Truly Fixing Seized Calipers

Ngonerogwu said:
It's easier to just coat the piston for sure.

Looking at pics of failed calipers, it appears that the seals suck, and let water past, and the top part of the bore above the seal becomes a horrible mess. If I apply the ceramic to the bore, then we should be good to go.
Click to expand...

I'm not really sure that the seals "sucking" is the main issue. After all, the square-cut seals effectively keep the high pressure brake fluid in the cylinder. If they were really letting water in at normal atmospheric pressure, then brake fluid would also be leaking out due to the increased hydraulic pressure. Obviously water is getting somewhere, otherwise we wouldn't be dealing with these issues. The natural degradation of the fluid through it's hygroscopic action introduces excess water from the inside. In my recent front caliper change, I initially intended (i.e.hoped) my pistons were in good enough condition to clean them up and install a new seal kit. I found my piston boots were toast. They just crumbled and as I tried to remove the C-clips I found several tears in the boot folds. So, water and all kinds of other grime was getting to the piston surfaces that way as well.

As annoying as it is, it seems that regular fluid flushes and regular maintenance of the rubber "dust" boots should keep them in the best condition. I can't see how the 5th gen brakes are any better... other than that they are brand new at installation. It shouldn't be any different than replacement 4th gen calipers. After market replacements probably have different metal compositions than OEM ( I guess). Maybe Toyota addressed the piston corrosion issue and made the 5th gen pistons out of a different metal/alloy/etc. I guess only time will tell if there has been that type of change. I know one of the 1st guys to do the 5th gen upgrade said the pistons were a different size. I don't suppose anybody could confirm the change in material to something less prone to corrosion... IDK, I'm just throwing out ideas. The ceramic coating seems like a good idea to my non-expert self...

Anyhoo... I now need to do a complete fluid exchange and I plan on installing a re-boot kit on my other front caliper and I think I'll look into a re-boot kit for the rears. I'm fairly sure those rubber boots are shot as well. Hopefully I can catch any potential issues before they cause problems.
 
Nice, keep it updated. Don't suppose they make that in an aerosol can? Picking up some Cerakote-d exhaust parts tomorrow, good stuff.
 
bob3dsf said:
I'm not really sure that the seals "sucking" is the main issue. After all, the square-cut seals effectively keep the high pressure brake fluid in the cylinder. If they were really letting water in at normal atmospheric pressure, then brake fluid would also be leaking out due to the increased hydraulic pressure. Obviously water is getting somewhere, otherwise we wouldn't be dealing with these issues. The natural degradation of the fluid through it's hygroscopic action introduces excess water from the inside. In my recent front caliper change, I initially intended (i.e.hoped) my pistons were in good enough condition to clean them up and install a new seal kit. I found my piston boots were toast. They just crumbled and as I tried to remove the C-clips I found several tears in the boot folds. So, water and all kinds of other grime was getting to the piston surfaces that way as well.

As annoying as it is, it seems that regular fluid flushes and regular maintenance of the rubber "dust" boots should keep them in the best condition. I can't see how the 5th gen brakes are any better... other than that they are brand new at installation. It shouldn't be any different than replacement 4th gen calipers. After market replacements probably have different metal compositions than OEM ( I guess). Maybe Toyota addressed the piston corrosion issue and made the 5th gen pistons out of a different metal/alloy/etc. I guess only time will tell if there has been that type of change. I know one of the 1st guys to do the 5th gen upgrade said the pistons were a different size. I don't suppose anybody could confirm the change in material to something less prone to corrosion... IDK, I'm just throwing out ideas. The ceramic coating seems like a good idea to my non-expert self...

Anyhoo... I now need to do a complete fluid exchange and I plan on installing a re-boot kit on my other front caliper and I think I'll look into a re-boot kit for the rears. I'm fairly sure those rubber boots are shot as well. Hopefully I can catch any potential issues before they cause problems.
Click to expand...

Bob, I do agree with everything you've said and making sure to not only maintain the dust boot but also I would add some brake grease inside the dust seal as a part of that maintenance... but I do think that when the OP said water is getting past the "seal" and causing the piston and bore to corrode and seize he meant the dust boot since he then stated that it was corroded above the "seal"...then he was meaning the actual brake fluid seal/oring in the bore, I also agree that water contamination in the brake fluid could also contribute to them seizing but I'm thinking that less of a problem than the dust boot allowing water, road salts, etc. in around the top of the piston, if this was a major contributing issue to them seizing then all calipers on all makes of vehicles would have just as much of an issue as we have on our T4Rs.
 
Fully agree... I don't believe water is getting past the square seals in the bore, so I didn't coat the bore below the seals.

The boot design is absolute crap, and its easy to see that the retaining ring can't do a good job of holding boot tight enough to prevent water from making it around. Other calipers have an insert at the top of the bore that gives a lip that prevents water making it around..

Other calipers are more like the design of our real calipers, where that seal is more inset into the body (brembo is a good example). After taking apart the rears.. i don't think I'm going to ceramic coat anything more than the pins. I don't see how water could possibly get past the outer boot.

You're right tho, fluid changes are KEY to protect the inside of the caliper. I'm just trying to control the external factor (crap boots).

bob3dsf said:
I'm not really sure that the seals "sucking" is the main issue. After all, the square-cut seals effectively keep the high pressure brake fluid in the cylinder. If they were really letting water in at normal atmospheric pressure, then brake fluid would also be leaking out due to the increased hydraulic pressure. Obviously water is getting somewhere, otherwise we wouldn't be dealing with these issues. The natural degradation of the fluid through it's hygroscopic action introduces excess water from the inside. In my recent front caliper change, I initially intended (i.e.hoped) my pistons were in good enough condition to clean them up and install a new seal kit. I found my piston boots were toast. They just crumbled and as I tried to remove the C-clips I found several tears in the boot folds. So, water and all kinds of other grime was getting to the piston surfaces that way as well.

As annoying as it is, it seems that regular fluid flushes and regular maintenance of the rubber "dust" boots should keep them in the best condition. I can't see how the 5th gen brakes are any better... other than that they are brand new at installation. It shouldn't be any different than replacement 4th gen calipers. After market replacements probably have different metal compositions than OEM ( I guess). Maybe Toyota addressed the piston corrosion issue and made the 5th gen pistons out of a different metal/alloy/etc. I guess only time will tell if there has been that type of change. I know one of the 1st guys to do the 5th gen upgrade said the pistons were a different size. I don't suppose anybody could confirm the change in material to something less prone to corrosion... IDK, I'm just throwing out ideas. The ceramic coating seems like a good idea to my non-expert self...

Anyhoo... I now need to do a complete fluid exchange and I plan on installing a re-boot kit on my other front caliper and I think I'll look into a re-boot kit for the rears. I'm fairly sure those rubber boots are shot as well. Hopefully I can catch any potential issues before they cause problems.
Click to expand...
 
jbtvt said:
Nice, keep it updated. Don't suppose they make that in an aerosol can? Picking up some Cerakote-d exhaust parts tomorrow, good stuff.
Click to expand...

Haha, no sadly they don't.

You gotta really control the thickness on this stuff, and its difficult even with a nice gun.

The hard part is really the prep and the masking honestly. If the prep is wrong, you gotta start over.
 
Squirt the boots full of silicone dielectric grease after you put 'em back together....it'll create a boundary seal and they'll work fine.
 
55gY5vi.jpg


Rears are done now.

Ton of smoothing on both the carrier and the caliper itself.

These are the nugeon branded calipers. The seals are CRAP. Picked up some Raybestos ones just in case.. glad I did. MUCH better quality. The Nugeon ones are crazy thin, and feel really junky.
 
Any updates?

Ngonerogwu said:
55gY5vi.jpg


Rears are done now.

Ton of smoothing on both the carrier and the caliper itself.

These are the nugeon branded calipers. The seals are CRAP. Picked up some Raybestos ones just in case.. glad I did. MUCH better quality. The Nugeon ones are crazy thin, and feel really junky.
Click to expand...
 
MikeinNH67 said:
It's been a little over 5 months since the last update. Still working well?
Click to expand...


I sold my 4th gen, buuuut I bet they’re still good. I bet the new owner is on here, but I also would believe he would never think to look at this thread.

I’m fully confident this fixed the issue for good.
 
Thinking you're from SW Indiana? I'm about to replace my 3rd right rear caliper in right at 20,000miles. Want to do another set? I have 2 sets of fresh cut GX460 rotors for the front and new Toyota OEM pads, guess which calipers I haven't had any issues with? haha
 
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