General guidance for people who work on engines. For exact figures always follow the vehicle or engine maker's workshop manual.
Start with the engine, not just the car
The same car model can carry different engines over the years, so identify the engine itself. In our product list vehicles are grouped by name: use the search box, and ask us if your engine is not listed.
Which bearing, in which position
Each journal uses two half-shells. Main bearings go in the block, rod bearings in the connecting rods, and a thrust washer sits at one of the main bearing positions to control the crankshaft's end float. Heavy-vehicle engines also use camshaft bushes and connecting-rod bushes.
What the size steps mean
A standard-size bearing is for a shaft in its original condition. If a crankshaft has been reground smaller, undersize bearings with thicker walls make up the difference. Never guess: measure the journals with a micrometer.
Each of our vehicle groups comes in three sizes (five for Peykan and Roa). Ask us which are in stock.
The checks that matter
- Oil clearance. The gap between shaft and bearing must be within the manufacturer's limits. Measure it with a micrometer and bore gauge, or with a crush-gauge strip.
- Journals and bores. Check for taper, out-of-round, scores and rough spots before fitting anything.
- End float. After fitting the thrust washers, check the crankshaft's end float with feeler gauges.
- Oil holes and tabs. The holes must line up with the oil passages, and each locating tab must sit in its notch.
Fit clean, fit once
Work in clean conditions. Do not file, scrape or reshape a bearing, and do not refit old shells. Tighten bolts to the specified torque and sequence, and turn the engine over by hand before the first start.