m-12 performance

americanjackie2 wrote: is there anyone who can work my m-12 over for better street performance

Really not much available in terms of what to do with these things. You can certainly get a convertor made for them, but that's about as far as it goes.

the modulator is adjustable??????

Yes, the modulator is adjustable. There's a screw adjustment inside the stem where the hose attaches. You need a very slim straight blade screwdriver. Turning the set screw inward (clockwise) raises the line pressure and correspondingly, the shift points. It takes a number of turns to notice a difference.
The factory pressure specs were set low primarily to make the shifts as soft and imperceptible as was the norm then of typical passenger car use. The settings were not spec'd for performance. Increasing the pressure raises the shift points at all throttle settings short of WOT, makes the shift transitions occur more quickly and more positively.

Crank up the pressure, give the car a road test and adjust accordingly. If you go too high you'll find the shifts very late and harsh. As they say with food seasoning, adjust to taste. You'll not hurt the trans by raising the pressure.

Any thoughts on raising the line pressure by shimming the pressure relief spring? That seems to be something else that is suggested often. I know in the Aussie BW35 transmissions it is called a 2 cent shift kit because you use a 2 cent coin to shim the spring, probably some other denomination in the US.