2024 ARP Catalog

2024

Accessory Studs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92 Accessory Cam Drive. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101 Air Cleaner. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103 Alternator. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98, 111, 135 Apparel. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 177 Auto Transmission Pan. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125 Balancer Bolts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108 Bellhousing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122 Blower (break-away). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107 Blower Pulley. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107 Bolts, SAE. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144 10/24 & 10/32. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145 1/4-20. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 146 1/4-28. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147 5/16-18. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 148 5/16-24. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149 3/8-16 Reduced & Standard wrenching. . . . . . . . . . . . 150 3/8-24 Reduced & Standard wrenching. . . . . . . . . . . . 151 7/16-14 Standard wrenching. . . . . . . . . . . . . . . . . . . . . 152 7/16-20 Standard wrenching. . . . . . . . . . . . . . . . . . . . . 153 1/2-13. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155 1/2-20. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 156 Bolts, Metric M6 x 1 0. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 157 M8 x 1 25. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 158 M10 x 1 25, M10 x 1 50. . . . . . . . . . . . . . . . . . . . . . . . . 159 M12 x 1 50, M12 x 1 75. . . . . . . . . . . . . . . . . . . . . . . . . 160 Brake Hat. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127 Bulk Fastener Bins. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 170 Cam. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112 Cam Tower . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113 Carburetor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102, 135 Carburetor Float Bowl. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105 Carrier Fasteners. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123 Circle Track Racing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133 Speed Studs & Nuts . . . . . . . . . . . . . . . . . . . . . . 133 & 134 Intake Manifold. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 134 Carburetor, drilled. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135 Header, drilled. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136 Front Mandrel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136 Clutch Cover. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124 Coil Bracket . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106 Cylinder Head Studs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58 Cylinder Head Bolts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72 Damper, Harmonic. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108 Diesel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137 Cylinder Head Studs. . . . . . . . . . . . . . . . . . . . . . . . . . . . 138 Cylinder Head Bolts . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139 Rod Bolts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139 Main Studs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140 Harmonic Damper . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140 Exhaust Fastener. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141 2 QUICK INDEX N EW & R E V I S E D K I T S F O R 2 0 2 4 (as of December, 2023 – scan the QR code below for the most up-to-date information on our website) Caterpillar C15 Head Bolt Kit (p 73) . . . . . . . . . . . . . . . . . . . . . . . 138-3701 Chevrolet Gen III/IV LS Stud Repair Kit, ARP2000 (p 61). . . . . . . . . . . . . 234-4348 Stud Repair Kit, Custom Age 625+ (p 61). . . . . 234-4348 Chrysler 5.7L, 6.1L & 6.4L Gen III Hemi Head Stud Kit, Custom Age 625+ (p 64). . . . . . 244-4301 Ford Coyote V8 5.0L (2011-2012) M12 Head Stud Kit, Custom Age 625+ (p 66). . . . . . 256-4304 Ford Coyote V8 5.0L (2018-2019) M12 Head Stud Kit, Custom Age 625+ (p 66). . . . . . 256-4305 Ford 5.2L Shelby GT350 Voodoo (2015-2020) Head Stud Kit, Custom Age 625+ (p 66). . . . . . 456-4305 Ford Big Block 429-460 with oil pickup standoff bolt Main Bolt Kit (p 84). . . . . . . . . . . . . . . . . . . . . . . . 155-5203 Ford Small Block 239-256-272-292 Y block (EBU) Rod Bolt Kit (p 47). . . . . . . . . . . . . . . . . . . . . . . . . 154-6007 Ford Power Stroke 6.7L Rod Bolt Kit, ARP2000 (p 47). . . . . . . . . . . . . . . . 250-6304 Thread Cleaning Chaser M10 x 1.50 x 6.00˝ OAL (p 174). . . . . . . . . . . . . 912-0019 M14 x 1 50 (p 174). . . . . . . . . . . . . . . . . . . . . . . . 912-0017 M14 x 2 00 (p 174). . . . . . . . . . . . . . . . . . . . . . . . 912-0018 Ford Godzilla 7.3L Rod Bolt Kit, ARP2000 (p 48). . . . . . . . . . . . . . . . 258-6301 Head Stud Kit, ARP2000 (p 67). . . . . . . . . . . . . . 258-4301 Main Stud Kit, ARP2000 (p 81). . . . . . . . . . . . . . 258-5601 Flexplate Bolt Kit (p 119). . . . . . . . . . . . . . . . . . . 158-2901 Balancer Bolt Kit (p 109) . . . . . . . . . . . . . . . . . . . 258-2501 Ford 4- & 6-cylinder 1.6L Ecoboost Main Stud Kit (p 80). . . . . . . . . . . 251-5402 2.3L EcoBoost Head Stud Kit, Custom Age 625+ (p 67) . . . . . . . . . . . . . . . . 251-4303 2.7L EcoBoost V6 Head Bolt Kit (p 76). . . . . . . . 253-3602 3.5L Ecoboost/Cyclone V6 Main Bolt Kit (p 84).253-3602 Revised Kits Ford 312 Y block (ECZ) (p 47). . . . . . . . . . . . . . . . 154-6004 Ford 4.0L (XR6) inline 6 (p 67) . . . . . . . . . . . . . . 252-4302 Ford 4.0L (XR6) inline M14 to 1/2˝ (p 67). . . . . 252-4301

Valve Cover . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141 Flywheel. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 142 Flexplate. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 142 Rocker Pedastal. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 142 Ring Compressors. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 142 Distributor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103 Driveline. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116 Drive Pins, Sprint Car . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127 Drive Plate. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127 Engine Accessory. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92 Engine & Accessory Kits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114 Engine Block . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96 Engine Case Kits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82 Engine Components. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108 Exhaust Studs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92 Fastener Assembly Lube, Ultra-Torque. . . . . . . . . . . . . . . . . 171 Flywheel. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116 Flexplate. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119 Fuel Pump. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101 Fuel Pump Pushrod. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111 Front Cover. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98 Front Mandrel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136 Harmonic Damper 108 Head Studs & Bolts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58 Header Collector Bolts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93 Header . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94 Insert Washers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 169 Installation Tools. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171 Intake. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102 Intake Manifold. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104 Lower Pulley Bolts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126 Main Studs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78 Main Bolts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83 Manual Transmission Case. . . . . . . . . . . . . . . . . . . . . . . . . . . 125 Motor Mount. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100 Nuts SAE 12-point . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161 Metric 12-point. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 162 SAE Hex . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 163 SAE & Nyloc . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 163 Serrated Flange. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 164 Self-Locking. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 164 Oil Pan. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96 Oil Pump. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97 Oil Pump Driveshaft. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110 Oil Pump Primer Kits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 176 Perma-Loc Adjusters. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88 Porsche Engine Case. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82 Porsche Transmission Mount. . . . . . . . . . . . . . . . . . . . . . . . . 125 Powersports. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143 Rod Bolts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143 Cylinder Head Studs. . . . . . . . . . . . . . . . . . . . . . . . . . . . 143 Cylinder Head Studs. . . . . . . . . . . . . . . . . . . . . . . . . . . . 143 Main Studs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143 Main Bolts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143 Pressure Plate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124 Rear End Cover . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123 Ring Compressors. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 175 Ring Squaring Tools. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 176 Ring Gear. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121 Rocker Arm Studs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86 Rocker Arm Adjusters. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88 Rocker Pedastal Studs. . . . . . . . . . . . . . . . . . . . . . . . . . . . 89, 142 Rod Bolts Aftermarket Rods. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 OEM Replacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 Length Monitoring Chart. . . . . . . . . . . . . . . . . . . . . . . . . 53 Rod Bolt Stretch Gauge 172 Rod Bolt Extensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 173 Rod Vise. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 173 Spark Plug Indexer. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 174 Seal Plate. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101 Sprint Car Drive Pins. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127 Square Drive Damper. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110 Stainless Fasteners . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144 Starter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100 Thermostat Housing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106 Thread Cleaning Chasers. . . . . . . . . . . . . . . . . . . . . . . . . . . . 174 Thread Sealer. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 172 Tools, Installation 171 Torque Converter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120 Torque Specs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37 Transmission Pan & Case . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125 Valve Cover. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90 Washers SAE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165 Metric. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 168 Insert Washers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 169 Water Pump & Water Pump Pulley. . . . . . . . . . . . . . . . . . 98, 99 Wheel Studs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128, 133 Weld Bungs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 169 Ultra-Torque Fastener Assembly Lube. . . . . . . . . . . . . . . . . . 171 Looking for the latest ARP kits, revisions and technical updates? Our catalog is printed once a year, but our website and online catalog are updated with the latest new kits Find the most up-to-date information by scanning the code below ARP-bolts com 3 QUICK INDEX

Engine Accessory 114 Kits Include: Motor Mount, Alternator Bracket, Water Pump, Front Cover, Fuel Pump, Intake Manifold, Valve Cover, Coil Bracket, Exhaust Header, Thermostat, Distributor Bracket, Oil Pan Driveline 116 Flywheel. . . . . . . . . . . . . . . 116 Flexplate. . . . . . . . . . . . . . . 119 Torque Converter. . . . . . . . 120 Ring Gear. . . . . . . . . . . . . . 121 Bellhousing. . . . . . . . . . . . 122 Carrier Fasteners. . . . . . . . 123 Rear End Cover . . . . . . . . . 123 Clutch Cover. . . . . . . . . . . . 124 Pressure Plate . . . . . . . . . . 124 Manual Transmission Case . . . . . . . . . . . . . . . . . . 125 Porsche Transmission Mount 125 Auto Transmission Pan. . . 125 Lower Pulley Bolts. . . . . . . 126 Drive Plate. . . . . . . . . . . . . 127 Sprint Car Drive Pins. . . . . 127 Brake Hat. . . . . . . . . . . . . . 127 Wheel Studs. . . . . . . . . . . . 128 Circle Track 133 Speed Studs. . . . . . . . . . . . 133 Speed Nuts. . . . . . . . . . . . . 134 Intake Manifold. . . . . . . . . 134 Carburetor, drilled. . . . . . . 135 Alternator. . . . . . . . . . . . . . 135 Header, drilled. . . . . . . . . . 136 Front Mandrel . . . . . . . . . . 136 Diesel 137 Cylinder Head Studs. . . . . 138 Cylinder Head Bolts . . . . . 139 Rod Bolts . . . . . . . . . . . . . . 139 Main Studs. . . . . . . . . . . . . 140 Harmonic Damper 140 Exhaust. . . . . . . . . . . . . . . . 141 Valve Cover. . . . . . . . . . . . . 141 Flywheel. . . . . . . . . . . . . . . 142 Flexplate. . . . . . . . . . . . . . . 142 Rocker Pedastal. . . . . . . . . 142 Ring Compressors. . . . . . . 142 Powersports 143 Rod Bolts . . . . . . . . . . . . . . 143 Cylinder Head Studs. . . . . 143 Cylinder Head Studs. . . . . 143 Main Studs. . . . . . . . . . . . . 143 Main Bolts . . . . . . . . . . . . . 143 Engine & Accessory. . . . . . 143 Rod Bolts 42 Aftermarket Rods. . . . . . . . . 42 OEM Replacement . . . . . . . 44 Head Studs & Bolts 58 Cylinder Head Studs. . . . . . 58 Cylinder Head Bolts . . . . . . 72 Main Studs & Bolts 78 Main Studs. . . . . . . . . . . . . . 78 Engine Case Kits . . . . . . . . . 82 Main Bolts . . . . . . . . . . . . . . 83 Cylinder Head 86 Rocker Arm Studs . . . . . . . . 86 Rocker Arm Adjusters. . . . . 88 Rocker Pedastal Studs. . . . . 89 Valve Cover. . . . . . . . . . . . . . 90 Accessory Studs. . . . . . . . . . 92 Header Collector Bolts . . . . 93 Header . . . . . . . . . . . . . . . . . 94 Engine Block 96 Oil Pan. . . . . . . . . . . . . . . . . 96 Oil Pump. . . . . . . . . . . . . . . 97 Front Cover. . . . . . . . . . . . . . 98 Water Pump. . . . . . . . . . . . . 98 Alternator. . . . . . . . . . . . . . . 98 Water Pump Pulley. . . . . . . 99 Motor Mount. . . . . . . . . . . 100 Starter. . . . . . . . . . . . . . . . . 100 Fuel Pump. . . . . . . . . . . . . 101 Seal Plate. . . . . . . . . . . . . . 101 Accessory Cam Drive. . . . . 101 Intake 102 Carburetor . . . . . . . . . . . . . 102 Air Cleaner. . . . . . . . . . . . . 103 Distributor . . . . . . . . . . . . . 103 Intake Manifold. . . . . . . . . 104 Carburetor Float Bowl. . . . 105 Coil Bracket . . . . . . . . . . . . 106 Thermostat Housing. . . . . 106 Blower (break-away). . . . . 107 Blower Pulley. . . . . . . . . . . 107 Engine Components 108 Harmonic Damper 108 Square Drive Damper. . . . 110 Oil Pump Driveshaft. . . . . 110 Alternator. . . . . . . . . . . . . . 111 Fuel Pump Pushrod. . . . . . 111 Cam. . . . . . . . . . . . . . . . . . . 112 Cam Tower . . . . . . . . . . . . . 113 4 FASTENERS BY GROUP

Terms & Conditions 179 ARP ARP Tech Guide A Brief History . . . . . . . . . . . . . . . . . . . . . . . 6 The Manufacturing Process. . . . . . . . . . . . 7 Behind the Scenes. . . . . . . . . . . . . . . . . . . 12 What ARP Can Do For You. . . . . . . . . . . . 13 The “Aerospace Quality” Myth. . . . . . . . 14 Motorsports Fastener Engineering for the Non-Engineer . . . . . . . . . . . . . . . . . . . 18 Recognizing Common Fastener Failures . . . . . . . . . . . . . . . . . . . . 22 Metallurgy for the Non-Engineer. . . . . . 24 Custom Fasteners . . . . . . . . . . . . . . . . . . . 31 Material Specifications. . . . . . . . . . . . . . . 32 Glossary of Tech Terms. . . . . . . . . . . . . . . 34 Head Fastener Measurements. . . . . . . . . 36 General Torque Recommendations. . . . 37 Proper Fastener Retention. . . . . . . . . . . . 38 The Importance of Proper Rod Bolt Stretch & Torque. . . . . . 52 Rod Bolt Length Monitoring Chart. . . . . 53 Rod Bolt Stretch & Torque Specs . . . . . . 54 Head Studs versus Bolts. . . . . . . . . . . . . . 73 Fasteners by Dimension 144 SAE Bolts 10/24 & 10/32. . . . . . . . . . 145 1/4-20. . . . . . . . . . . . . . . . . 146 1/4-28. . . . . . . . . . . . . . . . . 147 5/16-18 . . . . . . . . . . . . . . . 148 5/16-24 . . . . . . . . . . . . . . . 149 3/8-16 Reduced. . . . . . . . . 150 3/8-16 Standard . . . . . . . . 150 3/8-24 Reduced. . . . . . . . . 151 3/8-24 Standard . . . . . . . . 151 7/16-14 Standard. . . . . . . 152 7/16-20 Standard. . . . . . . 153 1/2-13. . . . . . . . . . . . . . . . . 155 1/2-20. . . . . . . . . . . . . . . . . 156 Metric Bolts M6 x 1 0. . . . . . . . . . . . . . . 157 M8 x 1 25. . . . . . . . . . . . . . 158 M10 x 1 25 159 M10 x 1 50 159 M12 x 1 50 160 M12 x 1 75 160 Nuts SAE 12-point . . . . . . . . . . . 161 Metric 12-point. . . . . . . . . 162 SAE Hex . . . . . . . . . . . . . . . 163 SAE & Nyloc . . . . . . . . . . . . 163 Serrated Flange. . . . . . . . . 164 Self-Locking. . . . . . . . . . . . 164 Washers SAE . . . . . . . . . . . . . . . . . . . 165 Metric. . . . . . . . . . . . . . . . . 168 Insert Washers. . . . . . . . . . 169 Weld Bungs. . . . . . . . . . . . 169 Bulk Fastener Bins - 170 Installation Tools 171 Ultra-Torque. . . . . . . . . . . . 171 Rod Bolt Stretch Gauge. . . . . . . . . . . . . . . . . 172 Thread Sealer. . . . . . . . . . . 172 Rod Bolt Extensions . . . . . 173 Rod Vise. . . . . . . . . . . . . . . 173 Thread Cleaning Chasers. . . . . . . . . . . . . . . . 174 Spark Plug Indexer. . . . . . 174 Ring Compressors. . . . . . . 175 Ring Squaring Tools. . . . . 176 Oil Pump Primer Kits . . . . 176 Apparel 177 Automotive Racing Products, Inc. 1863 Eastman Avenue, Ventura, CA 93003 Copyright MCMXC-MMXXIV Automotive Racing Products, Inc. All Rights Reserved. “ARP”, the ARP logo, Wave-Loc, Perma-Loc, ARP2000, ARP3.5 and ARP Ultra-Torque are registered trademarks of Automotive Racing Products, Inc. All other trademarks are property of their respective owners. ARP-bolts.com 800-826-3045 5 FASTENERS BY GROUP

6 A Brief History They say that to be successful you must identify a need and satisfy it. Back in 1968 racing enthusiast Gary Holzapfel saw that many of his friends’ broken engines were caused by fastener failure. At the time, there were no commercially available studs and bolts up to the challenge. So Holzapfel called upon his many years of fastener making experience for a leading aerospace subcontractor and founded ARP® (Automotive Racing Products). In the ensuing years, the firm has grown from what was literally a backyard garage workshop into a highly diversified manufacturer with five operational entities in Southern California with a combined area in excess of 148,000 square feet. These include forging, machining, finishing and packaging/warehousing facilities in Santa Paula and Ventura, California. There is even a unique racing-themed restaurant at the main Santa Paula facility (called “Hozy’s Grill” - which is open to the public). Today, ARP’s product line contains thousands of part numbers, and has expanded to include virtually every fastener found in an engine and driveline. These range from quality high performance OEM replacement parts to exotic specialty hardware for Formula 1, IndyCar, IMSA, NASCAR and NHRA drag racing and marine applications. ARP’s customer list reads like a “who’s who” of motorsports around the world. In the past several years, virtually every major championship on Three generations are now involved in the company – Gary: founder & chairman, Mike: president, Ryan: manufacturing Gary Holzapfel Founder and chairman ARP’s state-of-the-art manufacturing facility in Santa Paula. THE COMPANY

7 the planet has been won with engines prepared by ARP customers. These include Nascar, IndyCar, Formula 1, IMSA, NHRA Top Fuel, Funny Car & Pro Stock, Nascar Xfinity and Camping World Truck Series. And so it goes. ARP works closely with many, many teams as a supplier of engine and driveline fasteners, and has clearly become recognized as “the” preeminent source for serious racers. In addition to its core automotive business, ARP has 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. ARP also manufactures a variety of industrial fasteners on a contract basis, and is known for its ability to promptly provide efficient solutions to problems at hand. The Manufacturing Process In order to ensure optimum quality control, ARP has grown to be exceptionally self-reliant and now controls all aspects of the manufacturing process. All operations are performed Packaging, warehousing and sales operations are handled out of Ventura. Material comes from the mill in large coils...which subsequently will be fed into cold-headers and formed into bolts. THE COMPANY

8 in-house and closely monitored. This is how ARP has been able to establish a reputation for “zero defects” quality throughout the industry. The process begins right at the mill, where ARP orders only premium grade materials including several proprietary alloys. The ever-popular 8740 chrome moly steel, for example, comes from the mill in four distinct grades. The lowest is “commercial,” which is followed by “aircraft quality.” ARP uses only the top two grades (SDF and CHQ), which cost twice as much, but provide the foundation for defect-free fasteners. These materials come in bar stock (for studs) and huge coils (for bolts). Most ARP fasteners start off on a cold header, where the high quality wire is cut to length and the head and shank are formed in a multi-stage forging process that contributes to the strength of the overall fastener. A few of our fasteners are cut from bar ARP’s bank of cold-headers can handle material up to 5/8˝ diameter and form bolts in a multi-phase operation. Heat-treating is critically important in obtaining the correct tensile strength. Fasteners are placed in special vertical racks to ensure complete 360˚ penetration. An overview of part of ARP’s expansive machining operations. The shop is laid out for optimum efficiency. THE COMPANY

9 stock and hot headed. Following the cold/hot forging, material is heat-treated to desired levels. This crucial process is done entirely in-house to assure total quality control. ARP uses custom vertical racks to hold each piece individually and assure complete 360° penetration. This is far superior to commonly-used methods of dumping items into a large bin and batch-treating. Studs are centerless ground to guarantee concentricity. The thread rolling operation (to MIL-S-8879A specs) is done after heat-treat, which accounts for a fatigue strength up to twenty times higher than fasteners which are threaded prior to heattreat. ARP manufactures nuts in a multistep process that begins with raw material being fed into a giant forming device that “blanks” the hex and 12-point nuts and continues with highly sophisticated, atuomatic tapping machines that tap each nut with an accuracy of .001˝ (which is five times higher than the aerospace standard). This ensures an exceptionally close-tolerance fit The Grinding Department is where all studs are centerless ground to ensure that they are concentric and straight. Powerful cold-forging equipment is used to make ARP’s hex and 12-point nuts. Multi-stage dies are employed to precision-form the finished “blanks.” A series of CNC-threading machines are employed by ARP to accurately tap the threads in nuts. Tolerances held are better than aerospace standards. THE COMPANY

10 between the bolt/stud and nut. Metal finishing is also performed in-house at ARP. Operations include black oxide coating of chrome moly or polishing stainless steel to a brilliant luster. Also on the premises is a fully-equipped lab for R&D and quality control. It has everything required to ensure that ARP products measure up to the company’s ultra high standards. Some of the tests that ARP personnel perform on a daily basis include ultimate tensile strength (using a 120,000 lb. capability tensile machine), fatigue cycle (Amsler) and hardness (Rockwell). Visual inspections include use of an optical comparator (to check thread root contour, etc.), fixtured micrometers and microscopic grain flow analysis. The computer-controlled fatigue cycle testers allow ARP to take fasteners to a failure point in millions of cycles – as A bank of CNC machining centers are employed at ARP to perform specialty operations. State-of-the-art EDM technology is used to perform special operations, such as hex-broaching head studs. Fasteners are shot-peened to improve fatigue life. The finishing touch for most chrome moly fasteners is the black oxiding operation. THE COMPANY

11 opposed to the aerospace norm of 65,000 average to 130,000 cycles maximum. This allows ARP engineers to verify the design specifications of each fastener, and prove its ability to provide superior long-term service. Finished products are packaged and warehoused in ARP’s Ventura facility, which is also home to the firm’s customer service, technical and sales office. High powered magnifiers are used to carefully inspect critical components. ARP’s quality control team is relentless! ARP has two highly sophisticated Amsler fatigue machines, which test fasteners through millions of cycles. The finished goods are given a protective coating and stored in sealed containers, awaiting packaging. Millions are in stock! After final packaging the kits are placed in storage racks and are ready for order fulfillment. Over 5,000 SKU’s are warehoused. Components for each kit are placed on the appropriate display cards, sealed and labeled. Through-put has been significantly increased. THE COMPANY

12 Manufacturing high performance and race fasteners is very different from making commercial fasteners. As you read further into this catalog, you will get a better idea of the extraordinary steps taken by ARP to produce the strongest, most reliable fasteners of their kind on the market today. The foundations of ARP’s fastener technology were laid by founder Gary Holzapfel, President Mike Holzapfel and engineers Russell Sherman, P.E. and Dr. Kenneth Foster. This team used their vast experience in fastener manufacturing and design, metallurgy, mechanical engineering and stress analysis to create fasteners that suited the unique needs of racers in every form of racing. Building on this foundation, ARP worked with racing industry legends like Carroll Smith and Smokey Yunick to bring direct input from the racer’s perspective. As ARP’s involvement with professional race teams increased dramatically, the feedback loop drove continuous innovation in all of the fasteners ARP designs and manufactures. ARP has channeled those five decades of knowledge to continuously improve existing fasteners and kits, as well as create new ones for everything from diesel trucks to personal watercraft to the fastest land speed vehicles in the world. ARP has worked with Robert Logsdon to improve its quality control systems and create a culture of continuous improvement. He brought to ARP decades of experience in the areas of Metrology, Quality Control, Manufacturing, Acquisition and Configuration Management. Logsdon is a graduate of the U.S. Naval Academy of Metrology Engineering, the Defense Management College and U.S. Air Force Institute of Technology. Additionally, ARP has one of the industry’s most complete in-house R&D/QC facilities and a wide variety Robert Logsdon Q.C. Consultant Behind The Scenes A series of special checking devices are employed to monitor the quality of threads. For every thread size, there is a checking device. Two computer-controlled Instron tensile machines are used to determine the ultimate tensile strength of studs and bolts. THE COMPANY

13 of testing equipment. ARP also enjoys working relationships with many of the most respected professional engine builders and race teams from the world over — including those involved in Formula1, IndyCar, IMSA, Nascar, NHRA, IHRA, Lucas Oil Late Model Dirt, World of Outlaws and a host of others. Constant interaction with these racing experts to provide fasteners for a wide variety of competition applications enables ARP to stay on the cutting edge of fastener technology development. You will find ARP fasteners sold by leading performance retailers and professional engine builders around the world. These firms know that ARP fasteners are the standard of the industry, and smart consumers will accept no substitutions. All ARP fasteners are proudly made in the USA to the industry’s highest standards. ARP also supports racers through generous contingency awards programs with many racing programs. What ARP Can Do For You In addition to manufacturing a comprehensive array of cataloged fasteners for automotive and aerospace applications, ARP thrives on the challenges of developing fasteners to solve unique problems. Racers, Pro Street enthusiasts and street rodders have, over the years, approached ARP about manufacturing special fasteners for unique applications, and the company has responded with innovative solutions. ARP can provide complete R&D services, including metallurgical research, product design, prototype machining and extensive laboratory testing. Moreover, ARP has experience manufacturing fasteners from a wide variety of materials. All work can be performed under the strictest confidence. ARP is well versed in facilitating proprietary research and custom manufacturing for corporations the world over. It is for good reason that ARP is recognized as “The World Leader In Fastener Technology!” See page 31 for more information on our Specials Department. ARP fasteners are prominently featured at leading performance retailers worldwide. THE COMPANY

14 THE “AEROSPACE QUALITY” MYTH In areas from hose ends to engine fasteners the terms “Aerospace material and Aerospace Quality” have become buzz words implying the very best in design, materials and quality control. “It isn’t necessarily so”, says Gary Holzapfel, founder and CEO of Santa Paula, California based ARP, Inc. ARP (Automotive Racing Products) supplies extremely high strength and fatigue resistant threaded engine fasteners to NASCAR, IndyCar, NHRA, IMSA and Formula 1 engine builders and manufacturers. Holzapfel explained his reasons in an interview with Carroll Smith. Smith: “Gary, do you believe that the term “aerospace quality” is over rated in the specialty fastener industry?” “Yes I do. First of all, the term is meaningless. Any AMS (Aerospace Material Specification) material must be matched to the specific application. As an example, some airframe bolts (AN3-20) are legitimate “aerospace parts” and are very well suited for the low stress applications for which they were designed. But with a minimum ultimate tensile strength of 125,000 psi, and a relatively low temperature limit, they would be completely unsuitable for use in a racing engine. We started out in the aerospace fastener business and we understand it. That’s why we’re not in it any longer. What is not generally understood about aerospace fasteners is that the fastener manufacturers do not design the product. The nuts, bolts and studs are spec’d by the airframe or engine designers and put out for bid. As long as the supplier certifies that the product meets the minimum requirement of the specification and it passes the customer’s inspection procedures, low bid wins.” Smith: “Are you implying that the aerospace fastener manufacturers cut corners in order to win contracts?” “No, it’s a matter of manufacturing goals and simple economics. The aerospace market is price dominated. In order to get the contract, the fastener manufacturer’s goal is to meet the specification at the least cost, not to produce the best possible part. This means that they are going to use the least expensive steel and manufacturing processes that will meet the specification. There is nothing wrong with this approach. It certainly does not mean that certified aerospace fasteners are unsafe in any aspect. They will do the job for which they were designed. There is another factor. Airframe and aircraft engine manufacturers design their components to a very high margin of safety. Further, aerospace structures are designed to be “fail safe.” There is a back up or second line of defense for virtually every structural component so that an isolated failure will not lead to disaster. They are also subjected to frequent and rigorous inspections.” Smith: “What’s different about motor racing?” “Quite a lot, really. While the demands for strength, fatigue resistance and quality control can be similar, and the assembly and inspection procedures in racing can be as rigorous as aerospace, in professional racing very few parts are over designed and there are no fail safe features. FASTENER TECH

15 There are no back up provisions for component failure. A failed (or even loosened) nut or bolt in a racing engine means disaster – instant catastrophic failure. An expensive engine is destroyed and a race is lost. That is why random failures are unacceptable in motor racing, and why aerospace standards should be only a starting point. This means that a specialist in the production of high performance engine fasteners must design and manufacture the very best fasteners that can be produced.” Smith: “So where does the production for a new racing fastener begin?” “The design process begins with the customer’s requirements the operating conditions and loads to be expected, the packaging constraints and the weight and cost targets. This allows us to select the optimummaterial for the part, and to do the initial mechanical design. There is more to material selection than simply choosing the best alloy. It means using only the cleanest and purest steel available, which, in turn, means researching to identify the best and most modern steel mills. It means working closely with the mills both to insure consistent quality and to develop new and better alloys. There are not only a myriad of alloys to choose from; but for each alloy there are several grades of “aircraft specification” steel wire from which fasteners can be made. We believe that only the top (and most expensive) grade – shaved-seamless, guaranteed defect-free – is suitable for racing engine applications. We also believe that samples fromeach batch should be subjected to complete metallurgical inspection.” Smith: “How many alloys do you work with?” “We are currently producing fasteners from at least 10 different steel alloys from 8740 chrome moly to the very high strength chromium-cobalt-nickel alloys such as Custom Age 625+. We also use stainless steel and titanium. With UTSs (Ultimate Tensile Strength) from 180,000 to 270,000 psi, we can suit the material to the job and the customer’s cost restraints. We are continually researching and experimenting with new alloys and manufacturing processes – some with all around better strength and fatigue properties.” Smith: “Once the design work is done and material has been selected, what’s next?” “Next comes the actual process of manufacturing. It goes without saying that all high strength bolts must have rolled rather than cut threads, and that the threads must be rolled after heat-treatment. But there is more to it. The old saying to the effect of, “If you are doing something in a particular way because that’s the way it has always been done, the chances are that you are doing it wrong,” holds true in fastener technology. Technology advances, and we have to advance with it. All of the manufacturing processes should be subject to continuous experimentation and development. As an example, with some alloys, cold This spring was wound from un-shaved material. It failed on the seam line. 5 stage “Cold Header” used in the production of ARP bolts FASTENER TECH

16 heading produces a better product than hot heading, and vice versa. The number and force of the blows of the cold heading machine can make a significant difference in the quality of the end product. Excessive numbers of blows can lead to voids in the bolt head. ARP, in fact, holds significant patents on cold heading procedures for the higher nickel and cobalt based alloys. In a typical aerospace manufacturing process, these alloys are hot headed from bars, reduced in diameter from 48 to 50% by cold drawing, resulting in a hardness of about Rockwell C46 which is too hard for cold heading. So, the blanks are locally induction heated in a very narrow temperature envelope and hot headed. If care is not taken the process can reduce the hardness of the bolt head and the area immediately under it as much as 3 to 5 points on the Rockwell C scale. Subsequent heat-treatment does not restore this partially annealed area to full hardness and strength. Therefore, the final result can be a relatively soft headed bolt. This process is not preferred by ARP. Our patented process begins with a softer wire that can be cold forged. The process work hardens the head and the under head area to the desired hardness. We then power extrude the front end to achieve the reduction and hardness in the shank resulting in a bolt with even strength and hardness from end to end. The same is true of thread rolling. Temperature and die speed must be controlled and changed for different alloys. Many bolt manufacturers who meet the Aerospace Specifications don’t come close to meeting our standards. We consistently go beyond standard aerospace specs. Our concern with the manufacturing processes extends to the details of heat-treating, shot-peening, fillet rolling and grinding – down to the frequency of dressing the grinding wheels. In the arena where aerospace standards are a starting point and random failures are unacceptable, I feel ARP stands alone as a primary engineering and manufacturing source for specialty and custom fasteners for use in motorsports. It is important to realize that simply quoting an AMS (Aerospace Material Specification) number without strength and percentage of elongation numbers is meaningless. Statements that the use of a particular material will, in itself, result in extreme strength and resistance to fatigue can be misleading. In the world of high strength alloys, whether they are used for bolts or for landing gears, the manufacturing processes are at least as important as the material specification. Some in our industry claim to inspect materials at the “molecular” level. In metallurgical terms, molecules are not necessarily part of the vocabulary. Our engineers tell us that talking about molecules is misleading. When reference is made to metal, it is typically in terms of atom structures. We routinely check metallurgical features microscopically. By the way, the same is true for claims of manufacturing to “zero tolerance.” “Our engineers tell us that this is technically unrealistic.” FASTENER TECH

17 Smith: “How does the actual process work at ARP?” “For each new design, we produce a number of prototype parts using different design aspects and sometimes different methods. We inspect and test after each process, choose the best design and method of manufacture, and then freeze the design and write the manufacturing specification.” Smith: “You have mentioned the importance of fatigue resistance. Is there a difference in the procedures for strength and fatigue testing between aerospace and the specialty racing industry?” “Yes. While the ultimate tensile strength testing is the same, fatigue testing is different. Aerospace fasteners are fatigue tested to the relevant specification of fluctuating tension load and number of cycles typically 130,000 cycles with the high tension load at 50% of the UTS and the low load at 10% of the high load. If all of the test samples last 85,000 cycles (per AMS 5842-D), the lot is accepted. Even though racing fasteners are not continuously subjected to their maximum design load, at 18,000 rpm, 100,000 cycles takes just 5 minutes, thirty-four seconds. Except for drag racing, measured in seconds, no race lasts just 5 minutes. Therefore we consider this Aerospace Standard to be inadequate. At ARP, we fatigue test to elevated loads (10% above aerospace requirements) and to a minimum cycle life that exceeds 350,000 cycles. The majority of samples are routinely tested to one million cycles. During material development...and in the case of extremely critical new designs, we test to destruction. Thread rolling is the last mechanical operation in our manufacturing process. For each production run the thread rolling machine is shut down after a few parts. These parts are inspected for dimensional accuracy and thread quality, and are physically tested for both strength and fatigue before the run is continued. Random samples are inspected and tested throughout the run. Extremely critical components are individually inspected for dimensional integrity.” Smith: “What about out-sourcing?” “Economics often dictate that many processes in the manufacture of aerospace fasteners are farmed out. In the early days, ARP began as an out-source thread rolling shop. Over the years, however, we have found, through experience, that the only way to maintain the quality we require is to keep everything in-house. From heading through machining, grinding, heat-treat, thread rolling, and shot-peening to black oxide treatment we perform every operation in house on our own equipment with our own employees.” Smith: “Gary, One of the things that I am hearing is that every aspect of the manufacture of racing engine fasteners is more expensive than that of similar aerospace items.” “True, but the bottom line is that we have to look at the cost aspect of the very best fastener versus the cost aspect of a blown engine and a lost race. In the end, the manufacturing of fasteners for racing comes down to a matter of attitude; a refusal to accept published standards and procedures as the best that can be done and most of all a determination to learn and to make still better products.” Fatigue, tensile and hardness testing are key quality control checks. FASTENER TECH

18 There are literally hundreds of standards and specifications – for all types of applications, from bridges to rockets. None are as critical as those required for real-world motorsports applications. In an environment where lighter is faster there is clearly no room for redundant fasteners, like those found in military and aerospace applications. The mere nature of Motorsports requires designers to produce fasteners that are light; yet tough, fatigue-resistant and reliable beyond other acknowledged application standards. The design and production of fasteners, exclusively for racing, clearly involves many complex factors. Some are so unique and complex that no standards or design criteria exist. This means that everyone at ARP is entirely dedicated to the development and analysis of appropriate bolt designs exclusively for special applications. Our designs take into account the special loads that must be carried, the material selection, the manufacturing processes and the methods of installation required to deliver ARP quality and reliability. It is hoped that by providing an overview of the engineering, design and production techniques ARP applies daily, you – as the end user – will be better equipped to evaluate your initial fastener requirements, effectiveness and performance. Design Procedures for Automotive Bolts Presented by Dr. Kenneth Foster, PhD The design of automotive bolts is a complex process, involving a multitude of factors. These include the determination of operating loads and the establishment of geometric configuration. The process for connecting rod bolts is described in the following paragraphs as an example. The first step in the process of designing a connecting rod bolt is to determine the load that it must carry. This is accomplished by calculating the dynamic force caused by the oscillating piston and connecting rod. This force is determined from the classical concept that force equals mass times acceleration. The mass includes the mass of the piston plus a portion of the mass of the rod. This mass undergoes oscillating motion as the crankshaft rotates. The resulting acceleration, which is at its maximum value when the piston is at top dead center and bottom dead center, is proportional to the stroke and the square of the engine speed. The oscillating force is sometimes called the reciprocating weight. Its numerical value is proportional to: It is seen that the design load, the reciprocating weight, depends on the square of the RPM speed. This means that if the speed is doubled, for example, the design load is increased by a factor of 4. This relationship is shown graphically below for one particular rod and piston. Motorsports Fastener Engineering for the Non-engineer FASTENER TECH

19 A typical value for this reciprocating weight is in the vicinity of 20,000 lbs. For purposes of bolt design, a “rule of thumb” is to size the bolts and select the material for this application such that each of the 2 rod bolts has a strength of approximately 20,000 lbs. (corresponding to the total reciprocating weight). This essentially builds in a nominal safety factor of 2. The stress is calculated according to the following formula: so that the root diameter of the thread can be calculated from the formula: This formula shows that the thread size can be smaller if a stronger material is used. Or, for a given thread size, a stronger material will permit a greater reciprocating weight. The graph (see page 20) shows the relationship between thread size and material strength. It must be realized that the direct reciprocating load is not the only source of stresses in bolts. A secondary effect arises because of the flexibility of the journal end of the connecting rod. The reciprocating load causes bending deformation of the bolted joint (yes, even steel deforms under load). This deformation causes bending stresses in the bolt as well as in the rod itself. These bending stresses fluctuate from zero to their maximum level during each revolution of the crankshaft. The next step is to establish the details of the geometric configuration. Here the major consideration is fatigue, the fracture that could occur due to frequent repetition of high stresses, such as the bending stresses described above. Several factors “H” beam-deformed. Total translation contours. For loading in tension due to acceleration forces at 8000 RPM Motorsports Fastener Engineering for the Non-engineer FASTENER TECH

20 must be considered in preventing fatigue; attention to design details is essential. Fatigue failure is frequently caused by localized stress risers, such as sharp corners. In bolts, this would correspond to the notch effect associated with the thread form. It is well known that the maximum stress in an engaged bolt occurs in the last engaged thread. By removing the remaining, non-engaged threads, the local notch effect can be reduced. This leads to the standard configuration used in most ARP rod bolts: a reduced diameter shank and full engagement for the remaining threads. Providing a local fillet radius at the location of the maximum stress further reduces the local notch effect. Thus this configuration represents the optimum with respect to fatigue strength. The reduced diameter shank is helpful in another sense. It reduces the bending stiffness of the bolt. Therefore, when the bolt bends due to deformation of the connecting rod, the bending stresses are reduced below what they would otherwise be. This further increases the fatigue resistance of the bolt. A typical bolt configuration is shown below. Once the bolt configuration has been established, the manufacturing process comes into play. This involves many facets, which are discussed in detail elsewhere. Here, however, one process is of primary interest. With respect to bolt fatigue strength, thread rolling is a major consideration. Threads are rolled after heat treating. This process, which deforms the metal, produces a beneficial compressive stress in the root of the thread. It is beneficial because it counteracts the fluctuating tensile stresses that can cause fatigue cracking. If heat-treatment were to occur after rolling, the compressive stresses would be eliminated. This would therefore reduce the fatigue resistance of the bolt. An additional factor must be taken into account in defining the bolt configuration: the length of engaged thread. If too few threads are engaged, the threads will shear at loads that are lower than the strength of the bolt. As a practical matter, the thread length is always selected so that the thread shear strength is significantly greater than the bolt tension strength. This problem is especially important in bolts used in aluminum rods because of the fact that the shear strength of aluminum is much lower than the shear strength of steel. Motorsports Fastener Engineering for the Non-engineer FASTENER TECH

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