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1979-Up GM Metric Brake Rotor, 5 on 4-3/4 In, 5/8-11 In Coarse Studs
1979-Up GM Metric Brake Rotor, 5 on 4-3/4 In, 5/8-11 In Coarse Studs

1979-Up GM Metric Brake Rotor, 5 on 4-3/4 In, 5/8-11 In Coarse Studs

Dirt Late Model, Hobby Stock, Modified, Stock Car, Front Position, Round Rotor Shape, Steel

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1979-Up GM Metric Brake Rotor, 5 on 4-3/4 In, 5/8-11 In Coarse Studs
1979-Up GM Metric Brake Rotor, 5 on 4-3/4 In, 5/8-11 In Coarse Studs
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Part # 91031091
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Rotor Shape:
Rotor Diameter:
10.50 Inch
Rotor Type:
Rotor Style:
Plain Face
Rotor Material Type:
Rotor Finish:
Bolt Pattern:
5 on 4.75"
Thread Pitch:
MFG. Part #:
Sold in Quantity:


This 1979-up GM Metric front disc brake rotor will work with a Set # 6 inner bearing/race which fits most spindles. 5 on 4-3/4" with 5/8"-11 studs installed. 10.5" diameter x 1".  Must be used with 912-TS3 outer bearings for 1982-1987 spindle applications.  IMCA Approved.

This is a 1979-1981 Metric GM rotor with the bolt pattern changed to 5 on 4-3/4". It can be used on 1982-1987 GM metric spindles if you use our bearing/seal kit 91031048, or use at least the 1979-1981 style outer bearing 912TS3.

This rotor is designed for dirt track applications and should NOT be used for asphalt racing.


Proper Break-In Procedure for Steel or Cast Iron Rotors

New steel/iron rotors should be bedded in before being used in racing conditions. Proper bedding will prepare the rotor surface, prolong the rotor's life, and make it more resistant to thermal checking or cracking under severe braking conditions. The following procedures should be performed when bedding in both steel and cast iron rotors. It is best to bed in a new rotor using a used set of pads, preferably ones which will not create heat rapidly. Generating heat too rapidly will thermal shock the rotors. Likewise, when bedding in a new set of brake pads it is best to perform the process on a used rotor. This new/used bedding process permits controlled bedding of each individual component.

Make sure rotor surfaces are free from oils, grease, and brake fluid. Run vehicle up to a moderate speed and make several medium deceleration stops to heat up the rotor slowly. This will help reduce the chance of thermal shock caused by uneven heating of the rotor. Pull into the pits and allow the rotor to cool to ambient air temperature. Care should be taken not to ride the brakes into the pits as this may hot spot the rotor causing premature wear to the surface or structural damage.
Some parts are not legal for use in California or other states with similar laws/regulations

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