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

[Slideways]

What about titanium alloy pistons - https://www.silverlakeprojects.com/p...ns-for-porsche

[BigRussia]

Sucks that you are already on Girodiscs and rb blue. I was hoping Girodiscs would help a tonne given number of vanes and proper 2 piece efficient design.

I'm also on ti shims, and I've been using the Vorshlag shovels (per pic). Trimmed my shield even more this week, so need to retest. Qualitatively speaking, these shovels move more air than when I had the 2" hoses. Are you running cooling ducts other than stock tunnels?

IIRC, conduction from backing plate/ti shim to dustboot is not a transfer mechanism, but I need to double check. With new pads, if boots are properly installed, tip of the piston should be first part pressing on the shim/backing plate. After installing new pads, you have to pump the pedal a few times and that seats and pushes out the pistons a bit. Also remember that in these budget kits pistons are aluminum (vs high end kits using steel or even ti), which has higher conductivity and less resistance, so first line of defense for the tip of the piston is the boot.

Do you by chance have a size diff for the front pad between stock and Megane, like I provided at end of post 22 above. Would love to see the diff visually.

Yeah I was bummed that even with the Girodisc and slightly thinner PFC pads the RB blue boots cooked. I wanted to run caliper temp strips for that last track day but UPS lost the package from Alcon... I will be running temp strips next track day, hoping I see under 400F.

I dont have any brake cooling besides the stock factory 'brake duct' tunnels. Brake cooling is is my current project rn, I tried DIYing my own setup using OEM C6 Corvette brake ducts (like how AAF kit uses) but turns out need to not have A/C for that (evap blocks the RH duct)... Im still searching for a cooling solution that's streetable and with A/C. BTW I've had your DIY brake cooling video on my Watch Later list on Youtube for a while haha, and was considering the Vorshlag deflector kit at one point at well but just didnt want to deal with cutting my dust shields and reducing heat protection for the arm ball joints (though hypothetically they should be getting some cooling air lol).

Damn I didnt realize the budget kits Brembos had aluminum pistons, figured they were steel! At least they werent ceramic so I didnt think much into that. Yeah with the new 16mm GLOC pads the pistons were basically at bottom and the Brembo boots 'fold' was still touching the backing plates. As the piston moves out w/ pad wear then the boots should not be folding upwards into the backing plate as much, I imagine.

Do you mean the pad thickness of the stock pad size vs the D1001? Or the caliper's max space for the pads? If the latter id assume the stock calipers had a much wider gap for pads, since Ive been having dust boots issues since moving to the Megane Brembos.

I should've mentioned in my previous post that I'm running rear 996 Brembos, their stock dust boots have been holding up fine. I didnt even rebuild them, just installed the used calipers with the factory boots since they looked good and still no cracks or issues, though I havent looked at them since the last track day with the PFC08 pads. I was running lower friction compound GLOC pads rear and I think the fronts were basically doing all the braking work so maybe that's why they haven't been heat stressed and cracked yet (no boots touching either with the 737 pad shape).

[mrgizmo04]

Does this happen with the real deal Brembo GTs? Those aren't THAT expensive compared to the budget kits.

Per my last comment, they might use steel pistons which prob help. I'd also assume material composition for boots changed from originals to today. Folks have tried Stoptech, Brembo, Girodisc, RB with high temp variants and they all melt.

Essex is into something with their bootless kits for track.

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[mrgizmo04]

and new Girodisc rotors (no heatshields this time). While better, 3 of the 4 RB high temps had developed cracks next track day…

mrgizmo04 I was actually thinking the opposite, that as the pads for wear down in thickness with use maybe the dust boots will survive since won't (shouldn't) be touching the backing plates directly as much lol.

Sucks that you are already on Girodiscs and rb blue. I was hoping Girodiscs would help a tonne given number of vanes and proper 2 piece efficient design.

I'm also on ti shims, and I've been using the Vorshlag shovels (per pic). Trimmed my shield even more this week, so need to retest. Qualitatively speaking, these shovels move more air than when I had the 2" hoses. Are you running cooling ducts other than stock tunnels?

IIRC, conduction from backing plate/ti shim to dustboot is not a transfer mechanism, but I need to double check. With new pads, if boots are properly installed, tip of the piston should be first part pressing on the shim/backing plate. After installing new pads, you have to pump the pedal a few times and that seats and pushes out the pistons a bit. Also remember that in these budget kits pistons are aluminum (vs high end kits using steel or even ti), which has higher conductivity and less resistance, so first line of defense for the tip of the piston is the boot.

Do you by chance have a size diff for the front pad between stock and Megane, like I provided at end of post 22 above. Would love to see the diff visually.

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[repoman89]

Does this happen with the real deal Brembo GTs? Those aren’t THAT expensive compared to the budget kits.

[BigRussia]

Im in the same boat but with Renault Megane Brembos (Freakyparts kit). Melted the stock new dustboots with 16mm GLOC pads and only slightly worn ZCP rotors, since the pistons had to be fully compressed to fit them and was only able to put Ti heatshields on outboard side. I then replaced the inboard boots (which were completely melted vs the outboards) w the RB blue high temps, and put 14.5mm PFC pads and new Girodisc rotors (no heatshields this time). While better, 3 of the 4 RB high temps had developed cracks next track day… I mean it’s def from direct contact to the pad backing plates but still frustrating that even w a ‘thinner’ pad thickness they still touch n cook. I then installed new RB blues boots for the outboards along with the Ti heatshields both sides hoping now they will survive without cracking next track day, but I’ll have to replace the already cracked inboards again. This will get tiresome and expensive if I have to keep replacing dustboots after every track event.

mrgizmo04 I was actually thinking the opposite, that as the pads for wear down in thickness with use maybe the dust boots will survive since won’t (shouldn’t) be touching the backing plates directly as much lol.

[mrgizmo04]

Anyone confirm those blue RB ones hold up with pad less than 50%? Once pad starts getting low, heat capacity exits stage left and things start going south exponentially.

I'm getting tired replacing boots every other weekend. Although you really only need to do it if swapping to fuller pads where pistons need to be compressed back in (like to street pads). So I'm stopping swapping from track pads and will just let the pistons come out as track pads wear and when I need new track pads will clean off the pistons and replace dustboots. Hopefully blue ones are the answer?

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[mrgizmo04]

So I installed the RacingBrake seals from above, and it looks like I'm going to have the same issue mrgizmo04had here: https://nam3forum.com/forums/forum/m...511#post229511

The dust boots for the smaller piston don't have enough friction to stay in place. I plan on reaching out to RB about this, these weren't cheap!

Don't remember if I posted this, but this is an issue with using Stoptech/Brembo/Girodisc dust boots on these 996 calipers. I don't know why, some bore spec is off somewhere. Several kits from Brembo and several kits from Girodisc, still same issue. Stoptech boots in Stoptech calipers no problem, Brembo boots in Brembo (GT kits not these 996) calipers no problem. The way I "solved" the issue is I squeeze deliberately yet gently on the outer metal ring of the dust boot to slightly deform it to make it oblong/oval (very slight). And it seems to stay in.

🤷♂️ I'll live with it with that slight workaround.

Happy motoring!

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[Pklauser]

So I installed the RacingBrake seals from above, and it looks like I'm going to have the same issue mrgizmo04had here: https://nam3forum.com/forums/forum/m...511#post229511

The dust boots for the smaller piston don't have enough friction to stay in place. I plan on reaching out to RB about this, these weren't cheap!

[Obioban]

Would you advise running these high temp seals in daily street use? I'm contemplating swapping out my CSL/CS spec'd brakes with Megane RS Trophy-R / Buildjounal fronts with 996 rears on my e46 "m3" touring. I think can will see 2 / 3 track days a year at most.

I plan to do it, but, since I have zero experience with it (yet), don’t think I should recommend it.

[puma1824]

Update: High temp silicon seals held up!
(https://racingbrake.com/bp-404bs/)

Car was doing double duty, running in instructor and advanced group, back to back, all day. He was not running backing plates.

Disclaimers; 50-60 deg ambient and summit point raceway (not that hard on pads), so not WORST case scenario-- but I'm stoked. Will be installing this winter.

Would you advise running these high temp seals in daily street use? I'm contemplating swapping out my CSL/CS spec'd brakes with Megane RS Trophy-R / Buildjounal fronts with 996 rears on my e46 "m3" touring. I think can will see 2 / 3 track days a year at most.

[Casa de Mesa]

Hell yeah. That's fantastic news.

[Obioban]

Update: High temp silicon seals held up!
(https://racingbrake.com/bp-404bs/)

Car was doing double duty, running in instructor and advanced group, back to back, all day. He was not running backing plates.

Disclaimers; 50-60 deg ambient and summit point raceway (not that hard on pads), so not WORST case scenario-- but I'm stoked. Will be installing this winter.

[heinzboehmer]

Awesome, thanks for the link

[Obioban]

Looking forward to that too. Do you know where those are from?

At least the boots are easy to swap without removing anything besides pads...

My friend got the "high temp" (I believe silicon?) seals from here: https://racingbrake.com/bp-404bs/

He has an event 10/17.

He's quite quick, so should be a good test of them.