Product review (5 stars): Water Hammer Problem Caused by Temp Selector Switch
This is the best $28 I've spent in a long time.  I have a 2009 Whirlpool top loading washer, model WTW5300Vw2.  The machine has been plagued with a severe water hammer for a long time and I finally got around to doing something about it, for fear that it might tear my plumbing apart.  It was at its worst when the Warm wash was selected.  The two solenoids on the fill valve were so hyperactive that they were firing as often as several times a second which caused the severe hammering.  First I replaced the Sioux Chief water hammer arrestors on both the cold and hot lines, the arrestors being six or seven years old.  No change, still bad hammering.  Then I replaced the Whirlpool fill valve with thermistor (the water inlet valve W10144820).  No change, still bad hammering.  Finally I replace this Temperature Switch W10184148.  Problem solved, no more hammering.  So now when it is set to the warm position, the solenoids on the inlet valve no longer rapid-fire, and the inlet valve lets in hot water for 5-10 seconds followed by cold water for 5-10 seconds.  No more machine-gun-like solenoid behavior.  In all my hours of online research, I never ran into any suggestion that the temperature selector switch could be the culprit.  So don't give up if you have a similar water hammer problem, until you change this temp selector switch which takes about 10 minutes or less.