2 Liter Fiat TC crank - don't regrind it!

Crank, rods, sealing, pistons, block, flywheel etc
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Guy Croft
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2 Liter Fiat TC crank - don't regrind it!

Post by Guy Croft » Mon Nov 06, 2006 8:53 am

1. The 2 liter crank is nitrided En40B, the nitrided layer is so thin that if you grind, you will lose that layer (hardness, oil-retentive non-ferrous compound layer).
2. If you stress relieve, grind and re-nitride there is a serious risk of micro-cracking on the new surface; this is common with re-nitriding. I tried a batch once and scrapped 3 out of 5 cranks because of this.
3. It is possible to get round the problem by a costly and difficult series of heat treatments and grinds but the cost is so high it's better to get another crank. Heat treatment is costed on weight, so with a single crank the stress relief and nitride would cost over £200 plus vat with freight alone.

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