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Discussion Starter · #1 · (Edited)
So at this point I've about run out of patience with a small project that is turning into a major headache. While I had the car apart doing my front bushings I figured it might be a great time to have my calipers coated. I took my calipers apart, no problems everything went great. Dropped the parts off at the shop...didn't get the parts back for almost 5 weeks. Should have been my first clue something may be up. First issue was they sucked up the rear hardware in the vacuum, they had to order new hardware...no problem. Next they kept having issues with the decal shrinking after applying the clear. That happened twice. Essentially these calipers got media blasted a total of three times. Eventually I said fuck it and told them to forget the logo, ill apply the decal over the clear. So I take them home, put them together with the old seals as they did not have any cuts or tears....its a 26k mile vehicle. Long story short theyre leaking from the pistons..some pistons worse than others. Shit, ok well I managed to find a set of seals at orielly because the centrics are on backorder everywhere. Pop those seals in...same shit. Some of the pistons are actually dripping brake fluid...some just a tad bit moisture behind the dust boot. Take brakes apart yet again...at this point I'm looking at everything under a microscope...pistons seem ok. Seals are new so im left to believe something is up with the calipers. So im looking at the bores of the caliper wondering if these guys media blasted inside the bores...I would think that the bore would have a more machined appearance. To me they just look like an unfinished casting and I honestly don't remember what they looked like when I took them apart. What are your thought. Sorry for the long winded post bit im furious right now thinking this place possibly fucked my parts up.
 

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Should be nice and smooth, hopefully your pistons are still ok
 

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Discussion Starter · #6 ·
Ahh. Gotcha.

Should have very clean and pretty smooth bores.


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well they are smoothish. They just look, to me anyways, like theyve been media blasted and im almost certain thats something that shouldnt be done. I can see actual pitting in the aluminum. Something just seems off and im trying to get my ducks in a row before I show up there complaining.
 

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Definitely shouldn’t have been media blasted. I’m fairly certain they usually seal off the piston bores prior to any medial blasting or coating.


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Discussion Starter · #8 ·
Definitely shouldn’t have been media blasted. I’m fairly certain they usually seal off the piston bores prior to any medial blasting or coating.


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I agree completely they should have been sealed off. Did they? I dont know for sure, what do the pictures suggest?
 

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Good luck.

Shops hate accusations. Sometimes they really don’t know what they are doing but want to do the work, get paid, but perhaps should pass.

Not saying this happened here, but craft your comments to them carefully. Think before you talk with them about what are the facts, what is a reasonable outcome.


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Discussion Starter · #12 ·
Good luck.

Shops hate accusations. Sometimes they really don’t know what they are doing but want to do the work, get paid, but perhaps should pass.

Not saying this happened here, but craft your comments to them carefully. Think before you talk with them about what are the facts, what is a reasonable outcome.


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I completely agree, hell will only be raised if we cant some to some kind of agreeable terms. This place was supposed to be highly reputable in my area. I would think that I should not settle for less than a replacment of the calipers at very least.
 

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Have you ever rebuilt calipers before? Usually the seal is created between the piston and rubber seals, then on the seal and the inside caliper wall. If a surface is too rough then you’ll have the leaks your talking about. Good luck


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Discussion Starter · #14 · (Edited)
Have you ever rebuilt calipers before? Usually the seal is created between the piston and rubber seals, then on the seal and the inside caliper wall. If a surface is too rough then you’ll have the leaks your talking about. Good luck


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Ive rebuilt many hydraulic cylinders but this would be my first caliper rebuild. Im slowly figuring out my issues may be from the pitting on the wall. I really wish i would have noticed this a while ago. Thanks for your reply man.
 

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Ive rebuilt many hydraulic cylinders but this would be my first caliper rebuild. Im slowly figuring out my issues may be from the pitting on the wall. I really wish i would have noticed this a while ago. Thanks for your reply man.
That’s definitely been media blasted. You can try to hone the cylinder. They make brake hones. Or maybe have them agree to have calipers rebuilt before replacement and find a competent shop to give you a quote before you raise hell?
 

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Hydraulic actuators handle high pressure. A rubber seal isn't going to keep the fluid from leaking past. So that's not what the seals do. The bores should be smooth, polished even. It's the close tolerance between the piston and the bore that provides most of the "seal". The seals themselves are mostly just to keep crap from the environment from getting in to the assembled piston/bore.

I don't know if anyone sells oversize pistons you could buy, and then hone the bores. Honing alone isn't going to fix the problem because the tolerances are already "opened up" and honing is just going to remove even more material making the tolerances worse.
 

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Hydraulic actuators handle high pressure. A rubber seal isn't going to keep the fluid from leaking past. So that's not what the seals do. The bores should be smooth, polished even. It's the close tolerance between the piston and the bore that provides most of the "seal". The seals themselves are mostly just to keep crap from the environment from getting in to the assembled piston/bore.

I don't know if anyone sells oversize pistons you could buy, and then hone the bores. Honing alone isn't going to fix the problem because the tolerances are already "opened up" and honing is just going to remove even more material making the tolerances worse.
Good point. I should have clarified the need for oversized pistons.
 

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Hmm. Interesting thoughts here.

As a former brake designer…

Yes seals seal the bore…not the piston to bore clearance. That ish could be .0001” on the diameter and pressurized fluid would still get out. That said, a wallowed out bore could allow for piston cocking and resulting leaks.

Many brakes have a boot or a wiper seal that is to keep the piston clean as it travels in and out. Those would still have a high pressure seal doing the real work underneath.

The critical surface is the diameter located in the seal groove. It is that wall that seals the seal OD and then the piston seals the seal ID. It would have been hard for them to directly blast those faces, but they definitely got hit indirectly while the bore itself was blasted. Should have been taped up for sure.

Are all the calipers they touched leaking? And how did the pistons look?
 

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Perhaps find a 'before' picture of a new cylinder so they can see what they did.
 

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Fuck trying to save those calipers. Way too much work ,time and money to try and fix that.

By the time you fix all of them buy pistons and seals you'll be more than a new set .

Then you get the liability on you if something does happen down the road and the brakes fail.

I would tell the place to cover the cost of a new set of calipers at minimum. Even if you lose the money you spent to have Coated.

They don't have experience when it comes to calipers . The bores should never see any media as well as any machined sealing surface . I've seen some shops leave them partially assembled(everything but splitting the calipers) also.

Calipers get hot , really hot and still don't leak in heavy on road use. I've literally melted the brembo paint off a set before from heavy braking and not sprung a single leak. In fact the runner brake hose failed first.

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