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Explains engine failures | Previous attempts and stopgap measures | Our bearings aren't a stopgap, they're a fix | Custom bearing selection and purchasing details | Who are we and what do we do here? |
The original 088/089 BMW factory bearings were made by Clevite as a "Tri-Metal" design. Tri-Metal is a three metal process. The base steel layer, topped with copper, topped with lead. These are a very soft bearing and good for your crankshaft. The lead is soft and can absorb small foreign particles without damaging the crankshaft. The original factory bearings may not be of sufficient clearance, but they are a great design (no design flaw). In addition to being very maleable and soft on the crankshaft, the lead-copper bearings provide great early warnings of engine failure through Blackstone oil analysis. Having your oil analyzed regularly, one experiencing excessive wear would see elevated lead and copper in the oil analysis.
But the European Union (EU) mandated that all vehicles, except those already in production, and made 2011 or later, must remove the lead from the bearing material. Even though BMW had the choice to keep the 088/089 Clevite lead-copper bearings, they chose to make a new bearing. The new bearing manufacturer is Glyco, a subsidiary of Federal Mogul.
The new 702/703 bearing has about the same clearance as the older 088/089 Clevite bearing, but instead of being made of lead-copper, it is made out of tin-aluminum. The tin-aluminum is much harder at the surface, and much harder on the crankshaft. It is this extra hardless that is believed to contribute to increased engine failures on these engines with 702/703 bearings. In addition to extra hardness, early bearing wear is much more difficult to detect with a Blackstone oil analysis (due to lack of lead and copper).
BMW Part Number | Thickness | Hardness |
088 | 0.07875 | 16.2 B Scale |
089 | 0.07885 | 16.2 B Scale |
091 | 0.08370 | 16.2 B Scale |
090 | 0.08360 | 16.2 B Scale |
702 | 0.07855 | 61.8 B Scale |
703 | 0.07875 | 61.8 B Scale |
The new 702/703 tin-aluminum bearings are nearly 4-times harder than the previous Clevite 088/089 lead-copper bearings.
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Factory Reference
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VAC-1
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VAC-2
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Top (Blue) |
0.07885
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0.07880
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0.07885
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Bottom (Red) |
0.07865
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0.07890
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0.07895
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Factory Reference
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VAC-1
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VAC-2
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Top (Blue) |
0.07885
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0.07890
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0.07895
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Bottom (Red) |
0.07865
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0.07880
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0.07885
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Best Case FCT+VAC
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Worst Case FCT+VAC
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Best Case CARR+VAC
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Worst Case CARR+VAC
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Crank Journal |
2.04650
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2.04660
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2.04650
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2.04660
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Rod Bore |
2.04815
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2.04750
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2.04760
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2.04745
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Bearing Clearance |
0.00165
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0.00090
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0.00110
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0.00085
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702/703 Results |
R1
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R2
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R3
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R4
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R5
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R6
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R7
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R8
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MIN
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Max
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Official
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Min Dev.
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Max Dev.
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Top (Blue) |
0.07870
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0.07870
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0.07865
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0.07865
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0.07865
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0.07865
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0.07865
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0.07865
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0.07865
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0.07870
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0.07870
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-0.00005
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0.00000
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Bottom (Red) |
0.07855
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0.07855
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0.07850
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0.07850
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0.07850
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0.07855
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0.07850
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0.07850
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0.07850
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0.07855
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0.07850
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0.00000
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0.00005
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Calico Results |
R1
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R2
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R3
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R4
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R5
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R6
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R7
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R8
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MIN
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Max
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Official
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Min Dev.
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Max Dev.
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Top | 0.07850 | 0.07860 | 0.07855 | 0.07850 | 0.07860 | 0.07860 | 0.07850 | 0.07855 |
0.07850
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0.07860
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0.07860
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-0.00010
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0.00000
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Bottom | 0.07870 | 0.07875 | 0.07885 | 0.07875 | 0.07870 | 0.07875 | 0.07885 | 0.07885 |
0.07870
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0.07885
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0.07880
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-0.00010
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0.00005
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This was a stopgap measure to add a non-friction coating to the bearings. It was well intended, but poorly executed. Simply said: it was the wrong solution for the problem. Instead of increasing clearance, this reduced it. Recommendation to stay away from this approach.
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Factory Reference
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WPC-1
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WPC-2
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Top (Blue) |
0.07885
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0.07875
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0.07870
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Bottom (Red) |
0.07865
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0.07860
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0.07850
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WPC-1
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WPC-2
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Crank Journal |
2.04655
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2.04660
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Rod Bore |
2.04825
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2.04820
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Bearing Clearance |
0.00170
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0.00160
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Engine guy calls me back a few minutes later and says it's true...they did contract with Clevite to make some custom rod bearings. The new bearings, as he explained, were designed with 0.0005 inch extra clearance. VAC still adds the Calico coating, which he acknowledged takes up the extra 0.0005 inch -- returning the new bearings back to stock clearance.Now it's time to put that to the test. But first, there's one more thing I need to do.
So the bearings start life with 0.0005 inch extra clearance, have Calico coating added (which reduces by 0.0005 inch), and you end up with factory rod bearing clearance again.
Eccentricity
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5 degrees
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19.75 degrees
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45 degrees
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90 degrees
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175 degrees
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161.25 degrees
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135 degrees
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Virgin 702/703's
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Rod-1
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Rod-2
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Rod-3
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Rod-4
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Rod-5
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Rod-6
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Rod-7
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Rod-8
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Virgin 702/703's
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Rod-1
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Rod-2
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Rod-3
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Rod-4
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Rod-5
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Rod-6
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Rod-7
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Rod-8
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Min
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Max
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Official
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Min Dev.
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Max Dev.
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Rod B.E. Bore |
2.20610
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2.20600
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2.20575
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2.20580
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2.20580
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2.20590
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2.20580
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2.20570
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Rod Journal Diameter |
2.04650
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2.04650
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2.04650
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2.04650
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2.04650
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2.04650
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2.04650
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2.04650
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702/703 Bearings |
2.04800
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2.04795
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2.04800
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2.04800
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2.04805
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2.04800
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2.04800
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2.04800
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702/703 Clearance |
0.00150
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0.00145
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0.00150
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0.00150
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0.00155
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0.00150
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0.00150
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0.00150
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0.00115
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0.00200
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0.00150
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-0.00035
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0.00050
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VAC-Clevite Clearance |
0.00210
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0.00190
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0.00190
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0.00210
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0.00210
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0.00190
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0.00210
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0.00210
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0.00190
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0.00210
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0.00200
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-0.00010
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0.00010
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VAC-Clevite Bearings |
2.04860
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2.04840
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2.04840
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2.04860
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2.04860
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2.04840
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2.04860
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2.04860
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Rod Journal Diameter |
2.04650
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2.04650
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2.04650
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2.04650
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2.04650
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2.04650
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2.04650
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2.04650
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Bearing Thickness Top |
0.07840
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0.07840
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0.07840
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0.07835
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0.07835
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0.07835
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0.07830
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0.07825
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0.07825
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0.07840
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0.07835
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-0.00010
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0.00005
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Bearing Thickness Bottom |
0.07840
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0.07840
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0.07835
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0.07835
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0.07835
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0.07835
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0.07830
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0.07825
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I am looking at the Rotella T6 for my car on the next oil change. The T6 must be a stout oil since it has the JASO MA rating on the back...... Not many passenger car/ diesel engine oils meet motorcycle certifications which is a testament to the base stock it is blended from. Motorcycles throw a whole different curve at oils since they have to deal with lubricating a transmission and a wet clutch as well as an engine that can spin upwards of 15000RPM......... But judging by your username I don't need to tell you anything about motorcycles! -- BMRLVR
You are correct on the rotella in the motorcycles, along with my full-time job I also raced a zx-10r for a couple years. There have been some complaints over the last year or so about the t6 though, some of the high power bikes are having a touch of clutch chatter. The zinc and phosphorous levels have dropped from 1600 to about 13-1400 in the new t6. For engine bearings, flat tappet cams and the like that number is still plenty high. The tws oil is about 16-1700 on zinc numbers. BUT although it is higher that doesn't mean it is superior. Mobil 1 racing 4t is being sold as a motorcycle oil but it is really a normal engine oil with about 1500ppm of zinc and phosphorous. The problem is that it is a 10-30 so not really picking up much as far as our clearance problem. -- kawasaki00
Ok, then someone edumacate me. 10w-60 means SAE viscosity of "10" when cold, right? and "60" when at temp, right? soooo, what am I doing wrong here? -- Transfer
http://www.upmpg.com/tech_articles/motoroil_viscosity/
This explains it.
For this problem we have if there were a 5w-60 that would be the ultimate for us. Unfortunately there is no such grade. The 5w would help a ton at start up but still protect like a 60 weight at temp. This is why the rotella 5-40 is a trade off. It is better at low temps and flows better but the untimate high temp shear strength is not as much as a 60.
The second number is the protection factor not the weight. A 10w-30 and a 10w 60 is till the same weight at cold temp. -- kawasaki00
According to the lubrication system schematic for the S65 on BMW TIS it appears as though the engine uses a pressure compensated variable displacement main oil pump. (There is a signal passage off of the main oil gallery in the schematic which is shown as a dotted line...... In my industry, heavy equipment, dotted lines almost always symbolize signal oil in hydraulic schematics). The fact that the pump is variable flow (variable displacement) it would lead me to believe that pump volume should not be an issue in the S65. Variable displacement pumps are used to ensure that max pump volume is available regardless of engine speed. To me this is great news for any of us looking to run additional clearance or lighter oil. This also helps to explain why VCM power claims that the pressure stays constant from 2000RPM on up to redline........ with a pressure compensated pump pressure can remain nearly constant and the system will never have to go over relief except in the event of a system malfunction. -- BMRLVR
The 0w50 is a fantastic oil. The reason I dont bring it up is you need to be catless and be prepared to replace o2 sensors much quicker than normal. Although for most if the car has a supercharger on it they are not worried about a couple hundred bucks for sensors.
Why does the 0w 50 oil cause 02 sensors to go?
Because the 0w-50 that he is talking about is a racing only oil. It has over twice the zinc around 1850ppm I believe. That much zinc will burn coverters up and leave deposits on o2 sensors that skew the data. Kind of like running leaded fuel, but it just doesnt happen as fast. -- kawasaki00