TQ Converter Stall Question
 

I have an F150 Supercrew, 2001 Gen 1. Can someone tell me what the stall is on the converter?

Reason I ask is that the truck "shifts" 4 times and I assume that the last one is the converter lockup. It just seems like a large drop in RPM for that. This leads me to believe that there is a higher stall converter in my truck than I am used to.

Any insight here will be appreciated. I have a hard time, as others have pointed out to me before, understanding everything that is happening in these things. I think my capability to understand transmissions peaked just about the time they started putting syncros into them ;)

Chuck

HI!... IMUD : If you have the 4R70-W tranny then your stock stall should be around 1600RPM. It will vary slightly with the weight of the vehicle.

Hmmm,

I can rev the truck up to about 2200-2300 RPM before it starts to overpower the brakes so 1600 sounds about right I guess. Is it usual for a 400-500 RPM drop when the converter locks?

Chuck

IMud,

The fourth "shift" you are feeling is in fact the converter locking up, as you suspected. This actually takes place in third gear as well, but due to the speed and ratio it often isn't noticed. Bear in mind that stall speed varies with the amount of torque being spent to the converter. Your truck make "lock" as soon as it shifts into third under low throttle conditions. Put the pedal to the floor and the converter won't lock until much later.

As a note, bringing the revs up against the brake won't tell you the true lockup range, as the converter can overpower the brakes even if it isn't locked up.

As for the RPM drop, it will vary based on load. Under light acceleration in fourth gear, you will notice more of a drop when the converter locks up. If you stay in the gas longer, the lockup speed will be higher and the RPM drop would be slightly less.

Thanks everyone for the information. I now understand what is happening. I was a little paranoid because years ago, I owned a really old, beat up Mercury Capri that had a 3 speed tranny with 4 gears when it was really cold out! There was a sticking valve that "froze" up and would let loose fully after the fluid warmed a bit. Wanted to make sure that nothing bad like this was happening with the truck.

Chuck

Doesn't sound like much fun......

On my '95 it feels like five shifts under certain throttle conditions. Third, lockup, fourth, lockup. You can hear it more than feel it, but it's still strange.