ACL Race Main Bearings For Mazda MX-5 NA NB

From: £82.92

ACL Race Series performance engine bearings are meticulously crafted with precision in mind. They are manufactured to exact tolerances, ensuring consistent accuracy in critical characteristics such as wall thickness and crush. This attention to detail guarantees a reliable fit and the maintenance of consistent clearances, contributing to the bearings’ high strength and excellent seizure resistance.

These bearings are designed without flash plating, which not only enhances bearing retention but also maximizes heat transfer. Adjusting oil clearances is a common practice, achieved by mixing bearings of adjacent grades, such as HX-STD with H-STD or H-STD with H-001 or H-0.025. If your crankshaft requires regrinding to an undersize it’s essential to measure the assembled bearing IDs first and then have the required journal sizes ground to match the bearing measurements.


  • STDX -0.025 mm (looser than nominal)
  • STD +0.000 mm (nominal)
  • +0.025 mm (tighter than nominal)
  • +0.25 mm (first shaft cut)


  • Precision-manufactured with tight tolerances
  • High strength, seizure resistance
  • No flash plating
  • Adjust oil clearances

Additional information

Shipping Weight 0.225 kg
Shipping Dimensions 14 × 6 × 3 cm



0.25, 0.50, STD, STDX


Mk1 (89-98), Mk2 (98-05)

Warranty information

Warranties cover defects in materials and workmanship only. Warranty is for replacement of a similar product, repair of the original product or refund of the purchase value only and excludes all labour and incurred charges including towing, fitting, inconvenience, and purchases of other manufacturer's products. The warranty is good for the period stated in the additional info tab from the date of purchase. Mileage warranties are for road use only and proof of mileage is required. Products must be installed by an independent experienced professional mechanic and the suspected defect must be present at the outset. The warranty does not cover damage caused by incorrect installation, failure to comply with the maintenance requirements of the vehicle, processing or otherwise changing the product, ordinary wear and tear, or any other external influences. Warranties are invalid if the product is used for racing, rallying, drifting, track days or any other form of motorsport or competition. Please refer to the manufacturer's own warranty documentation for more information.

Making a warranty claim

Proof of purchase receipt showing the date of purchase, proof of mileage at installation, proof of current mileage and invoice of the work undertaken by an independent experienced professional mechanic must be supplied along with the returned products for a warranty claim to be considered. If your vehicle needs to be used whilst your warranty claim is considered replacement parts from the same manufacturer should be purchased through BOFI Racing. In the event of a successful warranty claim, we will refund the card that was originally used to purchase the replacement parts, in full or in part depending on the nature of the claim. BOFI Racing reserves the right to make full or partial compensation at its sole discretion depending on the condition and mileage use of the returned suspect parts. For example, if you have used the part for several thousand miles before a defect is noticed, only partial compensation may be offered.

Make Model Year
Mazda MX-5 I (NA) 1989 - 1998
Mazda MX-5 II (NB) 1998 - 2005