1987 g-body breaking trans cases? anybody have this problem?
 

i have a 1987 cutlass, bbc, 9 in rear and most of a 10 point cage. (stock interior) i've had problems busting powerglide cases at the bell housing.
i put on a ultra-bell and stopped that. now this weekend i cracked the main body. do i need more cage? the bars going out to through the firewall? any help would help. thanks in advance

Those g bodies do twist. For sure, I would do the rest of the 10 point cage.
THen, check the driveline angles. Also, you might want to midplate it...

what trans & engine mounts are you using?

solid engine, poly mount on modified crossmember

if you are using the stock style rear control arms you might need an anti-roll if the body is twisting .

2 QUESTIONS

1- do you have a Front Plate ?

2- Do you have Mid Plate ? As Terry mentioned above

I run the G body, and haven't had problems breaking the trans. I don't have down bars in the front but i do have a front motor plate, and i run the softer stock (not poly) rear trans mount. The only time i broke a trans case was when i broke a drive shaft and it pushes forward, actually i was running clips on the rear u-joint and it pulled the threads on the 5/16 bolts which cause the drive shaft to jump out of the rear yoke and go forward. Broke the trans in 8 pieces, the only thing holding it in the car was the converter, i put it back together with another case, didn't hurt anything and i was back in business.

Zip.

i'm running stock suspension, adjustable upper and lower control arms, custom cut drive shaft. i'm now thinking i might have a balance issue with the crankshaft. the engine vibrates the car pretty good. the cam in the motor has around .680 lift, so i was thinking the shaking was from this. i was told this could be a problem. so now its on with more cage and send the rotating assembly to the machine shop. i'm going to eliminate these two problems anyway. thanks for the info. i was hoping somebody had these types of problems to steer me right. i will post what i find.

I did forget to mention mine is backhalfed 4 link, that may make it a little stiffer.

Zip.

Put a stock rubber mount on your trans and it should stop breaking the solid mount want give enough i used a poly mount and did the same thing changed it back to the rubber mount and never broke another one.