Product Description
The Cummins 4955857 OEM Main Bearing Set (.020” / 0.50mm undersize) is a genuine crankshaft bearing set engineered for select 5.9L and 6.7L Cummins B-Series engines from 1989–2018. These bearings are precision-machined to a .020” (0.50mm) undersize specification, making them the correct choice when a crankshaft has been ground undersize during overhaul or machining. Built with Cummins-approved metallurgy and oil-groove design, this set ensures factory-level durability, proper oil film stability, and long service life in stock and high-demand applications.
Whether you’re rebuilding a high-mileage 12-Valve, refreshing a VP44 or early Common-Rail ISB, or completing a full 6.7L long block overhaul, the 4955857 main bearing set ensures true OEM fitment and performance—critical for long-term reliability under towing, work, and performance use.
Fitment
- 1989–1998 5.9L 12-Valve Cummins (6BT)
- 1998.5–2002 5.9L 24-Valve ISB Cummins
- 2003–2007 5.9L Common Rail Cummins
- 2007.5–2018 6.7L Cummins (pickup & select industrial)
- Also used across multiple B-Series industrial engines (verify via ESN)
Important: This bearing set is for .020” / 0.50mm undersize crankshafts only. Confirm crankshaft machining size before ordering.
Cross-Reference (Cummins-Only)
Related Cummins components commonly replaced during bottom-end service:
• Cummins 3900267 OEM Tappet Cover Bolt Grommet Seal
• Cummins 3915787 OEM Threaded Plug – Oil Filter Housing
• Cummins 3900625 OEM Hex Flange Head Cap Screw
FAQ
What does .020” / 0.50mm undersize mean?
It indicates the crankshaft journals have been machined to .020” (0.50mm) below OEM diameter. These bearings restore correct oil clearance on undersized journals.
Will these bearings fit both 5.9L and 6.7L Cummins engines?
Yes. This Cummins OEM set fits 1989–2018 5.9L and 6.7L B-Series engines when machined to .020” undersize.
How do I know if I need undersize bearings?
If your crankshaft has been ground by a machine shop, it will be labeled with the required bearing size. Never install undersize bearings on a standard-size crank.
Do these bearings include thrust washers?
Many OEM sets do not include thrust bearings. Always verify separately if your rebuild requires thrust washers.
Can these bearings handle towing and performance tuning?
Yes — genuine Cummins bearings use OE-grade metallurgy and overlay, making them suitable for stock, towing, and mild performance use.
Specifications for cummins 4955857
| Specification | Value |
|---|---|
| Brand | Cummins Genuine Parts |
| Part Number | 4955857 |
| Component Type | Main Bearing Set – .020” / 0.50mm Undersize |
| UPC | Not Published |
| GTIN | Not Published |
| Cross Reference | Fits undersize (.020”) crankshafts on 5.9L/6.7L Cummins B-Series |
| E-Codes | Applicable to multiple engine emissions tiers; ESN verification recommended |
| Shipping Weight | 1.0–1.5 lbs |
| Package Dimensions | 6 x 4 x 2 in |
| Prop 65 Warning | Not Applicable |
