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PostPosted: Sun Mar 13, 2011 5:02 pm 
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KC wrote:
Spoke to Paul Ivey. He says that when he was at Morris Motors developing
the S stuf, they used to end up with cranks heat treated to 0.060" deep,
or furtehr since they initiall used to run them at -0.060" to reduce
drag/friction, and they were still hard at that. He said these cranks
were simply left in the oven for over a week to get the depth. Obviously
impossibly expensive to do that now. After testing engines back to back
on the dyno with the standard journel cranks and the -0.060" ones and
finding no gain whatsoever, the depth of hardening was stopped and
standard size journals used. KC

--
Remember: Tuning should be a compromise between what is possible and what is necessary

www.calverst.com

Calver Special Tuning Limited
14, Riccal Drive
York Road Industrial Estate
Malton
North Yorkshire
YO17 6YE

Tel: 01653 691380




Ok kiddies......

Another thing I should have spelt out in my Epic post on metallurgy... (I think GT hinted at it)...

HEAT TREATMENT means the use of heat to alter the make up of a metal, in order to inhance its suitibility for a particular application.
Before I start, yes it's obvious that Keith is refering to the use of heat treatment for hardening and I will get to hardening in a sec.... but still.... while I've been sitting quitely on the topic of metals for the last year or so while people make comments like
Quote:
Mild Steel doesn't harden with heat treatment,


..... I've noticed that heat treatment is another miss understood topic.

Ok, so heat treatment. What goes on? With the use of heat, you can change the mechanical properties of a metal. Heat Treatment, does NOT always mean hardening. I'll explain how and why.....

So, what happens when we apply heat to a steel? It starts moving. The obvious changes we start to see are changes in colour and diamentional change...

STRESS RELIEVING is the first thing that starts to happen, this hppens in most steels at around the 600-650 mark. When you machine a metal, you place stresses in it (you can also relieve other stresses but thats got nothing to do with heat treatment)... so machining or trying to mechanically straighten (by bending) a metal will place stresses in it.... as will for forging... casting in somecases... basically a stress is a stored energy... if stress is rapidly released from a metal, it will cause cracking or excessive distortion/warpage.

...... So if you were to use heat treatment for stress relieving, you're gently removing stress out of the steel at a controlled rate. The work piece is heated up to that 600-650 degree mark, held there for the desired length of time (this will change depending on the material we're dealing with... but generally 600-650 for 30 min to 90 min) and then cooled at a very slow controlled rate. Normally you would control the cooling in a furnace with an inert atmosphere... problem with air cooling (which I mentioned much earlier in either thread or another one of the crank threads) is that it draws any carbon below the surface to the surface forming that black scale you always see on black bar... that black stuff is pure carbon, EXTREMELY HARD, and the material directly under it usually has no carbon in it at all (because its all been drawn to the surface) making it EXTREMELY SOFT and pretty much useless.... so if a material is air cooled, allowances need to be made so that there is enough material left to machine off the scale and soft layer.


Transormation Stage or critical point is where stuff gets exciting :) This is at about the 720-730 mark....

So, as I mentioned in my last post on metals, steel always has Iron, and Carbon in it.... when there is less than 0.2-0.3% carbon, what you see under the microscope is a crystal structure called "ferrite",, as the amount of carbon increases we start to see more of what is called "Cementite" which is an iron carbide... and if there is as much as 0.8% carbont it, it forms what is called "Pearlite" (gets its name cos the excessive abouts of carbon give it a "mother of pearl" appearance)..... Right, won't go into that anymore, people will start falling asleep :lol:

NOW.... what happens when we heat up this cocktail?????? Well, first off.... when you look at steel under the microscope (when its cold), the carbon and iron are clearly visable... and is sort of looks like a poorly mixed cake. You have clusters of iron without much carbon around them here, and clumps or carbon there.... this is what "Annealed" steel looks like (annealed meaning softened steel)..... and when you have extra crappy chinese "steel" you can measure the spacing between the iron and carbon with a rule! Meaning bits of it will machine really easy, and other bits will blunt your tools! :lol: But good steels won't have this problem,,, you'll only see the spaces under a microscope.... (incidently, for anyone interested, what I am talking about is called the "lattace structure".. and it looks just like that... lattace)

Soooooooo :).......

When we heat it up past that critical point (by 50-90 degrees C .... up to as much as 950 degrees C in some cases) you notice a few changes... While it is held at these tempretures, it is more malleable (hence blacksmiths keeping steel at this temp while they work them).... what is happening here is a change in the Lattace Structure... the carbon starts to move freely around the iron and begins to dispurse itself more evenly through the mix.... While its in this hot stage with the carbon evenly spread thru the mix, it is refered to as an "Austenitec State".... While its here, the carbon is moving around amoungst the iron at a rate of about 10 micron a minute (0.010mm/min) and this changes depending on the temp.

NOW what happens from here is very important as to what mechaical virtues we want the steel to hold....

If we are "Normalising" (as in full stress relieveing and bring back to original state) we would slowly let it cool,, and as it does so, the Carbon would slowly go back to where ever it was to start with, and it would no longer have that fine distribution through the mix...

If we are Hardening you need to quench it while its Austenitic.... what this does, is capture the steel in that state with the carbon finely spread around and amoungst the iron... once it is quenched, it forms "Martensite"... which is the name for the new crystal structure.

IT'S NOT THE GETTING HOT PART THAT MAKES STEEL HARD, IT'S HOW QUICKLY IT'S COOLED DOWN

To work how hard to what depth, you need to refer to a relevant TTT diagram (Time, Temperature, Transformation) for the steel you have.... they all behave differently. What a TTT diagram is, is basically a graph that you use for calculating what temp you need to get the metal to, how long you need to hold it there.. and how quickly you need to quench it/what temp to quench it too.
.
.
.
.
The above applies to nearly all common forms of heat treatment methods (Gas furnace, Oil furnace, Induction, Electric)..... Using these methods, you can harden a steel from a couple of thou (provided you don't need to do any more machining) to through harden.

So when someone says "heat treated to 0.060".." then yeah... sure... thats possible.... depending on the method of treatment....
.
.
.
Actually, this all reminds me....Anyone here ever bought after market conrods? And recieved one of those letters with them giving a full break down of the conrods you bought? A friend of mine just bought a set of conrods for a Subbie... They mentioned that they were "heat treated" ... he didn't read the whole letter, just skimmed it.. when I was talking to him about it later,,, he goes "Oh yeah, those rods, they've been hardened! They must be awesome!".... :roll: ..... What forces are conrods subject to????? Compressive, and Tensile.... What do we know about hard material???? Good compressive strength,,, poor tensile..... it copes well with being squashed, but doesn't cope with being pulled............ so.... "why would you harden them?" I thought..... I asked him the quesiton very specifically "Did it say hardened or heat treated"..... cos heat treated could mean stress relieved... he came back "Oh yeah.... it says heat treated for stress relieveing"....

I had to laugh at this exact same thing again very recently.... I was reading through this article in a mini magazine,, and this "engineer" was talking about how he had his conrods "hardened to 30HRc" .... I read it,,, I read it again.... and I had a bit of a chuckle to myself... the material most of these after market conrods are made out of, comes supplied (as in an annealed state) at between 250 - 300 Brinell Hardness (HB) which is 24 - 32 HRc :lol:..... always makes me laugh, watching someone tying to claim someone elses work as their own,,, THEN stuff up when they try and provide technical data on it.... chances are, this misguided "engineer" was told by the people he paid to make these rods for him that they were heat treated, and he assumed that they meant hardened.... and knowing nothing about metallurgy or mech engineering, he went off and did a hardness test on them :lol:

Anyway.... back on topic...
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.
.
Nitriding works differently.

For a start, you don't need to get it nearly as hot. Only between 520-650 degrees... so as GT and David alluded to earlier, at this temp the material will stress relieve.

Second of all... remember how I was just saying that in other forms of hardening you need to get steel right up into the Austenitic State so that the carbon becomes soluble and starts moving amoungst the iron? And then you quench it to form a hard martensite structure? Well, with nitriding, the work piece is heated up to 520-650, juuuust enough to start moving, in a nitrogen atmosphere.... the nitrogen is drawn into the steel and diffuses itself amoungst the ferrite to form hard "Nitrides".

Because this method relies on a gas diffusing itself into the parent material, the depth to which in can be absorbed is limited.... if there is no Nitrogen, there are no nitrides.... you need elements like Al, Cr and Mo to form nitrides,,, and they can pass nitrides between themsleves (which is how you get your depth).... but the depth that can be achieved is limited.... this reaction "runs out of puff" pretty quickly.... the temperature will have some bearing on the depth of diffusion as well obviously....

With other methods of hardening, ones that rely on temperature changes alone to produce changes.. the reason you ARE able to get deep penetration or even through hardening,, is because the work piece is Through Heated.... that is, the entire piece is Austenitic.... so the change (Transformation) is occuring all the way through. Steel isn't a sponge... you won't "soak" a gas the whole way through it.

So, the limit, for even the best nitriding steels, is ...... (drum roll) actully, in fact, only ever about 0.7-0.8mm.

The calcs I did on GR's sample, suggest it was immersed for 25-30 hours. Thats about it. And with nitriding (EN40b), it really does plateau out after a couple of days.... even at a couple of days, all that you are achieving is better consistancy (and stress relieving).
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.
.
So... why would you use nitriding at all, if the diffusion depths are so low????

Horses for courses.

Nitriding, even at the softest end of the scale, will still produce higher hardness levels than you will get with most normal heat treatment methods.

Another benefit, because its done at much lower temperatures, there is much much much less diamentional change.... when you quench harden (as in normal heat treament) you need to get it much hotter, and there is more change as a result.

And of course there is the bit of corrosions resistance.... but.. errr.... what was everyones remarks when I said "Resistance, not proofing... I've seen rusty nitrided tools"????? Well,,,,, what do you make of this??

Image

That wouldn't be surface oxidisation... surely..... :P


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PostPosted: Sun Mar 13, 2011 9:13 pm 
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Phat Kat wrote:
[ Well,,,,, what do you make of this??

Image



looks just like another broken mini crankshaft to me

:-)
:-)

good article Phat,,, lots of good quality info yet again, awsome!!!!

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PostPosted: Sun Mar 13, 2011 9:17 pm 
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TheMiniMan wrote:
Phat Kat wrote:
[ Well,,,,, what do you make of this??

Image



looks just like another broken mini crankshaft to me

:-)
:-)

good article Phat,,, lots of good quality info yet again, awsome!!!!


:lol:

Well, I may have seen the crank since it was tested.... I can tell you that, that is most certainly surface rust :lol: I'll ask GT m if he can get some better shots of the rust if you like :)

Cheers Matt :)

PS,, looked more like a Spridget crank to me :lol:


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PostPosted: Sun Mar 13, 2011 10:27 pm 
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TheMiniMan wrote:
Phat Kat wrote:
[ Well,,,,, what do you make of this??

Image



looks just like another broken mini crankshaft to me

:-)
:-)

Sorry Matt ,but you just failed your last and final mini entry exam. Mini crank Ha. :lol:
I will forgive you are still hung over.

Now serious matters, Morris 1100 ,sorry but I should not have had a go at you, but this topic always gets out of hand, but you may know something that I don't about the discussion concerning certain people. If so then please be open about it so we all know exactly what's going on so we all have a clear picture of the situation.

Now from my point of view over the years I have heard many stories concerning engineering and in many cases it is all bullsh*t. I think that this is the main thing that is being discussed, sort out the facts from the crap.

So we have a test done, and have information concerning heat treatment and there is a difference in opinion with this info. So all I can say is that I would agree with the test results going by my experience and what I learnt doing my engineering I would agree with the postings by Phat Kat and GT concerning heat treatment.

Bottom line is I am not interested in making a living or impress anyone from doing conversions and building componets for minis, so I do not give a rats arse what people think about my comments or what I make.Just do my own thing!!!!!!!, but if I see a pile of crap posted I will say it's a pile of crap and just find out the facts yourself.

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PostPosted: Mon Mar 14, 2011 9:36 am 
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1098cc
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GR wrote:
And yes 850 man my car did fail to finish on the week end split in the hose, and me not checking my gauge all the time it pumped all the water out and Lindsay burst to gear you get that now and then when you trying to put a lot of hp through the old 3 syncro gear box.
But both these cars were on the front row after practice and the yellow car by a long way so some where a long the line i must be doing some thing right.
Now i have to get back to getting my ready for Phillip Island see you there.
Graham Russell


Hi Graham,
I see you have mentioned me in this thread so I am happy to respond with my 2 cents.
Yes Both you and Lindsay were exceptionally quick at Wakefield, well done to you both, your car preperation and engines are very good. I gather that the use of flares, lightened components & various other mods would put your cars in the NC class (forgive me if I am incorrect) so your weight advantage & larger engine capicity and the fact that your countless hours of car prep at the Wakefield track should allways have you in front of the Nb cars.
I have had a few problems with gearbox compoinents as well, I have found that the straight cut gearsets available these days are nowhere near the quality of original BMC gearsets. I have sourced various NOS BMC parts for our gearbox from the UK and to date our gearbox problems have ended, we use straight cut transfur and Crownwheel & pinion gears made here in Melbourne, Steves gears are very good so give him a call and he will be happy to help you out if you like. Split cooling hoses on your car is just plain bad luck, we have not had this problem as yet so I hope there wasnt too much damage caused to your engine. I will not be at Phillip Island as I have other commitments, so our next race meeting will be Historic Winton in May, I hope to see you then.
Regards
David.

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PostPosted: Mon Mar 14, 2011 12:12 pm 
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Hi David
Thanks for the kind words,all nb nc engines are now the same size yes my car has some alloy panels on it but has a heavy steel roll cage my car weighs in at 600kg but there are a few NB cars that weigh in a lot lighter than mine down to 573 kg on the same scales as mine, we all have the same tyres so there is not a great deal of difference,as for the flares and wider track they only slow you down in the top speed department, i don't know if i will be at winton this year we'll see what happens.
Graham Russell

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PostPosted: Mon Mar 14, 2011 3:41 pm 
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850man wrote:
Yes Both you and Lindsay were exceptionally quick at Wakefield, well done to you both, your car preperation and engines are very good. I gather that the use of flares, lightened components & various other mods would put your cars in the NC class (forgive me if I am incorrect) so your weight advantage & larger engine capicity and the fact that your countless hours of car prep at the Wakefield track should allways have you in front of the Nb cars.


GR wrote:
Hi David
Thanks for the kind words,all nb nc engines are now the same size.
Graham Russell


GR Does your motor have any lightened components in it, eg I/H-beam con-rods, lightened pistons, alloy flywheel etc, etc?

I dont know (not that i know much about motors and racing) how that much more power can come from a head and camshaft? (I saw you were quite a bit quicker than the others until it broke) compared to others who have just about as much experience with motors and racing.

Umm question....
Nb class is up to 1300cc MAXIMUM is that correct?

Cheers and goodluck with the fix

Brenton

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PostPosted: Mon Mar 14, 2011 4:21 pm 
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Brenton,

My understanding is that Nb cars can have a massive overbore and short through crank to bring it under 1300 - over square engine. This is what I have in my Nb.

Nc cars are restricted to standard stroke with 30" overbore. I understand that they are reviewing this rule or have reviewed as engine blocks are getting hard to find.

Kuzzy

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 Post subject:
PostPosted: Mon Mar 14, 2011 10:49 pm 
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1098cc
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Joined: Mon Feb 12, 2007 2:40 pm
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Location: wasleys S.A.
Phat Kat wrote:
KC wrote:
Spoke to Paul Ivey. He says that when he was at Morris Motors developing
the S stuf, they used to end up with cranks heat treated to 0.060" deep,
or furtehr since they initiall used to run them at -0.060" to reduce
drag/friction, and they were still hard at that. He said these cranks
were simply left in the oven for over a week to get the depth. Obviously
impossibly expensive to do that now. After testing engines back to back
on the dyno with the standard journel cranks and the -0.060" ones and
finding no gain whatsoever, the depth of hardening was stopped and
standard size journals used. KC

--
Remember: Tuning should be a compromise between what is possible and what is necessary

www.calverst.com

Calver Special Tuning Limited
14, Riccal Drive
York Road Industrial Estate
Malton
North Yorkshire
YO17 6YE

Tel: 01653 691380


I have just read this again ,and I may not be the smartest person around, BUT, why would you use a expensive process and risk distorting the crank to harden it to a depth of .060", then grind it down to .060" undersize. Would it not be more logical and less expensive to grind the crank down to .060" U/S [or close to it] then do the "hardening".
This comment defies all logic and basic engineering and heat treatment fundamentals. Even to leave it in a oven for a week is well beyond the time frame to completely stress relieve the crank.
I am sure some one has either mis read,or mis printed or mis interperated the process pointed out.

In regards to heat treatment of the cranks, a EN16T has a higher carbon content than EN40B , and as the carbon content is critical for metal structure change it allows a EN16T to actually be made "tougher" than EN40B.

Now as we are discussing crankshafts there are a few questions I would like to ask concerning some statements made by some people regarding what causes a mini crank to break, and the methods of preventing a mini crank from breaking.

1 What force and how is it applied to break the crank. How does the break form and where is it located in the web.

2 Now there are postings/comments about grinding a large radius on the center main into the web to stop the crank from cracking/breaking. I believe that this is a process that is done by GR and others, so could someone please explain the engineering reasons for doing this.

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PostPosted: Fri Mar 18, 2011 4:43 pm 
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Matt, are you seeing your dad this weekend?

Could you remember to ask him;-

TheMiniMan wrote:

& i must admit, i have forgotten to have words with my dad about all this (((as i said i would))),,, so i`ll do it before weeks end & get his take on what was & did happen (back in the day)


Cheers

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PostPosted: Fri Mar 18, 2011 6:38 pm 
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yeah yeah yeah, i saw him yesterday but forgot to ask, he always finds a way of going off on a tangent , & whatever i wanted is forgotten till well after i drive off & nearly home :-)

so stop harrassing me mate!!! you been pickin on me since we got here,,, wanna fight???

:-)

oops wrong thread, damn it~~~!!!

:-)
:-)
:-)
:-)
:-)
:-)
:-)
;-)

Now get back to your shed !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

:-)

_________________
No offence intended here but--> anyone writing a book about minis 30 years ago may not have experienced such worn or stuffed-with components as we are finding these days.

You should put your heart & soul into everything you do.


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