ZF5 Gasser to Diesel Conversion

So I just finished my modification of my ZF5 yesterday. I was always a bit apprehensive about doing this. Concerned about shaft alignment. There is really no good way to indicate shaft to bolt hole/dowel pin location. I studied threads on this site and others. The top two holes in the bell housing are located the same place on both ZF5 versions. So as others have done I used the IDI adapter plate as drill jig template. As a machine builder, I'm **** about good fit ups, I like thinking and working to three decimal places, so I produced some tooling to get it as exact as possible. After assembly onto the adapter plate, the pins snapped perfectly into place on the bell housing, with no wobble or looseness

I created a pictorial library for myself as a record, to record how and what I did. I would like to share it with all of you who have thought about using the gas version ZF5 but were unsure about how to exactly go about it.

Bell housing bore/Gage pin size .472. Tap drill diameter in adapter plate .417/Gage pin

Adapter dowel pin hole gages at .377, reamer used .377. This works perfectly, as 3/8 dowel pin is pressed in engine block, adapter fits over pin at .377, so using adapter as drill jig/drill bushing works well at keeping things square and properly located.

Bolt hole piloted with 5/32 .156 drill. Bolt hole drill is 35/64 .547. You will need a aircraft drill (long shank) as you need to drill through 2.0 inches of aluminum bolt boss. Had to turn down shank of drill to .500 to fit my drill motor.

Final view of finished job. I feel very comfortable with the operation as it went quite smoothly. Bolt hole location is important, but dowel pin holes need to be spot on.

I was involved in “realigning” a gasser bell housing many years ago, your caution and exactness is time well spent. I had to resort to offset dowel pins, and extracting the old ones was not that much fun.

Good work and great documentation for the next guy who performs this conversion.