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Basic Weld-On Rear Disc Brake Kit for 1978-88 GM Caliper, 3 In BS
Basic Weld-On Rear Disc Brake Kit for 1978-88 GM Caliper, 3 In BS

Basic Weld-On Rear Disc Brake Kit for 1978-88 GM Caliper, 3 In BS

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Basic Weld-On Rear Disc Brake Kit for 1978-88 GM Caliper, 3 In BS
Basic Weld-On Rear Disc Brake Kit for 1978-88 GM Caliper, 3 In BS
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Part # 91031925
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Bolt Pattern:
Multi: 5 on 5"/4.75"/4.50"
Rotor Diameter:
11.75 Inch
Rotor Type:
MFG. Part #:
Rotor Hat Bolt Pattern:
8 x 7.00"
Rotor Thickness:
Rotor Shape:
Thread Pitch:
Hardware Included:
Sold in Quantity:
Includes rotors, rotor hats, caliper brackets, hardware, and instruction sheets.
Rotor Material Type:
Cast Iron


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 '78-'88 GM metric 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.

910-31925 Instructions (PDF)

Instructions (PDF)


Brake pad and caliper installation note:  

This bracket features a 90 degree bend in the bracket at the slider bolt threaded area for additional caliper support.  This part of the bracket may or may not interfere with the corner of the inner brake pad backing plate due to differences in brake pad manufacturers.  When this occurs, it will be necessary to simply remove a minimal amount of backing plate material at each corner of the inner brake pad to allow for the necessary clearance between the bracket and brake pad when the caliper and pads are fully installed.

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

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What's In The Kit

Each kit from Speedway Motors is carefully packaged and delivered right to your door. Below is a list of all the items you should expect to receive when you order this kit. Some of these items may also be available for sale individually if you're here looking for replacement parts.
  • Speedway Pro-Lite Vented Brake Rotor, 11.75 x .81 Inch
    Qty x 2
  • Speedway Stamped Steel Disc Brake Rotor Hat, 3 Inch Offset
    Qty x 2
  • Rotor Hat Bolt Set, 1/8 Inch Thick
    Qty x 2
  • Weld-On 1978-88 GM Metric Caliper Bracket
    Qty x 2
  • Instruct Sheet-Brake Kit
    Qty x 1
  • Speedway 1978-88 GM Metric Brake Pad Spacer
    Qty x 2

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