decending hills with an automatic
Senior User
Joined: Jan 2001
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decending hills with an automatic
The TC locks via a fluid coupling. The way fluid couples the two sides is through increasing the pressure inside the TC. There is not "hard lock" between the crankshaft and the trans, it's strictly a fluid coupling.
The reason auto manufacturer's are even required to use this methof is because of new emissiions laws. With the TC slipping at take off and lower speeds, vehicle emissions are reduced because you are not having to "dump" as much fuel into the cylinders to get the vehicle moving.
-Rich
The reason auto manufacturer's are even required to use this methof is because of new emissiions laws. With the TC slipping at take off and lower speeds, vehicle emissions are reduced because you are not having to "dump" as much fuel into the cylinders to get the vehicle moving.
-Rich
Senior User
Joined: Sep 2001
Posts: 238
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From: Troy USA
decending hills with an automatic
Don't disagree with what you just said. What I do disagree with is your statement about the engine not slowing you down below 35. That is WRONG. The Torque Converter still works below 35. IT NEVER FREE WHEELS. WHY DO YOU HAVE SUCH A HARD TIME UNDERSTANDING THIS? Drive your vehicle in 1st and try it out!
Senior User
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decending hills with an automatic
There's no need to get angry about it...every PSD I have driven, does not have ANY engine braking below 35mph. Period. I don't know what the difference would be, but I'm just stating what I have experienced. I have driven PSD's from 99-01, and they've all acted the same.
-Rich
-Rich
Frmr Ford Trans Engr
Joined: Aug 1999
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From: SE Florida
decending hills with an automatic
If you leave the shifter in OD there will be no engine braking in any gear except overdrive.
If you move the shifter to 2 or 1 there will be significant engine braking with or without the torque converter locked, assuming the transmission is working properly.
Mark
If you move the shifter to 2 or 1 there will be significant engine braking with or without the torque converter locked, assuming the transmission is working properly.
Mark
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Joined: Aug 2001
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decending hills with an automatic
Specs for the 4r100 auto... i guess everyone is right :-)
------------
A 4R100 electronically controlled 4-speed automatic overdrive transmission is available on select F-150 models, F-250 - 550 and E-Series models with 5.4L, 6.8L and 7.3L engines.
Features and benefits:
Overdrive fourth gear and mechanical "no-slip" power flow contribute to fuel economy
Split torque path in third gear transfers by torque converter 40 percent (hydrodynamically) and 60 percent (mechanically) of the engine torque through solid connection to the driveshaft
100 percent of the torque is transmitted mechanically in fourth gear
Heavy-duty components to satisfy light truck needs
Overdrive transmission control switch mounted on shift lever locks out overdrive fourth gear when additional engine torque is needed or to obtain third-gear engine braking on downgrades
Super Duty F-250-550 models offer an optional PTO provision
------------
A 4R100 electronically controlled 4-speed automatic overdrive transmission is available on select F-150 models, F-250 - 550 and E-Series models with 5.4L, 6.8L and 7.3L engines.
Features and benefits:
Overdrive fourth gear and mechanical "no-slip" power flow contribute to fuel economy
Split torque path in third gear transfers by torque converter 40 percent (hydrodynamically) and 60 percent (mechanically) of the engine torque through solid connection to the driveshaft
100 percent of the torque is transmitted mechanically in fourth gear
Heavy-duty components to satisfy light truck needs
Overdrive transmission control switch mounted on shift lever locks out overdrive fourth gear when additional engine torque is needed or to obtain third-gear engine braking on downgrades
Super Duty F-250-550 models offer an optional PTO provision
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