Wilwood Big Brake Kit

Wilhelm Raceworks Ultralite BBK

Ultralite Brake Kit Shown

Improve braking performance for track / race use, without adding extra weight!  Many other kits on the market for MR2 utilize 323mm (12.72") rotors off of the Supra and RX8, and while these are an economical solution, at 21 lb for the front and 18 lb for the rear, the rotors are HEAVY.

Built around two piece 12.19" rotors, the Wilhelm Raceworks heavy duty kit saves 7-8lb per corner  (~30lb total) compared to a kit based on Supra / RX8 rotors.  The rotors are actually about 3lb lighter (each) than stock 93+ MR2 Turbo rotors.  The calipers (including brackets) will save ~14lb compared to stock calipers, making the complete brake system weight nearly identical to 91 MR2 Turbo brakes.  Compared to the larger and heavier 93+ Turbo brakes, the heavy duty kit saves about 25lb.  The Ultralite kit saves another 10lb beyond that.

The kit uses Wilwood Forged Superlite (FSL) or Forged Narrow Dynalite (FNDL)  four piston calipers for all four corners plus Wilwood MC4 mechanical parking brake calipers.  Removal of the stock rotor dust shields is required.

Made in the USA!

Heavy Duty Big Brake Kit

Wilhelm Raceworks Heavy Duty Front BBK Installed

Wilhelm Raceworks Heavy Duty Rear BBK Installed

Heavy Duty Brake Kit Installed

The complete Wilhelm Raceworks Brake Kit consists of the following parts:

  • Aluminum caliper brackets, front and rear
  • Hardware for attaching the brackets and calipers
  • Four custom made Wilhelm Raceworks aluminum rotor hats
  • Socket head cap screws and "jet nuts" for attaching rotors to hats
  • Techna-Fit Steel braided brake lines front and rear
  • Aluminum bracket for parking brake calipers with attachment hardware
  • Custom parking brake cables
  • 2x Wilwood FSL front calipers with 1.38" pistons
  • 2x Wilwood FSL rear calipers with 1.12" pistons
  • 2x Wilwood MC4 mechanical calipers
  • 2x Wilwood HD curved vane front rotors
  • 2x Wilwood HD curved vane rear rotors
  • Wilwood BP20 brake pads, suitable for street and moderate track use.
Heavy Duty Big Brake Kit

Ultralite Big Brake Kit

For those looking for a more budget friendly and even lighter weight option the following kits use the Wilwood Forged Narrow Dynalite calipers and Wilwood Ultralite rotors.  The calipers and pads are slightly smaller, and the rotors are lighter weight.  Not only does this save you $350 on a complete kit, but it saves an additional 10 lb off the brake system weight.  Suitable for street, autocross, and occasional track use, not recommended for heavy track use.

Ultralite Big Brake Kit

Beginning July 2019, all brake Wilhelm Raceworks brake kits come with socket head cap screws and Mil-Spec MS21042-5 self locking "jet nuts" for attaching the rotors to the hats.  NO MORE SAFETY WIRE REQUIRED!  If you have an older kit and want to convert to the new attachment I can modify your hats for $10 each, plus $10 per rotor for the new hardware kit. >

Rotor hardware

International shipping (other than to Canada) is usually prohibitively expensive on a complete brake kit.  For my international customers I recommend purchasing the "Basic Big Brake Kit" found below and finding a local Wilwood dealer to source the rotors, calipers, and pads.

Installation Instructions

The calipers included in the complete kit provide a moderately conservative brake bias to reduce the chances of rear brake lock-up.  If you have an adjustable proportioning valve a larger rear caliper can provide slightly better overall bias.  Please note above if you prefer a different piston size.  Feel free to contact me if you wish to discuss brake bias in more detail.

If you have a favorite brand of brake pads you wish to use, the pads can be eliminated from the kit, or an alternate Wilwood pad can be substituted.  Please contact me to submit a custom order if you would like pads other than the Wilwood BP20. 
Note: The BP20 pads can handle quite a bit of track abuse, but can be a little noisy for street use.  If you prefer a more street friendly pad please let me know and I will substitute the BP10 instead!

The slightly lighter weight and less expensive Wilwood Ultralite rotors or the slotted GT versions of the standard HD rotors are also available as a custom order.  For those looking for extra front wheel clearance, I can also substitute the thinner rear rotors and hats for the normal fronts, along with a narrower front caliper.  This will save you ~0.44in (11mm) of caliper to spoke clearance.

Note: The standard color of the main calipers is a medium gray as shown here.  The parking calipers are available in black, red or silver (black is standard, please let me know if you want one of the other colors).  If color matching is important to you the main calipers (HD kit only) can be powder coated black for an extra $40 each.

Note: The calipers, rotors, and pads ship directly from Wilwood and will arrive separately from the rest of the parts.

Note: The calipers available for this kit do not include dust seals.  This can be a problem for passing inspections in some locations.

Basic Big Brake Kit

Wilhelm Raceworks BBK brackets and hardware

If you prefer to purchase the rotors, calipers, and pads yourself, the basic kit consists of the following parts.  This is usually the best option for international customers.

  • Aluminum caliper brackets, front and rear
  • Hardware for attaching the brackets and calipers
  • Four custom made Wilhelm Raceworks aluminum rotor hats
  • Socket head cap screws and "jet nuts" for attaching rotors to hats
  • Techna-Fit Steel braided brake lines front and rear
  • Aluminum bracket for parking brake calipers with attachment hardware
  • Custom parking brake cables
Basic Big Brake Kit - No Calipers, Rotors, or Pads


To complete your brake setup you will also need to purchase or already have:

  • 2x Wilwood FSL or FNDL calipers for front
  • 2x Wilwood FSL of FNDL calipers for rear
  • 2x Wilwood MC4 mechanical calipers
  • 2x 12.19" x 1.25" rotors with 8x7.00" bolt pattern
  • 2x 12.19" x .81 rotors with 8x7.00" bolt pattern
  • 2x Brake pad set for your choice of calipers

Approximate cost for these items should be $1000-$1450 for a full front / rear setup with parking brake, depending on where you buy them and your choice of rotors, calipers, and pads. 

Installation Instructions

Technical Info


This kit can use virtually any 12.19" rotor with an 8x7.00" bolt pattern, 1.25" thickness for the front and .81" thickness for the rear.  There are numerous options from various manufacturers including Wilwood, Afco, Colman Racing, and many others.  They are available with straight or curved vanes, and slotted, cross drilled, or both.  The Wilwood options are shown in the chart below.  There are many others on the market as well.  Be sure to purchase one right and one left if buying curved vane rotors!


Front Rotors (12.19"x1.25")
Brand / Model LH Part # RH Part # Vane Style Price Weight
Wilwood GT48 (slotted) 160-11840 160-11839 Curved $139 12.7lb
Wilwood HD48 160-11836 160-11835 Curved $125 12.7lb
Wilwood Ultralight 160-2895 160-2894 Curved $70 10.5lb
Rear Rotors (12.19"x.81")
Wilwood GT36 (slotted) 160-12292 160-12291 Curved $120 9.5lb
Wilwood HD36 160-12290 160-12289 Curved $99 9.5lb
Wilwood Ultralight 160-0277 160-0277 Straight $38 8.9lb



Caliper choice is important to optimize brake bias for maximum braking potential, while minimizing the chance of locking the rear brakes before the fronts.

For MR2s equipped with the non-turbo brake proportioning valve, front calipers with 1.38" pistons and rears with 1.25" pistons will provide optimal brake bias for most street cars with street tires and street pads.   However, this combination requires an adjustable proportioning valve for use with high friction race pads and / or high grip race tires.  For those looking for a less aggressive setup or who don't want to bother with an adjustable proportioning valve, the 1.12" piston calipers for the rear will provide a more forward biased setup.

For those with the turbo proportioning valve the 1.38" / 1.12" caliper combination will provide optimal bias at about 1g deceleration.  Again, high grip race tires and high friction pads may require an adjustable proportioning valve.

More details on brake bias and the effects of various caliper / pad / proportioning valve combinations can be found on my Brake Bias page.  Please contact me if you have questions about choosing calipers for your setup.  Note: FSL = Forged Superlite, FNDL = Forged Narrow Dynalite

Recommended Wilwood Calipers
Caliper Type Part # Piston Diameter Rotor Width Position Notes
FSL 120-11130 1.38" 1.25" Front Standard piston sizes supplied with kits.
FNDL 120-11576
FSL 120-11126 1.25" .81" Rear OK with NA proportioning valve on street pads / street tires.  Adjustable proportioning valve recommended.
FSL 120-11125 1.12" .81" Rear Standard piston size supplied with kits.  Optimal with Turbo proportioning valve, slightly conservative bias with NA proportioning valve.
FNDL 120-11578


Another caliper option is to use the 1.62" calipers in the front, paired with either the 1.38" in the rear for those with the NA proportioning valve, or the 1.25" in the rear with the turbo proportioning valve.  This setup is a bit more conservative than the setup above, but should provide good performance.  It will also reduce overall brake system pressure.  This may also be an option for those who already have a set of calipers they want to use.  Part numbers for this option are listed below.

Alternate Wilwood Calipers
Caliper Type Part # Piston Diameter Rotor Width Position Notes
FSL 120-11133 1.62" 1.25" Front  
FNDL 120-14333
FSL 120-11128 1.38" .81" Rear Use with NA proportioning valve.  Adjustable proportioning valve may be required for race use.
FNDL 120-11575
FSL 120-11126 1.25" .81" Rear Use with Turbo proportioning valve.


The parking caliper used with the kit is the Wilwood MC4.   One of each LH/RH is required.

   Wilwood MC4 Parking Calipers
LH Part #  120-12070-BK
RH Part #  120-12069-BK

The part numbers above are the black powdercoated version.  Red and silver are also available.


Brake Pads

Many companies make pads in many different compounds for the Wilwood FSL caliper, including but not limited to: Wilwood, Porterfield, Performance Friction, Hawk, Raybestos, etc.  The pad shape is for the FSL calipers is #7420, and for the FNDL is #7816.   For other manufacturers, TopBrakes.com has a good selection at good prices.


Custom Parts / Clearances

The Wilhelm Raceworks hats and main caliper brackets in this kit are machined from 6061-T6 aluminum, and black anodized.  All are designed around the brake torque required for 1.4g deceleration, and with a factor of safety of 2x on the 500 million cycle fatigue strength of 6061-T6 aluminum.

The parking brake system in this kit is capable of achieving deceleration rates of ~.3g.  More than enough to pass the emergency brake function tests that I am aware of.  However, it is ultimately designed and intended to be a parking brake, or for that once-in-a-lifetime emergency situation.  If you are drifting or doing hand-brake turns, you may find it to be insufficient.

The front calipers sit about 1/8" closer to the wheel than they do on the typical Supra rotor based kit.

Assuming adequate spoke to caliper clearance, most 16" wheels should fit over the front brakes without issue.  The parking caliper in the rear might cause an issue with some 16" wheels.  Use the template below to check fit on your wheels before ordering.

Caliper Clearance Template for HD Brake Kit

Caliper Clearance Template for Ultralite Brake Kit