Interest in ZCP-Sized Carbon Ceramic Rotors?

[Bimma360]

I rest my case you have way too much money to throw around LOL. Two words, GT3 or GT4 and close the case.

All that shit doesn't apply to me personally as I got my stuff 20 years back when it was dirt cheap and nearly free so here's my POV:

Giro disc it's only $1500 on a bad day for all four 355mm rotors. Pads are not too expensive either especially for track use when you do a bit of hunting. So yeah no where close to your $3500 (no idea how you can across that figure). You paying $2k for pads?!?!?!

So I about decided that I am just going to do ZCP girodisc and oe pads on this car. That’s actually about $2500 all in. Spending double that for reduced weight, no dust, better performance and at least twice the lifespan of the girodiscs/oe pads doesn’t seem that crazy to me. Haha that’s why I said I’d like to use these with factory calipers. It is a lot of money for sure. But I don’t think it’s insane insane.

[bigjae46]

I rest my case you have way too much money to throw around LOL. Two words, GT3 or GT4 and close the case.

All that shit doesn't apply to me personally as I got my stuff 20 years back when it was dirt cheap and nearly free so here's my POV:

Giro disc it's only $1500 on a bad day for all four 355mm rotors. Pads are not too expensive either especially for track use when you do a bit of hunting. So yeah no where close to your $3500 (no idea how you can across that figure). You paying $2k for pads?!?!?!

As the guy who bitched about an $800 battery...I can actually see why $5000 rotors would be appealing. Most of the weight loss is sprung mass so losing 25lbs of unsprung mass is not really possible any other way. Maybe carbon fiber wheels. The advantage here is the carbon rotors last WAY longer vs carbon fiber wheels which I think would be less durable. 25lbs of unpsrung mass would be a massive performance improvement. Think about the acceleration gain on top of the cornering gains. $200 per lb is not a terrible cost/weight reduction ratio. I am waiting to spend $1700 on a Tilton single disc clutch to save 8 lbs.

Agree on the cost perspective, a 355mm x 32mm Girodisc replacement is $730. My front rotors will last about 50 track days, rear rotors will last forever. Breakeven is about 6 rotors. If the pads last longer, make that break even is reduced to 3 or 4? So waiting that long for payback doesn't make sense. So many things can happen.

This is track car math. The street would be different. Most of all, getting a rock or debris to kick up and hit the rotor is a much higher likelihood which results in rotor replacement. Or you'd probably need to take it off and x-ray it. Of course, could always just send it if you hate life.

[bigjae46]

I think these guys should make a rotor/pad for the Alfa Romeo Giulia/Stelvio QV. Stock Alfa rotors F/R are 360/350mm, same as the E9X M3. With different hats, their hypothetical Alfa kit (rotors and brakes) would also fit both the e46 M3 and E9X M3. Almost 3 birds with 1 stone.

I am selfishly wondering if they would be willing to do a 355x32 Brembo/Stoptech replacement rotor ring? That is the most common rotor size across many platforms.

[tnord]

5-10 years ago I half jokingly posted about anything worth doing on this car will end up costing you 5k, and that seems to be holding up over time.

I’m not ready to pull the credit card out, but from a $/lb perspective this seems better than nice forged wheels.

[0-60motorsports]

As the guy who bitched about an $800 battery...I can actually see why $5000 rotors would be appealing. Most of the weight loss is sprung mass so losing 25lbs of unsprung mass is not really possible any other way. Maybe carbon fiber wheels. The advantage here is the carbon rotors last WAY longer vs carbon fiber wheels which I think would be less durable. 25lbs of unpsrung mass would be a massive performance improvement. Think about the acceleration gain on top of the cornering gains. $200 per lb is not a terrible cost/weight reduction ratio. I am waiting to spend $1700 on a Tilton single disc clutch to save 8 lbs.

Agree on the cost perspective, a 355mm x 32mm Girodisc replacement is $730. My front rotors will last about 50 track days, rear rotors will last forever. Breakeven is about 6 rotors. If the pads last longer, make that break even is reduced to 3 or 4? So waiting that long for payback doesn't make sense. So many things can happen.

This is track car math. The street would be different. Most of all, getting a rock or debris to kick up and hit the rotor is a much higher likelihood which results in rotor replacement. Or you'd probably need to take it off and x-ray it. Of course, could always just send it if you hate life.

I absolutely agree with you on the track perspective bro. For street for this car it doesn't make sense to me cost wise. Maybe having kids made me more reasonable/responsible bahahaha.

[tnord]

nothing fun makes sense.

regards,
the accounting department

[Bimma360]

I am selfishly wondering if they would be willing to do a 355x32 Brembo/Stoptech replacement rotor ring? That is the most common rotor size across many platforms.

So I read a few pages of the rennlist thread. Some did ask about replacement CC rotors for aftermarket BBK. Sounds like they are open to it, but mentioned it’s a bit more complex due to details on said kits not being readily available.

[discoelk]

Arguably, this makes more sense for a street car bc of the unsprung weight. It's roughly the same cost per pound as a set of non-china forged wheels. I'd be a little more concerned about rock/gravel damage on a track car but probably not a real issue.

[Bry5on]

I absolutely agree with you on the track perspective bro. For street for this car it doesn't make sense to me cost wise. Maybe having kids made me more reasonable/responsible bahahaha.

Or having kids makes you want a fun wagon. So no Porsche will solve your problems but a tarted up e46 just might

Seems like the folks interested in CCBs mostly have already experienced the benefits of CCBs, funny how that works.

[0-60motorsports]

Or having kids makes you want a fun wagon. So no Porsche will solve your problems but a tarted up e46 just might

Seems like the folks interested in CCBs mostly have already experienced the benefits of CCBs, funny how that works.

I need to make me a wagon lol

[Bry5on]

I need to make me a wagon lol

It’s the best!

To keep this just slightly more on topic - 420mm PCCBs from my last wagon

[0-60motorsports]

It's the best!

To keep this just slightly more on topic - 420mm PCCBs from my last wagon

Damn now that's sexy

[Cronenberged]

I’d be interested to if there’s a 345mm or 328mm ring option for the CSL/ZCP setup. I’m not going to out-perform the brakes on this car, and I can’t complain about the unsprung weight savings it makes even daily driving more enjoyable. My only concern with setups like this is long-term support and parts availability. I also understand the pricing if they last two or three times longer than regular steel rotors, the company still has to stay profitable even though customers will be replacing them much less frequently.

Additionally, the whole argument about people being bored or having too much money is kind of pointless everyone values things differently. I actually appreciate the people who continue to modernize these cars and bring newer technology to them. Seeing that kind of development for older platforms is amazing.

If someone wants cheap, they can go find a pre-COVID, beat-up M3 there are plenty out there that some high school or college kid didn’t take care of but still thinks it’s worth twice what it is.

If I were buying another E46 M3, I wouldn’t mind spending a little more for a well-sorted car where the owner didn’t cut corners or throw cheap parts on it. To me, these cars can be both a great investment and something that’s genuinely enjoyable to own and drive.

[SQ13]

I’ve asked John to drop in here to answer any questions y’all may have and discuss details. Hopefully we’ll see him here soon.

[JohnBSPK]

Hey! Hopefully not overstepping but Shariq had asked me to pop in here and potentially answer some of the questions that were being asked.

At a high level, I am happy to make setups to support the e46 community. As I mentioned to SQ13, I am a big e46 fan and ironically, I recognize your car Sharocks . I've seen you at Lars.

More seriously though, I've been offering these in various communities for a bit over a year now. The Rennlist group buy was obviously new but you can find a lot of discussion of the product on G80 bimmerpost and 4c-forums, on the latter you'll find a lot of people tracking these with tiny 305/292 discs, so there's no real concern with the robustness of the smaller discs for demanding use cases. I've made a lot of obscure fitments actually, so doing a setup or two for the e46 community would be relatively straight forward. There's obviously data I would need but I can figure that part out.

At a headline level, I see someone mentioned above that the CSL rotors weight ~68 lbs across the set of four. I haven't designed the fitment yet obviously but simply interpolating to 345x28/328x20 based on similar, known fitments, I would expect you'll save about 30lbs off that with a set of BSPK CCBs.

These are 3D continuous long fiber discs with an integrated SiC shield (not a coating, it's achieved through a porosity gradient so that it extends to the core of the disc). BSPK CCBs will easily outpace the life observed by any OEM chopped tow disc and should achieve service life parity with the best aftermarket CCBs on the market (e.g. Surface Transforms). The reality is that I would expect life longer than that but, while my current installed (on car) base is about 73 units, no one has come even remotely close to exhibiting any wear on them yet so ultimate lifespan is a little academic for the time being (and probably will be for some time).

This type of rotor construction is much harder to chip - I saw someone mention that above. It's a much denser disc overall than what people are accustomed to with traditional, legacy CCB products. Obviously you do still need to be careful with them but no where near the levels that people are conditioned to expect with a carbon ceramic product.

There's some info on my website www.bspkforged.com, and more being updated as I did several long write-ups for rennlist as part of that group buy process. One that I think it particularly notable is adherent versus abrasive friction modalities, as that ties directly to why the service life on these should exceed what's in the market currently. If can be found here:

https://rennlist.com/forums/718-gts-4-0-gt4-gt4rs-spyder-25th-anniversary/1502394-bspk-carbon-ceramic-brakes-o-introduction-and-tech-talk-4.html?utm_source=share-link&utm_medium=button&utm_campaign=share&utm_content=post

(post 57 if the link doesn't bring you right there).



Again not trying to necessarily be exhaustive in this post but obviously happy to answer any questions that people had and would welcome interested parties to email me at [email protected]

Thanks,
John