Panhard Crankshaft Truing

As I said in my blog, it was a little too cold to work in the attic today, so I spent a few hours at the workshop. I had some bespoke round bar stock lying around, that I was planning on making a crankshaft truing tool, but I wasn’t ready to mess with crankshafts whilst I was doing all the liner related work. Anyway that is virtually done now, bar a phone call to the piston company, so it was time to jump on the Elliot mill, and make a new tool.

This is what I had in mind, but I was limited by what bullnose endmills I had, so I used a smaller radius than I would have liked.


After a couple of hours, it was done. It took longer because I needed to keep checking by placing it in a crankshaft making sure I wasn’t taking too much metal away.


As I was making it I was testing it in Martin McClarence’s crankshaft that had turned. Fortunately it was the rear web that had moved, so I could refine the size of the tool to fit it.

Imagine my surprise when i got home and tested Brian’s crankshaft, and I discovered this had moved ever so slightly on the front web. I knew the rear web had moved, but interestingly it had been pulled outwards, because the crankshaft was too long between the main bearings. I can only put this down to rear bearing movement, due to a shimming error in the rear bearing backplate, but this was assisted by the oscillating crank due to the misalignment.

Anyway, the front web of the crankshaft is true now, after giving it a very hefty whack with the #4 Thor copper hammer, but the rear web is ever so slightly out. Next up on the crank is to press it together again, so the rear web has the correct connecting rod clearance, and then I’ll true the crankshaft up finally.
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