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ARP 156-2501 Harmonic Balancer Bolt Kit with Square Drive

Manufacturer

ARP

<h3>The Gold Standard in Performance Fasteners</h3> <p>When racing enthusiast Gary Holzapfel recognized that fastener failure was causing many engine breakdowns in 1968, he founded Automotive Racing Products (ARP) to solve a critical problem in motorsports. Drawing on his aerospace fastener manufacturing experience, Holzapfel created a company that would revolutionize the performance fastener industry. Today, ARP stands as the world's premier manufacturer of high-strength bolts, studs, nuts, and specialized hardware for racing and high-performance applications.</p> <p>ARP controls all aspects of the manufacturing process in-house, with all operations closely monitored, enabling the company to maintain its reputation for zero-defect quality. Every fastener undergoes forging, heat treatment, thread rolling, and precision finishing at ARP's Southern California facilities, which span over 115,000 square feet. This vertically integrated approach ensures that each component meets exacting standards for strength, fatigue resistance, and reliability under extreme conditions.</p> <h3>Engineered for Championship Performance</h3> <p>ARP's customer roster reads like a who's who of professional motorsports. The product line ranges from quality high-performance OEM replacement parts to exotic specialty hardware for Formula 1, IndyCar, NASCAR and NHRA drag racing and marine applications. The company's fasteners have secured victories in virtually every major racing championship worldwide, from Top Fuel dragsters to Formula One cars, proving their worth under the most demanding conditions imaginable.</p> <p>The brand's <a href="/48-arp-engine-cylinder-head-bolt-set-10306">engine cylinder head bolt sets</a> represent the cornerstone of ARP's catalog, offering engine builders the clamping force and reliability needed to prevent head gasket failure in high-boost and high-compression applications. These precision-engineered fasteners utilize proprietary materials and heat treatments that deliver up to ten times the fatigue strength of conventional bolts, making them essential for any serious performance build.</p> <p>For engine internals, ARP manufactures <a href="/48-arp-engine-connecting-rod-5276">connecting rods</a> designed to withstand extreme cylinder pressures and high RPM loads. Each rod is manufactured to aerospace standards with tight tolerances and superior material properties. Whether you're building a street performance engine or a full competition powerplant, ARP connecting rods provide the strength and consistency that professional engine builders demand.</p> <h3>Complete Fastener Solutions</h3> <p>Beyond engine components, ARP's product range extends throughout the entire vehicle. The company's <a href="/48-arp-wheel-lug-stud-7680">wheel lug studs</a> offer critical safety and performance benefits for racing and high-performance street applications, providing greater clamping force and durability than factory studs. ARP's product line contains thousands of part numbers and has expanded to include virtually every fastener found in an engine and driveline.</p> <p>Individual <a href="/48-arp-engine-cylinder-head-bolt-5308">engine cylinder head bolts</a> are also available for custom applications or specific replacement needs, manufactured to the same exacting standards as complete sets. This flexibility allows builders to source exactly what they need for specialized builds or repairs without compromising on quality.</p> <p>What sets ARP apart is not just the breadth of their catalog, but their willingness to develop custom solutions for unique applications. The company maintains complete R&D capabilities, including metallurgical research, product design, prototype machining, and extensive laboratory testing. This engineering expertise ensures that whether you're installing a simple head stud kit or building a record-setting race engine, ARP fasteners deliver the reliability and performance that professionals trust.</p>

Part Number

156-2501
07/12/2036 2:30 AM
Sale Price

$37.47

1 left at this price

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Usually delivered within 2 days

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No Hassle Returns

No Hassle Returns

Live-in-stock inventory

Live-in-stock inventory

Fitment guaranteed

Fitment guaranteed

Product Details

The ARP 156-2501 is a high-strength harmonic balancer bolt kit engineered to withstand the extreme kinetic energy absorbed by the balancer as the crankshaft flexes and twists. These ultra-strong bolts are rated at 200,000 psi tensile strength, allowing maximum clamping force to ensure the balancer remains locked in position under the most demanding conditions.

Key Features:

  • 200,000 psi tensile strength for superior clamping force
  • 12-point head design accepts deep sockets and resists stripping
  • 1/2" square drive forged into bolt head for engine rotation with standard 1/2" drive ratchet or breaker bar
  • 1/4" thick wide-area washer distributes load evenly
  • Extra tall head provides enhanced tool engagement
  • Constructed from heat-treated 8740 chrome moly steel
  • Heavy-duty black oxide finish for corrosion resistance

This square drive version combines the strength of ARP's premium balancer bolts with the convenience of a built-in 1/2" square drive, enabling easy rotation of the crankshaft assembly during engine building, installation, or maintenance procedures. The forged square drive eliminates the need for separate rotation tools while maintaining the bolt's structural integrity.

Products specifications

Overall Diameter

M12 x 1.50

Fastener Finish

Black oxide

Fastener Material

Chromemoly

Fastener Yield Strength (psi)

200,000 psi

Head Style

12-point

Quantity

Sold individually.

Socket

18mm

Thread Size

12mm x 1.50 RH

UHL

1.8

Underhead Length (in)

1.880 in.

Washer Included

Yes

So far so good. Ordering was seamless.

great

Great products and great delivery time

Good people

It's what I ordered

#1

Great turnaround time. Product was exactly what as displayed. Great service!!

Fast shipping cheapest I could find, easy to deal with, great product

All was good,except delivery wait time..it was longer than usual and delayed from the 8th to the 10th.

Very good deal and simple buying experience.

Very good prices and good shipping prices. found my parts cheaper then any place else. Thanks to Autoplicity for filling my order #8498 of 4/02/12 quickly and accurately. I will be back.

The item has not been delivered yet. But the email updates are great. And I found this much cheaper than elsewere.

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