Big-end bearing set 320/09207 JCB Dieselmax undersize, aftermarket

Big-end bearing set 320/09207, undersize is an aftermarket part for the JCB Dieselmax 444 engine. The card also lists 320/09340. The size is confirmed by the marking on the back of the shells and by measuring the crankpin.

A big-end shell consists of a steel back and a thin bearing lining; it sits in the rod with crush and a tab stops it turning. After a spun bearing the crankpin and rod bore must always be measured, because a new shell in a damaged bore soon spins again. Keeping to the oil and filter change intervals is the main factor in bearing life. The shell size is marked on the back of each shell, showing standard or the undersize value.

Specifications

Compatibility

The part is listed for JCB 3CX and 4CX backhoe loaders. An undersize set is chosen after the crankshaft has been reground, to the journal size given by the grinding shop. The catalogue also has the aftermarket version and genuine version of this part. For the rod bolts see the connecting rod bolt 320/03040. Other parts are in JCB Dieselmax engine.

Fitting

Before assembly the crankpin is measured and the oil clearance checked; the shell tabs go into the rod, the cap is fitted to its mark and the rod bolts are torqued to JCB figures. Renewing the rod bolts is recommended.