What is a "GOOD" Automatic Shift?

[Rhymingmechanic]

The "Is Lubegard Necessary" topic got me thinking about this most recently, but I wonder about it every time a topic about shift feel comes up.

One guy does a flush with X fluid or puts in Y additive, and it makes his shifts "smooth." The next one does the same, and his shifts become "crisp" or "firm."

So, which is it? Is fluid's effect on shift feel totally subjective? Or does it depend on the specific trans--meaning one that shifts too hard would get softer and one that shifts too softly would be firmer with the same fluid?

My own bias is that a shift should be firm and quick. My first car was a Pontiac with a 400/Turbo 400. I put a shift kit in, and thought I'd found paradise the first time I barked the tires on a downshift driving around town. Currently I have a Silverado with a 4L60E, programmed for firmer shifts with a Hypertech. Stock, shifts seem too mushy and gear engagement is delayed. I also "thought" switching over to Mobil 1 ATF around 35,000 miles made the shifts firmer. My most recent pan drain unexpectedly seemed to do the same.

Considering that history, if I put in Lubegard, for instance, and my shifts became "smooth as silk," I would be mad. The next guy might be happy, though. Is it really about what we wanted the fluid/additive to do, and not what it actually did?

 

[bullwinkle]

I've always thought they should be firm, but not rough, definitely no flaring or delays. Trucks should be firmer still-I'm not a big fan of automatic transmissions anyway.

 

[NHGUY]

An automatic transmission is an engineering marvel.To put pressures thru rotating parts,and to keep those pressures sealed at all speeds and conditions,without slipping or hiccups between shifts....just amazing.To think they perfected that way back in the 50s...its unimaginable.Now,the poor quality parts used today,with the constant useage of newer fluids to mask over the lousy engineering and manufacture of some of these transmissions today is just sad.Nobody in the 60s would have thought to engineer a Hemi TorqueFlite with plastic and feeble electronics and then have to come up with a new fluid to keep it from slipping itself to death,but thats what happens today.And then the $3000 bill for a rebuild when things dont quite hold up.

 

[wirelessF]

I agree with the above but most of it probably comes from the programming. The A340 in my Toyota Tundra has a firmer shift than the A340 in a Tacoma. And then it might vary in Jeeps or other cars that use the A340/AW4.

 

[Colt45ws]

4R70W in my CV. Removed the bottom 1-2 and 2-3 shift accumulator springs. Enlarged the Reverse, 1-2, 2-3, and 4-3/4-2 shift feed holes in the separator plate.
I followed instructions posted around by Jerry Wroblewski, a retired Ford drivetrain engineer formerly a part of the AOD/4R70 project. This is how he thinks it should shift, and not what the NVH guys think. IMO, that's enough for me.

 

[01rangerxl]

Mine varies anywhere from barely perceptible to banging through the gears at 5,000 RPM depending on how it is being driven. It has adaptive shifting, which seems to do a pretty good job.

 

[SteveSRT8]

too many people here lamenting the past when modern slushboxes are MUCH better.

Any modern box, 4L80-E, NAG1, etc., can handle MORE torque than your late lamented Torqueflite and do more for ya than you'll ever know. They have nifty stand-alone control boxes so you can slap them in an older car, and BTW, they don't even cost 2 grand for ridiculous builds.

Even my old rock solid built turbo 400's were more fragile than the NAG1 in my car today. And they never had infinitely variable lockup, overdrive, variable shift duration, variable pump pressure, etc.