• ARP Main Stud Kit, BMW S38 - 5150 AutoSport
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ARP Automotive Racing Products

ARP Main Stud Kit, BMW S38

ARP Main Stud Kit, BMW S38

$199.99 USD
$199.99 USD $199.99 USD
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This ARP Main Stud Kit is designed to replace BMW 07119912680 for the S38B35, S38B36, and S38B38 found in the E24, E28, and E34 M5 and M6 chassis. 

Upgrading from factory main bolts to ARP Main Studs is a simple, yet greatly beneficial upgrade. ARP Main Studs offer the following benefits: 

- Uniform Clamping Force: ARP Main Studs provide a uniform clamping force that OEM bolts cannot. With the improved distribution of pressure across main bearing caps comes better, more precise crank alignment for stability and longevity. 
- Improved Block Stability and Rigidity: ARP Main Studs improve block rigidity and therefore stability. This ensures maximum power transfer from the crank to the drivetrain, which in turn ensures: 
- Improved Throttle Response
- Greater Horsepower
- Higher Torque Output
- Prevent Main Cap Walk: This occurs as main caps shift and move out of position, which can cause crank and engine damage
- Reduced Risk of Fastener Stretching: Under high RPM applications and high loads, factory main bolts are prone to stretching and deforming. ARP uses advanced manufacturing techniques and high quality materials for hardware that is much less prone to deformation under load.
- Safeguard Engine Block Threads: Because ARP Main Studs have unmatched tensile strength, they are much less likely to deform or strip block threads under high loads. Additionally, ARP’s precision machining and manufacturing ensures that stud threads are both highly accurate and consistent.

When opting for main studs instead of factory bolts, it's important to note that the engine builder should mic the bores. Using studs may require a line hone to ensure proper fitment and alignment. A line hone is a machining process that can be used to resize and reshape the main bearing bores, ensuring that they are perfectly round and concentric. This is crucial for ensuring proper oil clearance and preventing premature bearing wear. By mic'ing the bores and performing a line hone if necessary, engine builders can ensure that the main studs are installed correctly and that the engine will perform reliably and at its best.

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.

BMW S38B35 Applications:

BMW 5 Series

1985-1987     E28     M5 [European Market]
1987-1988     E28     M5 [American Market]

BMW 6 Series

1984-1989     E24     M635CSi [European Market]
1987-1989     E24     M6 [American Market]

BMW S38B36 Applications:

BMW 5 Series

1988-1992     E34     M5

BMW S38B38 Applications:

BMW 5 Series

1992-1995     E34     M5 [European Market]

ARP-MSK-S38

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