5 spd auto??

[Dudenhymer]

I've got an 03 F250 SD with an auto and the 7.3. Don't drive it much cause I drive 55 miles each way to work. Anyway this may sound stupid but I alway thought it was a 4 speed but it's actually a 5spd. The shifter of course reads 1 2 D(with outline), but it shifts 4 times into 5 different gears. Why did Ford set it up like this?

Thanks.

[dirtbikeguy2003]

I think the 5th gear you are feeling is the torque converter locking.

[injection direction]

Yes, that is right. It just feels like there are 5 speeds.

[Dudenhymer]

What does the torque converter locking do?? I've read about people installing manual lockers, what would they be good for??

Thanks

[Jake]

Its the converter locking that feels like an extra gear. If you floor it from a standstill it will only have 4 shifts.

Locking the TC acts like a clutch on a manual, it locks the engine and trans together so there is no slippage between them. Slippage = power loss.

[Dudenhymer]

How much power loss was is there? Does a converter lock add stress to the tranny or motor? Do you keep it locked thru all gears with the lock? Where can I get one??

Thanks again

[Jake]

The truck will shift with the TC locked on its own under factory operation. As long as you aren't a moron and try locking the converter when there is a lot of TC slip goin on, such as taking off from a stop, you won't hurt anything. I've heard to not lock the TC under 1000 RPM due to not having enough line pressure to keep it from slipping, however ive had mine locked down to idle with my foot to the floor with no slippage, that seems to be more of an OBS thing. I have seen them slip under 1000 RPM.

To get one, you actually make it yourself. I have the schematic most people use here. Are you any good with wiring?

[Dudenhymer]

Ya I can handle some wiring, no prob. When would it be beneficial to lock the converter? I've noticed that when I'm running the truck hard (floored) it seems like it takes too long to shift at higher RPMs. It will get to 3K+ RPMs then it feels like it just holds there for a couple of seconds then finally shifts. Is this TC slippage??

[Jake]

No, TC slippage is when you can push the pedal down harder and the engine revs higher than what you are actually moving. Make sense?

[JakeLewis79]

Lockup TC = better mpg's and less power loss.

BTW, This is why I like this forum! People helping others instead of flaming. I know on a lot of other forums, there would be 5 or 6 useless posts flaming the OP before somebody came up with a useful answer. Keep up the good work, Jake.