Stoptech ST40 Race Only Brake Kit, 328mm

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$2,095.00 $2,089.00
(You save $6.00)
40.00 LBS
Allow 1-2 weeks assembly time before product ships.
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VW MK5 GTI, Golf , Jetta 2.0T, 2.5L, 1.9TDI - Big Brake Kit ST40 Brake Kit, 328mm


Includes 4-piston ST40 Red calipers, 328x28mm 2-piece floating and directional slotted brake rotors, adapter brackets, StopTech brake pads, and brake hoses.

  • Fully forged aluminum construction
  • ALL finished parts are 100% leak down and pressure tested to 2500 PSI
  • ST-40 uses standard FMSI D372 pad
  • ST-45 uses standard FMSI D609 pad
  • Any combination of 8 piston sizes available to match kit to vehicle application
  • Differential piston sizes minimize pad taper
  • Dust boots are standard
  • Weight: 7.94 lb (3.6 kg) unloaded
  • Same caliper used by top Speed® World Challenge and Grand-Am Cup Teams

Calipers may also be special ordered in these colors: Silver, Black, Yellow, & Blue.

Rotors may be special ordered in a cross-drilled pattern.

The last 2 digits of our brake kit part number designates the caliper and brake rotor finish options. Popular options are:
.72 = Red caliper / drilled rotor
.73 = Red caliper / slotted rotor with Zinc plating
.74 = Red caliper / drilled rotor with Zinc plating
.51 = Black caliper / slotted rotor
.52 = Black caliper / drilled rotor
.53 = Black caliper / slotted rotor with Zinc plating
.54 = Black caliper / drilled rotor with Zinc plating

Big Brake Kits give your vehicle that Supercar look and feel, and exceed stock performance in two areas. First, larger rotors increase heat capacity. Second, stiffer calipers and stainless steel lines reduce system compliance.

The key, however, is to increase heat capacity and reduce compliance without upsetting the stock front to rear brake torque ratio. If the brake upgrade you select adds too much front torque (as many do), you reduce your car's ability to utilize the tractive capacity of all of the tires to the maximum practical extent (even on ABS equipped cars) and you therefore create performance sacrifices. In addition, too many pistons or pistons that are too large will make the brake pedal much more difficult to modulate, which limits a driver's control of brake input on the race track.

Advantages of StopTech over other brake upgrades:

  • Shorter Stopping Distances
  • Better Brake Modulation
  • Firmer Brake Pedal
  • Less Brake Fade

Feature Benefit Summary:

  • Balanced Brake Upgrades™ with optimum brake bias offer the shortest stopping distance with the best pedal feel
  • Our patented AeroRotors® with the best airflow available result in better cooling, less fade and longer rotor and pad life
  • The stiffest aftermarket calipers with patented bridge result in better clamping under hard braking and less pad taper
  • Track testing of new applications ensures optimum performance

Improved cooling and heat capacity means less fade

StopTech has incorporated several design innovations to improve rotor airflow, cooling and heat capacity. The ability to absorb and dissipate heat is essential to brake system performance.

Benefits of Improved Airflow

  • Less fade
  • Longer rotor and pad life
  • Beter performance


The patented AeroRotor® features curved vanes with innovations on leading and trailing edges. The uniquely designed vanes inside the disc optimize airflow through the rotor. This improved directional design minimizes turbulence and flows more air than any rotor tested. The result is up to 80% better airflow over original equipment rotors and 10-30% better airflow than directional vaned racing rotors currently available.



Outer rotor faces run hotter. The patent pending AeroHat™ has directional stand offs between the rotor and mounting bell (hat) that increase airflow to the outside faces of the rotor by 50-100%. Increased airflow reduces the temperature difference between the inside and outside faces of the rotor resulting in less distortion and better performance compared to other fully floating designs. Outer pad wear is reduced. AeroHat™ improves entire brake system airflow by up to 4%.


The below chart shows that StopTech (top red line) has the highest induced airflow of any rotor tested. Leading aftermarket and original equipment rotors were tested for airflow from 30mph to 150mph. AeroRotor® dramatically outperformed all other rotors, with improvements from an impressive 11% to a staggering 80% increase in airflow (corrected to 20°C and sea level.)



Using finite element analysis (FEA) modeling software, we have designed a bolt-in bridge strong enough to stop distortion without sacrificing cooling through the top of the caliper. Distortion is virtually eliminated. The fully forged StopTech ST-40 caliper has the least flex of any tested aftermarket and OE caliper. The air channel in the bridge is designed to help air flow through the retainer, resulting in better cooling.


Benefits of Stiffer Calipers:

  • Better performance with less vibration, noise and pad taper
  • Better pedal feel under extreme braking conditions
  • No radial pad taper

Caliper Deflection

The chart below shows the results of testing 25 leading caliper models by the major caliper companies. Each caliper was subjected to the same pressures and deflection was measured with a dial caliper. StopTech's is the stiffest caliper of the major brands tested.


Caliper Color Options

Calipers are available in the following colors:


Rotors are available slotted, drilled or plain. Drilled rotors are $100 extra per axle.

Caliper Color Options

Calipers are available in the following colors:

Blue, gold and yellow calipers have a 30-45 day lead time and are $200 extra per axle.
Silver calipers are available at no extra charge, but do have a 30-45 day lead time.


Rotors are available slotted, drilled or plain. Drilled rotors are $100 extra per axle.

StopTech now offers an anti-corrosion gold zinc coating for all AeroRotors. The coating benefits customers who live in cold climates where snow and road salt are commonly encountered, and customers who would prefer to not have visible surface rust on the vanes and outer circumference of their rotors. Zinc coating does not have a negative environmental impact like other coatings. Gold zinc coating costs $70 per axle extra.

StopTech = Quality

StopTech is a serious company that puts great emphasis on quality materials and suppliers. The high standard of our parts and manufacturing processes are part of what makes StopTech brakes the best value in the market today.


StopTech's ST-40 and ST-60 calipers are fully forged for optimal strength and light weight. All caliper finish machining (such as piston bores sized correctly for the application) and assembly/testing is done in our Southern California facility. StopTech tests every single finished caliper to 2800 psi using brake fluid on a special test bench designed by StopTech engineers.


AeroRotors are made using StopTech's patented vane design and our proprietary cast iron formula, which was specified with durability in mind. StopTech has had several sets of rotors run entire 24 hour races on winning cars. StopTech did extensive testing before settling on our final top-secret formula. To test rotor durability, we rented the California Speedway and ran a heavily weighted down car with StopTech rotors on one side and a competitor's rotors on the other. In this test, StopTech rotors were approximately twice as durable as the competitive rotor.

Hats and Brackets

StopTech's hats and brackets are made with a special type of billet aluminum that was designed for the AeroSpace industry in the United States. The German TÜV were so impressed with the durability of these parts during testing that they replicated the bracket and repeated the test with a steel imitation of our part. The steel version failed early.

Hats and brackets are machined to ISO standards at StopTech's manufacturing facility in Torrance, California, using the latest CNC machines that feature active tooling.

Stainless Steel Brake Lines

StopTech makes our own stainless steel brake lines in Southern California. StopTech is a DOT (U.S. Department of Transportation) registered supplier of Stainless Steel Brake Lines. Line material and fittings are all made from the highest quality parts available. Lines feature a clear abrasion-resistant cover for maximum protection against chaffing. Necessary quality control procedures are in place to ensure lines are the correct length, etc. Every fully assembled StopTech Stainless Steel Brake Line is tested to a pressure of 4,500 PSI.

Quality Assurance of Parts

All parts are bench tested prior to shipment. Each caliper is 100% pressure tested to 2,500 PSI. Every brake line is 100% pressure tested to 4,500 PSI. Every assembled two-piece rotor is tested for runout. Hats and brackets are made by StopTech to exacting standards on our own CNC machines. Since StopTech has complete control over our entire design and manufacturing process, we are able to deliver completely integrated kits with a very high standard of quality.

StopTech was the first aftermarket brake upgrade company to offer Balanced Brake Upgrades and is the only company offering optimized kits for over 277 applications. To our knowledge, no other brake upgrade manufacturer takes these design and test steps.

Highly Structured Test Process of New Applications Ensures Optimum Performance

After measuring a car for physical dimensions and calculating the correct piston sizes, StopTech builds a prototype kit and takes it out to the track. StopTech first tests the stock brakes, then tests the exact same car outfitted with a newly designed StopTech Big Brake Kit. StopTech performs the following series of stops, measuring deceleration, stopping distance and rotor temperature for each stop:

1. Series of stops with increasing speed:

  • 10 Stops from 60mph
  • 6 Stops from 80mph
  • 4 Stops from 100mph

2. 1 high speed stop with ABS disabled to see if the front or rear brakes lock up prematurely.

3. Modified J-Turn test to determine how the brakes interact with ABS and traction control. This sophisticated test is used by engineers who design ABS systems.

J-Turn test set-up:

A skid pad is laid out with cones and very carefully measured calibration points are market with dots of paint. A car is driven through the course to determine the maximum speed possible with constant radius turns. At maximum speed, the driver locks the brakes and comes to a stop. Using a computer, the delta between departure angle and intended direction is measured, taking into account car wheelbase and track. If the delta is outside a narrow range, the kit’s piston sizes must be adjusted.

Most cars require upgraded wheels to fit over a big brake kit, but some kits do fit in stock wheels. When a kit fits stock wheels, this is noted in the kit description. To view this description, click on the part number for the particular kit of interest after searching on make, year and model in our online ordering system.

General guidelines for wheel fitment are below, but more important than the diameter of the wheel is the space between the face of the caliper and the inside of the wheel spokes. Wheel width and offset have nothing to do with this clearance area. Clearance is strictly a function of the spoke design. Even is the diameter of your wheel is sufficient, we still recommend that you check fitment.

Easy-to-use templates and instructions on how to use them are under Technical Information/ Wheel Fitment on this web site. These templates will allow you to accurately test fit any wheel. Be sure you check wheel fitment before committing to a wheel set.


Kits usually require these minimum wheel diameters:

328mm rotor (12.9 inches) - 17 inch wheel
332mm rotor (13 inches) - 17 inch wheel
355mm rotor (14 inches) - 18 inch wheel
380mm rotor (15 inches) - 19 inch wheel

For wheel fitment Templates Click on the link below

Checking wheel fitment is the responsibility of the customer.


 Centric Parts obtained the information reflected in this catalog from reliable sources and believes this information to be complete and accurate as of the time of printing. Centric Parts does not make any warranty, express or implied, as to the correctness, accuracy, or completeness of the information in this catalog, NOR as to MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE in relation to any of the products described herein. Centric Parts specifically disclaims any responsibility or liability for any errors, omissions, changes, and updates in the information in this catalog and shall not be liable for direct, indirect, incidental, or consequential damages resulting there from. Under no circumstances should replacement parts be used when they do not appear to fit properly, or should the parts be forced to fit or modified in the field in any way. Confirm that you are using the correct replacement part.

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