Product Summary

Universal Fit, Rear Position, 11.75 Inch Rotor Diameter

  • Replace those old drum rear brakes with modern disc brakes using this universal weld on disc brake kit
  • Features reinforced weld on brake brackets for use with '69-'77 GM brake calipers
  • 11.75" OD vented rotors which are .81" thick ensure cool operation for fade free braking performance
  • This basic kit includes rotors, brake hats, and caliper brackets to allow you to choose your own calipers
  • The 3" backspace steel brake hat accommodates 5 on 4-1/2, 4-3/4", and 5 on 5" bolt circles

Comes as a Kit

Key Specs

MFG. Part #91031920
BrandSpeedway Motors
Rotor Diameter11.75 Inch
Rotor TypeVented

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Replace those old drum brakes with modern rear disc brakes. Included steel caliper brackets weld to your 3" tube rearend, making this a universal kit for a variety of applications. Basic kit includes caliper brackets for '69-'77 GM mid-size car front calipers, Pro-lite vented .810" x 11-3/4" iron rotors, steel brake hats (3" backspace, 6-1/4" I.D.), and rotor bolts.

Hat fits 5 on 4-1/2", 5 on 4-3/4" and 5 on 5" bolt circles.

Caliper Brackets:

  • Mounts 1969-1977 GM mid-size car front caliper to any 3" tube rear end using 11-3/4" diameter rotors
  • Fully machined steel with punched lightening holes
  • Measures approximately 7" between mounting holes

Vented Brake Rotor

Every rotor is cast from premium grade, long grain carbon iron which exhibits long wear, high thermal stability, and excellent resistance to distortion in high heat. Modern foundry and machining techniques hold close tolerances on face and vane thickness. Combining the correct face thickness with a 32 vane casting provides superior heat management and long service life with low rotating and unsprung weight. The straight vane design also makes it possible to use the same rotor on left or right hand mounting locations.

  • Thickness: GM .810"
  • Outside Diameter: 11.75"
  • # Holes: 8
  • Bolt Circle: 7"
  • Thread: Thru
  • Weight: 8.00 lbs

Stamped Steel Disc Brake Rotor Hat

Stamped steel hat with all three bolt patterns: 5 on 4-1/2", 5 on 4-3/4", and 5 on 5" bolt circle patterns. Weighs just 2 lbs. and is IMCA approved.

  • Rotor Bolt Circle:  7" x 8 holes
  • 3.00" offset
  • 3.05" diameter center hole
  • 5.83" I.D. clearance
  • Stud Hole Diameter: 1/2"
  • Rotor Mount Bolt Hole: .325"

Rotor Hat Bolt Set

  • Ultralight, 5/16-24 thread
  • Self-locking nuts


Kit Includes:

(2) Caliper Brackets

(2) 11.75" Rotors

(2) Brake Rotor Hat

(2) Rotor Hat Bolt Kits

(1) Instruction Sheet




MFG. Part #91031920
BrandSpeedway Motors
Rotor Diameter11.75 Inch
Rotor TypeVented
Bolt PatternMulti: 5 on 4.5" | 4.75" | 5"
Parking Brake ProvisionNo
Rotor Hat Bolt Pattern8 x 7.00"
Rotor Thickness.81"
Rotor ShapeRound
Stud Diameter.5"
Thread Pitch7/16"-20
Sold in QuantityKit
NotesIncludes caliper brackets, rotors, rotor hats, bolts, and instructions.
Rotor Material TypeCast Iron
Front Rotor IncludedNo
Rear Rotor IncludedYes
Front Caliper IncludedNo
Rear Caliper IncludedNo
Front Spindles IncludedNo
Master Cylinder IncludedNo
Brake Booster IncludedNo