What does the +0.25mm sizing mean for these bearings?

The +0.25mm sizing indicates that these bearings are slightly larger than standard. They are intended for use when the engine's crankshaft has been machined (ground) undersize by 0.25mm during a rebuild. This ensures a proper, tight fit between the bearing and the crankshaft journal.

What is the construction of these main bearings?

These bearings are constructed with a bimetal design, utilizing an aluminum base. This material choice is common in modern engine bearings for its ability to manage heat and provide good wear resistance.

Are these bearings a direct replacement for all BMW M20/M50/M52 engines?

Yes, these bearings are designed to fit the specified M20, M50, and M52 engine variants across a broad range of BMW models. However, it is crucial to confirm that your specific engine code and crankshaft condition (standard or undersize) match the bearing specifications.

Specifications

Brand: King Engine Bearings
Part #: MB7720AM0.25
UPC: 611500209314

King Engine Bearings BMW M20B20/M20B25/27/M50B20/25/M52B20/25/28 (Size +0.25mm) Main Bearing Set

Name: King Engine Bearings BMW M20B20/M20B25/27/M50B20/25/M52B20/25/28 (Size +0.25mm) Main Bearing Set
Brand: King Engine Bearings
SKU: king-engine-bearings-king-engine-bearings-bmw-m20b20-m20b25-27-m50b20-25-m52b20--t14-771095
Price: 124.76 USD
Availability: BackOrder

$124.76

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King Engine Bearings BMW M20/M50/M52 main bearing set (+0.25mm). A well-built bimetal bearing set for engine rebuilds.

Key Features

Fits BMW M20B20, M20B25/27, M50B20/25, and M52B20/25/28 engines.
Main bearing set is sized +0.25mm for use with a ground crankshaft.
Features a bimetal construction with an aluminum base for durability.
Designed for a wide range of BMW vehicles including 3 Series, 5 Series, Z3, and Z4 models.

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About this part

Product Details

King Engine Bearings is known for making solid engine bearings, and this main bearing set is no exception. If you're rebuilding the bottom end of your BMW M20, M50, or M52 engine, these bearings are a critical component. They are designed to handle the loads and heat generated by these engines, helping to keep your crankshaft spinning smoothly and within spec. This set is specifically sized at +0.25mm, which is important if you've had your crankshaft ground undersize during a rebuild.

These bearings feature a bimetal construction with an aluminum base, a common and effective material choice for modern engines. This design helps manage heat and wear effectively. They fit a wide range of BMW models, including popular ones like the E30 325i, E36 328i, and E39 528i, among many others. Ensuring you have the correct size bearing is key to a successful engine rebuild, and this +0.25mm set is ready for that job.