6R140 Harsh Shifting 2nd/6th

[Keith Browning]

Most notably 1-2 upshift and 3-2 downshift.

 

Performed non-intrusive diagnostics which led to removal and teardown. The only thing I found wrong was the intermediate clutch clearance was excessive - 1.5mm which is three times the maximum clearance specification (0.24mm to 0.50mm) The interesting thing here is that there was nothing wrong what so ever with the clutch or the center support, piston, spring plates or disks. no discernible wear, not one heat mark, snap rings and  grooves looked good too.  The maximum sized select fit sap ring would not have brought it into spec either.

 

So, on the HotLine recommendation I replaced the center support and all of the clutch parts and I set the clearance to 0.28mm.

 

Shifted real nice like!

 

But here is the thing. I am thinking this clutch was probably sloppy from day one and as it wore a little from normal use it exceeded the TCM's ability to adjust so it ramped up the pressure and you have a hard shift. But no code?  I am used to seeing "shift element * apply time or performance" DTCs for this kind of fault.

 

Moral of the story for the lesser experienced transmission guys is that you are not always going to find something obvious - broken or smoked parts, bad seal, cracked this or stuck that. Check your tolerances.