So if I have a cooper s crank (EN40B, Nitrided) that is ground 20 thou under, the hardening will be lost?

So I have to get it re nitrided?

Can it be tuftrided instead?

Basically, how far can they be ground before the hardening is lost?

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68 Deluxe.... it's shiny..... I like shiny!!

May be a engine reconditioner could answer your questions,,someone on here is bound to know....Just think of all the cranks out there that have been reground,,ive seen a few and there didn't seem to be a problem with them,,I think 0.20 might be safe any more and i think they need treating...but i'm not sure on this.. it will be interesting what people on here say about it.....

Yeh, I thought I had heard that 20 thou was safe, any further needed redoing.

Anyone actually KNOW this for sure, or if there is a test that can be done to see if it is still alright?

Cheers

matt

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68 Deluxe.... it's shiny..... I like shiny!!

Ive got a crank that was ground 60thou the bearings are huge!! the crank is not being used though...

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68 Mini
70 Moke

I have had many cranks nitrided and I was always told the nitriding itself is only about .010" or so when crank is finishes. Usually when they do the Grind they have to leave the crank still unfinished as they always have to re grind them after the process because of distortions and to get a good finish. If a crank is re ground after that it should be Nitrided again.

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DID I MENTION THAT I AM THE BEST SUPPLIER FOR MINI ELECTRICAL PARTS AND REPAIRS?
"Let us remove your "SHORTS"

I've been told by various people that BMC in the 60s managed to get the nitriding on the EN40B S cranks lots deeper than .010".
My spare Mk1 S crank is now -.030" on the mains and -.020" on the rod journals, the guy who regrinds GR's cranks (Spiro, at St George Crankshafts) says it is still hard as hell.
I've also been told by various engine reco people that nitriding EN16 cranks to `harden' them is a waste of time- that article (and others) bears this out. It really only works on nitriding steels, eg EN40B or other steels containing aluminium or vanadium.

Tufftriding is very hard to get done in Oz now, apparently the EPA jumped on all the heat treaters that were doing it, for health and safety reasons.
it is a hot arsenic salt bath process.
There is supposed to be one place in Melbourne that still does it, for the aero industry.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

So it can be tested to check if the hardness is still there? Spiro can do this? Can he get them re-nitrided etc if needed?

Cheers

matt

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68 Deluxe.... it's shiny..... I like shiny!!

Whether crank is still hard on not is apparent during the grinding process.
Yes I'm sure if you want it re-nitrided, Spiro can arrange it.

Beware though, cranks have been known to bend after re-nitriding. One ausmini member had to get the crank changed in his reconditioned motor because of this.


<edit> typo

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

I wont be touching mine since Spiro said it was perfect

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Stop Licking the Dog...I Don't Care Who Started It

The crank i have is already reground to 20 thou under. Can it be checked without more grinding?

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68 Deluxe.... it's shiny..... I like shiny!!