A Primer on 356 Bearing Sets

Main bearings are a constant source of confusion for early air-cooled Porsche owners. The Factory long ago stopped producing full sets, and the engines can take a variety of different sizes, based upon the year of manufacture and the machine work done to account for wear. Here’s a handy guide to the bearings available for your 356 or 912.

The 356A and 356B were built with a three-piece engine case and a crankshaft with 50mm bearing journals. The bearing sets for this engine are listed with 546 part number prefixes.

The Super 90 (S90) came with a different crankshaft that had 55mm journals. These bearing sets are numbered 616-100-130-XX (where XX varies based upon sizing). While we do have the standard / standard size in stock, the sets for machined cranks are hard to source.

The 356C, SC and 912 engines had a 55mm crankshaft as well, but require a slightly different #1 bearing. These bearing sets are numbered in the 616-100-138-XX range.

To fix wear issues, you can machine the crankshaft and use a correspondingly thicker bearing. You can also line-bore the case to account for slight wear of the case. The naming conventions vary for this: some sheets list it as case (outside) / crank (inside), others as crank (inside) / case (outside). Either way will work, as long as the part numbers match up to what you need. The chart below lists it case / crank.

• First machining is .25mm
• Second machining is .50mm
• Third machining is .75mm

Finally, our replacement main bearing sets typically use a modern steel-based bearing. We’ve replaced the prefix of each set with NLA and listed this in the name and description of each bearing set: you can search on either the NLA- or the 546 / 616 prefix to find what you need. We also have individual bearings in the original aluminum style.

Main bearing sets

546 prefix = 50 mm crank; 616 prefix = 55 mm crank, including S-90. “1st / Std” means the case is 1st size larger and the crank is Std size. This order is listed differently than in our print catalog, but the part numbers are the same and correct.

Rod bearing sets

For “late” rods only.