HI all,
I need to replace the pilot bearing in Lurch's engine. When I separated the transmission from the flywheel housing, the bearing (bushing) just fell out. This could be the smoking gun that points to the squealing noise that he's been making.
I ordered a new bearing from one of the usual vendors and its outside diameter (OD) is also too small for a press fit.
Here's the stats:
1. As best that I can measure, the inside diameter (ID) of the hole at the end of the crankshaft is .818" in diameter.
2. The OD of the new brass bushing is .8155" in diameter, or .0025" smaller that the hole in the crank. So, it slips right in and would spin nicely, which it isn't supposed to do.
3. The ID of the new bushing fits the OD of the input shaft of the transmission well. They both seem to be .625-ish".
I first thought of knurling the OD of the new bushing to expand its OD a little, but I read online (in a machinist discussion) that this method is not a good solution. In the long run, the knurl would wear down and become loose.
So, I ordered a new Oilite Bronze bushing that has an ID of .625" and an OD of .875" so I can turn it down to what I need on my lathe.
The BIG question is, what constitutes a 'press fit'? Or put differently, what OD should I shoot for to get a good press fit in a .818" hole?
Keep in mind that I don't want too much of a press fit, which would compress the bushing and then I would have to ream out the ID of the bushing to get back to the good .625" for the tranny input shaft.
I've read online that adding .001" for every 1 inch in diameter will give a good press fit.
What say you folks? How do you figure out the optimal OD for the pilot bearing in your old Chevys?
Thanks, Dean
