Datsun Roadster Engine Main Bearing - Sets OEM JAPAN
OEM main bearing setw/oversize center thrust flange surface (5 MAIN BEARING).
OPENED ENGINE BEARING SETS ARE NOT RETURNABLE
OVERSIZE THRUST EXPLAINED BY YAMATO-SHOKAI NISSAN DISTRIBUTOR:
ALL aftermarket Nissan import bearings from 1990 and later are made with an oversize center thrust. The center thrust surface are dimensionally wider than the original bearings from the factory. The 20 year old and now 52 year old engines may have center thrust surfaces that are worn, grooved or rough orthey may be just fine. As manufacturers of bearings have knowledge of limited replacement new crank shafts, they make an oversized center thrust bearing that can then be fitted specifically to address the problem of crankshaft thrust surface wear.
The assembly process of these bearings is the same for crankshafts that are worn and not worn. Fit the bearing thrust to the repaired crankshaft or acceptable thrust surface crankshaft, machining first, then working the shell bearings on a flat surface, equally on both sides until you get an acceptable end thrust of .003 to .005.
Some, cheat and cut the crank thrust surface to the bearings regardless of thecondition of the crankshaft. The only bearings that never had an oversize thrust were Nissan bearings at $200.00 per set. Nissan believed that if the center thrust of the crankshaft was worn, a new replacement should be purchased. Price was around $800.00.
New Nissan bearings and crankshafts are no longer available.