American Standard Whirlpool
I'm new to this forum, but I have an American Standard Whirlpool (Cadet) and it also creaks in a few places when taking a shower (I'm 6'6" and 235 pounds). I didn't own the house when it was installed, but the installers followed the manual (quoted below) -- i.e. they did
not use a foundation base such as cement, mortar, etc.
Replace whirlpool and re-shim the integral support feet, shimming the entire length of the support feet. Secure the shims using construction adhesive, silicone, mortar or equivalent materials. While not a necessity, the use of a foundation base consisting of cement (e.g. Sakrete), mortar, or grout will help provide a solid and secure installation.
I don't have a warranty on the bathtub, so I hope this isn't a sign that it is going to crack or worse over time. Okay, wishful thinking I suppose. But if this is a common problem, then it seems that American Standard should mandate that their tubs be installed with a foundation base that won't allow the tub to creak.
Dang....