A340H 2 overdrive gears?
06-22-2011, 09:32 PM
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A340H 2 overdrive gears?
Was towing a hefty load on my 94 3vze pickup that has this transmission, I turned off the overdrive to avoid overheating and I was cringing at the high rpm it was running @ 55mph (stock 31" wheels, stock 4.56 gearing, everything stock) so I turned on overdrive and noticed there's actually TWO extra gears it doesn't use when OD is off. What the hell? Anyone mind explaining? Truck seems to do fine in the gear before the actual last gear, which I'm assuming is the OD gear. So if I keep it between 62-68 I can stay in this gear and it seems MUCH easier on the motor and tranny. At 70mph is when it goes to OD, which is almost impossible with the 3.slow. By the way, was towing a 7x12 v nose trailer that totalled (with gear) about 2700.
Input?
Input?
07-30-2011, 11:26 AM
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In many newer AT's, the torque converter "locks" above a certain speed in top gear. This provides "direct drive", i.e. eliminates lost energy from the natural slipping of the torque converter. If anything, when the TC locks, there is less friction affecting the fluid and it should stay cooler.
that's why it feels like you have two gears in OD -- the actual OD ratio, and the little "kick" you feel when the TC locks. That's also why you seem to have more torque in the "lower" top gear, because the TC can still slip and let the engine turn a bit faster than the drivetrain.
that's why it feels like you have two gears in OD -- the actual OD ratio, and the little "kick" you feel when the TC locks. That's also why you seem to have more torque in the "lower" top gear, because the TC can still slip and let the engine turn a bit faster than the drivetrain.
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