Callipers leaking 6 months after rebuild

[Roadrunner]

I was doing some routine check ups in prep for the track day on Sunday when I noticed the dust boot on the passenger side front calliper had two tears, is very twisted and was brittle to the touch and when I pulled it back a little some fluid came out from behind.
The callipers were rebuilt only a few months ago. Do you think it was just a poor job or something heat related?

Installed at the same time were carbotech xp10s.

Taking the car back to the mechanic tomorrow to get him to check it out and get his opinion, but would like some suggestions of the cause from here just in case he says it's heat and therefore not his fault.
Car has only done 2 track days since the rebuild.
Before that the car had done noumorous track days and had no leaking albeit a small hole in the dust boot. It was still soft and no leaks. Got them rebuilt to replace the dust boot and because the car has 150k on it.
Seems the preventative maintainance has caused a major problem

Either way looks like I won't have this car for the track day on the weekend

[manga_blue]

the dust boot on the passenger side front calliper had two tears, is very twisted and was brittle to the touch and when I pulled it back a little some fluid came out from behind.

It says to me that substandard seals were used in the rebuild, not able to take the heat. What were they? Where did they come from?

[NitroDann]

Or scored bores.

[Magpie]

Did the calipers get too hot?
Are the pads worn evenly?
Are the brakes ducted?
Cool down laps?

Sounds like heat damage to the seal based on my own experience, however mine did not leak.

[Roadrunner]

As far as I'm aware brakes haven't overheated (no fade etc)
Mechanic did the rebuild so don't know what parts were used. I do know one piston was replaced, not sure which side.
Pads are barely worn but are even. Car has hardly been used.
No ducting at this point.
Always very mindful of cool down laps not to use the brakes etc

[Magpie]

This is what mine looked like after too much heat, however these had done many a track day and were rebuilt about 12 months ago.

DSCN3591 by Eipeip, on Flickr

[Roadrunner]

My dust boot looks full on twisted a good quarter of a turn.
Forgot to take photos, was far too devestated, annoyed and tired.

And I should add that the fluid is contained behind the rubber boot.
Non is dribbling out onto the calliper body or the ground etc. nothing visible until you swing the calliper body up poke around the boot so very minor but still a major problem.

I assume genuine Mazda seals and rubbers are better quality than generic stuff which I'm assuming has been used.

[manga_blue]

Check on Miataroadster, Flyinmiata and 949 for high performance kits first. If they don't have anything then I'd get genuine Made in Japan Mazda seal kits. They've been fine for years of lightly modified track work in mine. You can get them from Mx5parts.co.uk or Amayama. Mx5parts can be very fast if you let them know you're in a hurry (like less than 2 days). If you're forced to buy from Mazda here then they are very pricey and I'd ask to see the packets first to make sure they don't have Made in Banglaonamesia in little writing hidden down the bottom. There is a possibility that that was your original problem.

Contaminants in the brake fluid or incorrect lubricant used in re-assembly are other potential causes of the problem. Ask your mechanic about those too.

[RS2000]

And I should add that the fluid is contained behind the rubber boot.
Non is dribbling out onto the calliper body or the ground etc. nothing visible until you swing the calliper body up poke around the boot so very minor but still a major problem.

May be just 'assembly fluid' in the boots, & the piston seals are still ok?
Don't know why the boots are torn so soon, but they are a bitch to correctly position.

[Roadrunner]

So got a call from the mechanic.

The boots is perished from excessive heat. Its crumbling as he touches it. The seal is also melted which is why its weeping.
The inside pad has been heated to the point that is has shrunk causing it to rattle (i though the metal rattle was something else but clearly not).

The left side appears ok but he's taking a closer look now.
The slide pins and the caliper itself is moving freely so its not dragging.

He's investigating further to work out why it gotten so hot on the passenger side.

I didn't think about it but he didn't say the rotor was warped or anything. There's certainly no shudder or pulse under brakes.

On the plus side he's getting in a kit overnight to replace the seals tomorrow to get me on the track for Sunday, but I don't know if I want to use it if theres something causing brake issues

[Magpie]

Like your my seal damage was confined to one side (drivers) passenger side was fine. Further, the pad wear was less and even...

DSCN3590 by Eipeip, on Flickr

My guess is that the slider pins were not allowing the pad to fully back off the rotor and was very lightly dragging causing the heat build up.

Invest in some temperature strips to put on your calipers, this allows you to monitor the temperature of them. If the caliper temp exceeds the temp rating of your fluid then there is a good chance that the fluid will need to be replaced.

Look at some ducting as well.

[RS2000]

I'd had similar problem on my first track day after buying car, but it was one side of the rears - caused by incorrectly adjusted handbrake cable at the wheel not allowing pad to fully release.

[Roadrunner]

Just stuck my head in and had a look. The front left pads both are glazed. Strangely the rotor looks fine but knowing my luck they're probably stuffed too.
The back of the pads are heat scored.
The red backing of the XP10s has turned white.
The inner pad has about 4mm of movement up and down.
Mechanic said the slide pins are perfect. So not sure what's caused it but said he'll also check for a kinked hard pipe which might possibly not allow pressure off that piston.
Hasn't had a chance to check the drivers side yet (I did kinda lump on him today)
The rebuild kit should come tomorrow, put it all back together and test it out.

I guess if the drivers side is the same it's me and I've farked brand new pads and calipars by overheating then, if it's just the passenger side something else is a miss.

[manga_blue]

http://mx5cartalk.com/forum/viewtopic.php?f=30&t=46321

http://ww.w.mx5cartalk.com/forum/viewtopic.php?style=3&f=30&t=61741

[Roadrunner]

Thanks for the links Magna Blue.

The symptoms in those threads far worse than what I've experienced but still worth looking in to. I haven't noticed any smoking of the brakes after a drive or the car slowing quicker than normal when coasting but will definitely check the free play in the pedal and monitor everything as I go over the next week or so)

Mechanic didn't have time (but did manage to rebuild the passenger side to get me back on the road to get home and barely charged me for it) so I checked the passenger side myself and although I couldn't get the lower caliper bolt off I could see through the inspection hole that the drivers side dust boot is much the same as the passenger side with at least a hole and a bit brittle to touch with my pinky finger.
Also checked the heat markings on the DBA rotors on both sides after remembering about them, the highest temp marker is black.
According to the DBA website the hottest temp marker changes from red to white at 630degrees. Mine are from coldest marker to hottest - white, yellow, black. Some serious heat has been through both rotors.

Now other than a possible mechanical issue with the brake system that wasn't there (or apparent) before the rebuild, the only other thing that I can think of that has changed is the ducting I have done for the radiator.
I'm wondering if closing off the front bumper opening to just the radiator has scavenged air that would normally flow out the side to the rotors?
Adding in to that my times at the last wakefield day dropped from 1:14s down to high 1:10s and I was consciously braking later and later as I had confidence in new XP10's, rotors and freshly rebuild calipers, its possible that lack of air flow as cooked them?

Consulting with the other half we both came to the conclusion that the brake rattle started (or became obvious) after the last Marulan driver training day. It was rather warm and with the lack of long straights like Wakefield to allow the brakes to cool between brake points, this could have done it?

Is this the kind of heat than you'd expect from late hard braking? or does it look more like constantly dragging brakes?

I'm ordering brake ducts from Trackspeed Engineering and will have to replace the pads too.
Might even replace the front hubs while its there as they don't spin anywhere near as freely as the other MX-5 I have here.