B58 ARP Main Stud Kit

ARP B58 Main Stud Kit

This ARP Main Stud Kit is designed to replace BMW main bolt part numbers 11128644674 and 11127613127 on B58, B58A, B58C, and B58D engines found in various BMW chassis, including the F22, F23, F30, F31, F32, F33, F34, F36, G01, G02, G20, G22, G23, G26, G29, G30, G42, and G43, as well as the Toyota GR Supra A90/A91.

Upgrading from factory main bolts to ARP Main Studs is a simple but highly beneficial upgrade for high-performance and high-horsepower engine builds. Increased clamping strength and consistency help improve bottom-end stability while keeping the main caps and crankshaft properly located under extreme loads.

Benefits of ARP Main Studs

• Consistent Clamping Force: Provides more uniform and repeatable clamping across the main caps, helping maintain proper main bore and crankshaft alignment.
• Improved Block Rigidity: Increased clamping strength helps stabilize the bottom end under high cylinder pressure, RPM, and horsepower.
• Reduced Main Cap Movement: Helps minimize main cap walk and movement under extreme loads, improving crankshaft and main bearing stability.
• Reduced Fastener Stretch: High-strength ARP materials provide greater resistance to stretching and deformation compared to factory fasteners under high RPM and heavy loads.
• Improved Main Bearing Stability: More consistent main-cap clamping helps maintain bearing alignment and oil clearance under demanding operating conditions.
• Precision-Manufactured Threads: ARP's precision manufacturing provides consistent thread engagement and reliable clamping while minimizing unnecessary stress on the engine block threads.

Installation Instructions

1. Thoroughly clean all threaded holes in the engine block. If necessary, use an ARP thread chaser to ensure clean threads and proper engagement.
2. Inspect all studs, nuts, and washers for damage and verify proper fit, length, and dimensions before installation.
3. Install the main studs into the engine block by hand until snug. Do not overtighten.
4. Install the main caps and check for proper fit, alignment, and any binding.
5. Apply ARP Ultra-Torque Fastener Assembly Lubricant to the stud threads, nuts, washers, and washer contact surfaces.
6. Install the washers and nuts and tighten them by hand. Do not substitute motor oil or other lubricants for ARP Ultra-Torque.

7. Following the manufacturer's recommended main-cap tightening sequence, torque all main stud nuts progressively in three steps using ARP Ultra-Torque:

   Step 1: 20 ft-lbs
   Step 2: 40 ft-lbs
   Step 3: 60 ft-lbs

8. After final torque, measure the main bearing bores and verify proper size, roundness, and alignment.
9. If necessary, line hone the main bores with the ARP main studs installed and torqued to specification.
10. Verify final main bearing oil clearances before engine assembly.

Important Installation Note

When converting from factory main bolts to ARP Main Studs, the main bearing bores should always be measured after the studs are installed and torqued to specification.

The increased and more consistent clamping force of the studs can affect main bore geometry. Depending on the engine block, a line hone may be required to restore proper bore size, roundness, and alignment.

Proper main bore geometry and bearing oil clearance are critical for crankshaft stability, oil pressure, and bearing life. Always verify all measurements before final engine assembly.

Fitment

BMW 2 Series

• F22 / F23 M240i
• F22 / F23 M240i xDrive
• G42 / G43 M240i xDrive

BMW 3 Series

• F30 / F31 / F34 340i
• F30 / F31 / F34 340i xDrive
• G20 M340i
• G20 M340i xDrive

BMW 4 Series

• F32 / F33 / F36 440i
• F32 / F33 / F36 440i xDrive
• G22 / G23 M440i
• G22 / G23 M440i xDrive
• G26 M440i xDrive Gran Coupe

BMW 5 Series

• G30 540i — B58A (2017–2019)
• G30 540i — B58C (2020+)
• G30 540i xDrive — B58A (2017–2019)
• G30 540i xDrive — B58C (2020+)

BMW X3

• G01 X3 M40i

BMW X4

• G02 X4 M40i

BMW Z4

• G29 Z4 M40i

Toyota GR Supra

• A90 / A91 GR Supra