68rfe

[TCDiesel]

Well, it's hard to please everyone at once. A shift that one person calls "smooth" will be perceived as "mushy" by another. And a "firm, crisp" shift for one person is critiqued as "harsh" or "rough" by another.

As far as shift "flares" go, typically an actual flare (engine RPM increase) during an upshift is caused by a change in the Torque Converter Clutch (TCC) slip rate. For example, if the TCC is locked in 4th gear (no slip), then a 4-5 upshift may actually use this sequence:
• Unlock (or change to partial lock) the TCC (this will raise engine RPM)
• Perform the 4-5 upshift (engine speed will drop)
• Wait a second or so
• Relock the TCC (engine speed will drop further)

In this case, the TCC unlock (or partial lock) is used to avoid a harsh jerk that might be felt if the 4-5 upshift was made with the TCC fully locked. So the "flare" is deliberate, and produces a smoother upshift.

To diagnose shift complaints, get a scan tool that can display current gear, target gear, and TCC state. You can then watch the display during a shift sequence and see exactly what's going on. For example, you can verify whether your "flare" is actually the TCC changing states.

I hear Ya, But some owners are just to lazy to back off the go pedal when in Lockup, I've ask several customer to practice this and it will become habitual. You are right about pleasing everyone... You cannot replace hope for iron, the 68RFE internals are just not robust, if you add HP the internals just snap and break and destroy everything. Thats why the cost $6-8K for billets and upgraded internals. If you leave the 68RFE at factory power it will last if maintain properly and NOT abused.

 

[Newsa]

I hear Ya, But some owners are just to lazy to back off the go pedal when in Lockup, I've ask several customer to practice this and it will become habitual. You are right about pleasing everyone... You cannot replace hope for iron, the 68RFE internals are just not robust, if you add HP the internals just snap and break and destroy everything. Thats why the cost $6-8K for billets and upgraded internals. If you leave the 68RFE at factory power it will last if maintain properly and NOT abused.

Over the past 2 years, I've heard how the Aisin shifts hard and locks up too early often lugging the engine in some gears.
But maybe some people and their wives have gotten used to it?
And now I hear the opposite is true of the 68rfe and that maybe the Cummins has outgrown the 68rfe.

Sounds like the 68rfe-equipped Cummins should have been derated to 700 ft lbs?

 

[TCDiesel]

Lugging unlikely and next to impossible in the 69RCS, if the engine cannot pull out you have other problems on factory programing. Manually another story.