Engine Building Fundamentals: Thrust Clearance
Thrust Clearance
01.18
00:00 | - An often overlooked clearance in the engine, is the crankshaft thrust clearance, or end play as it's also known. |
00:07 | This is the amount of longitudinal movement that the crankshaft has when installed in the engine block. |
00:13 | The thrust movement is dictated by the width of the thrust bearings, and the distance between the thrust faces on the crankshaft. |
00:22 | The reason the thrust bearings are required is to stabilise the crankshaft longitudinally, as well as to support the crankshaft when thrust forces are applied. |
00:32 | Such as when the clutch is depressed. |
00:35 | Due to the loads being applied to the thrust bearings, the clearances here are not nearly as critical when compared to those of the big end main bearings, and they're also usually quite a lot greater. |
00:48 | For example, a typical thrust clearance may be in the range of ten thou, or a quarter of a millimetre. |
00:54 | I always use the OEM manufacturer's recommendations for thrust clearance, even on heavily modified engines. |
01:02 | There's more danger if the thrust clearance is too tight. |
01:06 | As this may result in the thrust bearing and the thrust surface of the crankshaft quickly wearing, which can do extensive damage to the entire engine. |