Brake piston boots necessary?

[R13]

I note that after three track events on the stock front calipers, that I have crispy-fried the piston dust boots.

1x little talladega on stock-size sumitomo timres
1x little talladega on star specs
1x (three days though) on VIR also with star specs.

Is there some trick to keeping these things from melting, or do most dedicated track cars do without them? I know they serve no fluid-retention purpose as that is the job of the seal, it's purely to keep debris out of the piston bore when you push them in to change pads.

(as a note, I will be adding more substantial brake ducts before the next outing).

I will be rebuilding the left front caliper next week due to a leaking piston seal, so I was curious.

 

[CL65 Captain]

You can install tispeed.com titanium shims thats will keep some ofbo the heat away from the boots.

sent from my Evo4

 

[nsxtasy]

You've described their purpose accurately. They keep dirt out of the piston bore.

The cooling ducts will help.

The brakes also tend to get less hot when you use them harder over a shorter distance.

 

[R13]

You've described their purpose accurately. They keep dirt out of the piston bore.

The cooling ducts will help.

The brakes also tend to get less hot when you use them harder over a shorter distance.

I've been using proper technique by-and-large. I think where I ran into trouble was a very well-attended porsche club weekend at VIR. I ended up braking longer and more gradually I would have liked on account of traffic....and that was probably coupled with less airflow to the brakes.

I'll see if I can get ahold of some of those shims. The boot that melted almost completely wasn't properly installed and came into contact with the pad backing. The rest of them are in place doing their job, but I can tell they're a bit crunchy.

 

[stuntman]

I've been using proper technique by-and-large. I think where I ran into trouble was a very well-attended porsche club weekend at VIR. I ended up braking longer and more gradually I would have liked on account of traffic....and that was probably coupled with less airflow to the brakes.

I'll see if I can get ahold of some of those shims. The boot that melted almost completely wasn't properly installed and came into contact with the pad backing. The rest of them are in place doing their job, but I can tell they're a bit crunchy.

The one that wasn't installed properly came out and touched the pad/got cooked?

If so, and if these are original dust boots, just replace them and they should last you quite some time when properly installed. It's a good idea to make sure the dust boots are in and working so no brake dust/dirt/material/or moisture can get in there and jam up or corrode the inner caliper.

I had a dust boot on my M3 come up like this and water corroded the inner part of the caliper causing a high spot where the piston hung up on and eventually jammed - piston/pad would not retract. Overheated the wheel, melted the wheel weights off, and warped the rotor. Keep the dust boots on.

 

[nsxtasy]

If so, and if these are original dust boots, just replace them and they should last you quite some time when properly installed. It's a good idea to make sure the dust boots are in and working so no brake dust/dirt/material/or moisture can get in there and jam up or corrode the inner caliper.

Yup. I've had my front calipers rebuilt a few times over the years, due to the piston boots getting crispy. Not often, though - maybe averaging 3-6K actual track miles (or 5-15 sets of brake pads) between rebuilds. They usually replace the pistons while they're in there.

Check the piston boots whenever you replace the pads. (You'll be looking right at them anyway when you push the pistons back in.)

 

[R13]

These calipers were "remanufactured" when I bought them a year and a half ago. The boot that melted looked like it was folded a little funny, but I could not tell that it might touch the pad backing as the piston moved when I installed everything originally.

I expect the pistons to be fine unless they were jacked up to begin with...

I will replace the boot as well.

 

[NSX2398]

Yup. I've had my front calipers rebuilt a few times over the years, due to the piston boots getting crispy. Not often, though - maybe averaging 3-6K actual track miles (or 5-15 sets of brake pads) between rebuilds. They usually replace the pistons while they're in there.

Check the piston boots whenever you replace the pads. (You'll be looking right at them anyway when you push the pistons back in.)

I have one that probably should be replaced and I was told by the local dealer that the rubber boot can only be replaced during a rebuild. You seem to be suggesting that's when yours were done Ken so were you told the same thing .. or just had them done then because it was convenient? What does a caliper rebuild go for these days?

 

[nsxtasy]

My mechanic recommended replacing the pistons; it's been a while, but I seem to recall him saying they were scorched. It's not that expensive, maybe a couple of hours of labor for both sides (?), plus of course the parts (pistons, piston boots, piston seals) whose prices you can view here.

 

[R13]

except that the little piston's boot & seals are on national backorder.

fortunately mine is leaking from the large piston, so I'll see if I can do just that one for now since it's not an issue of the age of the part.