AP Racing / VAC Competition E30 M3 Brake System: Awesome!

You wanted it, we built it! After the success of these systems on the E36 and E46, we created our own version for the E30 M3... What a killer setup!

Finally; an affordable system that will handle all the horsepower you can fit into an E30 chassis and at the full weight of a street car; all while being light enough for even the most feather weight E30 M3 race car. ALL the features you want and a brand you trust! After testing on two prototype configuration E30 M3s that see constant abuse, the feedback is tremendous. Read more to see all of the awesome features of these BBKs:

NOTE: For use along with 17" or larger wheels with antiquate brake clearance, often times, a 10mm spacer may help a great deal.*

E30 M3 Competition Brake Kit: (Complete Front System)

While some E30 M3s have built S14s, more and more have 6 and even 8 cylinder swaps, turbos and superchargers. These cars are getting faster and stresses are growing as we continue to help owners go faster and faster... This kit was developed with a competition mentality, not to gain points at a car show.

AP has been supplying professional race teams at the highest levels of motorsport with brake systems and components: They know what works and what doesn't. Optimization is our focus so we've assembled our kits with components that are durable, efficient and light weight. From 20min sprints to 24hr endurance races, our competition kits are up to whatever you can through at them.

Let’s take a look at how the VAC / AP Racing / Essex competition brake system for the BMW M3 sets itself apart...

Calipers- AP Racing CP8350 Four Piston Forged

Let's first take a look at the calipers. They are the most eye-catching piece of the system, and the one most often touted in marketing material from the manufacturer. ‘Racing inspired’ is the most common term bandied about, but what does that really mean? In this case it just means that the caliper is a fixed, opposed piston caliper with a company logo. Beyond that, there aren’t all that many similarities between the those calipers and true aftermarket race calipers. Let’s take a look at some of the design elements.

The first obvious weakness when looking at a standard Brembo or other aftermarket caliper is the finish. Most aftermarket calipers come in a painted finish, whether they are red, black, or gold. This painted finish is for corrosion resistance and appearance. Unfortunately, for all of the compliments pretty calipers generate, there is an associated price if you drive the car in a track environment. That price is the chipping, flaking, fading, color shift, and general decimation of the finish in a fairly short period of time. 

How many features from the best racing calipers in the world can you cram into a $500 caliper? Probably more than you ever thought possible! AP Racing’s CP8350 was designed to be the market leader in performance and features while maintaining a wallet-friendly price point. AP’s newest design brings real racing technology like stainless steel pistons, anti-knockback springs, and integrated hydraulic protection to the average enthusiast at lower prices than the competition charges for watered-down street components. Incredibly, this is achieved while maintaining an unloaded weight of only 4.8 lbs. The CP8350 completely redefines the content/cost ratio among aftermarket brake calipers.

This caliper was designed to be ultra-lightweight, stiff, and durable under all track conditions. The finish we chose is a hard anodizing. Hard anodizing is the business under track conditions.When raw aluminum reacts with the oxygen in the air, a hard surface film develops on aluminum which prevents further degradation. The process is called oxidation, and you can think of it like rust. The anodizing process leverages this natural phenomenon, and takes it a step further to produce an extremely hard protective layer of aluminum oxide on the aluminum. It does so by running an electrical current through an acid bath, and dying it to the desired color. If you want to know more, Google it.

The result is a finish that is far more appropriate for racetrack use. Anodizing creates a uniform surface that is much more abrasion resistant than paint or powder coat. That means if you ding an anodized caliper with a box wrench when bleeding it, a big chunk of the finish isn’t going to chip off into your hand. While anodized calipers will still exhibit color shift, it will take a lot more heat to get them to change, and they won’t change as dramatically. They will go from semi-ugly grey, to a semi-ugly grey-brown (see below). In short, they’ll look like the race calipers they are. More importantly though, you aren’t going to have bits of anodizing sticking to the sides of your pistons.

(Please do keep in mind however, that every yellow AP logo is hand painted on the caliper. It will degrade over time, particularly if you slop brake fluid all over it. Our customers asked us for something with at least a little visual punch and some brand recognition, so we had to give them this token. Also keep in mind that an anodized finish is not designed to be driven through road salt.)

Brake Pads, Thick 20mm (Inexpensive ones too!)

Race pads aren’t cheap, and you burn through them quickly if you spend any amount of time on track. The average set of race pads for the OEM BMW calipers are roughly $250, while the average set for the AP Racing CP8350 costs $175. How many sets of brake pads do you go through in a season? Some people find that they could pay off their brake system in a short period of time on pad savings alone.

Also, since this pad shape is used by a wide range of racing calipers, it’s available in just about every popular racing compound on the market (Essex alone sells close to 20!). That means you’ll never end up in a pinch without pads. Cheap, thick, and available is a great combination for a consumable like race pads.

Caliper Pistons

Brembo style aluminum piston vs. AP Racing machined stainless steel piston

There are people out there who will tell you that aluminum pistons are great for track calipers. They will tell you that the expansion rates of the pistons and caliper body need to be the same when heated. This argument is completely invalid and unproven. Those same people tend to get upset when you point out the fact that every serious race caliper, from every serious race caliper manufacturer on the planet uses either stainless or titanium pistons, period. There is a reason for this: they work better!

Stainless steel pistons are far superior to aluminum pistons in creating a thermal barrier. They are much better at keeping heat out of your brake fluid and preventing a soft pedal from fluid fade on the track. This has been proven over and over again at all levels of motorsport. Don’t fight it, just accept it.

While the most aftermarket calipers uses a pressed aluminum piston, the CP8350 uses an expensive machined stainless steel piston. As discussed above, this is to slow and repel the influx of heat into the brake fluid.

Anti-knockback Springs

Not only are the pistons stainless steel, they are fitted with anti-knockback springs. Springs in pistons you ask? Yes, springs. If you’ve ever gone through a series of S turns and then had your pedal drop when going into the following brake zone, you have experienced knockback. To say it is disconcerting is an understatement. You’ll often see pro drivers ‘pre-tap’ their brakes lightly when approaching a brake zone. They are fighting knockback.

Knockback is a phenomenon that is common with fixed calipers. Knockback occurs when your car’s wheel, hub, and bearings deflect during cornering, allowing your brake disc to move out of sync with your caliper and brake pads. The caliper is less prone to movement because it is attached to the more rigid upright. As the brake disc deflects, it actually pushes the pads away from each other, forcing the caliper pistons back into their bores. The piston seals don’t have enough tension in them to return the pistons to their original location. That means there is slack in the system that needs to be taken up. When you press the brake pedal, it will continue to drop until that slack is taken up.

Anti-knockback springs help alleviate this situation by putting some tension on the back side of the pistons. When the disc deflects and pushes the pistons, the springs push the pistons back into their proper location, reducing slack in the system. That means less pedal drop and far fewer pucker-factor moments when going into heavy brake zones.

The downside to springs is that they create slightly more drag by continually exerting force on pistons towards the disc. That said, we’re talking about a 4 lb. spring. The miniscule amount of additional pad and disc wear you’ll see is more than a fair tradeoff for making sure your brake pedal is there and firm when you need it most. Having confidence is crucial while clicking off hot laps.

Integrated Hydraulic Protection

Pictured above is a set of calipers we pulled from a car we were testing (Lancer Evo). We saw that the right hand caliper had a bent crossover pipe. Most likely it was bent when a wheel was being installed. Or, it could have been hit by a piece of track debris. Regardless of how it happened, this is precisely the type of damage the CP8350 was designed to prevent.

On the CP8350 the bleed screws and crossover pipe are hidden in little coves that protect them from contact. If you frequently pull your wheels on and off your car, you probably know how easy it is to bump your caliper with then inner barrel of the wheel. How easy would it be to ruin your weekend if you happened to knock off a bleed screw and kill your caliper? The integrated protection on the CP8350 will prevent anxiety the next time your friend is putting your wheel back on and you hear that dreaded ‘clunk.’

Also, there’s no need to worry about access to the bleed screws. Fitting a box end wrench on the bleed screw when bleeding isn’t an issue.

High Temperature, Low Drag Seals without dust boots

Dust boots and the track just don't mix very well

Most aftermarket calipers are designed for year round road use and as such come with a bellows style external dust seal. “So?” You ask. Well, we’ve seen them burn up in a single 20 minute session, and all they do is make a big mess. They usually look something like the above pics before and after track use.

Additionally, the OEM caliper seals aren’t designed to handle repeated trips to several hundred degrees without becoming brittle and leaking, etc. On the other hand, the CP8350 caliper has the exact same AP Racing high temperature seals used in NASCAR Sprint Cup, ALMS, DTM, etc. They are designed to operate at extreme temperatures without leaking, and require less frequent replacement and servicing. You won’t see a ragged mess here.

Simple Pad Change with One Bolt

After the countless times you’ve changed your brake pads, you’re probably never too excited when it comes time to do so. Changing pads will no longer be a chore with the CP8350. No more fiddling with a hammer, punch, and pliers, and no tinkering with that annoying spring clip. AP’s bridge bolt pops out easily with a 5mm hex wrench and a 7mm socket. It will take you longer to pull off the wheel than it will to change pads. Less time futzing around in the paddock, and more time driving= fun.

Pistons Sized Specifically for the BMW M3

The piston sizes for our system were specifically chosen for the BMW M3 and move a small amount of bias to the rear. This will help keep the car balanced on track since most OE systems are designed with significant front bias. Our front system can be bolted to an otherwise stock brake system with no ill-effects, negative impact on ABS, etc. The vehicles stock master cylinder can remain, as can the OEM rear brake system.

Compact, Ultra-lightweight Package

Our brake system follows a simple philosophy: Anything larger than necessary to get the job done is simply dead weight to drag around. One of the major problems with many of the brake packages currently on the market is wheel fitment. You’re offered gigantic discs and 12 piston calipers, with a pat on the back and a, “Good luck finding wheels to clear those things (insert sinister chuckle here).” The reality is that many casual racers want to use their OEM diameter wheels on the track, or the smallest, lightest wheel they can find. Not only is saving unsprung weight critical, R compound tire are much more plentiful and cheaper for smaller wheels. If the components are designed properly with heavy use in mind, you don’t need to cram boat anchors under your wheels. Our brake system easily clears the OEM 18” option wheels and most aftermarket 17" wheels. Please feel free to download the wheel template at the top of this page to verify wheel fitment with your current wheels.

If you’re worried about the loss of stiffness due to mass reduction, don’t. AP’s CP8350 is an extremely stiff, forged design, and the pedal feels rock hard on the M3.

We saved some of the best news about the CP8350 caliper for last. With pads, it weighs over three pounds less than the OEM caliper and that doesn't include the brakcet! All told, we shave nearly 7lbs per corner. That’s 7lbs. less unsprung weight per corner to drag around. As mentioned above, the pads retain nearly the same mass as the OEM shape due to their added thickness. For the competitive individual, weight savings often becomes the holy grail of modifications. A lighter car means greater acceleration, superior handling, and less mass to bring to a halt. At some point reducing weight becomes extremely expensive on a dollar per pound basis. When viewed in this manner, our system becomes an even greater bargain.

Lifetime Professional Reconditioning Service

Essex is AP Racing's official North American caliper reconditioning center. We have skilled service technicians rebuilding hundreds of AP Racing calipers each year for the top teams in NASCAR Sprint Cup, ALMS, etc.

Hardness testing: After disassembly your calipers will be Rockwell hardness tested against the standard for that particular caliper type as sold new. This test provides a relative understanding of how much fatigue and stiffness loss your calipers have experienced. Tired calipers lead to pad tapering, increased pad wear, leaky seals, and a loss of pedal firmness, all things you want to avoid. Essex will make a replace or rebuild recommendation based on the results of this test.

Ultrasonic cleaning: After passing the hardness test, your calipers will be placed in an ultrasonic cleaner to remove all dirt, debris, brake fluid, etc. This method produces results that are far superior to what the average racer could accomplish via hand-cleaning.

Inspection and re-assembly: All serviceable parts of the caliper will be inspected and replaced if necessary, including the seals, abutment plates, pistons, and bleed screws.

Cyclical Pressure Testing: After your calipers have been rebuilt, they will be cycled at high and low pressure on a pressure bench to ensure proper functioning. This is important, as certain leaks only show up under specific pressure conditions.

Price: The labor price to rebuild a CP8350 is $78 per caliper. That does not include parts. Assuming there has been no damage to the caliper, Essex typically recommends replacing the seals ($40) and bleed screws ($15) during the standard reconditioning process. For roughly $125, you can have a fresh, professionally serviced caliper in peak operating condition.

Two-piece Floating Design with Aluminum Hat

As is the case with most metal, iron brake discs grow substantially when heated. As it is heated, a disc expands radially, increasing in diameter and circumference. One-piece disc designs run into problems when this occurs. Look at the picture below and imagine the disc is being heated on the track. As the disc expands, the outer edges of the disc are pulling away from the center of the disc, but there are no built-in provisions to allow for that expansion. The edges of the disc therefore pull, lift, and distort, which is called coning. Now imagine that disc vertical on the car, running in your caliper. Coning directly impacts the brake pads’ contact with the disc, leading to uneven wear and tapering, and even a long brake pedal.

Two-piece discs on the other hand, compensate for the expansion of the disc as it heats. This is accomplished by building ‘float’ into either the disc itself, or the disc hat/bell. In this case, the float is in the disc. If you look closely at the picture below, you can see that the mounting holes for the hat attachment bobbins are not round. They are an oblong shape. These channels allow the hat mounting hardware to slide as the disc is heated and expands, allowing the disc to run true in the caliper without distortion. That means less distortion, stress cracks, and pad taper.

Mounting Hardware and Anti-Knockback Spring Clips

If you look closely at the mounting hardware we use in our Competition Kits, you’ll notice a few details that are often overlooked in lesser products. These components are specially made for their intended purpose. These are not cheap bolts found at your local big box store. They are custom made in the USA for Essex and AP Racing, and they are the exact same components we use on professional racing products.

As discsussed above with regards to the piston springs, knockback can be a serious issue when tracking a car. In order to help control the lateral motion of the disc, which pushes the pistons back into the caliper, we use an anti-knockback spring clip on every other disc attachment point (on a ten bolt disc there are five spring clips, while on a twelve bolt disc there are six). These spring clips help keep the disc hat and iron ring in alignment, while still allowing the disc to expand and float radially. As an added bonus, they prevent the hat and iron disc from rattling and making noise.

Hat Design

Floating two-piece discs also have the added benefit of reducing heat conduction to the hubs and bearings, decreasing wear and tear on these costly components. The disc hats themselves are manufactured from 2024-T351 heat-treated billet aluminum, with an anodized coating. This material was specifically chosen for its strength at high temperatures, as it will be in direct contact with the searing hot iron discs. The hats feature scallops on the underside, to allow for heat evacuation along the outer disc face once installed.

Vane Design

Notice the huge difference in size between the inlet ports on the inside of these discs.

The internal vane design on AP’s CP3908 is quite a bit different vs. the OEM discs. After extensive CFD and thermal stress analysis, AP designed the Heavy Duty J Hook with 70 curved vanes and a wide 16.5mm air gap to increase airspeed and heat transfer, while reducing deflection and remaining reasonably lightweight. The increased directional vane count on the J Hook Heavy Duty Disc amplifies air speed through the disc, reduces air recirculation between vents, and also increases convective heat transfer and heat distribution. In other words, both air and heat move more quickly and evenly through the disc, creating increased stability under the extreme loads of racetrack use. The disc is less prone to coning, distortion, and cracking than the OEM disc, while providing less brake fade, reduced judder, and a longer service life.

Exclusive AP Racing J Hook slot pattern

When you cut a slot or drill a hole in a disc you impact heat transfer. The area around the slot or hole acts as a cool spot when the disc heats up, which is not ideal. Ideally, heat is distributed uniformly around the disc so it can be hit with the cooling air that is pumping through the disc, radiate outwards away from the disc, etc. Cool spots create stress risers and increase the likelihood of the disc cracking. They also cause the face of the disc to distort unevenly, leading to uneven pad deposits, vibration, and judder.

The OEM discs avoid this problem by simply leaving the face blank. While the risk for NVH goes down, so does the pad bite and feel of the disc through the brake pedal.

During exhaustive R&D testing, AP's J Hook design was found to create a constant pathway of evenly distorted material on the face of the disc. The hooks are spaced out as evenly as possible both around the circumference of the disc, as well as from the inside edge (where the hat attaches) to outer edge, with a slight overlap to promote even heat distribution/distortion. In addition to reducing cracking, the even heating of the disc also helps provide an even transfer layer of pad material on the disc when you bed them in.

Additionally, the J Hook slot pattern produces a greater number of leading edges for the pads to bite into vs. a traditional curved slot pattern, and particularly a plain-faced disc. While this may lead to slightly more whirring or scraping noises from the discs when applying the brakes, the benefits of more even heat distribution, less propensity to crack, cleaner pad material transfer during bed-in, and more bite far outweigh the slight increase in NVH for the serious enthusiast.

Feature: Complex metallurgy developed through 50+ years of experience

AP Racing has been designing brake components for more than 50 years. They've had their components on cars that have won more than 600 grand prix's (Formula 1). On any given race weekend, AP J Hook discs can be found on 75% or more of the NASCAR Sprint Cup grid. AP has learned from these experiences, and have developed a proprietary iron alloy with extreme durability, designed specifically for what you intend to do with it (flog the hell out of it).

The primary objectives with OEM discs are simple: they must be cheap and easy to produce. The design objectives for these two products are vastly different.

Weight

As with the calipers, the discs in our system offer additional weight savings over the OEM units. Despite being 4mm wider, the two-piece AP discs provide a weight reduction of over 1lbs. unsprung weight per corner!

Reasonable replacement cost

Let's face it, no matter how good a brake disc is, it's still a consumable item. They're no different than brake pads or gasoline. You beat them up until they crack to pieces, then you throw them away. If replacement iron is too expensive, you're always driving in fear, waiting to shell out big bucks for a new set. Despite having the most expansive set of features on the market, the 325x32mm Heavy Duty J Hook's retail for a budget-friendly $249 each.

Going to the track is expensive! Event entrance fees, hotels, fuel, and tires all add up. While you obviously want the best product available, you can't afford to pay a small fortune for something you're just going to destroy. You can buy a cheap set of $150 discs for every event, have relentless heat issues, and find yourself constantly swapping them out. When you do the math, the long-term value of the AP J Hook's is tough to beat. You'll enjoy all the benefits without breaking the bank, and you'll spend more time driving and less time wrenching.

Elite level teams choose AP Racing discs because they know the work has been done to provide the best available product at any price level. The AP Heavy Duty J Hook is a direct derivative of AP's vast racing experience. You can buy with confidence knowing that you're getting the best product available at any price point. A note of caution however: the J Hook design is often imitated, and there are a number of lesser quality imitations on market. Before purchasing, make sure you are getting an authentic AP Racing J Hook!

Caliper Brackets & Hardware

Caliper brackets for our kit are machined from heat-treated 6061 T6 billet aluminum, and hard anodized, ensuring strength and durability. All included socket head bolts are a high tensile strength steel.