I have a nnbs 6.0 with the 4l70 trans yank tt 3000 converter bb tuned arh long tubes and i keep breaking the rotor in the trans pump! And not while beating on it! I have the correct spacing the dowel pins look great no sign of egging out the holes in the flywheel I have the heavy pump rings to rev over 5500 rpm i don't get it this is the second pump and assembly ( pump body) I also have vette servos any input greatly appreciated harp PS i just talked to Dave at yank he said that the converter was fine no run-out hes going to send me a new one just in case. piece of mind

 

Are you measuring the pump slide and rotor and matching it to your pump body? You could be installing a rotor and slide that are too thick. What brand are you using? I've only had good luck with AC Delco's.

 

man you might be on to something, I have not measured those. what are the specs? I mean do i mic the rotor and slide and pocket of the cover? How much clearence is there suposed to be? Im using gm parts and that cover comes together with rotor and slide installed but both times the body has come from a differeant dealer same part number though. the new stuff should be here tomorow from gm my buddys the parts guy there thank god!