Product Description
Interstate-McBee M-4955857 Main Bearing Set .020 (0.50 mm) – 1989–2018 5.9L & 6.7L Cummins
Aftermarket OEM-style .020" undersize (0.50 mm) main bearing set for Cummins B-Series 5.9L (12V/24V) and 6.7L ISB engines. Ideal for crankshaft regrinds requiring .020" undersize bearings. Built for stable oil film control and long service life in performance and heavy-duty use.
- Correct undersize: .020" (0.50 mm) for reground crank journals.
- OEM-style geometry: Supports proper oil clearance and crank stability when installed to spec.
- Durable materials: Manufactured to meet demanding Cummins B-Series operating conditions.
- Value vs. OEM: Interstate-McBee aftermarket quality at significant savings over genuine OEM.
Specifications
| Interstate-McBee Part | M-4955857 |
|---|---|
| OEM Reference | Cummins 4955857 (Set, Main Bearing .020 / 0.50 mm) |
| Size | .020" undersize (0.50 mm) |
| Engine Families | 6BT 5.9L (12V), ISB 5.9L (24V), ISB 6.7L |
| Years | 1989–2018 (see vehicle fitment below) |
| Includes | Main bearing set for all mains; verify thrust components per ESN/application. |
Vehicle Fitment
Always verify by engine serial number (ESN) for exact configuration.
- Dodge Ram 2500/3500
- 1989–1998 5.9L 12-Valve (6BT)
- 1998.5–2007 5.9L 24-Valve (ISB)
- 2007.5–2018 6.7L ISB
- Additional B-Series platforms: Certain cab-and-chassis, commercial, and industrial ISB/QSB applications (confirm by ESN).
Install Notes
- Measure crank journals with a micrometer; confirm journal size and roundness before ordering.
- Verify oil clearance with Plastigage or mic/ID bore gauge during assembly.
- Check thrust end-play; replace thrust components if worn (per engine build spec).
- Use assembly lube, observe cleanliness, and torque main cap fasteners in sequence to spec.
Warranty
Interstate-McBee new parts carry manufacturer warranty. Coverage and terms vary by component category; contact us for details specific to main bearings.
Cross-References & Related Sizes
- OEM: Cummins 4955857 (Main Bearing Set, .020 / 0.50 mm)
- Related family (size options): M-4955855 (STD), M-4955856 (.010 / 0.25 mm), M-4955857 (.020 / 0.50 mm), M-4955858 (.030 / 0.75 mm), M-4955859 (.040 / 1.00 mm)
Why Buy From CPP Diesel
- ESN-verified fitment help for Cummins B-Series builds
- Fast shipping, expert support, and hassle-free returns
- Deep catalog of complementary bottom-end parts and gaskets
FAQ
Is .020" the same as 0.50 mm?Yes. .020" undersize equals 0.50 mm undersize on the main journals.
Will this fit both 5.9L and 6.7L Cummins?
Yes—this set covers B-Series 5.9L (12V/24V) and 6.7L ISB platforms from 1989–2018; confirm by ESN for edge cases.
Does the set include thrust bearings?
Applications vary. Many B-Series builds use thrust integrated at the center main; verify thrust component configuration by ESN.
Do I need machine work to run .020" undersize bearings?
Yes—.020" undersize bearings are used after crankshaft journals are reground to the matching undersize specification.
Torque specs?
Always use the Cummins service manual for your exact engine; torque values and sequences vary by model year and fastener type.
