What's it actually doing??

[gijoecam]

OK, I profess to be completely green with respect to automatic transes. They're the one thing I haven't worked on in an Explorer (yet). So with that in mind, be gentle....

When cruising in 5th gear on the freeway, say, 70 mph, the engine is running at 2400 rpm. If I let the throttle close completely for even an instant, when I crack the throttle again, it's running at 2600 rpm for about two or three seconds, then feels like a soft slip back into OD. Is that the torque converter locking and unlocking, or some other shifting strategy? Either way, given the semi-fragile nature of the high-mileage 5R55Es, would it be a good idea to minimize that constant slipping in and out if possible?

Thanks, gang!

-Joe

 

[IAmTodd]

Yes, thats the torque converter locking back up. Its best to minimize this. Although sometimes it unaavoidable.

And if you smash the gas at 70mph, the first "shift" is the converter unlocking. Then you procede through the gears.

 

[Glacier991]

Joe you hit the nail on the head. The computer utilizes various inputs to lock and or unlock or pulse width modulate the TCC clutch in that circumstance. OD on/off usually nets a higher RPM change... when you see a couple/three hundred, it's the torque convertor. It's a fuel saving strategy.

So...Nothing is wrong, but one thing people fail to realize in computer controlled "feel" trannies like the 5R is that there are two kinds of things to consider as we program in "slip". First is the ability to stop rotation of parts, as in a gear change. This is largely a function of friction material and apply pressure. The other, and a ctritical one in these transmissions is the ability to hold a stopped part stationary, or let it slip slightly, and this is more a function of the fluid properties. As for your question regarding this event happening... it is not hurting anything.

My position on the 5R's is simple... they need frequent fluid changes to maintain that second quality.

I appreciate your expertise on a wide range of subjects on this board. Hope this answered your Q.

 

[gijoecam]

Tip o' the hat right back at'cha, buddy!

This isn't a new development, just something I've become more cognisant of as the truck ages. It's my daily driver, and funds are a bit tighter than usual, so I'm just trying to make sure I squeak every mile out of it that I can.

Thanks, gang!