Mustang II Disc Brake Rotor, 5 on 4-3/4 Inch

#91031002

Mustang II Disc Brake Rotor, 5 on 4-3/4 Inch

Name: Mustang II Disc Brake Rotor, 5 on 4-3/4 Inch
Brand: Speedway Motors
SKU: 91031002
Price: 56.99 USD
Availability: InStock
Rating: 4.7 (30 reviews)

30 Reviews

9 Questions

This 9-1/4" diameter rotor for Mustang II spindles is factory made with 5 on 4-3/4" GM bolt pattern
Premium cast iron vented rotor construction dissipates heat to reduce or eliminate brake fade
New bearing races come installed in this rotor with bearing and seal kits available separately to complete the installation

Bolt Circle Pattern:

5 on 4-3/4 Inch

5 on 4-1/2 Inch

$56.99

/each

In Stock

Quantity

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Product Summary

Front Position, Round Rotor Shape, Vented Rotor Type

This 9-1/4" diameter rotor for Mustang II spindles is factory made with 5 on 4-3/4" GM bolt pattern
Premium cast iron vented rotor construction dissipates heat to reduce or eliminate brake fade
New bearing races come installed in this rotor with bearing and seal kits available separately to complete the installation
Includes 7/16" fine thread wheel studs (installed)
Bearing and seal kit to finish installation is sold separately

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Key Specs

Rotor Diameter	9.25 Inch
Rotor Style	Plain Face
Rotor Material Type	Cast Iron
Rotor Thickness	0.88"
Bolt Pattern	5 on 4.75"

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Speedway Motors 91031002 Details

Vented stock 9-1/4" diameter brake rotors for 1974-1980 Mustang II, Pinto, or Bobcat spindles (or Speedway brake kits using '49-'54 Chevy spindles). Brake rotors are new, not plugged or re-drilled. Has a 5 on 4-3/4" bolt pattern with corresponding 7/16" diameter fine thread wheel studs.

Vented, stock diameter Mustang II style rotor
Outside Diameter of rotor disc - 9.256"
Thickness of vented disc - .884"
I.D. of back side of rotor - 6.256"
Rear rotor face to bearing hub - .290"
Outer hub diameter where wheel will mount - 5.834"
Outer hub height - 1.450"
Bearing snout is 1.60" tall, 2.55" diameter at bottom and 2.384" at outer end
Races are included and installed

Be sure to install new bearings and seals (910-31000) with your new disc brake rotors.

CA WARNING:

Can expose you to lead, a carcinogen and reproductive toxicant. See www.P65Warnings.ca.gov

Speedway Motors 91031002 Specifications

KEY SPECS
MFG. Part #	91031002
Brand	Speedway Motors
Rotor Diameter	9.25 Inch
Rotor Style	Plain Face
Rotor Material Type	Cast Iron
Rotor Thickness	0.88"
Bolt Pattern	5 on 4.75"

GENERAL
Position	Front
Rotor Shape	Round
Rotor Type	Vented
Rotor Finish	Plain
Flange Diameter	5.74"
Stud Length	0.93"
Stud Diameter	0.44"
Thread Pitch	7/16"-20
Weight	14.6 lbs.
Sold in Quantity	Each
Notes	Fits Mustang II/Pinto/Bobcat spindles. Replacement bearing cups for OEM: 912TLM12710 (cup, outer), 912TL68110 (cup, inner), Knurl dia. 0.475".

Ratings & Reviews

4.7

30 Reviews

Overall Assessment

Customers applaud the product's quality, usability, and seamless fit on varying car models, particularly vintage Chevrolets and Fords. The product stood out for its functionality and practicality, improving car performance and alignment, and facilitating smoother and safer driving experiences. Many users highlighted that it perfectly resolved different rotor and bolt-pattern issues, which couldn't be solved with products from specialized stores. Moreover, customers appreciated the superior quality of materials used and the ease of installation highlighting the component's perfect fit, as opposed to competitors' products, thus becoming a reliable solution for mechanic challenges. Lastly, the ready placement of studs was positively noted. Some comments suggested lower quality perception, but were outweighed by the overall approval and product satisfaction.

Write A Review

4.7

30 reviews

Most Liked Positive Review

5.0

Perfect fit

Used to run GM 5 lug 4 3/4BC rims on my 1937 International D2 pickup with mustang II front suspension.Nice product for GM wheels to Ford Mustang II suspension without using wheel adapters.Great setup when used with the bearing and seal kit and new dust caps also sold here at Speedway

Most Liked Negative Review

1.0

Small 9" GM rotors (mustang II)

these are low quality.. I decided to keep my US made rotors and was able to get them turned... While these rotors would have worked I really was disapointed in the quality

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Yes

5.0

11 months ago

Shorty

Madera California

Verified

The product was absolutely perfect thank you very much

Would Recommend

good product quick shipping

5.0

3 years ago

Bill

Verified

rotor worked great

Would Recommend

Mustang II front end Chevy bolt pattern

5.0

5 years ago

48 Chevy

The Couve

Verified

Helps the car stop holds the wheel on pretty good. haha

Would Recommend

good

5.0

5 years ago

Muck

Rindge, New Hampshire

Verified

These are going on a 49' Chevy with straight axle set up.

Would Recommend

I would definitely buy this again

5.0

5 years ago

gospelpreacher

Longview, Texas

Verified

No one could help me with my mustang II front end with rotor and brake pad. Speedway had just what I needed. I even called the people that specialize in them, and they couldn't help me. Thanks Speedway!!

Would Recommend

yes i would buy this product again

5.0

6 years ago

jaymie s

hamilton ohio

Verified

went together like a dream all the parts

Would Recommend

Finally after 20 years of 4 hole wheels on front and 5 on bk

5.0

7 years ago

Grandpa

Great Falls, Montana

Verified

It's nice to have 5 hole wheels all the way around my 26 Chevy 2door sedan after 20 years! 😎

Would Recommend

I would definitely buy this product again

5.0

7 years ago

Daddy O

Phoenix, Az

Verified

Perfict fit for my 35 chevy mustang ll front with 14' wheels

Would Recommend

These are a good part and replacement quality

4.0

8 years ago

Billy Clyde

Birmingham, Alabama

Verified

I like the fact the studs are in place and no issues at all with these , they are a decent replacement part.

Would Recommend

Perfect

5.0

8 years ago

Jimbo

Oklahoma

Verified

Couldn't find these locally

Would Recommend

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Questions & Answers

9 Questions • 10 Answers

Sort Questions

What brake caliper do you use ?

by Jarett

• 3 years ago

1 answer

View Answer

Can you tell me if these have been stress relieved with heat treating or are they as cast?

by Roy

• 7 years ago

1 answer

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Do these rotors widen the track like the 11 inch conversions?

by Lee

• 7 years ago

1 answer

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Dust cap?? what is the correct p/n dust cap to use with these rotors?

by Jnizzer

• 11 years ago

1 answer

View Answer

Would these fit on a 64 Mustang? Would these rotors and the calipers 91031045 be able to fit on the front of a 64 Mustang? Or is it very specific to a 1974 to 1980 Mustang? Changing from drums to disk.

by neble

• 13 years ago

1 answer

View Answer

Races on new rotor Hello do these new rotors already have the bearing races installed? I am replacing my old mustang 2 rotors hopefully with your new setup and figured I'd replace bearings as well just wasn't sure if I needed the bearing kit with races or the 910-31000 kit thanks

by Docerz

• 13 years ago

2 answers

View Answers

do you get the pair or just one rotor when you order?

• 15 years ago

1 answer

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What size are the rotors and can you get them crossdrilled and slotted?

by Murphy

• 15 years ago

1 answer

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Can you tell me the stud size and thread size used on these hubs?

by Wayno

• 15 years ago

1 answer

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9 of 9 questions shown

Fitment

1974-1978 Ford Mustang II

1974-1980 Ford Pinto

1975-1980 Mercury Bobcat