kkritsilas
Well-Known Member
AMP762, good point about the possibility of the /6 not getting the lockup torque convertor. I only have V8 J bodies, and the fender tag codes read A998 for the 318 2bbl and A999 for the two 318 4bbls, so I don't have any personal evidence. It may be that the /6, and the Super 6 were deemed fuel efficient enough that they didn't need the lock up torque convertor, or that their power curve was such that they would not have benefitted from the lockup torque convertor significantly.
The idea behind the lockup torque convertor was to eliminate the losses in a fluid only convertor. There are always some losses in a fluid only convertor, the actual amount of loss being based on the design of the torque convertor. The lockup torque convertor mechanically locks the two sides of the torque convertor so there is no loss. This should only be done if shifting is not going to be happening, for obvious reasons. This means highway cruising in top gear, essentially. I have read that the mileage improvement can be as high as 5%, and that transmission fluid temperatures tend to run lower with the lockup engaged. On the other hand, the lockup mechanism was never designed for heavy duty use (towing, in pickup trucks that haul/tow heavy loads, or high performance use), so in those cases, the failure rate for lockup torque convertors can be high.
Kostas
P.S. In the early/mid 1960s, GM had a similar idea with their variable/switch pitch torque convertors. They had a mechanism that would vary the (I believe) stator blade angle to allow for a variable rate of torque multiplication depending on load. They stopped it though; not really sure why.
The idea behind the lockup torque convertor was to eliminate the losses in a fluid only convertor. There are always some losses in a fluid only convertor, the actual amount of loss being based on the design of the torque convertor. The lockup torque convertor mechanically locks the two sides of the torque convertor so there is no loss. This should only be done if shifting is not going to be happening, for obvious reasons. This means highway cruising in top gear, essentially. I have read that the mileage improvement can be as high as 5%, and that transmission fluid temperatures tend to run lower with the lockup engaged. On the other hand, the lockup mechanism was never designed for heavy duty use (towing, in pickup trucks that haul/tow heavy loads, or high performance use), so in those cases, the failure rate for lockup torque convertors can be high.
Kostas
P.S. In the early/mid 1960s, GM had a similar idea with their variable/switch pitch torque convertors. They had a mechanism that would vary the (I believe) stator blade angle to allow for a variable rate of torque multiplication depending on load. They stopped it though; not really sure why.
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