BMW B48 Head Stud Thread Insert Kit

The MINI Toyota BMW B48 Head Stud Thread Insert Kit provides your machine shop everything needed to repair or upgrade the engine block threads on B48 engines. Designed for precision and durability, this kit allows you to restore damaged threads or prepare the block for oversized head studs for improved clamping strength.

Please note, this product does NOT include head studs. Head Studs are available for purchase here.

Each BMW B48 Head Stud Thread Insert Kit includes:

• (1) Specialized drill bit for proper thread preparation
• (1) High Speed Steel 3-Flute Tap
• (1) High Speed Steel Extended 3-Flute Tap
• (10) Precision stainless-steel thread inserts
• Red threadlocker

Available in 11mm for OEM-spec head stud thread repair or 12mm for use with our Oversized Head Stud Kit, this thread insert kit ensures a secure and permanent repair capable of withstanding extreme cylinder pressure and torque loads.

How these inserts work:

Our insert design supports the use of both factory head bolts and high-quality aftermarket ARP head studs. These fasteners use rolled threads, which are up to 20% stronger than cut threads, and are engineered to flex and return to shape as the engine heats and cools—maintaining consistent clamping pressure on the head gasket throughout every heat cycle.

Benefits of Installing Oversized Head Studs:

1. Repair Worn or Damaged Threads
   When an engine block’s head bolt holes become stripped or elongated from repeated torque cycles or overheating, a standard-size stud may no longer hold properly.
    
   By drilling and re-tapping the holes to a larger diameter and using oversized studs, you restore proper thread engagement and strength—often stronger than original.
   
   
2. Increase Clamping Force
   Oversized studs can have a larger shank diameter, which increases tensile strength and reduces stretch under high cylinder pressures. This is particularly beneficial for high-boost turbo where combustion pressures are extreme.
   
   
3. Reduce Head Gasket Failure
   Stronger or larger studs provide more uniform clamping across the cylinder head, which improves gasket sealing and minimizes the risk of head lift or gasket blowout.

Not all engine blocks are suitable for oversize head stud installation. Due to differences in casting thickness, core shift, and material distribution, some blocks may not have enough surrounding material to be safely machined for larger fasteners.

A skilled and experienced machinist must inspect the block and be confident in its integrity before performing any machining. Improper assessment or installation may result in cracking, coolant passage intrusion, or structural failure. All modifications are performed at the installer’s own risk.

Please Note: Installing oversized head studs requires precise machining; drilling and tapping the block must be completely straight and to the correct depth. 

BMW B48 Applications:

1 Series

2016-2019    F20    120i / 125i
2019-2023     F40     118i / 120i / 128ti / 135i / M135i
2024-Present     F70     120 / M135i 

2 Series

2014-2021     F22/F23     218i / 220i / 230i
2014-2017     F45     220 / 225i
2021-Present     G42     218i / 220i / 230i
2021-Present     U06     223i
2020-2024     F44     218i / 220i / 228i / M235i
2025-Present     F74     M235

3 Series

2015-2019     F30/F31/F34     320i / 330i / 330e
2018-Present     G20/G21     318i / 320i / 330i / 330e

4 Series

2016-2019    F32/F33/F36    420i / 430i
2020-Present     G22/G23/G26     420i / 430i / 430e

5 Series

2017-Present     G30/G31     520i / 530i / 530e

6 Series

2017-Present     G32     630i

7 Series

2015-2022     G11/G12     730i / 730Li / 740e / 740Le

X1 Series

2015-2022     F48     sDrive18i / sDrive20i / xDrive20i / 25i / xDrive25i / 28i
2022-Present     U11     sDrive18i / xDrive20i / xDrive28i / M35i

X2 Series

2018-2023     F39     sDrive18i / sDrive20i / xDrive20i / 25i / xDrive25i / 28i / M35i
2023-Present     U10     xDrive28i / M35i

X3 Series

2017-2024     G01     sDrive20i / xDrive20i / xDrive30i / xDrive30e
2025-Present     G45     xDrive20e / xDrive30e

X4 Series

2018-Present     G02     xDrive20i / xDrive30i

X5 Series

2018-Present     G05     xDrive25i / sDrive25i

Z Series

2018-Present     G29     Z4 sDrive20i / sDrive30i

Toyota B48 Applications:

A90 / A91 Supra

2019-Present     J29/DB82/DB22 Supra
2020-Present     GR Supra 2.0  

MINI B48 Applications:

MINI Hatch [F55/F56/F57]

2014-Present     Cooper S
2015-Present     John Cooper Works (JCW)

MINI Clubman [F54]

2015-Present     Cooper S
2016-Present     John Cooper Works (JCW)

MINI Convertible [F57]

2016-Present     Cooper S
2016-Present     John Cooper Works (JCW)