Product Description
Genuine Cummins
Cummins 4955858 — Main Bearing Set (.030" Undersize / 0.75 mm)
MPN: 4955858 | Also Known As: crankshaft main bearings (set) | Size: .030" undersize (0.75 mm) | Cross-Ref: 3802013
Why This Part
- ✓ OE bearing geometry & material designed for durability and oil film stability.
- ✓ .030" undersize set for cranks ground .030" under; restores correct clearances.
- ✓ Broad B-Series coverage across 5.9L (’89–’07) and 6.7L (’07.5–’18) when journal size matches.
- ✓ Matched shells for all mains; precise crush and alignment.
OE Fit .030" Undersize Complete Set
Quick Specs
| Type | Main bearing set (upper & lower shells) |
|---|---|
| OE Part # | 4955858 |
| Size | .030" undersize (0.75 mm) |
| Thrust Bearing | Sold separately (common OE: 4938948) |
| Qty Required | 1 set per engine |
| Cross-Reference | 3802013 (ID only) |
Verified Fitment (Automotive)
| Year Range | Engine | Chassis |
|---|---|---|
| 1989–1998 | 5.9L B-Series 12-Valve | Ram 2500/3500 |
| 1998.5–2002 | 5.9L B-Series 24-Valve (VP44) | Ram 2500/3500 |
| 2003–2007 | 5.9L ISB (24-Valve Common-Rail) | Ram 2500/3500 |
| 2007.5–2018 | 6.7L ISB (24-Valve Common-Rail) | Ram 2500/3500 |
Notes: This is a .030" undersize bearing set for a crankshaft that has been ground .030" under. Always measure journals and verify by VIN/ESN before ordering.
Often Paired With
- Thrust Bearing: Cummins 4938948 (sold separately)
- Other Sizes: 4955853 (STD), 4955856 (.010), 4955857 (.020), 4955859 (.040)
- Plastigage & Assembly Lube for clearance check and pre-lube
- Oil Pan Gasket Set and fresh oil/filter after service
What’s In The Box
- (1) Genuine Cummins Main Bearing Set 0.030" Under (4955858)
- Thrust bearing & hardware sold separately
Install Tips
- Confirm crank journal size (.030" under) with micrometer; line-bore check recommended on rebuilds.
- Clean oil passages thoroughly; pre-lube shells and journals before assembly.
- Torque to factory spec and verify oil clearance with plastigage.
FAQ
IS 4955858 THE .030" UNDERSIZE SET?Yes—this kit is .030" undersize (0.75 mm). Use on a crankshaft ground .030" under.
WILL THIS FIT BOTH 5.9L AND 6.7L B-SERIES ENGINES?Yes—when the crank journal size matches (.030" under). Coverage spans 5.9L (’89–’07) and 6.7L (’07.5–’18) ISB applications.
DOES THIS SET INCLUDE THE THRUST BEARING?No—the thrust bearing is separate (common OE: 4938948).
HOW DO I KNOW WHICH SIZE I NEED (STD, .010, .020, .030, .040)?Measure crank main journals and consult your machine shop. Order the bearing size that matches the actual journal size.
IS THIS A GENUINE CUMMINS PART?Yes—OE Cummins bearing set with factory tolerances and materials.
