Thrust Bearings

Has your crankshaft developed too much fore-and-aft play, or is the engine stripped down for a rebuild? Thrust bearings and thrust washers keep the crankshaft in place lengthwise. They are for you if you are rebuilding or upgrading an engine and want to hit the correct end play.

What does the thrust bearing do?

The thrust bearing is fitted either as separate thrust washers or as a flange on one of the main bearings. It absorbs the forces that push the crankshaft back and forth, e.g. when the clutch pedal is pressed. If the bearing wears, the end play increases, and in the worst case this can damage the block and crankshaft. If the thrust face is part of the main bearing itself in your engine, you will find that part under main bearings. The rest of the range is under bearings and spacers.

How to choose thrust bearings

• Engine code: The parts are listed for specific engines, e.g. Honda D16A1 and K20A2, Toyota 1ZZFE or Mitsubishi 4B11T. Always check the part number against your engine.
• Size: Many thrust washers come in standard size. If the crankshaft thrust faces have been ground, a different thickness may be needed, depending on what is available for the engine.
• Design: King Engine Bearings, for example, offers thrust washer sets, while ACL has thrust washers in standard size. Clevite and Hot Rods are also represented in the category.

Installation and checking

Measure the end play with a dial indicator after installation and compare it with the engine specification. The oil grooves should typically face the crankshaft, and the surfaces should be lubricated during assembly. If the engine has been taken apart, it makes sense to also check the rod bearings.

Frequently asked questions

How do I know if the thrust bearing is worn?

The reliable sign is excessive end play, measured with a dial indicator on the crankshaft. A changed clutch feel or scoring on the thrust faces can also point to wear, but always measure before replacing parts.

Are thrust washers and main bearings the same thing?

No, but they are related. In some engines the thrust face is part of a flanged main bearing, in others there are separate thrust washers. It depends on the engine, so check the design for your engine code.

What can make the thrust bearing wear quickly?

Typical causes are high pressure from the clutch, an incorrectly installed torque converter, poor lubrication or dirt in the oil. If you are fitting a stronger clutch in your project, you should therefore check the end play.