The importance of measuring bell housing runout.

Didn’t read this whole thread yet… but wanted to reply specific to your mentioning the automatics and front seal leakage and flexplate cracks.

B&M flexplates are supplied with instructions for checking runout and they even say that the flexplate is good for stock to somewhat mild engines… but more then that and it can and probably will crack the plate.

How do I know….. cause I just did it within 500 miles of install. And the front seal started leaking and it got worse and worse….Motor is a 408 stoker with 592hp and 577 torque.

The car has always had a bad pulsating vibration in the trans hump area that started after a front end collision years ago. But it ran fine on the previous flexplate and the front seal didn’t leak.

Everything on the car is new now…even insides of the trans and torque converter. Motor…. suspension (Reilly)… etc…. The only thing left of the car that is the same is the trans case itself (vin matching case) and the rearend housing and axles. Yet still I have the vibration issue. Never could figure it out. Even had the pinion angle checked with the wheel alignment… all good.

My guess is the trans case is worn and while it does fit and mate up with the dowels… it’s not centered well and maybe the dowel holes are wobbled… possibly from the wreck.

The crappy thing is the guts of the trans would have to come out to check it…so I’m going tremec tkx from sst. Hence why I started reading this thread. But I can say… the autos def need to be checked after all these years id say. 53 year old trans case could be bad.

I look forward to reading the rest of the thread. :)