When did this Forum become "AusSprite"? Maybe next time we can get a Mini crankshaft tested... [/quote]

it's only a north /south engine ,so it deserves getting the chop.

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Research is the difference between speculation and investment. Anyone who copys some one else will always be second
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The results are in.

I have sent them to GR out of curtesy for his perusal and will post them up here shortly.

This has been a bit more drawn out than all of us would have liked, there were a few delays, not the least of which was Australia Post.

Just a brief recap on what this was all about;-

The claims:-


and;-



and;-



The doubt;-


The offer;-


The challange;-


The test parameters;-


The acceptance of the agreement;-


and so, above all else, remember;-

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I am trying to work who I am going to put my money on!

Are we running a book?

What odds are we looking at?

WOW there is some interest in this topic, nearly 100 views in the last hour and a bit.......

OK, all measurements are in metric, so to help out, here's a quick conversion table

Metric Imperial (to the nearest thousandth)
50.80 mm 2.000"
41.24 mm 1.624"
0.15 mm 0.006"
0.25 mm 0.010"
0.35 mm 0.014"
0.45 mm 0.018"
0.55 mm 0.022"
0.65 mm 0.025"
0.75 mm 0.030"
0.85 mm 0.033"
(25.4000 mm = 1.000 inch)














So.........

From the measured jounal diameters, the crank has not been ground.

Any useful depth of Nitriding is all over between 0.006" and 0.010", although by definition is stated to have a 'case depth' to 0.022". So, no matter how you want to look at it, the Nitriding does not go anywhere close to 0.060".

By formula composition, EN40A does contain Nickel and does not contain any aluminum.

The sample as tested contained Nickel and very small traces of Aluminum.

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GT many thanks for arranging for the tests and posting the results, which speak for themselves when you can see that the hardness is pretty much back to base levels somewhere between 0.45mm & 0.55mm.

When you convert it looks an awful lot like 0.020"!

Not only does it have traces of Al but titanium too!

cheers,

Jacob

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'72 Clubman Van - 1022cc, 295 head, 731 cam - Daily Driver
'69 Morris 1100 S - Dinged by a bus, in shed under repair
'64 Morris 1100 - Early 1100, long term project

NO WAY!



You'll have to excuse me Jacob apparently I "Have some dents to pull"

well there you go....

thanks GT

cheers

Kevin

Great work GT Mowog. It is about time we got some proper information rather than " If sound like I know everything, people will belive it as gospel" comments.
Well done.

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HAHA..... well done GT mowog, nice work.

As others have said good to see some actual scientific proof rather than "I know cause i just do... And if you dont believe me im gunna sook" approach that often takes place in some threads.

Well done

Brenton

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well very interesting. the hardness is only .006" deep, after that it is not much harder than the base material.
So when you look at the test results they obviously put that "folk lore comment" about mini cranks to rest.

Now with this info all I can say is exactly what the heat treaters I deal with have said the same thing. You will not get the hardness any deeper than .006" and that will only be on the machines surfaces. If you "case harden" the crank all over and if you could achieve a greater depth then it would be as brittle as glass.
You can slightly change the "tuffness" of the parent material [if it is the correct alloy] by heating and quenching but there is a risk of again making the crank more brittle.
The only advantage that you might get by leaving a crank in a salt bath for days at 800deg C is than it will stress relieve it to a certain level. Not much more, as the surface hardness will be achieved in a matter of hours.

_________________
Research is the difference between speculation and investment. Anyone who copys some one else will always be second
www.minisprintgt.com

So all in all - any tufftriding/nitriding to a crankshaft is wasted money?

I think you want to have a good look at the application and then put that in to the context of funds. It is only intened to be an improved surface hardness of the bearing journals (in the case of a crankshaft). So in the case of the Cooper S, it allowed the engine to usually be rebuilt 2 or 3 times without the need for a crank grind. That is all. It will not increase it's fatigue life.

After some lengthy discussion with another knowledgable member here, as a by-product or side benifit of treatment, because it is done at an elevated temperature and for 15 to 48 hours +, what it can do (NOT always) is stress relieve / normalise the cranks and it IS this which may increase the cranks life. You can certainly do this WITHOUT Nitriding.

Nitriding is good, but it will only do what it is intended to do! It is not a 'miracle saviour'.

Generally, I don't get cranks nitrided or tuftrided (as is applicable to the material) because 60% of the time they come back bent. Grinding them back, IMO, is the incorrect way of correcting them, as the nose and in particular, the tail end up off centre. Mind you this would work if you got a blank (ie a crank straight from being forged / cast) ground it back to about 0.150" oversize, then have it normalised, then finish the grinding process.

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Good work!

It appears that the surface treatment could reduce fatigue cracking at the journal radii by leaving a residual surface compressive stress but rolling these radii is maybe a better way of getting this outcome.

Now, can you do tests of:
(1) Venturis after supercharges as a way of removing charge heat.
(2) Pre-loading of helical coil springs as a way of making them have a variable rate.

Thanks GT, the price of 'S' cranks has just dropped....maybe I can now afford one!