| Also known as | E3586 |
| Diagram | Fig. 1 — CRANKSHAFT AND CONNECTING RODS · ref 12 |
| Subsystem | engine bottom |
| Listed in parts books | 1960–1962, 1964–1965, 1967–1968, 1970–1971, 1974, 1976–1980, 1985 |
Big end bearing (available in ·010 in. and ·020 in. undersizes)
Big end (connecting rod) bearing shell for the Triumph twin crankshaft, available in .010 in. and .020 in. undersizes.
70-3586 is the big end (connecting rod) bearing shell for the Triumph twin crankshaft, showing up across the CRANKSHAFT AND CONNECTING RODS figures in the parts books. It's the shell that sits between the rod and the crank journal, taking the load every time the piston comes down on the power stroke. This one is offered in both .010 in. and .020 in. undersizes, which matters when a crank has been reground - you match the shell size to whatever the journal was cut to.
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The older parts-book form of this number is E3586, so if you're working from an early book or a rebuild log with that prefix, it's the same physical part as 70-3586.
This one appears across a long run of catalog years, so it's a part that stuck around in the lineup for a long time without a design change. If you're rebuilding a bottom end, check what your crank was actually ground to before ordering - standard, .010, or .020 - since fitting the wrong undersize shell against the wrong journal diameter will leave you with the wrong clearance.
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