SlyFX4Guy

iTrader: (-1)

I've been noticing this happening and finally getting around to getting some input/opinions and curious if anyone else is experiencing this with their 6sp trans.

3rd gear under normal acceleration around 30-35mph right about 2500rpms the RPM drop approx 500rpm as it continues to accelerate to 40+ then shifts into 4th.

If you didn't know it wasn't shifting gears, you would think it was just a normal gear shift. Anyone else experience this and/or know why the RPM drop?

BadAV

Same answer as given on the eco site - the torque converter is locking.

SlyFX4Guy

iTrader: (-1)

ecosite?

so is this a TSB or a normal occurrence in 6sp trans?

TomB985

Completely normal for just about every automatic made since the mid-1990's. On my phone at the moment, but do a google search for "torque converter " and you'll learn a lot.

admlshake

man i'd love to know the answer to that...mine has the same issue!

antho

It's not a issue. As posted above, It's the torque converter locking.

caperJ

So if you do not tow your essentially getting a six speed? Doesnt seem like a large advantage.

Aj06bolt12r

100% totally normal. It is functioning exactly as designed.

Torque converter does not lock up in 1st or 2nd gear. After it shifts into 3rd gear the converter locks up and stays locked up through the rest of the gears if you maintain steady acceleration.

Sometimes you will notice this in other gears under certain conditions. Like if you are on a 2 lane highway and you have to slow down for someone turning in front of you. Instead of dropping 2 or 3 gears the transmission will stay in 5th but unlock the torque converter when you get back in the gas, then once you are getting back up to speed the tranny will re lock the tourque converter in 5th before shifting back into 6th.

Again there is no TSP for this.... it is supposed to do that.

BadAV

The exact same question was asked on the ecoboost site the day before you asked it here.

As others have already answered, it's totally normal. The OEMs are locking the torque converters in most gears now in an attempt to eke out every last 0.1 mpg they can.

If I remember correctly from looking at the F150 6 speed auto programming, the converter locks in 3rd, 4th, 5th, and 6th. I've re-programmed mine so that it does not lock in 3rd or 4th.

Indy2015

This thread brings to mind the time I retrofitted a 700r4 transmission into my 1970 C10. Figuring out the TC lockup function was a little work. Since the 700r4 came from an early 90's silverado and was "mostly" electronically controlled, I had to pull out all the old wiring and then figure out where to install new line pressure switches in the valve body so that the TC would only lockup shortly after the transmission shifted into overdrive and then unlock again when it downshifted into 3rd or below.

I was swapping parts between the old TH350, a TH400 and the new 700r4 to get a solid and reliable installation.