Build Journal Megane RS BBK Kit available this morning.

[Nick_P]

Yes, good point about FCPeuro. That should bring costs down over time

[liam821]

How do the CSL/ ZCP rotors take track duties, being drilled and not particularly thick vs aftermarket BBK options?

They don't last as long - the ZCP/CSL rotors are notoriously soft. However, with FCPeuro's lifetime warranty, it's not that much of a big deal.

[S14]

Is brake bias affected by the larger rotor diameter? It's the same caliper (so same piston sizes) using the same pads, isn't it?

One upside to me is that Girodisc makes E9X M3 fronts.

Brake bias can change when any of these components are changed
- MC piston size
- pressure regulator (often used in BMW's to attenuate rear pressure)
- Caliper piston size
- pad size
- pad compound
- rotor size
- tire size
- tire compound

going from standard M3 discs to ZCP/CSL disc alone moves the bias forward by almost 2%, one reason why the CSL runs a larger rear piston; the other is that more rear bias is a good thing... until it's too much.

[Nick_P]

How do the CSL/ ZCP rotors take track duties, being drilled and not particularly thick vs aftermarket BBK options?

[r4dr]

R&D seems a bit farfetched when other people have already executed the concept, doesn't it? Hmm.

[Bigo1087]

The Buildjournal description (at the top) lists the calipers as new. But if you scroll down, it says "TUV Certified reconditioned calipers"
I guess it depends on what is reconditioned, but in any case I would still consider it as a used item.

Thank you for pointing this out to me.

Ive been in email contact with them for an explanation.

And they did confirm they aren't brand new, and when i asked about the price difference on other vendors in UK that can ship more complete kits with new calipers for $750ish after conversion.

He explained the lines are custom by portfield, USD weak vs sterling pount, R&D costs, and obv USA material and labor costs are higher.

Which is all fine and dandy to me.. i get it (I'm a design engineer, and i work in manufacturing)

He did update the website, as "new" meant the kit was new, but he agree'd it was confusing.

But i wanted more details on the calipers, where they come from and why they can't source new calipers. OR if i can source my own new calipers.

I'm now torn between price i paid for this this kit i ordered vs freakyparts.

[liam821]

Got it, thanks. 345mm it is then.

As an added bonus, they fit under almost all 18" wheels nicely.

[r4dr]

Yeah, a larger rotor will increase the front braking force. Think of it like this, the circumference (outside edge) of the CSL rotor is 2167mm, while the e92m3 is 2261. The pad is going to travel another 100mm for each rotation of the wheel.

Got it, thanks. 345mm it is then.

[liam821]

Is brake bias affected by the larger rotor diameter? It's the same caliper (so same piston sizes) using the same pads, isn't it?

One upside to me is that Girodisc makes E9X M3 fronts.

Yeah, a larger rotor will increase the front braking force. Think of it like this, the circumference (outside edge) of the CSL rotor is 2167mm, while the e92m3 is 2261. The pad is going to travel another 100mm for each rotation of the wheel.

[r4dr]

ZCP/CSL 345mm rotor is around 20lb
E92M3 360mm rotor is around 22lb

Since the brake bias is pretty spot on using the 345mm rotors, I'd probably stick with that.

Is brake bias affected by the larger rotor diameter? It's the same caliper (so same piston sizes) using the same pads, isn't it?

One upside to me is that Girodisc makes E9X M3 fronts.

[liam821]

Not sure about the brake bias, but they also sell AMG 6-pot front caliper brackets...

https://freakyparts.co.uk/collection...per-adaptors-1

[liam821]

That FreakyParts kit looks good, especially the 360 mm version. Would the only downside be increased unsprung weight?

ZCP/CSL 345mm rotor is around 20lb
E92M3 360mm rotor is around 22lb

Since the brake bias is pretty spot on using the 345mm rotors, I'd probably stick with that.

[CrookedCommie]

I mean, I spent 7 years racing with SCCA in SM/ITA, built multiple cars for myself and others, crewed/co-drove on multiple winning enduro teams, and finished 4th at the ARRC sprint race and 1st in the endurance race. but I guess I'm a canyon boi.

https://www.diyautotune.com/news/res...-of-champions/

Do Miatas have brakes? I thought they just lifted.

[tnord]

realistically, how different is the CSL from the reg M3 in weight distribution?

To your second sentence, what is the correct bias to aim for if you have other than stock E46 M3? Say you took 300lbs out of the car, stiffened the suspension and made it adjustable outside of standard form (camber plates/adjustable lower control arms etc.) would it be most correct to keep the stock bias, or would more rearward brake bias be better?

"better" can have different definitions. for street use, really anything between a base M3 and a CSL bias should be fine. if you're talking about lowering lap times, or in a racing environment, it's going to be driver dependent on their driving style. in a very overly simplistic view you just keep increasing rear bias until the rears lock up, then back off of it.

it doesn't necessarily have to be done via bias, you can work around it with pad choice as well.

[ATB88]

To your second sentence, what is the correct bias to aim for if you have other than stock E46 M3? Say you took 300lbs out of the car, stiffened the suspension and made it adjustable outside of standard form (camber plates/adjustable lower control arms etc.) would it be most correct to keep the stock bias, or would more rearward brake bias be better?

That's a good question. As a physicist and engineer (in areas largely unrelated to anything involved here lol) I would expect that it's a difficult one to answer without doing a lot of expensive R&D akin to that which was done in the design process for both the stock and CSL M3s. But maybe someone who knows something about automotive engineering can chime in and say how much of a big deal and how hard it is to meaningfully optimize for these kinds of things?