Can Anyone Tell Me How To Cheeply Keep A Th400 From Shifting Out Of 1st Gear At 52 Hundred Rpm. Thanks.

Play with the weights and springs in the govenor, and modify the shift kit to keep line pressure in reason.

Yep, B&M offers a shift point calibration kit with various springs and weights. It's under $20 I believe. It takes trial and error to get it right but I hear accessing the governer on a 400 is much easier than it is on my TH350.