Dumb question but...what is converter lockup
04-20-2007, 02:13 PM
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OK - shooting for lamens terms here...so don't pick on me for technical inconsistency or inaccuracy..
The torque converter is driven from the engine crankshaft (via flexplate) The input shaft to the transmission is driven by the fluid in the torque converter. This 'fluid-coupling' is not a 100% positive mate. In other words - it slips...the crank may turn 1 revolution and the input shaft to the transmission turns something less than one turn. How much less depends on how 'Loose' it is. Getting a little off subject here..but this is where you get a stall. How loos it is is basically the convertal stall. So when you 'lock' a converter (back on subject here) you mechanically lock the input shaft of the transmission to the crankshaft (this all happens inside the torque convertor of course). So now, with the convertor 'locked' the input shaft is rotating at exactly the same speed as the crankshaft. You can tell when the trans does this because your RPM will drop a couple hunded points...it feels like the transmission shifts into 5th gear...but it is really just locking the convertor. Then if you step on the gas a little you may notice a 'small' down shift - that is unlocking the convertor. Step on the gas hard and it will actually shift down to 3rd gear...but that small pick up in RPM with little throttle is just unlocking the convertor.
The torque converter is driven from the engine crankshaft (via flexplate) The input shaft to the transmission is driven by the fluid in the torque converter. This 'fluid-coupling' is not a 100% positive mate. In other words - it slips...the crank may turn 1 revolution and the input shaft to the transmission turns something less than one turn. How much less depends on how 'Loose' it is. Getting a little off subject here..but this is where you get a stall. How loos it is is basically the convertal stall. So when you 'lock' a converter (back on subject here) you mechanically lock the input shaft of the transmission to the crankshaft (this all happens inside the torque convertor of course). So now, with the convertor 'locked' the input shaft is rotating at exactly the same speed as the crankshaft. You can tell when the trans does this because your RPM will drop a couple hunded points...it feels like the transmission shifts into 5th gear...but it is really just locking the convertor. Then if you step on the gas a little you may notice a 'small' down shift - that is unlocking the convertor. Step on the gas hard and it will actually shift down to 3rd gear...but that small pick up in RPM with little throttle is just unlocking the convertor.
