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I'd like to shift gears and brag a little bit. Below are some shots of professional racecars/teams running the AP Racing Radi-CAL and J Hook. I've also included a few links to our blog if you'd like to see/learn more about these cars and teams. These images should not only give you a sense of what our brakes look like on the car, but what they can actually do! The Radi-CAL has been kicking butt and taking names all over the world in recent years.
We supported the Action Express Daytona Prototype Corvettes during their run of championship wins leveraging the Radi-CAL mated to both J Hook Iron discs and carbon/carbon discs. You can see an article on our blog with some great pics from a book they published.
Corvette Racing/Pratt & Miller have won Le Mans eight times with numerous combinations of the AP Racing Radi-CAL and J Hooks.
The AP Racing Radi-CAL has won many times in Super GT in Japan:
The Flying Lizard 911's:
The vast majority of the iconic factory BMW racecars have been equipped with the AP Racing Radi-CAL:
A rather iconic prototype wearing some AP's. They aren't technically Radi-CALs, but the car is sick and I figured I'd post it anyway because I think it's one of the all-time prettiest racecars!
Williams Formula 1 Radi-CAL...okay, now we're getting a bit far afield from production-based cars!
The Radi-CAL has been dominant in NASCAR Cup, helping to win the championship most years since it's introduction. I'd post pretty on-car pics, but you can't really see the brakes behind the tiny 15" wheels! The pic below pretty much sums up what the Radi-CAL and J Hooks have accomplished in NASCAR over the past decade.
I hope you enjoyed some of these pics. We have a huge stash of others, but I think you probably get the point. When I have a bit more time I'll post some pics of enthusiast (non-pro) cars sporting our brake packages.
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'09 Carrera 2S, '08 Boxster LE (orange), '91 Acura NSX, Tesla Model 3 Performance, Fiesta ST
Jeff Ritter
Mgr. High Performance Division, Essex Parts Services Essex Designed AP Racing Radi-CAL Competition Brake Kits & 2-piece J Hook Discs Ferodo Racing Brake Pads Spiegler Stainless Steel Brake Lines
704-824-6030 jeff.ritter@essexparts.com
Yes sir. As mentioned previously, we are doing custom front and rear discs specifically for this application. For reference, the disc breakdown looks like this:
Discs in Essex Designed AP Racing Radi-CAL Competition Brake Kit
Front 394x34mm, 22? lbs., 84 directional internal vanes, J Hook Slot
Rear 380x32mm, 20? lbs., 72 directional internal vanes, J Hook Slot
Our goal with the discs in our complete brake kit is to provide ample thermal mass in the disc without any unnecessary weight. In terms of diameter, our front disc is going to be between the OEM iron and PCCB discs. As mentioned previously, we had to use a larger diameter than the OEM iron disc in order to have enough space for a caliper mounting bracket. Keep in mind, that a 14mm increase in diameter only means a 7mm increase in radius. In other words, the front disc is only going to stick out 1/4" farther towards the wheel barrel than the OEM iron 380mm discs. That is good news for wheel fitment. On the rear, our caliper is substantially shorter than the OEM caliper, so we are able to use the same 380mm diameter as the OEM iron. We added a couple mm to the stock thickness for aditional durability.
The potential downside to going to larger iron discs is weight. We get around that by using a shorter radial depth. Radial depth is the distance between the disc OD and ID. In other words, the height of the area that is swept by the pads. Many OEM / road car setups use a very tall radial depth, because they're trying to spread the heat out over a large surface area. They do so, because the discs used in road car systems aren't terribly efficient. This is especially true on carbon ceramic systems. They don't have the intricate internal vane system to efficiently evacuate air from the disc. That's why in carbon ceramic systems you always see discs and pads that are larger in diameter and have a taller radial depth than you do on their iron counterparts on the same model of car. The objective is to spread the heat out over a larger surface area.
With a proper racing disc design, efficient design allows us to solve the heat issue in a different manner. We use a high internal directional vane count that is capable of flowing a lot more air than the typical OE disc. As such, we can use a pad that isn't quite as tall, and still have enough thermal mass because the discs run cooler. The high vane counts we use in our discs (72 - 84 vanes) also provide a very stable backbone for the disc face. The high vane count, coupled with the J Hook slot pattern distributes the heat more evenly throughout the entire disc structure. Temperature gradients and swings is what cracks discs. If you can keep a more even temperature distribution, there is a lower propensity for cracking. Also, the pads stick to the disc face in a more even manner if the entire disc face is at a more uniform temperature. When the pads stick to the disc face in uneven splotches, it creates judder/vibration/pulsation...no fun.
I don't have final weights on our discs yet (I will soon), but I expect them to be lighter than all of the iron discs listed above. I'm going to ballpark them at 22 lbs. per front disc and 20 lbs. per rear disc. Only the PCCB's will be lighter. When you combine the disc weight savings with the caliper weight savings, it should be a very healthy net loss of unsprung weight from the car.
For reference on the caliper and pad weights, we have:
Front OEM caliper= 9.0 lbs
Front OEM pad shape= 3.9 lbs.
Front OEM caliper/pad corner= 12.9 lbs.
Front AP Racing CP9661 caliper= 6.1 lbs.
Front CP9661 pad set=3.2 lbs.
Front CP9661 caliper bracket= 0.8 lbs.
Front AP Racing caliper/bracket/pad corner=10.1 lbs.
Caliper and pad weight savings per front corner= 2.8 lbs.
Rear OEM caliper= 7.4 lbs.
Rear OEM pad shape= 3.1 lbs.
Rear OEM caliper/pad corner= 10.5 lbs.
Rear AP Racing CP9449 caliper= 4.85 lbs.
Rear CP9449 bracket= 0.8 lbs.
Rear CP9449 pad set= 1.5 lbs.
Rear AP Racing caliper/bracket/pad corner=7.15 lbs.
Caliper and pad weight savings per rear corner= 3.35 lbs.
Total front and rear unsprung weight savings on Calipers/Pads=12.3 lbs.
Anticipated front and rear unsprung weight savings on discs (compared to OEM iron)= 12 lbs.
Total unsprung weight savings from car= 24 lbs.
In summary, I expect our complete brake package to shave in the ballpark of 20 unsprung lbs. from the car. That is by no means an uncommon number. For example, on the e92 M3 we shave roughly 40 unsprung lbs. from the car with our four wheel brake package!
In terms of a dollar per pound comparison, the GT2 RS Weissach Package offers an approximate 60 lbs. (29 kg) of weight reduction for $31,000 (11.5 kg (25 lbs.) of that weight is unsprung savings due to the lighter magnesium wheels). We will likely be offering a similar amount of unsprung weight savings at a fraction of the price, not to mention the host of other benefits our brake system will provide. Maybe we should rep our hood and call our brake kit the "Cramerton Package."
Again, the disc weight numbers above for our package are still estimates at this stage. They could vary a bit. I just wanted to illustrate what we're trying to achieve with our setup, and how we will do so. Thanks!
Discs in Essex Designed AP Racing Radi-CAL Competition Brake Kit
Front 394x34mm, 22? lbs., 84 directional internal vanes, J Hook Slot
Rear 380x32mm, 20? lbs., 72 directional internal vanes, J Hook Slot
Hi Jeff - with the extra diameter on front discs, did you do anything to compensate for the additional resulting front bias vs. rear? Different piston sizes, perhaps? Looks like a great system
Hi Jeff - with the extra diameter on front discs, did you do anything to compensate for the additional resulting front bias vs. rear? Different piston sizes, perhaps? Looks like a great system
Yes, absolutely. Our system is designed to very closely match the OEM brake torque output on both ends of the car. We used a special variant of the AP Racing CP9660 caliper, which is called the CP9661. The CP9661 has smaller piston bores than the standard CP9660, and it is most appropriate for this application. Keeping the front/rear brake bias as close as possible to stock was a major priority for us (as it always is on cars that don't plan to go with a competition master cylinder/pedal box setup).
Below is a video we made on our brake kit design process. Thanks!
Here's another one. I talk about brake bias starting around the 3:30 mark...I also talk about sizing discs around the 5:00 mark. This one has a funny ending too, geared towards all the hard-parkers and shiners out there.
One more note on the proper sizing issue...the Porsche aftermarket is absolutely notorious for doing exactly what we discourage customers from doing all the time, which is slapping the brakes from one model onto a different model with little to no regard for the impact on brake torque. If I had a dollar for every time I dealt with this issue over the past 15 years, I'd be able to afford a GT3 of my own! The conversation always begins, "I got a great deal on a set of monster discs and some 'big reds,' and I'm going to install them on my (insert car model XYZ)." If there was a face-palm emoji I'd insert 42 of them right here. If it's not done right, you lengthen your stopping distances, trash your pedal feel, and throw your ABS into fits.
We've been getting calls from customers for the past couple weeks inquiring about pre-orders for this brake kit. If you'd like me to add you to our list, please shoot me an email at jeff.ritter at essexparts dot com. I will send out a notice to all interested parties as soon as pre-orders open. Orders will be filled in the order in which they are received.
Lots of Numbers!
As you all know, when selling a used Porsche GT car, the brakes receive close scrutiny. People know that these cars are frequently driven hard, and they also know that replacement brake components are expensive. One of the best features about switching to our brake system, is that it will allow you to shelve your OEM brakes in good condition until the time comes to pass your car along to the next owner. With PCCB brakes, this is especially valuable. If you beat your OEM brakes up on track, you may need to replace the pads, discs, and calipers to make the car presentable for sale. To completely replace an iron setup, that would cost about $8,900 front and rear. For a PCCB-equipped car, you'd be looking at roughly $30,000!
Below are the retail prices on OEM components from a dealership. I'm sure you can get a bit of a price break from some dealers, but this provides a pretty good ballpark idea of what OEM brake components cost to replace when you burn them up / destroy them on the track.
OEM Iron System
Front disc pair= $1839.62
Front caliper pair= $2460.60
Front OEM pads= $524.83
Total front=$4825.05
Rear disc pair=$1623.22
Rear caliper pair=$1973.10
Rear OEM pads=$551.27
Total rear=$4147.59
Total front/rear car set iron brakes=$8,972.64
OEM PCCB System
Front disc pair= $12874.02
Front caliper pair= $2460.60
Front OEM pads= $508.89
Total front=$15843.51
Rear disc pair=$12982.72
Rear caliper pair=$1973.10
Rear OEM pads=$519.54
Total rear=$15475.36
Total front/rear car set PCCB brakes=$31,318.87
Our target retail price for our front brake kit is $5,999.00, and $4,999.00 for our rear kit ($10,998). That doesn't put us too far off of the price for OEM iron replacement components, but our kit is a far superior investment. One of the best features of our brake systems is that they hold their value extremely well due to their durability, serviceability, and AP Racing's stellar reputation as a top supplier. Our brake kits typically change hands on the used market for about 65-70% of what they cost new. If you spend roughly $11k on our four wheel kit, you'd typically expect to get $6,000-$7,000 back if you sold them used. That means you can buy them, enjoy them, beat them up, sell them for thousands of dollars, and still have your fresh OEM brakes sitting in your garage, ready to drop on your car when you're ready to sell it. That is absolutely not the case with OEM brake equipment. If you destroy your ceramic caliper piston caps, ruin the red or yellow painted caliper finish, or crack your OEM discs, those components are worth very little, or even nothing in some cases.
In summary, the scenario described above can mean the difference between laying out many thousands of dollars for new brake components when you sell your car (only to hand that money to the new owner) vs. collecting thousands of dollars at the time of sale. If the new owner prefers the AP Racing setup, you'll still have a fresh set of OEM brakes on the shelf. You'll be able to either factor them into the deal, or sell them to another GT3 or base 911 owner for a handsome sum. Regardless of which brake system the new owner prefers, you still win.
We've proven the above over and over again in other markets, and our brake systems truly are an investment. When you run the numbers, the value of our product becomes obvious.
Don't forget that you also get to enjoy all of the performance and convenience benefits during your time of ownership! The time and hassle saved on pad changes, bleeding fluid, etc. is quite valuable. If you have a shop doing that work, it will save you billable hours as well. Our system turns a multi-hour brake job into a multi-minute brake job.
Hey JRitt, any chance you guys are going to start putting an anti-corrosion coating on your discs? My AP discs unfortunately rust like crazy wherever the pad doesn’t touch and the internal vanes are all rough and red now. Would love to keep the beauty of these brakes with a silver or black coating on all surfaces!
I wanted to share a few pics with you. A generous customer loaned us his 718 Boxster S the other week, and we took the opportunity to shoot some comparative pics of the OEM calipers vs. the calipers we're using in our Essex Designed AP Racing Radi-CAL Brake Kits. Again, the Porsche calipers in these pics are off of the 718 Boxster S, but they are fairly similar to those used on the 991 GT3/RS, 981 GT4, and Turbo. I mainly wanted to show a size comparison. I've had a few owners ask about size, weight, etc., and they're trying to wrap their head around how we can shed so much weight. I've also had some questions about wheel barrel clearance, since there have been some PCCB owners running into issues with debris getting caught between the wheel barrel and the top of the caliper. Hopefully these pics will clarify.
First up is our AP Racing CP9661 Radi-CAL shown alongside the four piston OEM front off of the 718 Boxster/Cayman S. Keep in mind that the 718 caliper is actually smaller than what's on the front of the GT3. The difference between the six piston OEM front GT3 caliper and the CP9661 is going to be even greater, since it will have a couple more pistons than the red one in the pics! You can see the considerable height difference in these pics, and why we'll be able to go to a larger diameter than the stock 380mm iron size while still providing wheel barrel clearance.
Here we can see the difference in bridge design. With the OEM calipers, the bridge is fixed and they must be removed for a pad change. With the AP Racing Radi-CAL, you simply remove two hex bolts and the bridges pop right out. You can also see that the overall footprint of the AP Racing caliper is smaller, and there will be even more of a size difference vs. the GT3's front six piston. Also note that the AP Racing Radi-CAL has no external crossover pipe, which the OEM caliper does. All fluid pathways are internal on the AP caliper, which decreases the likelihood of the pipe being hit by debris, a trapped rock, a wheel being removed or installed, etc. Finally, the AP Racing caliper only has two inner bleed screws, rather than an inner and outer. Again, this greatly reduces the odds of a bleed screw getting clipped by a wheel barrel when swapping the wheels out.
The rear OEM 718 S calipers are considerably smaller than the rears on the 991 GT3, and they don't have the fixed bridge like the GT3 calipers. I figured I'd show the relative size difference anyway since I have the pics on-hand. Our rear CP9449 caliper is very similar in size to the OEM 718 rear. The difference will be greater when our caliper is compared to the OEM rear GT3 calipers. Again, note the overall design of the Radi-CAL, the negative space (gaps) throughout the caliper, the internal fluid pathways, the offset Rad-CAL stiffness-enhancing shape, etc.
Below is a nice shot that illustrates the difference in the AP Racing disc construction vs. OEM. We have roughly twice as many full internal vanes, which increases airflow, improves disc face stability, and more evenly distributes pad material adhering to the disc face.
The last shot is a comparison between the rear OEM 718 disc (299x24mm) vs. the 340x28mm AP Racing disc we're using in our 718 rear kit. You can see that our disc really puts the mass where it's needed (the ring portion), and takes it away from the area where it is not needed (the hat/bell portion). Despite the huge increase in both diameter and thickness, our disc actually weighs less than stock!
Hopefully these pics provided some additional insight into the benefits our brake kit will provide!
Jeff, are the hats different from the AP OEM iron replacement or for those of us with the older set up, do we need both new hats and rings?
Unfortunately the new complete brake kit will require all new components, including discs/hats. Regarding the disc hats themselves, the PCD (Pitch Circle Diameter) of the holes on the hats in the complete BBK needed to be different from those on the hats in our OEM replacement discs. That means the hats can't be interchanged on the iron rings from one setup to the other.
Our initial goal was to offer calipers that would just bolt up with our existing 2-piece discs, but we just don't have any AP Racing calipers that would work or be modified to work. The big problem is the radial depth of the discs. OEM discs aren't terribly efficient, and therefore use a tall disc to spread the heat. Racing discs are much more efficient/effective, and can get away with shorter radial depths. They use higher vane counts, more advanced vane shapes, etc. to improve cooling, all while reducing unsprung weight.
For the full kit, we had to go back to the drawing board and start from scratch.
I have started taking Preorders for the 991GT3 Essex/AP BBKs call me for details. As Jeff has previously said the orders will be filled.....in the order they are placed.
I wanted to thank you all for your continued interest in this exciting project. Quite a few of you have contacted us to reserve a pre-order slot for one of our new kits, and we really appreciate it! I'd also like to provide you with a couple of updates:
Forgeline Wheel Fitment- Several of you have asked whether or not our brake kit will clear Forgeline wheels without a spacer. The short answer is, yes, they will! Earlier this year Essex supplied the president of Forgeline Wheels with an almost identical AP Racing Radi-CAL brake kit for his personal Corvette, so he is very familiar with the components in our systems. He provided us with the following list of popular 991 GT3 wheel models that will clear our kit front and rear:
Front= GE1R, GS1R, and GA1R in 19x9 +52, 19x12 +47
Rear= GE1R, GS1R, and GA1R in 20x9 +52, 20x12 +47
We'll be checking some other wheels as well, including the stock ones, but we were specifically asked about the Forgelines so I wanted to get back to everyone who asked. We'll also be posting the downloadable wheel fitment templates for those running other wheel brands.
Pre-orders- If you're interested in reserving a pre-order slot, please contact us or Apex Performance to reserve one. Our list is growing quickly, and orders will be filled in the order in which they are received. If you want a kit out of the first batch, it would be prudent to get your name on the list sooner rather than later. There's no commitment, and we don't charge our customers a dime until the final product ships out the door!
Prototype Parts- Our prototype parts are starting to trickle in, and below is a sneak peek at our caliper brackets. Our engineers pulled as much weight as possible out of them (speed holes!) while still retaining the required strength. Like all of our brackets, the production version will be anodized for added durability. Based on our current delivery forecasts from AP, we're hoping to start shipping kits by the end of February or early March.
If you don't hear more from us this month, we hope you have peaceful and restful holiday season.
11-08-2017, 01:06 PM
Below are some shots of professional racecars/teams running the AP Racing Radi-CAL and J Hook. I've also included a few links to our blog if you'd like to see/learn more about these cars and teams. These images should not only give you a sense of what our brakes look like on the car, but what they can actually do! The Radi-CAL has been kicking butt and taking names all over the world in recent years.
