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Originally Posted by Striker73
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Was just about to post this up. I was considering to get the CP5555 rear (378x36mm) and the CP6602 rear (352x26mm) but was contemplating with the older Essex kit and then this popped out which looks spectacularly bada$$
But I did notice that the rear 5000R 4piston (rear) caliper by AP Racing doesn't accommodate a larger brake disc, which is a problem.
I do have a question though. Is there a specific ratio that would cause imbalance towards the car's handling characteristics if you have a larger diameter front disc VS smaller diameter rear disc? That would be interesting to find out.
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We might release a Pro5000R rear kit somewhere down the road. As mentioned above though, AP's current CP9441 Pro5000R isn't appropriate for the rear of the M3.
You can however bolt the new front 372mm Pro5000R BBK onto a car with either the OEM rear brakes, or
our current CP5040/340x28 BBK.
Brake torque output is impacted by piston size, disc diameter, and pad mu (we hold pad mu as a constant). Our brake kits are designed to very closely mimic the OEM torque output on the axle on which they are installed. We do so by carefully sizing the discs and caliper pistons.
Disc diameter/size is primarily about heat. You choose a disc for a particular application based on its thermal mass. You look at the platform and ask yourself, "Will this disc have enough mass and cooling capacity to handle what a modified M3 on slicks, at a fast track, with a good driver at the wheel can throw at it?" Once you choose the disc that will manage the heat appropriately, then you choose your piston sizing. We choose piston sizes that in conjunction with the chosen disc diameter will provide a brake torque output that is very close to stock. By doing so, you keep the integration seamless...no ABS issues, no overamplifcation of brake torque on a given axle, no extreme pedal effort required, etc.
As such, installing our front kit on your car will only have a negligible impact on brake bias, and you could even run our rear BBK with the OEM front brakes without any issues.
In other words, the disc diameter front relative to the rear isn't an issue as long as the pistons mated up to those discs are sized properly. That's the key point.
We now have a whole bunch of our rear 340x28mm discs on the rear of e92 M3's. We have not had a single incident of a customer fading or having any issues with our rear setup (including being
pushed to the limit in a 25 hour race). As such, there is no need to go to a larger rear disc (other than aesthetics). Adding a larger rear disc simply adds unnecessary weight to drag around. Also keep in mind that our current rear disc is large enough to keep the factory rear parking brake, which is important to some people.
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I've been looking forward to this but I'm a bit disappointed really. To me it doesn't make a lot of sense to get the new 372mm Radi-Cal front kit and match it to the proportionally much smaller 340mm rear kit with the old style caliper.
Looks like I'll have to wait for Essex to come out with a more evenly matched Radi-Cal based rear kit before I jump in.
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It actually makes perfect sense.
If there's anywhere the e92 M3 needs a larger disc and heat capacity, it's on the front. That is where the bulk of the brake demand is on these cars. From a functionality standpoint, there is zero need to go to a larger rear setup. It's just unnecessary added unsprung weight (see my points above). If you can win all-day endurance races with the current rear setup while still having plenty of disc life left, why would you want anything bigger?
Also as mentioned above, if you're dead set on waiting for a different rear, there's no reason you can't just install the front kit and see if you even need or want the rear after beating on the front for a while. Again, our front kits bolt onto an otherwise stock car and integrate seamlessly with the OEM rear brakes. We have tons of customers who do exactly that, and the kits work spectacularly as a front-only solution. If you install the fronts and find out that you're not having any rear brake issues at all, that your rear pad and disc wear rates are acceptable, etc...you just saved enough $ to pay for a few sets of tires.
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can the pro5000r caliper be used with the 355mm disk for the most weight savings?
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No sir. For the foreseeable future we will only be offering the 355x32mm discs with
our existing BBK. We're trying to keep the number of kits we have for each platform manageable. We'd like to have 17 different kit options for every platform, but we just don't have the resources to do so. I will say that the more success we have on a given platform, the more likely we are to cater to every customer need and want. As an example, we've had tremendous success in the Corvette market over the past few years. As a result we now have seven front brake kit options and a couple of rear kit options. Our 'menu' for those cars looks like this:
Available front BBK's for C6 Corvette:
CP8350/325x32mm
CP5060/355x32mm
CP9660/355x32mm
CP9668/355x32mm
CP9660/372x34mm
CP9668/372x34mm
CP9040/362x32mm (Factory...painted calipers)
Available rear BBK's for C6 Corvette:
CP8350/325x32mm
CP5040/340x28mm
The point is, the more owners that support us in a given platform market, the harder we will try to cater to that market's every specific need. We're busting our humps flat out every day to keep up while working with limited resources, so it has to be that way. It is a good problem to have though, and we're trying to provide the solutions for which we are getting the most requests. In this case, the number one request among e92 M3 owners over the past year has been a larger front kit with the latest AP Racing technology...so that's what we're producing next! Hopefully if all goes well we'll keep the momentum going for this chassis and produce more killer products that people want.
Regardless, our new front 372mm kits are going to be totally bad@ss. The only other place you can find similar products and technology is on race cars worth many hundreds of thousands of dollars to millions of dollars. I think the fact that we're putting that in peoples' hands for around $4k is a pretty ridiculous deal.
Now I'm off to explain to some Dodge owners why we can't provide our kits with yellow calipers that have a viper logo.
Thanks for your patience gents. I can assure you that these kits will be worth the wait.
