Porsche Brembo 996 BBK Conversion-- let's figure out how to fix the dust boots/seals

[D-O]

Copy that. I’ll bleed them again!

If you have not tried one, the Motive Power Bleeder is really nice.

[Pklauser]

Heat capacity of the already small pad exits stage left and you are left with a pad that gets really hot, wear accelerates exponentially, other issues ensue with potentially fading pad, boiling fluid, etc.

Ah ok, so nothing specific to this kit.

[mrgizmo04]

Ah ok, so nothing specific to this kit.

Well...point of a bbk is not to stop better/faster/etc, it is to manage heat better and have more heat capacity, that's what first "b" in bbk is, big. 996 kit front pad is pretty much same size as stock, so it does not provide more heat capacity. Rotor hat is made to block air flow , kit itself came from a mid engine layout where not as much front stopping power was required. So everything on this kit is undersized for our car to extract max performance on track. So like I said, for daily highway cruising, enjoy the kit. For those going fast on track, we are dealing with a lot of pain as this kit gets overwhelmed , and for some of us that goes beyond just melted dust boots.

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[BigRussia]

Just wanted to see the brake pad comparison vs stock overlaid, like attached. Front 996 kit pad is barely larger than stock (if you can call it that). D1001 pads I think are slightly larger.

Yes, I do have a pic! And of the rear 737 vs stock.


I finally got my APracing caliper temperature strips after USPS lost the Alcon ones I first ordered, and will be going to my usual home track this Sunday. I also sucked it up and bought the Vorshlag brake cooling deflectors. Im going to get the front brakes temperature readings without them during the first couple sessions, then go home during the very long break between 2nd and 3rd session and attempt to install the deflectors (along w fresh temp strips) then go back to the track. So should be an ideal test of the effectiveness (or lack of) of the deflectors!

I am not planning to cut or trim any of the dustshield, my thinking is the deflectors should direct their air right into the hole the dustshield have that’s right at the hub, and thus right into the center of the girodisc hats and hypothetically get sucked up from the center up the discs’ vanes (rather than shooting air onto the exposed inward rotor face with the dust shields cut)

[Obioban]

Good point, how would one go about doing this?

INPA has a procedure that does this while you pressure bleed the brakes. You start it, it tells you what corner to open, and it activate the DSC valves for that corner.

PITA, but if you get air in the module it's the only way to get it out.

[Nate047]

Interesting, I don’t have INPA and I don’t really know anything about that subject. If there is a good thread with info vs me asking a bunch of dumb questions, I’d be grateful to read and get up to speed!

[Cronenberged]

Interesting, I don’t have INPA and I don’t really know anything about that subject. If there is a good thread with info vs me asking a bunch of dumb questions, I’d be grateful to read and get up to speed!

Go over to coding and tuning section. Inlinesix made a good comment on my question in there, 4th-ish post down.

[BigRussia]

Update: new Racing Brake high temp blue dust boots still didnt hold up even with ti heatshields and vorshlag brake cooling deflectors (though the deflectors were installed after the boots had gone through two track sessions and without yet cutting away the rotor dust shields). IMO these dust boots are useless and not worth the premium, i think their flaw at least for the Rebault Megane calipers is that they dont sit flush enough, theyre cracking due to being too thick/raised and touching the pad backing plates/ti heatshields. I have them pressed in as far as possible, even pushing them in with a punch but thats the lowest they seat (see pics).

I ordered a single caliper set of basic Girodisc dustboots, going to install them and see if they sit better. Theyre not high temp rated but theyre cheaper and want to see if them sitting flush like oem brembos boots will make them last longer. The rear 996 calipers’ 20yr old factory dustboots are still holding up without any wear, but granted the rears dont see anywhere near the same heat or abuse

[heinzboehmer]

[Bry5on]

Just a thought. Rust (inside the vanes) is a pretty good thermal insulator. Maybe we could experiment with passivating rotor internal surfaces with citric acid? It’s pretty easy to DIY passivate.

[mrgizmo04]

Update: new Racing Brake high temp blue dust boots still didnt hold up even with ti heatshields and vorshlag brake cooling deflectors (though the deflectors were installed after the boots had gone through two track sessions and without yet cutting away the rotor dust shields). IMO these dust boots are useless and not worth the premium, i think their flaw at least for the Rebault Megane calipers is that they dont sit flush enough, theyre cracking due to being too thick/raised and touching the pad backing plates/ti heatshields. I have them pressed in as far as possible, even pushing them in with a punch but thats the lowest they seat (see pics).

I ordered a single caliper set of basic Girodisc dustboots, going to install them and see if they sit better. Theyre not high temp rated but theyre cheaper and want to see if them sitting flush like oem brembos boots will make them last longer. The rear 996 calipers' 20yr old factory dustboots are still holding up without any wear, but granted the rears dont see anywhere near the same heat or abuse

You need to cut the dust shields to allow for radiated heat to escape easier, the shield sits super close to the inner disc surface in a lot of places retaining that. Close to half of heat transfer is radiation. I did not fully remove mine around the joints to protect them, I know you had similar concern. In the rear I run aluminum tape (trimmed shield), could use the same in front for the joints if needed.

In your setup the Vorshlag deflectors are not doing much. With trimmed shields you will get much better benefit (i saw better results going from hoses to Vorshlag scoops but i trimmed my shield to allow more of that air to hit the rotor vs hitting the dust shield). They are not channeling much air into a single small opening in the shield in front of the hub most of the time (as the wheel turns, etc). They are a bit of a shotgun approach vs a rifle, so they need more open area to hit. If you want to keep the dustshields you will benefit much more from something that concentrates air flow into that hub opening, either hoses or Bryson's design (connect with him).

Vorshlag shovels need to be modified slightly to run with non drilled rotors, so I bent the last part of them (bottom that is closest to rotor) so it doesn't hit the inner disc surface as much. With drilled/csl it was ok as holes let some of the air through (and prob do better than veins/hat), but for solid/slotted like Girodisc you need to really channel into the hat and let the veins do the work.

For your dustboot problems, I think I read a while back in a different thread that you ran 2 pad thicknesses and thicker one is really problematic, is the thinner one also compressing the pistons all the way when new? To be fair, none of the boots sit perfectly flush in the bores.

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[D-O]

Is the current consensus that there is no boot that will stand up to the heat and I may as well remove them when installing track pads?

Also - how about a recommendation for track pads. First track day in the M3, but I know the Akebono ceramics are not going to cut it.

[mrgizmo04]

Is the current consensus that there is no boot that will stand up to the heat and I may as well remove them when installing track pads?

Also - how about a recommendation for track pads. First track day in the M3, but I know the Akebono ceramics are not going to cut it.

Depends on your pace/experience and how you use brakes. They are probably fine to high/intermediate pace. I would not remove as you will get metal shavings into piston bores as you compress the pistons and can score them or worse damage the pressure seals.

Pads, that's a can of worms. PFC08 were loved by a lot of folks. If using FCP, Pagid29 Yellow or DTC60 (some people are allergic to these because they theoretically destroy wheels if they get wet, although not my experience, even running in heavy rain).

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[jager911]

Is the current consensus that there is no boot that will stand up to the heat and I may as well remove them when installing track pads?

Also - how about a recommendation for track pads. First track day in the M3, but I know the Akebono ceramics are not going to cut it.

I'm using Racing Brake gray hi temp silicone boots. Only 2 events on 996 BBK, need to inspect on lift to see how they're holding up. I'm running Pagid Yellow F/R, pleased with feel, progressive bite and modulation coming from PFC.

[George Hill]

Do the Porsche guys have this problem? If so, what do they do?