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ARP 661-1003 Metric Hex Bolt Kit M6 Stainless Steel 5-Pack

Manufacturer

ARP

<h3>About ARP – Automotive Racing Products</h3><p>Few names carry as much weight in the performance fastener world as <strong>ARP</strong> — short for Automotive Racing Products. Back in 1968, racing enthusiast Gary Holzapfel noticed that many of his friends' broken engines were caused by fastener failure, and at the time no commercially available studs or bolts were up to the challenge — so he drew on his years of experience as a leading aerospace subcontractor and founded ARP. That problem-solving spirit has driven the company ever since.</p><p>From a backyard garage workshop, ARP has grown into a highly diversified manufacturer with 18 buildings across Southern California, totaling more than 275,000 square feet of forging, heat-treating, machining, quality control, finishing, and packaging facilities in Santa Paula and Ventura, California.</p><h3>Engineering That Goes Beyond &quot;Aerospace Quality&quot;</h3><p>ARP uses only top-quality materials — far above the usual &quot;aerospace quality&quot; others settle for — in a highly exacting manufacturing process to create fasteners with the strength and durability to last race after race. Fastener materials are available in 8740 Chrome Moly, ARP2000, and Custom Age 625+, each engineered for specific performance thresholds. In order to ensure optimum quality control, ARP controls all aspects of the manufacturing process entirely in-house — a discipline that has allowed it to build a reputation for &quot;zero defects&quot; quality throughout the industry.</p><p>Automotive Racing Products has achieved ISO 9001:2008 and AS9100 registration, certifications the company has maintained as a testament to its unwavering dedication to producing the highest quality fasteners available. ARP also operates an Aerospace Division and is one of the very few companies in the world fully licensed by the United States Government to manufacture MS-21250 fatigue-rated fasteners.</p><h3>Trusted by the World&apos;s Top Racing Programs</h3><p>ARP enjoys working relationships with professional engine builders and race teams across Formula 1, IndyCar, IMSA, NASCAR, NHRA, IHRA, Lucas Oil Late Model Dirt, and World of Outlaws — constant interaction that keeps ARP on the cutting edge of fastener technology. Whether you&apos;re building a weekend bracket racer or a full-time professional race engine, ARP has a solution engineered to hold things together under the most extreme conditions.</p><h3>ARP&apos;s Engine Fastener Lineup</h3><p>Today, ARP&apos;s product line contains thousands of part numbers and has expanded to include virtually every fastener found in an engine and driveline and throughout the suspension and frame. Among the most popular are <a href="/48-arp-engine-cylinder-head-bolt-set-10306">Engine Cylinder Head Bolt Sets</a>, <a href="/48-arp-engine-connecting-rod-bolt-5280">Engine Connecting Rod Bolts</a>, and complete <a href="/48-arp-engine-connecting-rod-5276">Engine Connecting Rods</a> — three categories that represent the critical fastening points where engine integrity is made or lost. ARP&apos;s High Performance series head bolt kits are rated at 170,000 psi — 15 percent stronger than Grade 8 fasteners — and are available with hex heads or reduced-wrenching 12-point heads that eliminate the need for valvetrain removal when re-torquing.</p><p>ARP stands behind its products indefinitely with respect to materials and workmanship, making every fastener a long-term investment in engine reliability rather than a consumable component.</p>

Part Number

661-1003
09/12/2036 7:40 AM
Sale Price

$12.77

In Stock (7)

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Usually delivered within 2 days

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No Hassle Returns

Live-in-stock inventory

Live-in-stock inventory

Fitment guaranteed

Fitment guaranteed

Product Details

The ARP 661-1003 is a premium 5-piece metric hex bolt kit designed for differential and ring & pinion installations, as well as general automotive, marine, and trailer applications. These high-quality fasteners are manufactured from specially alloyed ARP 300 stainless steel, providing exceptional strength and corrosion resistance.

Key Features:

  • Nominally rated at 180,000 psi tensile strength for superior clamping force
  • Constructed from ARP 300 stainless steel for rust-free, maintenance-free performance
  • Premium polished finish for professional appearance
  • Substantially stronger than standard Grade 8 hardware
  • 12-point head design for easier installation in tight spaces
  • Includes matching washers for complete installation

ARP fasteners are the choice of professional engine builders and performance enthusiasts who demand reliability and precision. Each bolt is manufactured to exacting tolerances and undergoes rigorous quality control to ensure consistent performance in critical fastening applications.

Products specifications

Fastener Finish

Black oxide

Fastener Head Style

Hex

Fastener Material

Chromemoly

Fastener Yield Strength (psi)

170,000 psi

Material

Black Oxide

Quantity

Sold as a set of 5.

Size

M8 x 1.25 x 30

Underhead Length (in)

1.181 in.

Underhead Length (mm)

30mm

Washers Included

Yes

Wrench Diameter

10mm

Wrenching

10mm

all good

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No hassels... exact match to old worn tires.

thanks

I had to place my order 4 times to get the system to accept the quantity I needed. I also checked into your email to check on my order and was told that my order did not exist. I had to call to make sure it hadn't been lost. Love the shocks, just installed this morning.

Easy peasy It was quick Didn't have time to change my mind

Straight forward pricing and great product!!!

Arrived in good working order.

Easy transaction, great price.

Autoplicity gave quick shipping and great status notifications of my order. Products were as advertised. Best prices around. Would definately recommend this company to people.

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