Transmission hard shifting (bump) when cruising @ highway speeds

[burtman]

My daughter has a 2001 Outback/L.L. Bean; 3.0 Engine, 4EAT transmission. At ~151K, I replaced Trans. Duty C Solenoid, seals, clutch plates, several drain/refills on the transmission fluid and the front and rear axle differentials. Generally speaking, the OB transmission has performed well since.

Since the work above, there is a very noticeable hard “bump” (hard shift) coming from the transmission (or differential) whenever the accelerator is disengaged/reengaged while “cruising” at highway speeds (60MPH+). I’m not certain if the “bump” existed before the transmission work, but my daughter thinks that it did not exist before.

• If accelerator is pressed ever-so-gently while cruising at highway speeds, the bump doesn’t occur. In other words, it can be minimized/eliminated if a conscious effort is made to VERY gently press accelerator while cruising.

 

• “Bump” not noticeable at lower speeds when accelerating/decelerating in low-speed, stop-and-go traffic

 

• I checked the dropping resistor - OK.

 

The condition may be just normal/natural of an aging Suby, but I wanted to check to see if anyone here might have some ideas/advice on what is happening, whether it is a real problem worth concern, and what might be done to fix it.

 

• Could the clutch plate replacement @ 151K be related?

 

• Maybe something associated with the accelerator feedback in the ECU and/or the TCU?

 

• Or is it common and nothing to really worry about?

 

Thanks in advance for any thoughts or advice…