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Straightening crankshaft

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Is it OK to straighten a crankshaft with a round ground chisel and a hammer like in that video:

https://www.youtube.com/watch?v=NSnzdWSgEFs

Or will it weaken it seriously?

I've performed that on an OEM CA18DET crank and it had worked really well. It was not very much I had to correct, just 0.03mm runout on the 4th main. Now there is almost no runout measurable on all the mains, but I am not sure if it got weakened by that or not.

Please never do that! You're going to inevitably leave a mark on the fillet radius from the chisel which may end up being the source of cracking and failure at a later point. If a crankshaft is going to be straightened it's normally done in a hydraulic press and the journals are supported in V blocks.

Yes you are absolutely right, that is exactly what happened. I thought the same about it probably being a nasty stress raiser. In the meantime I managed to grind it out though. It is perfectly smooth again. I am confident again that its going to be alright. And I am not gonna go crazy on power with that car anyway.