more about it lengthening caliper lifespan. I've had the pedal go to the floor. Pads still had 3/4 of the lining, but rust got behind a pad and it came off one day. I forget, must have been 6 years old, something like 175k, but the other 3 pads were still at 3/4 the lining--so why would I change them? Today, after 2 or 3 years I inspect the pads annually, looking for rust jacking; 5 years or 100k is about the max I push now, there's something to condemn them at that point. No brakes is no fun. These pads have certainly seized a couple of times, but I don't recall ever having a dragging brake--no hot brake smell. Just the sense the brakes aren't right. Sure enough, I'll find the works seized up. I'm starting to think this design is somehow deficient, it's been needing the most attention of any brake system I've owned. I am hesitant to remove these calipers--they have a hard line behind them, and I'm hesitant to twist that off in the driveway. I've done conventional calipers, those I feel comfortable with, but these give me pause. I'm sure this would be a grand at a shop.
A healthy diet and exercise certainly doesn't preclude one from falling ill, but they do lessen the risk of it and are considered good practices. I didn't mean to single you out in the respect, especially since you say you do perform that maintenance, but there is a certain level of denial present that I just find confounding in a place dedicated to best practices…at least for certain parts of the vehicle. It seems that you're aware that the harsh operating conditions your vehicles see qualify as severe duty and warrant extra vigilance. But there also seems to be an element of rationalization that despite those circumstances, you expect the components to maintain, or perform according to more normal circumstances, and most feel that may not be the best approach. That is, of course, your prerogative ("Live Free or Die" right?), but you are taking chances by not being completely proactive and keeping a vital safety system in the best condition possible. No one looks forward to a future "I crashed my truck" thread, and the fact that you've asked showed you have doubts or concerns as well. Those you've asked have advised you to follow through and take action.
 
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ON, Canada
Originally Posted by supton
These pads have certainly seized a couple of times, but I don't recall ever having a dragging brake--no hot brake smell. Just the sense the brakes aren't right. Sure enough, I'll find the works seized up. I'm starting to think this design is somehow deficient, it's been needing the most attention of any brake system I've owned. I am hesitant to remove these calipers--they have a hard line behind them, and I'm hesitant to twist that off in the driveway. I've done conventional calipers, those I feel comfortable with, but these give me pause. I'm sure this would be a grand at a shop.
If your truck doesn't see regular use, that probably doesn't help the rust/seizing. That is part of the problem with mine. The front brakes aren't my favourite design and other than the pins requiring regular service to keep from seizing in the calipers, I find them less problematic than the rear with the more conventional design. Removing the calipers isn't hard. I have done it lots of times. There is a bolt on the steering knuckle that holds the brake line place. Remove that and the line is free and you won't bend the hard line at the caliper. If the hard line is getting rusty, you can get new ones from Toyota for relatively low cost, or just make some new ones yourself if you want to save money.
 

supton

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NH
Well, I do expect the components to last much longer than this. This is sub-standard performance as far as I'm concerned.
 
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