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ss3011 · 08-06-2012, 11:58 AM

It is good that you have a production style transmount. Two things, first, have you trimmed off the ears to make it easier to install the trans past the headers ? That metal is in a critical place for stiffness of the bellhousing, and trimming it away just weakens it. Second is, there were no Heavy Duty 350 THM cases for Buick, Olds, Pontiac (BOP), but you may be able to find a Composite Case, which has both the BOP and Chevy bolt patterns, that bellhousing has more meat and may last longer. One last thought, is to make sure you don't have a worn out case extension bushing, the one that rides on the driveshaft yoke. Too much clearance could cause extra vibration that works on the bellhousing. If the crack starts at the dowel pin, and spirals back, it could be the bell bolts have worked loose, make sure they are torqued to specs, about 35 ft lbs.

08-06-2012, 11:58 AM	#3
ss3011 Senior Member Join Date: Feb 2002 Location: Southeast Michigan Posts: 909 Likes: 70 Liked 239 Times in 114 Posts	Re: Bellhousing Breakage It is good that you have a production style transmount. Two things, first, have you trimmed off the ears to make it easier to install the trans past the headers ? That metal is in a critical place for stiffness of the bellhousing, and trimming it away just weakens it. Second is, there were no Heavy Duty 350 THM cases for Buick, Olds, Pontiac (BOP), but you may be able to find a Composite Case, which has both the BOP and Chevy bolt patterns, that bellhousing has more meat and may last longer. One last thought, is to make sure you don't have a worn out case extension bushing, the one that rides on the driveshaft yoke. Too much clearance could cause extra vibration that works on the bellhousing. If the crack starts at the dowel pin, and spirals back, it could be the bell bolts have worked loose, make sure they are torqued to specs, about 35 ft lbs.