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Melting brake caliper seals

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#1
Alberto

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I seem to keep melting the seals in my calipers resulting in fluid leaks and squishy pedal.  The rear calipers lasted 1/2 of the pad life and they were bought new at Mazda Motorsports.  I had been running Carbotech 10f / 8r.

One of the fronts was also leaking.

 

Anyone else experience failures this frequently?  

How many seasons do you get out of your calipers?

Are there any sort of backing plates that I should be using between the piston and pad?

 

This is getting annoying.  And expensive...

 


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#2
Bench Racer

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You talking about the piston to caliper housing seal which fits in the caliper housing?

Never viewed the rear caliper that hot. Never had one melt.

If the e-brake is not dragging, quit using the brakes so much, take your foot off the brake pedal. :bigsquaregrin:


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#3
callumhay

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I've had issues with the caliper seals leaking. Here are some of the things I do now and it seems to have helped/ eliminated the problem for me

I Don't buy remanned calipers from the auto parts stores ( imo a lot of slop in some of the Pistons/bores)

I Use old OEM Miata calipers or buy new from Mazda. Was told new not available but lo and behold showed up 2 months later from Japan as an "emergency order" Thanks Mazda!

Stopped removing the rear brake adjuster internals. Not an issue for me as I will never win a race because of that

Over the years with my 1.6 and 1.8 have had enough issues to say that these tips have worked for me. Ymmv.

I do rebuild my calipers front and rear and use the Mazda brand OEM seals. I don't think they have any issues unless installed incorrectly

Leaking calipers are annoying as heck because if you don't have confidence in your brakes then . ...you just won't push driving harder

Cal

#4
Ron Alan

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To be clear...and not confuse terms, there is a piston seal and a piston dust boot. If you were truly melting your piston seal, I would feel at the time of failure it would be a far bigger deal than a squishy pedal :(

Cracked and shitty looking dust boot is another story...this is pretty common. In fact the worst I've seen basically were 6 months new...cheap kits from local auto parts store. Shitty rubber I guess. But the piston seal was never and issue...in fact we got the brakes so hot the caliper forks embedded into the pad metal(25 hour Miata with sport brakes and more HP). 

Only leaks I have seen are at the bleeder, brake line connection or the back of the piston where the e-brake mechanism is at(this seal can be damaged or forgotten when messing with e-brake disable).

If you are truly having piston seal failure(more than once)I'd be looking at your rebuild process :noidea:


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#5
Alberto

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To be clear...and not confuse terms, there is a piston seal and a piston dust boot. If you were truly melting your piston seal, I would feel at the time of failure it would be a far bigger deal than a squishy pedal :(

Cracked and shitty looking dust boot is another story...this is pretty common. In fact the worst I've seen basically were 6 months new...cheap kits from local auto parts store. Shitty rubber I guess. But the piston seal was never and issue...in fact we got the brakes so hot the caliper forks embedded into the pad metal(25 hour Miata with sport brakes and more HP). 

Only leaks I have seen are at the bleeder, brake line connection or the back of the piston where the e-brake mechanism is at(this seal can be damaged or forgotten when messing with e-brake disable).

If you are truly having piston seal failure(more than once)I'd be looking at your rebuild process :noidea:

 

^Yeah, the dust seals tear but that doesn't result in any observable change to usage - other than to allow dust to get to the piston seal which can cause the issue that i'm having.  Namely the piston seal leaks brake fluid resulting in squishy pedal and such.

 

I haven't rebuilt any calipers yet.  The most recent failure was on calipers sourced from Mazda Motorsports.  

 

I have also seen some leaks at the bleeder and brake line connection.  Can usually address that by tightening a bit more.


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#6
Ron Alan

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^Yeah, the dust seals tear but that doesn't result in any observable change to usage - other than to allow dust to get to the piston seal which can cause the issue that i'm having.  Namely the piston seal leaks brake fluid resulting in squishy pedal and such.

 

I haven't rebuilt any calipers yet.  The most recent failure was on calipers sourced from Mazda Motorsports.  

 

I have also seen some leaks at the bleeder and brake line connection.  Can usually address that by tightening a bit more.

So, the inside of your dust shields have been wet with fluid? Fluid seeping out thru a crack in the dust shield? At some point you removed a caliper piston to find your "melted" seal? You have pictures?

 

I have no doubt you have or had a squishy pedal...I'm just trying to wrap my head around your conclusion. 2 bubbles of air will cause a horrible pedal...I've chased many of these. A leak in theory would cause the same reaction as opening a bleeder...pedal to the floor? And if this happened there would be very obvious fluid somewhere? I guess if somehow as that fluid leaves air was entering back in at that leak...a squishy pedal would occur?

Many smart guys here...I will gladly be corrected if my thought process is flawed. If in fact the caliper(from Mazda)failed...there has to be something more definitive an explanation than a squishy pedal. Over heating a caliper(or 3) is not feasible assuming everything is normal. 


Ron

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#7
Alberto

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So, the inside of your dust shields have been wet with fluid? Fluid seeping out thru a crack in the dust shield? At some point you removed a caliper piston to find your "melted" seal? You have pictures?

 

Yep.  Fluid seeping aka leaking our of the dust shield.

I haven't actually removed the piston yet.  I wound up getting parts store calipers on Sunday since I needed to get the car together and finish troubleshooting the soft pedal in prep for the race this weekend.  Otherwise, I would have ordered calipers from Drago / East Street Racing - which is what I would have preferred.  


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