THSCC Forums

So, when I went home for lunch today to toss on the Hawk HPS's I now realize that BOTH piston surround boots are severed along the outer edge towards the outside of the caliper. It looks like the boot's function is just keep dust and moisture from the inside of the piston. With that said, does anyone know if these things are replaceable?

It looks like the piston can be purchased for about $20 versus $130 for each caliper, although I'm not sure the rubber surround is replaceable, any ideas? I was wondering if anyone (especially the track folks) have experienced anything like this. The Hawk HP+'s that I just removed wore VERY quickly and I wouldn't recommend daily driving on them in retrospect. I'm guessing the heat melted the rubber or the pads started making contact with the boot.

thanks!

you can't replace the dust boot without a rebuild so just do them yourself, easy peasy. you'll need a rebuild kit (usually $10 - $15 per caliper), compressed air to pop the piston out, and some brake fluid to bleed them. i did all four on my race car last winter, couple of hours and they were good as new.

the piston is ok right? pic is blurry, i assume that's just crud or grease that i see on the piston lip.

I told Matt that those dust boots are next to worthless and most cars burn them to dust on their first track event. I read a thread where all this little Vette boy got scared when his piston dust boots melted at his first track event and he thought his car would explode into a ball of flames if he drove the car at all in this state. The piston oil seal is far enough down the cylinder that grit that gets in the grove at the top will never affect the seal that far down.

Anyway, I don't track a car and I pulled a mangled boot off one of my old Honda's front calps and put about 52k miles on the car that way....no leaks, no uneven wear.

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2015 Fit

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it's not only about protecting the piston seal but also the piston itself, without the outer seal it'll be more prone to pitting and corrosion. but overall i wouldn't worry too much about it, every one of my track cars has had cracked dust seals with no ill effects.

Just remove the whole brake and seal off the line. Brakes are overrated. They add extra weight and don't contribute to going fast. Just plan your stops a little sooner on the way to the event.

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1990 Faded Reddish CSP Lite Miata
2002 Electron Blue Corvette Z06
2005 Mazda 6 Wagon
2003 Nissan Pathfinder DTV (Dog Transport Vehicle)

Yeah - the pic makes it look like the rotor has contacted the piston and ground part off of it. I'm assuming that's not the case. or else

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Yeah, I thought the same too about the stuff on the piston when I saw the photo but it's just caliper grease. Damn sure does look like it's taking a beating though.

Unless the brakes start feeling different, I think I'll roll with it like this for a while since I only have 50k on the car.

Matt, FWIW, I ran my old GS-R without those seals for many, many years. I never did figure out how to replace them without tearing them again, so eventually, I gave up.

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Karl S.
2014 Baby, 2014 House, 2013 Ford Focus ST, 2013 BMW 328i, 1994 Mercedes E320
(Insert passive aggressive signature line here)

Matt,

I've found using Ti plates between the brake pad and the piston helps tremendously. It cuts down on conduction heat transfer via two thermal interface resistances plus the poor conductivity of Ti. It also shields the dust covers from thermal radiation heat transfer off the pad backing plate since it will then "see" (from a radiation standpoint) the Ti shim which will be at a substantially lower temperature than the pad backing plate.

Using these Ti plates, I've never had a dust cover heat damaged (whereas prior, I've melted them and even melted a piston seal resulting in fluid leaking!).

These are especially needed as pads wear down. The pad material behaves as a thermal insulator between the backing plate and the pad/rotor interface. As the pad material gets thinner, the pad backing plate temperature goes up.

If you're using floating calipers (most likely) that have a pad clip on the piston side pad, you'll have to make a cutout in the Ti shim to accommodate the spring clip as some sources sell these without accommodation for the clip.

Since these degrade that heat transfer path to the piston, they also help to significantly lower brake fluid temperatures too.

Chuck

_________________
Current stable:
2019 BMW M2 Competition slicktop 6MT
2011 BMW M3 sedan slicktop 6MT
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1975 CanAm 125MX2

Like this?
I knew the HP+s were noisy, but not noisy enought to drown the grinding that was taking place on the driver's side. The lip on the front edge is actually the backing plate that was grinded down. Ouch! Strangle the passenger side had at least 4-5mm left so hopefully there's no brake bias issues...

Thanks for the feedback on the titanium shims, I'll probably check that out but won't look forward to cutting them to fit. I know from mountain bike components that ti is reeeeeally hard to cut. Definitely makes sense though.

Good to know Karl; I'll probably keep them the way they are for now b/c you and James sound like you've just run with it in the past without issues. If I decide to go back to uberdust pads, I'll change 'em out and do a rebuild.

-Matt (self diagnosed automotive hypochondriac)

Make sure to remove the guide pins, clean them, and relube with a silicone based synthetic grease (don't use organic grease on the rubber boots). You might have had sticky sliders and hence the uneven wear....ask Zach Hill about that .

_________________
2011/2012 Autox VP
2013/2014.5 President
2013 Top Gun

2015 Fit

22R-EC => 4G63 => D16Y7 + D16Y8 => EJ255 + K24Z2 => K20Z3 + K24Z2 => K24Z2 + M54 => L15B

Yeah, I was pm'n Zack and he told me about that, which really stinks.

The pins feel smooth, but how do you get those out anyway? Do they just pull straight out?

Bah, that's nothing Matt. Take a look at our front caliper after about 10 hours at the Lemons race at CMP.





The friction material was gone, the backing plate was bent, and the piston was welded to the backing plate.

_________________
Vincent Keene
'06 Ford Mustang GT (track rat)
'15 Dodge Charger R/T (yeah, it's got a HEMI!)
'07 Ford Fusion SE (205,000 miles and counting)
'98 Chevy Z-24 (retired)
'93 Acura Integra (Team SWB 24HOL Car)

Yes, the rubber boot may come with the pin or it may stay on the calp. I use qtips to get the old grease/gunk out of the caliper and rubber boots.

_________________
2011/2012 Autox VP
2013/2014.5 President
2013 Top Gun

2015 Fit

22R-EC => 4G63 => D16Y7 + D16Y8 => EJ255 + K24Z2 => K20Z3 + K24Z2 => K24Z2 + M54 => L15B

Vincent, suddenly I feel safer in my Civic after seeing that.

That's unbelievable!