Brembo 2-piece disc, brake fluid, and pad install on GMG Racing’s 991 GT3

GMG Racing 991 GT3 – Brembo Performance Install & Review

GMG Racing, an Official Brembo dealer, is one of the premier high performance and professional racing shops in Southern California who specialize in Porsche track preparation. GMG Racing’s background in professional racing campaigning multi-car efforts in the Pirelli World Challenge series with both Porsche and Audi FIA GT3 platforms. Using this extensive racing experience accumulated over the years, GMG Racing also offers up the same upgrades supplied by their technical partners that they trust on the racetrack.

James Sofronas, owner driver of GMG Racing, also owns a personal 991 GT3 shop car to showcase GMG’s capabilities on and off the track. One such way is by holding track day and driver training specifically for 991 GT3 owners at The Thermal Club raceway which is very demanding on brakes and tires.

GMG Racing 991 GT3 Trackday. Photo Credit : GMG Racing

GMG Racing 991 GT3 Trackday. Photo Credit : GMG Racing

One of the first major upgrades done to the GMG Racing’s 991 “WC-GT3” was improve the braking reliability, longevity, and performance under track use. GMG Racing swapped out the Porsche OE discs, pads and fluid on the 991 GT3 with Brembo 2-piece discs, Race Technologies pads, and Brembo Racing HTC64T fluid.

GMG Racing 991

GMG Racing 991 “WC-GT3”

INGREDIENTS REQUIRED:

  • Porsche 991 GT3
  • GMG Racing
  • Brembo 2-piece front disc assemblies.
  • Brembo 2-piece rear disc assemblies
  • Your choice of front and rear pads although Race Technologies TS20’s were used.
  • 6 bottles of Brembo HTC64T Racing brake fluid.
  • Tarett Engineering brake caliper studs (*optional, supplied by GMG Racing)
GMG Racing 991 GT3.

GMG Racing 991 GT3 in stock form.

BRAKE DISC COMPARISON

While the 991 GT3 has very sophisticated brakes for an OE brake package, there is always more that can be done with certain components to improve overall longevity and performance. The OE Porsche brake discs, pads and fluid are all engineered with comfort, serviceability and cost effectiveness in mind.

Brembo OE co-cast discs

Brembo OE co-cast discs

As the braking system’s primary function is to dissipate heat, Brembo uses purpose-designed discs in order to increase the fade resistance and thermal capacity of the system. These discs are directionally ventilated for enhanced cooling and slotted for better performance and continuously refreshing the pad surface. Brembo 2-piece discs are made up of a proprietary advanced cast-iron alloy which offers an exceptional coefficient of friction and resistance to thermal shock and fatigue.

The same Brembo Racing discs trusted every weekend in professional motorsports are also utilized in the Brembo Performance program (GT, GT-R & club race systems).

The OE 991 GT3 co-cast Brembo discs are sized 380 x 34 mm in the front and weigh 24 lbs, and 380 x 30 mm in the rear weighing at 23.4 lbs. The Brembo Racing Heavy Duty “HD” type V front disc assemblies are 24.5 lbs, and the rear Type III assemblies are 22 lbs. The 991 Turbo discs are substantially heavier than the GT3 discs as the Turbo models are harder on front brakes than the GT3 models. Brembo 2-piece disc assemblies on a 991 GT3 or Turbo will offer a net gain in weight savings.

Brembo Porsche OE discs vs Brembo Performance 2-piece disc assemblies

Brembo Porsche OE discs vs Brembo Performance 2-piece disc assemblies

There are many advantages to replacing the OE discs on a Porsche GT3 or Turbo, some of them are:

  • OEM Integration: Brembo upgrades are designed to work seamlessly with the OE Master, ABS and existing brake systems (Example: Integration with the rear parking brake)
  • Weight Savings: Reducing overall un-sprung weight helps improve vehicle dynamics such as handling, braking, and acceleration.
  • Durability: The Brembo discs for these Porsche disc assemblies come from the Brembo Racing program. These discs feature proprietary metallurgy which is resistant to fatigue, cracking, and are engineered for maximum longevity on the street or track.
  • Different Slot Types: Extensively used in professional motorsports, Brembo type III and type V disc face types can be used to tune or adjust the brakes’ technical characteristics to the chassis or driver.
  • Range: Brembo offers lightweight and heavy duty “HD” disc options to suit the needs of the driver, car model (Turbo or GT3) /setup and environment.
  • Replacements: Brembo replacement rings are comparably priced to OE, and when the Brembo discs are worn, only the outer disc ring and hardware needs to be replaced.
  • Drivability: Brembo 2-piece discs maintain the drivability of the OE brakes by using anti-rattle hardware. Brembo’s specific anti-rattle disc hardware utilizes a spring fastener in order to slightly preload the assembly which eliminates the noise (clattering) generally associated with floating discs.

Brembo OE Porsche disc vs Brembo 380 mm 72 vane racing disc

Brembo McLaren spring

Brembo McLaren spring

NOTE: Brembo’s specific anti-rattle hardware which is commonly used in high performance brake disc assemblies was actually developed in the 1990s. This innovation was initially engineered exclusively for the McLaren F1 supercar which is why the hardware is often nicknamed the “McLaren” spring.

 BRAKE DISC INSTALLATION

GMG technicians Ruben and Sergei (who drives a 997 Turbo himself) used their extensive Porsche know how to install the Brembo 2 piece disc assemblies on the GMG 991 GT3 shop car.

GMG Technicians working on GMG 991 GT3

GMG Technicians working on GMG 991 GT3

 FRONT DISC ASSEMBLIES

The OE front discs were the first to be installed. The Brembo performance 2-piece discs and Race Technologies pads are a direct replacement to the OE units. GMG made sure to push the pistons all the way back in to ensure proper stack width (2 pads and brake rotor total width). The Porsche center lock “lug” was then removed and the Brembo 2-piece disc assembly and pads were then installed. Once the Brembo performance disc assemblies were fitted, the OE Caliper was re-installed using brand new caliper studs. The entire process was done on the front right disc, and then the front left disc.

Porsche 991 GT3 OE front brakes

Porsche 991 GT3 OE front brakes

Porsche centerlock unit

Porsche centerlock unit

Brembo Porsche OE front disc vs Brembo 380 mm racing disc and pads.

Brembo Porsche OE front disc vs Brembo 380 mm racing disc and pads.

The Race Technologies TS20 compound was specified as the baseline pad since the car will be street driven and used on the track. The TS20 offers low noise, dust and good pedal feel. It is also an excellent dual purpose compound for street and light track use.

Brembo 2-piece disc assembly fitted

Brembo 2-piece disc assembly fitted

Brembo 2-piece disc assembly installed

Brembo 2-piece disc assembly installed

Since the GMG Shop car is also their test car, the car will see extended track time on many southern California circuits. A Brembo Type V 380 x 34 mm front disc was specified for the lowest disc and pad wear under heavy track conditions. An optional Race Technologies endurance compound was also supplied for dedicated track use.

  • Brembo Type V (endurance face type): motorsport developed face type with marginally less initial response compared to the type III face type. The Brembo Racing type V face type was also designed to have lower pad and disc wear for certain long distance endurance races (mostly 10, 12 and 24 hour races).

REAR DISC ASSEMBLIES

Once the front disc assemblies were installed, GMG then turned their attention to the rear discs and pads. The exact same installation procedure was followed for the rear disc assemblies as well. The rear right corner was installed first, and then the rear left corner was installed. GMG installed new caliper studs on the rear as well when re-installing the OE Porsche calipers. Race Technologies TS20 compound pads were used for the rears as the baseline pad.

Porsche 991 GT3 rear brakes

Porsche 991 GT3 rear brakes

Porsche OE 991 GT3 rear discs vs Brembo performance Type III discs

Porsche OE 991 GT3 rear discs vs Brembo performance Type III discs

Tarrett Engineering Caliper studs used by GMG Racing.

Tarett Engineering Caliper studs used by GMG Racing.

GMG installed Tarett Engineering caliper studs.

GMG installed Tarett Engineering caliper studs.

RT TS20 rear pads

RT TS20 rear pads

The Brembo Type III 380 x 30 mm rear brake disc was specified for optimum balance and brake release under heavy track conditions. This is because the 991 GT3 shifts its’ brake balance towards the rear under braking. The smooth release characteristics of the Brembo Type III face type can help a driver avoid rear tire in stop lock up while still maintaining optimum braking performance.

  • Brembo Type III (aggressive face type): motorsport developed face type with an emphasis on high initial response while maintaining a smooth pedal release.
Brembo 380 x 30 Type III rear disc fitted.

Brembo 380 x 30 Type III rear disc fitted.

Brembo Performance Type III rear discs installed on GMG 991 GT3

Brembo Performance Type III rear discs installed on GMG 991 GT3

As mentioned earlier in this article, the Brembo 2-piece disc assemblies are compatible with the Porsche factory parking brake. One does not have to compromise and lose the parking brake functionality when installing the Brembo disc assemblies.

BRAKE FLUID AND BLEED

Upgrading brake fluid for spirited, track or racing use is easily one of the most overlooked things when thinking of upgrading any component or part of the brake system. Brembo’s HTC64T brake fluid is the top fluid used in the top professional racing categories around the world (Examples: F1, FIA GT, LMP1). This is because the Brembo fluid offers low compressibility, good after boil recovery, and high boiling points.

  • Brembo HTC64T Typical Applications: Open Wheel*, Stock Car, Rally, Endurance & Sprint GT**, Track Day.

*Brembo HTC64T is one of a very few select fluids being actively used by F1 teams.

**Brembo HTC64T and LCF600 Plus are both racing brake fluids which are actively used and homologated for FIA GT3 & GTE based sports-car racing.

  • Independently proven low Compressibility at severe temperatures.
  • Dry Boiling Point: 335 C (635 F)
  • Racing Use Only
Brembo HTC64T

Brembo HTC64T (used in F1, FIA, GT, LMP1)

Brake fluid performs a very critical function as it is the “life blood” of the brake system, as it is the foundation to hydraulically transfer brake pedal effort to the brake caliper’s pistons. Brake fluid also performs a vital function of lubricating caliper piston seals brake fluid performance (or the lack of) can directly affect brake pedal feel, pressure and consistency through the operating temperature range. It is also one the most cost effective ways to improve brake pedal consistency (avoiding spongy pedal) under high temperature use.

Once the Brembo performance 2-piece disc assemblies and RT pads were installed on all four corners, the OEM brake fluid was flushed and bled with Brembo Racing HTC64T brake fluid. As the fluid was being bled on each corner, GMG made sure to keep an ample amount of new fluid filled in the master cylinder reservoir to ensure that air did not enter into the hydraulic system.

Brembo fluid bleed

Brembo fluid bleed

Brembo HTC64 being poured in

Brembo HTC64 being poured in

ON TRACK IMPRESSIONS

To evaluate the results of the new Brembo discs, fluid bleed, and RT pads, the GMG Team took the 991 GT3 shop car to Thermal Club.

Driver (James Sofronas) and GMG Team comments: Testing out a new setup @thethermalclub today! @jamessofronas had the GMG 991 GT3 out and with the new Brembo Brake pad and Rotor setup says that the car is even more amazing! A predictable pedal feel without activating the ABS too early. A must have for any car that is going to see some track time! Combined with Pirelli Trofeo R tires it is just a winning combo!

Thermal Club Track layout. Image: Thermal Club

Thermal Club Track layout. Image: Thermal Club

Thermal Club located in Palm Springs, California often has very high ambient temperatures which can be demanding on the car, tires, and brakes. The effectiveness of brake cooling is only as good as the temperature of the air flowing thru the brake ducts (if the ambient air is hotter, the brakes will not cool down as much). The track layout and surface can be very similar to some of the European GT tracks, featuring many high speed to low speed braking zones, and a high level of mechanical grip (the more grip you have, the harder you can brake). GMG Racing has setup their shop GT3 understanding the demands of the various tracks around Southern California, and the Porsche 991 GT3, for optimal results.

GMG Racing 991 GT3 and R8 LMS Ultra at Thermal

GMG Racing 991 GT3 and R8 LMS Ultra at Thermal

Modern sports cars have very sophisticated OE ABS systems and engaging the ABS under braking can lead to poor threshold braking, lack of pedal feel, and potentially result in a slower lap time. Having a high overall level of braking confidence and control, usually allows the driver to spend less time on the brake pedal. If the brakes offer enough performance and control for the driver to stay out of ABS engagement (depending on their driving style and car setup), the result is usually a faster lap time on track.

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PORSCHE 911 GT3 (991): BREMBO 2-PIECE TYPE III DISCS

PORSCHE 911 GT3 (991): BREMBO 2-PIECE TYPE III DISCS

Porsche’s 911 GT3 (991) is a demanding platform on the OE brake package with unique demands (475 horsepower, over 3200 lbs curb weight, and multiple electronic braking / traction aids). The Brembo OE brakes equipped on the Porsche 911 GT3 & Turbo models are some of the most sophisticated designed for an OE application. The Porsche Brembo OE brakes utilize 6-piston aluminum fixed monobloc calipers front and 4-piston aluminum fixed monobloc calipers rear. The brake discs are heavy duty 380 x 34 mm ventilated front & 380 x 30 mm rear brake discs. The Porsche 911 GT3 brakes use a wide annulus (radial depth) front and rear pad for maximum swept area. The OE pads are also 18 mm thick front and rear which is comparable to most high performance aftermarket calipers.

Generally speaking about later model 911 platforms: The GT3 has always been more demanding on the rear brakes due to aggressive rear brake balance while the Turbo models are generally more demanding on the front brakes. While the OEM specification Porsche brakes all look similar, the caliper piston sizes, hydraulic systems and car balance can be considerably different.

There are certain limitations with the OE components on any high performance application as they are designed specifically for the car manufacturers to their requirements of comfort, wear rates in various road environments, cost and serviceability.

As the braking system’s primary function is to dissipate heat, Brembo uses purpose-designed discs in order to increase the fade resistance and thermal capacity of the system. These discs are directionally ventilated for enhanced cooling and slotted for better performance and continuously refreshing the pad surface. Brembo 2-piece discs are made up of a proprietary advanced cast-iron alloy which offers an exceptional coefficient of friction and resistance to thermal shock and fatigue.

The same Brembo Racing discs trusted every weekend in professional motorsports are also utilized in the Brembo Performance Program (GT, GT-R & Race Systems).

GMG 991 GT3 with Brembo Type III 2 piece discs. Photo Credit : GMG Racing

GMG 991 GT3 with Brembo Type III 2 piece discs. Photo Credit : GMG Racing


BENEFITS OF BREMBO 2-PIECE DISC UPGRADES:

  • OEM INTEGRATION: Brembo 2-piece disc upgrades are designed to work seamlessly with the OE calipers and systems (manufactured by Brembo for Porsche). This guarantees the utmost in safety and seamless fitment.
  • LIGHTWEIGHT: Disc assemblies include an outer iron disc with aluminum bell/hat and provide decreased corner weights to improve vehicle dynamics including handling, acceleration, and braking.
  • TYPE III SLOT PATTERN: Extensively used in professional motorsports, the Type III slot pattern offers a high initial response with excellent release characteristics.
  • HIGH THERMAL CAPACITY: Greatly improved thermal capacity and heat management over OE discs and other aftermarket discs in the market. This also improves braking performance and allows for greater longevity of the components.
  • FRICTION MATERIALS: Everything we learn by supporting top professional racing teams throughout the world goes into selecting the best brake pad options for all levels of street, track and racing use.

PACKAGES INCLUDE:

  1. Outer Brembo Type III discs (qty 2)
  2. 6061 T6 aluminum (machined from billet), hard anodized bell/hat
  3. Complete Brembo disc hardware (D-type bobbin) w/ anti-rattle springs. (Full Floating Option Available Upon Request
GMG Racing 991 GT3 Equipped with Brembo Racing discs. Photo Credit: GMG Racing

GMG Racing 991 GT3 Equipped with Brembo Racing discs. Photo Credit: GMG Racing

BREMBO 911 GT3 (991) 2-PIECE DISC OPTIONS:

FRONT BREMBO 2-PIECE DISC OPTIONS: 911 GT3 OE IRON EQUIPPED

MSRP COMPLETE AXLE SET: $1,895.00
911 GT3 Front disc specifications:

–          380 x 34 disc – Lightweight
–          Type III slot type
–          20 mm air-gap (wide air-gap for overall brake disc weight reduction)
–          72 vane ventilation
–          21 lbs – disc ring
–          23 lbs – complete 2-piece disc assembly
–          Compatible with 911 Turbo (991) Models

911 GT3 Front “High Thermal” disc specifications:

–          380 x 34 disc – High Thermal
–          Type III or Type V “Endurance” slot type available.
–          17 mm air-gap (narrow air-gap for the brake disc to have extra thermal capacity and durability under higher brake demand conditions)
–          72 vane ventilation
–          23 lbs – disc ring
–          24.5 lbs – complete 2-piece disc assembly
–          Compatible with 911 Turbo (991) Models

REAR BREMBO 2-PIECE DISC OPTIONS: 911 GT3 OE IRON EQUIPPED

MSRP COMPLETE AXLE SET: $1,895.00

911 GT3 Rear “High Thermal” disc specifications:

–          380 x 30 disc – High Thermal
–          Type III slot type
–          16 mm air-gap
–          48 vane ventilation
–          20 lbs – disc ring.
–          22 lbs – complete 2-piece disc assembly
–          Compatible with factory braking brake (e-brake)
–          Compatible with 911 Turbo (991) Models

PORSCHE 911 GT3 (991) OEM DISC WEIGHTS – FOR REFERENCE:

– Front, 380 x 34: 24 lbs
– Rear, 380 x 30: 23.4 lbs

PORSCHE 911 Turbo (991) OEM DISC WEIGHTS – FOR REFERENCE:

– Front, 380 x 34: 27.8 lbs
– Rear, 380 x 30: 24 lbs

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2015 BREMBO RACING AND PORSCHE MOTORSPORTS INVOLVEMENT:

Brembo Racing works very closely with Porsche Motorsport as a technical partner on multiple factory motorsport programs. Some of these include, but are not limited to, the 2015 spec Porsche 919 Le Mans Prototype program for the LMP class and the 911 (991) RSR for the GT Class. The 919 Hybrid is Porsche Motorsport’s latest fully factory supported effort since 2014 and features various cutting edge technologies which will eventually be carried through to road going vehicles.

LMP Class:

For 2015, to be competitive in the top prototype class, the Porsche 919 Hybrid has been re-engineered from the ground up. One of the many key changes is a Brembo Racing carbon brake package to maximize braking performance and reliability since the new 2015 model has an upgraded chassis, aerodynamics and has more power compared to 2014.

Brembo Racing Porsche 919 brake package:

Brake Calipers: Brembo Racing motorsport calipers.
Brake Discs: Brembo Racing carbon-carbon brake discs.

2015 Porsche 919 Hybrid LMP1 Car. Photo Credit: Porsche AG

2015 Porsche 919 Hybrid LMP1 Car. Photo Credit: Porsche AG

GT Class:

Porsche’s 911 (991) RSR is built to compete at the 24 hours of Le Mans and is the most sophisticated GT racing sports-car offered by Porsche Motorsport unlike the Cup Cars designed generally for customer / private teams. The 991 RSR is also specified with a Brembo Racing cast iron brake package. Teams can choose disc and pad configurations based on their individual car balance, setup, circuit and brake demand.

Brembo Racing Porsche 991 RSR brake package:

Brake Calipers: Brembo Racing motorsport calipers (6 piston – front, 4 piston – rear)
Brake Discs: Brembo Racing 380 mm and 355 mm cast iron brake discs.

Brembo is the OE brake supplier to Porsche, offering Performance upgrades for the various 991 platforms (Carrera S, GT3, Turbo models) using similar components and technology developed for professional motorsport.

MOTORSPORTS IMAGERY
Photo Credits: James Boone, Porsche Motorsport

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