2012 F-250 6.2 gas 4X4 SC/SB: when I run WOT, or near that, from a slow speed, I hear a short "hiss" between the 1-2, 2-3, and i think 3-4 shifts. I can also feel that the engine eases up quite a bit during the shift, and it is kind of a slow, soft shift. It has about 2,000 miles on it. I bought it in March 2013 as a leftover (great price!). The door sticker says it was manufactured in 4/2012, so it sat on the lot for quite a while before i bought it. But i don't remember it doing this when it was newer (~500 miles).

With the lite weight of this configuration (it is an XL so it isn't even carrying around 4 speakers ha ha), and me rarely carrying a very heavy load (yet) or towing anything, I rarely have to step on it very much in normal driving... it hardly ever gets above 2,500 rpm unless I am just running it faster for fun.

The hiss and slow shift happen at any transmission temperature. Of course, it never has been above the left side of the "gear" pic on the temp gauge, where it always is after full warm-up.

Well, I'm hoping it is just shifting soft like this because it has "learned" my lite-foot driving style (even when I'm in a hurry of course the engine rarely has to work very hard). What do you think?

 

I get the hiss to. No slow shift though.

 

2013 6.2 Liarat here, tranny is noisy for sure. Same thing you are speaking of as well. No worries, I have used mine a bunch for towing.

 

Thanks for the responses. On driving it some more, the shifts are really not that slow, and I could guess that the engine "pause" is just the spark / fuel injection being stopped during the shift, to "unload" the transmission and / or keep it from revving up, if the torque converter gets unlocked, during the shift. This is by far the heaviest-duty tranny I have ever driven - last F-150 had the 4R70W, and I have had small cars since then - so it should be really no surprise it's more noticeable. Looking at this transmission under the truck, it looks like it is bigger than the entire engine and transmission from a car - it's HUGE! It looks like a jet engine or something!

We used to "speed shift" our small dirt bikes (RM125 etc.) without the clutch, just pressing the kill switch for a second for the shift, to take the load off the tranny.

Well anyway I think this transmission keeps the torque converter locked a lot more than previous automatics; I drove an Econoline before with a 5.4 / auto and if you were cruising in 4th gear and the converter was locked, and you started slowly pressing on the gas pedal, first it would unlock the converter, and then if you kept accelerating more it would actually downshift. I think the idea with these heavier transmissions is to keep the converter locked almost all the time, eliminating the heat and inefficiency of the hydraulic loss of the converter unlocked. So that would be part of the need for more transmission speeds. I can imagine towing up a heavy load up a long grade; if the torque converter was unlocked the whole time it would be very inefficient and generate a lot of heat.

This 6R140 feels so much different from any other automatic I have driven (remember the old "slushbox" three-speeds, like the one in my Dad's '72 Gran Torino?). I guess I should expect a lot of differences from something designed to carry more than two times the torque load than my last truck. I am really happy they decided to use the same transmission for the gas engine that they use for that mammoth diesel engine! It really bothers me when a vehicle is designed with an inadequate transmission - my brother has a Windstar, which i think is just basically a minivan on a Taurus chassis, and after the second transmission burned out (after about 125,000 miles) he had it replaced by a company with a lifetime guarantee; now it seems like he is just on some lifetime transmission replacement program, like it is a maintenance item... "yeah, I need to bring it in for an oil change, new air filter, and transmission swap"... ha ha. I am always picking on him about that porky van, everything about the chassis seems to be overloaded.

Well, rambling on... Thanks again for the responses.