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Wilwood 120-6478-RS Grand National III RH Caliper, 3.5 Inch Mount
Wilwood 120-6478-RS Grand National III RH Caliper, 3.5 Inch Mount

Wilwood 120-6478-RS Grand National III RH Caliper, 3.5 Inch Mount

Universal Fit, Six Caliper Pistons, 1.38" Rotor Thickness, Aluminum, Anodized, 1.75" Bore Size

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Wilwood 120-6478-RS Grand National III RH Caliper, 3.5 Inch Mount
Wilwood 120-6478-RS Grand National III RH Caliper, 3.5 Inch Mount
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We estimate this item will ship on or before December 20th.
Part # 8351206478RS
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Important Messages:

  • This item ships directly from the manufacturer. It may take an additional 2 business days for Wilwood to ship this item.
  • Get FREE shipping when your order includes this item and exceeds $99! Ground shipping only in the contiguous US.
  • This item ships via Ground Shipping only. Expedited and Air shipping options are not available.


Caliper Pistons:
Rotor Thickness:
Material Type:
Bore Size:
Centerline of Holes:
Thread Pitch:
1/8-27 NPT
Rotor Diameter:
13.06 Inch
Caliper Mounting Type:
Mounting Side:
Right Hand
Bore 2 Size:
Bore 3 Size:
Total Piston Area:
5.40 sq. in.
Mount Hole Size:
Mounted Height:
Pad Area:
11.31 sq. in.
Pad Volume:
6.90 cu. in.
GTIN Code:


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. 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.
Some parts are not legal for use in California or other states with similar laws/regulations

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