Grand National Caliper – Part No: 120-6479-RS
Call (805) 388-1188
Grand National III
Prod #: 120-6479-RS
Price: $385.50

Grand National III - Product Summary
Caliper No: 120-6479-RS

Piston Count 6
Piston Area (in²) 5.40
Piston Type Stainless
Dust Boot No
Rotor Dimensions
Rotor Width (in) 1.38
Rotor Diameter(in) 13.06
Pad Dimensions
Pad Area (in²) 11.1
Pad Volume (in³) 6.9
Duty Rating & Material
Material Aluminum
Weight(Lbs) 7.1
Colors & Finish
Color Black
Finish Black Anodize

Mount Center(in) 3.50
Mount Position Rear Mount
Mount Side Left Hand
Mount Type Lug
UPC Number
UPC 889545004663
Product Documents
Product Data Sheet

Click To Download
Installation Instructions

WARNING: Cancer and Reproductive Harm
Applicable to Brake Pads Only

120-6479-RS - Product Description

Grand National III

Wilwood’s GN lll is a time proven caliper that has been widely used with 5 on 5 hubs for stock car, road course, and off-road competition. The 3.50" mount configuration (also available in 6.00” mount) incorporates this legacy of enduring performance, with options available for the latest brake system heat management technology.

3.50" mount with taller height for 12.19" rotors. The new generation GN lll uses the same popular 3.50" mounting pattern found on the Superlite caliper series, but are built with a taller mounting height. This feature accommodates the installation of 12.19" diameter rotors on the same spindle brackets used with a Superlite caliper and 11.75" diameter rotor. The GN lll can be run with either a 1.25" or 1.38" thick rotor. This makes it possible to run three different bolt-on brake setups, without the need for bracket changes on the spindle.

High strength, low deflection, and superior stopping power. Each GN lll is manufactured from a precision casting using a tight grained, high-density aircraft alloy. It is a two-piece, closed bridge design with grade 8 thru-bolts and external stiffening ribs. The GN lll utilizes a unique six-piston configuration that generates high clamping force with balanced loading for extremely even pad wear. The 1.75" / 1.38" / 1.38" bore pattern contains a total of 5.44 square inches of effective piston clamp area. This makes the GN lll one of the largest calipers available, with weights starting at 5.94 pounds. The caliper bridges are fitted with stainless steel plates to reduce wear and provide smooth pad operation. Dual center bridge bolts add to the overall caliper strength and provide positive retention for the top loaded pads. Dollar for dollar, this combination is unmatched for high strength, low deflection, and superior stopping power.

Vehicle Applications
Driving Environment Street Performance
Vehicle Sub-Types Domestic
Application Duty Heavy Duty
Driving Environment Street Performance
Vehicle Sub-Types Import
Application Duty Heavy Duty
Driving Environment Rally
Vehicle Sub-Types
Application Duty Heavy Duty
Driving Environment Road Race
Vehicle Sub-Types
Application Duty Heavy Duty
Driving Environment Late Model Asphalt
Vehicle Sub-Types ASA, All Pro, SW Tour, etc...
Application Duty Heavy Duty
Driving Environment Stock Cars
Vehicle Sub-Types NASCAR, BGN, CTS, ARCA, etc...
Application Duty Heavy Duty
Driving Environment Off Road
Vehicle Sub-Types
Application Duty Heavy Duty
Driving Environment Industrial
Vehicle Sub-Types
Application Duty Heavy Duty

Product Specifications

Rotor Compatibility
Rotor Width (in) 1.38
Maximum Rotor Width (in) 1.38
Minimum Rotor Width (in) 1.25
Maximum Rotor Diameter(in) 13.06
Minimum Rotor Diameter(in) 12.19

Brake Pad Specifications
Brake Pad Type 1 7520
Brake Pad Type 2 N-A
Brake Pad Type 3 N-A
Total Pad Area (in²) 11.1
Total Pad Volume (in³) 6.9
Piston Specifications
Piston 1 Bore (in) 1.75
Piston 2 Bore (in) 1.38
Piston 3 Bore (in) 1.38
Total Piston Area (in²) 5.40

Mounting Specifications
Mount Type Lug
Mount Side Left Hand
Mount Center(in) 3.50
Mount Hole Size(in) 0.45
Mount Height(in) 3.07
Inlet Thread Size 1/8-27 NPT
Pad Dimensions & Part Numbers
Mount Dimensions & Part Numbers

Additional Notes

Thermlock® or stainless steel pistons. The standard GN lll uses six stainless steel cup pistons. Stainless is used for its slow heat transfer properties and high corrosion resistance. The GN lll/ST models feature Wilwood’s exclusive Thermlock® pistons to minimize the direct heat transfer from the pads. These pistons can reduce caliper temperatures by more than 30% over stainless steel pistons, without the need for fluid recirculation systems. Fluid temperatures are reduced, seal life is extended, and caliper service life is prolonged with less distortion and reduced wear in the piston bores. Cooler temperatures translate into maximum performance and ultimate reliability over the longest run. Thermlock® pistons are also available for the 6.00” mount, see page 109 for details. Using EXP 600 Plus racing brake fluid will guarantee success with trouble free performance in all extreme conditions.

The 3.50" mount GN Ill calipers use the 7520 style pad. The longer and wider pad face provides a full two cubic increase in pad volume over a 7320 style Superlite pad. Larger pads mean longer wear and additional heat resistance in extreme duty conditions. Four brake compounds are available to match brake torque and heat range requirements on any application.

Parts & Accessories

O-Ring Kit 130-3084
Replacement Dust Boot N-A
Replacement Piston 1 200-7531
Replacement Piston 2 200-7516
Replacement Piston 3 200-7516
Replacement Piston 4 N-A
Cross-Over O-Ring Kit N-A
Bridge Bolt Kit 230-12241
Wear Plate L/H 300-3053
Wear Plate R/H 300-3053
Pad Retainer 180-0053
Bleed Screw Kit 220-0627
Self Bleeder Tube 190-3615
Cross-Over Tube 190-3664

Additional products you may be interested in

Follow Wilwood on Facebook Follow Wilwood on Twitter see Wilwood Disc Brakes see Wilwood Disc Brakes
All images shown are for illustrative purposes only. Actual product received may be different than what is portrayed on the web site.
Wilwood makes every effort to maintain our web site to ensure the accuracy of prices and product information. However, product information and prices are subject to change without notice. Please call (805) 388-1188 before ordering to verify current prices and product information.
     Copyright © 2020 Wilwood Engineering, Inc. - All Rights Reserved