Quote:
Why would you pick these over a Stoptech setup that's anywhere from 1000-1500 less?
Looking for a technical answer, not a salesy one.
For the record, I've used Stoptech on another platform and loved them.
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How our Radi-CAL Competition Kits compare to, and differ from, StopTech Big Brake Kits is a question we receive quite often. Below I've put together a comparison between the two brands. Pretty much everything below applies to our system vs. most OEM brake systems, and all of our competitors' aftermarket kits vs. our Essex Designed AP Racing Radi-CAL Kits.
For reference, I was the sales manager at StopTech for 4-5 years back in the early to mid 2000's when they were just getting their legs. I was there when they did their first BMW brake kit designs (the owner drove an e36 M3). I also ran the StopTech ST-60 system on my C5 Z06 while I worked for them, so I'm intimately familiar with their products. The StopTech system is very nice with high quality parts. When we designed our Essex/AP Racing kits however, we set out to make every component in our kits lighter, stiffer, more durable, and far more effective than anything else on the market.
Calipers
Core Design
The StopTech ST-60 is a basic, no frills, conventional design from roughly year 2003. It was designed to be as versatile as possible to service a wide range of vehicles from sports cars to trucks out of the same casting. Over time it has undergone some changes, moving from a casting to a forging, losing a little weight, etc. It is a quality road caliper. The Trophy version was conceived in roughly 2009, originally as a 'special edition'. It is the same caliper with a bit of fat trimmed, and the option of running AKB springs at an added cost.
The Pro5000R Radi-CAL's, CP9660 and CP9668, were designed in 2014 using AP's collective knowledge gained from roughly 7 years of Radi-CAL designs in Formula 1, NASCAR Sprint Cup, DTM, etc. You can
read about The Radi-CAL design philosophy here, and the huge impact they had at the elite level of racing. The primary benefits of the Radi-CAL design are:
• Massive Stiffness Increase- A 30+ % increase in both static and dynamic stiffness allows for far less deflection under load, which means superior pedal feel & modulation, more even pad wear, and longer caliper service life.
• Considerable Mass Reduction- Removing all extraneous caliper mass lowers the caliper weight, despite the huge stiffness increases
• Optimized Airflow- Air moves around and through the caliper more efficiently, providing superior heat evacuation.
• Efficient Packaging- The wide, asymmetric caliper profile and internal porting allows the caliper to fit into tighter spaces.
From a technical standpoint, the Radi-CAL design makes everything else on the market a bit of a dinosaur. They are the current state-of-the-art in caliper design, and the gold standard in elite racing.
Anti-knockback springs
AP Racing has them, StopTech doesn't, unless you pay extra for their Trophy Kit. As noted earlier in this thread, people severely underestimate how valuable these springs are. After going through S turns, you'll have a much lower pucker factor in the next brake zone with the springs installed.
Piston type
StopTech= cast aluminum
AP= Domed-back, ventilated, machined stainless steel
Stainless is far superior at keeping heat out of your brake fluid. The domed-back provide added stiffness and superior pedal feel, and the ventilation also allows them to run cooler. StopTech will tell you that SS pistons are a problem because they expand at a different weight than the aluminum caliper body when they are heated, which can lead to piston cocking and problems. That is complete nonsense. Every serious racing caliper on the planet runs either SS or titanium pistons. I've been with Essex/AP Racing for ten years now, and we've sold thousands of calipers with SS pistons in the aftermarket at this point, and we have NEVER had an issue with a piston cocking, etc. Literally, not once.
Weight
AP Racing CP9660 Pro5000R weighs 6.2 lbs. without pads. Our CP9668 (which is wider and takes a 25mm thick pad) weighs only 6.8 lbs. The StopTech ST-60 weighs roughly 8.8 lbs, and the Trophy version is something like a pound lighter.
Dust Boots
StopTech uses a street caliper, and as such it uses dust boots. AP Racing Competition calipers have none. If you've ever run dust boots on the track, you'll find that they burn up and cause a big mess almost instantly. Their only value is if you're driving on winter or debris/dirty roads and you don't want to have to wipe your pistons off during a pad change. As soon as they go on track and get destroyed they essentially lose all value.
Seals
Both calipers have quality, high temp seals.
Hydraulic protection
StopTech has an external crossover pipe for fluid, and outer bleed screws, while the Radi-CAL Pro5000R's have internal porting and don't even have an outer bleed screw. This feature protects the hydraulics from track debris, and when you're swapping wheels. No chance of knocking a bleed screw or bending a crossover tube.
Materials and Bridge
The caliper bodies on the ST-60 and Pro5000R are both high quality forged aluminum parts. The bridge on the AP uses two bolts and is easier to manipulate. On the CP9668, a spring clip quick-change bridge option is also included, which reduces pad change time to about six seconds. You squeeze the spring clip and lift...that's it, no tools required! With four bolts, the bridge on the ST-60 can be a hassle to get in and out. On my Z06 I had to wrestle with it a bit to get it seated properly, particularly after it was heat-cycled numerous times.
Pad choice/cost/size
Both the ST and AP calipers use an old AP Racing pad shape and have tons of pad options. The radial depth on the Pro5000R calipers is 54mm vs. 51mm, so you get a tiny bit more pad volume with the AP's. Thickness on the ST-60 and CP9660 is 18mm, but our CP9668 offers 25mm thickness if you're endurance racing, or if you're just lazy and don't like to change pads as often!
Stainless Steel hardware
Both calipers have high quality stainless steel hardware.
Footprint/size
In addition to weighing much less, the CP9660 has excellent wheel fitment, partially because it has no outer bleed screws and it is tapered on the corners. It fits inside OEM wheel options without a spacer. Despite being considerably wider, the CP9668 is still a compact package and will fit many wheels. On the M2 Competition the wider 9668 fits the OEM wheel without a spacer. Because we use a 372mm diameter disc, we can still fit inside 18" wheels, and our disc is about as large as you can squeeze inside most 18's.
Finish
StopTech= painted. Look pretty, but will not look as good after hard use. Paint and powdercoat tend to change color dramatically at track temps. If you're driving through road salt however, they will be better protected than anodized.
AP Racing= anodized. Do not color shift nearly as much. An added bonus is that they also look 'racier' (like what you see on full-blown race cars).
Rebuild Service
Essex offers a lifetime professional reconditioning service. You can send your calipers to Essex and have them rebuilt by the same techs who service NASCAR and IMSA teams. I'm unsure of ST's procedures, policies, and prices on rebuilds at this time.
Discs
Design
Both companies offer high quality discs for the kits in question. Discs from both manufacturers are quality castings that are crack resistant and will last a long time under heavy track use. That said, the StopTech discs are a more pedestrian 48 vane design, whereas the AP Racing discs have 84 vanes (nearly twice as many). That means more disc face stability and higher airflow. Our discs also have the patented J hook face slot are the #1 choice at the elite level of motorsports (NASCAR, IMSA, DTM, Aussie V8, Super GT, etc.).
Size/Mass/wheel fitment
The discs in the front StopTech kits are typically either 380x32mm or 355x32mm. Our front discs are 372x34mm. We have the largest disc that will fit behind most 18" wheels. Our discs are thicker, have nearly twice as many vanes, and you'll have more wheel fit options than you will with a 380mm disc.
StopTech 355's with hats weigh about 18 lbs., their 380's weigh about 21 lbs. Our 372's weigh approximately 21 lbs. assembled.
Spare iron price
StopTech 355's are $345 each, and 380's are $375 each, and our 372mm discs are $399. We believe that the tiny premium for our disc is more than offset by the technology and longevity embedded in our discs.
Disc hats
Both have a quality design and are made from aircraft grade aluminum. Both are optimized for weight and airflow.
Disc Burnishing
For $100, Essex will burnish your discs with the pad compound of choice. That means you don't have to fiddle around with bedding-in your discs, or worry that you're doing it properly. Our patented burnishing machine and process make sure it's done properly every time. We burnish thousands of discs each year for pro race teams. StopTech does not offer this option/service.
Brake Lines
Both systems came with a high quality set of brake lines, but the Spiegler lines in our kit are the highest quality available. They feature stainless fittings with a unique swivel system that prevents twisting and kinking.
Other Factors
Initial Purchase Price
StopTech ST-60/380mm kit=$3695
StopTech ST-60/380mm Trophy Sport Kit= $4495 (if you want dust boots, it's more)
Essex Designed AP Racing CP9660/372mm kit= $4399
Essex Designed AP Racing CP9668/372mm kit= $4799
Obviously I'm a bit biased, but it's almost inconceivable that anyone would pay a similar amount for the aging StopTech technology vs. our latest AP Racing Pro5000R offerings. The Pro5000R Radi-CAL kits are a step beyond the ST kits in every facet. Yes, our kits are initially ever-so-slightly more expensive than the basic ST-60 kit. However, there is a huge difference in the level of hardware you're getting in each kit. Our setup is the same as what is delivered on factory-built racecars from Audi, VW, BMW, Ford, etc. Every component is designed to be stiffer, lighter, and more durable than anything else on the market. There's nothing even close.
Long-term Running Costs and Value
As noted above, spares for our kits are nearly the same price as StopTech. The difference is, ours will be burning at a slower rate. The initial purchase price difference is made up over the course of ownership, and it is definitely made up at resale time.
As with most premium brands in any segment, AP Racing products hold their value better competing brands. As noted previously, our brake kits change hands for a nice chunk of their original price. People know that even after a considerable amount of abuse, the components are going to hold up and keep performing. They also know they can have Essex service them and make them good as new again for a reasonable price.
Brand/Reputation/Panache
StopTech has a solid reputation for supporting grassroots racers, providing quality parts at an obtainable price (I like to think I was actually a large part of building that reputation early on ). Lots of lower-level racing series use ST products successfully.
AP Racing is the best of the best, with over 700 Formula 1 wins on their brake components. Just about all factory BMW race cars run and trust AP Racing. They have the most cutting-edge products, and when people see the AP Racing logo, they think "the best."
Aesthetics
Other than not being available in fancy colored paint, I don't think it's a remotely close comparison as to which kit looks better. Behind the wheels, 380mm discs effectively look nearly identical to a 372mm. The radius of the 380mm disc means it only sticks out 3mm closer to the wheel on either side vs. a 372mm, which is negligible visually. The J Hook slots also look way cooler than a straight slot.
Service
Often overlooked, but a critical aspect of ownership when you're out flogging your brakes every weekend. Essex has some of the best customer service in the industry. We jump through hoops to help our customers, and we treat our retail customers the same way we treat our OEM and professional racing customers. Read reviews of our systems, and something you'll always see are comments about the lengths we go to ensure a positive ownership experience. We have been in business for nearly 35 years, and we always have a live human picking up the phone during regular business hours.
In summary I'll say that I'm not trying to bash StopTech. I have nothing against them, and they make nice products. I also still have friends who work there. That said, time has moved on. We now have superior technology and offerings available to the average enthusiast that hadn't even been conceived 10 years ago. The initial purchase price of our AP systems is a higher, but so is the value of what you're actually getting. If you want the best, I believe we have it. The image below from our SEMA booth gives a pretty good idea of what AP Racing components accomplished last year in racing...those are all championships, and there are many others. It was more of the same in 2018...AP Radi-CALs won the NASCAR Sprint Cup championship this year, Le Mans GTLM class on the Porsche 911 RSR, etc.
