broken 4 speed

[fastlane666]

well i'm new to lateral-g, but i've had my 66 chevelle for 24 years and it's my first car. heres my conundrum; i'm running a built up 408 sbc. about 500 hp.i run a super t-10 lakewood scater shield, center force 11 inch dual friction and a 4 inch high speed balanced drive shaft and 355 gears in a 12 bolt posi. my problem is the trans shifts difficultly at high rpm and i've broken the trans housing on every tranny i've ever used. either through the center of main case or the mounting ears.the bellhousing is aligned within .05 thousanths. any thoughs on why i'm a. breaking housings and b. why can't i powershift this thing?:question:

[FrankZ]

The symptoms you are describing sound very much like those experienced by those running solid trans mounts and a clutch that isn't releasing fully.Just my .02.

[fastlane666]

the thing is i'm running a urethane mount and solid engine mounts. i've tried all the different mount combos any way. and the clutch fully disengages and low rpm and the car doesn't creep when stopped. i always push the pedal to the floor when shifting.