Mustang II Disc Brake Rotor, 5 on 4-1/2 Inch
Mustang II Disc Brake Rotor, 5 on 4-1/2 Inch
Speedway Motors

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#91031001

Mustang II Disc Brake Rotor, 5 on 4-1/2 Inch

  • Brand new vented stock 9-1/4" rotors for use on '74-'80 Pinto or Bobcat and '74-'78 Mustang II spindles or Speedway kit for early Chevy spindles
  • Available for either 4-1/2" Ford/Mopar or 4-3/4" Chevy/ small GM bolt pattern with corresponding wheel studs
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Bolt Circle Pattern:

5 on 4-1/2 Inch

5 on 4-3/4 Inch

$56.99

/each

In Stock


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Product Summary

Front Position, Round Rotor Shape, Vented Rotor Type

  • Brand new vented stock 9-1/4" rotors for use on '74-'80 Pinto or Bobcat and '74-'78 Mustang II spindles or Speedway kit for early Chevy spindles
  • Available for either 4-1/2" Ford/Mopar or 4-3/4" Chevy/ small GM bolt pattern with corresponding wheel studs
  • 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
  • Be sure to install new bearings and seals, pt# 910-31000 with your new disc brake rotors
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Key Specs

Rotor Diameter9.25 Inch
Rotor StylePlain Face
Rotor Material TypeSteel
Rotor Thickness0.88"
Bolt Pattern5 on 4.5"
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Speedway Motors 91031001 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). These five lug conversion brake rotors are new, not plugged or re-drilled. Has a 5 on 4-1/2" bolt pattern with corresponding 1/2" diameter fine thread wheel studs.

  • 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.

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

Speedway Motors 91031001 Specifications

KEY SPECS
MFG. Part #91031001
BrandSpeedway Motors
Rotor Diameter9.25 Inch
Rotor StylePlain Face
Rotor Material TypeSteel
Rotor Thickness0.88"
Bolt Pattern5 on 4.5"
GENERAL
PositionFront
Rotor ShapeRound
Rotor TypeVented
Rotor FinishPlain
Flange Diameter5.75"
Stud Length1.25"
Stud Diameter0.5"
Thread Pitch1/2"-20
Weight13.95 lbs.
Sold in QuantityEach
NotesFits Mustang II/Pinto/Bobcat spindles. Use 912TLM12710 (outer cup) and 912TL68110 (inner cup), Hub flange is 5.740". OD of snout for wheel clearance is 2.50".Uses a .565 Knurl wheel stud.

Ratings & Reviews

4.9

49 Reviews

Overall Assessment

Customers consistently praise the product for its high quality, excellent fit, and superb functionality. The product's compatibility with various car models like Mustang, Pinto, and Ford models is consistently highlighted, enabling diverse usage scenarios. Many customers note the smooth running and reliability of the product, even after extended periods and miles of use. The product's ease of installation is a key theme, with customers enjoying the simple process. There is a unanimous agreement on the product's solid value for money, with the competitive pricing frequently mentioned. The product's adaptability for wheel conversions and customizations is reflected in positive feedback. Despite differing car models and uses, customer reviews represent a broad consensus on the durability, functionality, usability, and value of the product.

Write A Review

4.9

49 reviews

5

47

4

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Most Liked Positive Review

5.0

Nice Product, Imported but well made!!

I got my '39 Pontiac with mustang II R&P. It had Ford 4 lug rotors on it and I wanted all 4 corners to be GM 4 3/4 pattern. Didn't know what I was going to do at first. Called [...]...no go, called [...]..nothing. Then someone mentioned Speedway..did my search and there they were...just what I needed. Got the new Inner and outer bearings and races at the same time. Right On Speedway!! I just wish changing out the rear from GM 5 on 5 to 4 3/4 was as easy as swapping out to these front rotors!!

Most Liked Negative Review

3.0

Too soon to tell!

Very easy to install, good fit, inexpensive, but foreign-made (explains inexpensive?)

Filter by Ratings

Happy they had them in stock

5.0

a year ago

Canuck

Glendale, Arizona

Verified

Needed front rotors for my Hot Rod and Speedway was the only place in town that had them. Great price too.

Would Recommend

yes

5.0

2 years ago

Cobra 2 Girl

N.Wilkesboro N.C

Verified

Great place to find the parts your looking for

Would Recommend

yes, a very good product

5.0

2 years ago

an old Ford guy

Valley Springs Ca.

Verified

these rotors went on a 1937 Ford street rod, with mustang rack and 9 1/4" rotors very good quality bearing races included a plus best price around, I shop around, my local auto parts store in town , had them in the warehouse, but not in stock, more than double the cost from Speedways price, good product good quality good price

Would Recommend

Great product

5.0

2 years ago

Rv

Las Vegas, NM

Super fast service, great product

Would Recommend

Would buy again

5.0

4 years ago

Jerry

Nevada

I have run these on a bucket for eleven years and 8000 miles and they still work like new. I did have to turn one rotor when first installed as it was a little out, but they have both run since then without any problem. Nice smooth silent stops every time.

Would Recommend

i will buy again

5.0

4 years ago

rob

dayton ohio

Verified

perfect for my 36 ford

Would Recommend

Yes

5.0

4 years ago

Al

Al

Verified

Ok

This was just what I needed to finish the front brakes on my

5.0

4 years ago

T Builder

Willis Texas

Verified

This was just what I needed to finish the front brakes on my 23 T-Bucket . No one locally could get the right parts but Speedway has had almost everything I've needed

Would Recommend

Bought it for the mustang 2 on the willys

5.0

4 years ago

Mr Crawley

Belleville mi.

Verified

Nice to have a street rod speed shop that's reasonable.

Would Recommend

I would buy again if needed.

5.0

5 years ago

Easy

CLT

Verified

Perfect fit, works great.

Would Recommend

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Showing 10 of 49 reviews

Questions & Answers

14 Questions • 14 Answers

Thought I was buying 5 on 4.5. Studs measure more like 5 on 4 5/16. Won't fit my wheels. Which rotors actually measure 5 on 4.5?

by Steve

• 8 years ago

1 answer

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Can i use these on my 85 mustang to convert it from 4 lug to 5 without changing the spindles or calipers .

by joshs

• 8 years ago

2 answers

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What brake kit fits this hub. (What caliper and mount?) Is it stock MII/Pinto or does the GM metric caliper fit with the right caliper mount? Thanks

by BDub

• 9 years ago

1 answer

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Will this work on a 1953 chevy pickup

by Tiny

• 10 years ago

1 answer

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1. Can this rotor be installed on and work with the Speedway Motors Mustang II 2" drop spindle, part # 91034304? 2. Will this rotor work with the stock Mustang II caliper bracket and caliper? Thanks!!

by Tom Terrific

• 11 years ago

1 answer

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Are these manufactured by Heidts?

by DIckP

• 11 years ago

1 answer

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are all dimensions the same as stock mustang ii rotors besides the lug pattern

by HomerJ

• 12 years ago

2 answers

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Will this fit a 1971 pinto spindle?

by bseries

• 12 years ago

2 answers

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Will these work with the stock brake calipers of a '79 pinto? I want to make sure these will work with all the stock front end components of a 1979 Ford Pinto like the OEM 4 lug brake calipers

by clharper93

• 12 years ago

2 answers

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Are these rotors a Ford 5 lug bolt pattern?

by robby

• 12 years ago

1 answer

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