From:Russell Hughes
Subject:RE: RE: oil pan cases Date:Sat Dec 12 00:06:37 2009
Response to:2708
Sometime after the I finished the KJ engine project I was allowed to briefly see some pics of the original Henderson engine manufacturing processes. (TRANS MAIN SHAFT)The assembled cases were mounted in a fixture that drilled the tap drill size hole for the trans main shaft all the way through in one pass. Then a tap about 2 feet in length with a continuos shank but with two cutter groups with starting taper on them was powered through the case assembly. This gave you the two threaded holes that were on the same center line and a unbroken thread pattern.
On several cases I chased the threads from side to side and found this to be true. The threads on one side are a continuation of the other side. I did not make a long tap because after use the left and right bearing threads are rarely the same diameter anymore. I had to make four tap sizes to accomadate the variety of 1-7/8" - 14 threads sizes. Yes I made these four different taps! No mater how difficult you think the engine jigs and fixtures are...they are much more difficult than that.


Russell, could you show a picture [or you Mark] of how to thread or re thread the transmission cross shaft bearing threads and the jig necessary for this? Most are not aware you can't just put unmatched cases together without fixing this area.
Marty: Here is a picture of a fixture I used to cut new threads on one side of my KJ lower case where it was broken and welded. The brass set screw fits into the threads on the shaft and moves the cutter as the shaft rotates. The cutter is adjusted for each pass. The shaft is turned with a hand crank. I am not sure whether the threads on both sides of Henderson cases were cut with one set up at the factory. If the threads on the side of the case being repaired did not correspond with the threads on the good side then I suppose the set screw could be relocated along the sleeve where the threads did line up. It worked well on my case. The mounting angles could be modified so it would work on an upper case and clear the flywheel housing web. One piece of the fixture that is missing is the clamp that holds the sleeve to the crankcase on the good side. Hope all this makes sense to you.