When a broken crank is good news!

Well we got Befur’s engine back into the workshop, and stripped it down to see if we could locate the source of the knocking we have been suffering all season.

Befur’s Engine ready to be stripped.

On lifting the crank out it looked perfect, and did not have any obvious loose or moving joints My heart sank, as this was really my only theory on what was wrong.

However, mounting it on the lathe between centres the problem revealed itself as we spun it up. The centre main bearing journal wobbled in an erratic and non-cyclic manner. Once this was revealed it was clear that one of the main-bearing journal to crank web had indeed become loose – result!

Crank in lathe to check for truth.

So, I think this resolves the question about the suitability of Loctite and pinned crank construction – this is not the way….

The two videos below show the spinning crank, which showed the movement and the movement in the joint when moved by hand.

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2 thoughts on “When a broken crank is good news!

  1. Lionel Connell

    I am in the middle of setting up to make a couple of 15HP LiFu crankshafts from solid P20 tool steel for a customer in the UK, would you like a quote to have a new crankshaft machined from solid for your engine?

    Reply

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