Grinding a phoenix crank

[John L]

I havnt posted in a while. Happy New year to all.
Can a phoenix crank be ground? If so is there a limit? 
Are shells readily available? Thanks in  advance

[Bob Culver]

I have no experience of Phoenix cranks but have been involved for decades with Javelins most of which are fitted with relatively reliable aftermarket cranks and many of these originally nitrided. Have followed the subject.

Nitriding greatly increases fatigue resistance and is presumably the reason original undamaged Phoenix cranks are reasonably reliable. The nitride layer is usually thin and more or less removed by grinding and its protective effect then largely lost. Special care is necessary or heat cracks are created. Cranks can be re nitrided but must be free of cracks in the nitride due being dropped, or from blow ups, unskilled grinding etc.. It is an expensive process, opinions differ about the extent and method of final finishing etc. The increase of diameter of main bearing journals a complication. For quality truck cranks etc a second light grind. Firms probably more familiar with now than in the past, when they often ruined.

Nitrided cranks are very hard and should not wear significantly, certainly not with white metal bearings.

I suspect all the crack testing and general mucking about could approach cost of a new one. Whether it can be made to run or not, put in an engine and sell as “Phoenix “ crank! Probably known to the sellers, I have been sold several dud ordinary Seven cranks in ages past.

[Charles P]

Mine was ground 0.25mm (~10thou) under about 15 years ago and is going strong.
Generally 10 thou under is fine and is unlikely to go through the nitriding. Going further than that might go through, or then again it might not. It depends upon the thickness of the casing which depends upon a heap of manufacturing variations. 
Shells are available. 

Charles

[John L]

Would I be better to hold off until I could afford a new one? Also when cranks are being balanced I presume material has to be removed in areas. Is this done by grinding or drilling unwanted material? Is the nitriding process just carried out on the journals?

[Colin Reed]

HI John,
            The easiest  way is to ask the manufacturer  and they will tell you how thick the  hardness goes,
            this will give you peace of mind

Colin

[Stuart Giles]

Phoenix are doing me a billet crank at the moment, IIRC Marc said that the nitriding on it would be 0.020" deep

[leaf200]

I had a phoenix crank reground -10thou. sent it back to phoenix and they reground it and sent it back with a new set of shells

[John L]

Thanks for your replies! My question is well and truly answered!

[Zetomagneto]

Phoenix are doing me a billet crank at the moment, IIRC Marc said that the nitriding on it would be 0.020" deep

Are they doing you a special? Normally their A 7 cranks are from forging, not billet

[Stuart Giles]

Phoenix are doing me a billet crank at the moment, IIRC Marc said that the nitriding on it would be 0.020" deep

Are they doing you a special? Normally their A 7 cranks are from forging, not billet

Yes, it is a special. Current Phoenix A7 cranks are from forgings as you say; Some earlier A7 Phoenix cranks were investment cast and then HIP treated. I have a 1 1/2" version of those here.