This is a quote from an extreamly intellegent & immensly experienced mechanic/engineer


""""""It does not matter how clever, or how qualified a designer or engineer may be, if a piece of machinery or equipment fails in its work place, then the design and construction must be questioned.""""""""

& not it`s not my quote i`ve just borrowed it

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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.

That is dead right Matt, they should not fail. If I was to drive a truck down the road and it had a structural failure and an accident there would be a big outcry. Just because it is a Mini does not make it exempt from the rules.

How many standard Mini subframes have you seen with a structural failure? (I have seen a few cracks in the towers from very hard rally/race use, but that is about it.)
So why is it acceptable for a modified subframe to fail?

Who said it was acceptable?

I dont think anyone has gone out of their way to make a structurally unsafe subframe. They are made in good faith that the engineer signs off on them. They are the ones being payed to check them, most people are not qualified or had the training to make that decision. Who is responsible in the end?

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Starlet Conversion:
http://www.ausmini.com/forums/viewtopic.php?t=15484

I suppose I should not have said acceptable, it probably should have been inevitable.
There seems to be a theory that you build a frame and when it brakes you make it stronger. This is not engineering.

Why is it OK to build a chunk of crap and then go shopping for some poor sap (engineer) to sign it off as acceptable. Then blame the poor sap when things go wrong.
The thing that is missing from the whole process is engineering.

Is the frame designed by an engineer? No.
Is the frame welded by an engineer? No.
But the engineer has to say if it is safe or not.

It is not a system that will work well with a complex conversion like these.

I'd like to know who is responsible when it breaks under way and hurts somebody, and this poor engineer who signed it off retires/moves overseas/carks it/whatever..
Seems to me to be a very poorly thought out system that the RTA etc have come up with.
I would have thought that a properly engineered frame, given type approval would have been a better way to go.

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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.

Hmm, I think we are going off on a tangent here.......

To answer Matt's statement about 'standardising a design', this wont work, because there are so many ways to skin a cat, and we all have different views on how to achieve the set outcomes that a 'standardised' frame would not become a reality.

I based my subframe on Matt Powers (3 years daily driver, no failures of any kind), because I could see the design intent was there as structurally integral. I did not base my frame on Mr Enforcers or Tony Yager's subframe, even though I saw them before Matt's, as I didnt have any faith in the design of them and I could see flaws that I didnt want to emulate.

I have markedly altered Matt's original design, and now I am into the 3rd successive iteration with my own design, because of the philosophy of continual improvement. If I can make it lighter and the same strength I will. If I can make it cheaper for the same strength I will. If I can mke it easier for the same strength I will. But I will never compromise on structural integrity.

And there in lies the rub, somtimes you need failures along the way to progress forward, if major car manufacturers did not test until something broke, then they would not know where to improve the design. Racing teams do it all the time - design a part that is successively lighter than the one before and test it until it breaks, then go back one iteration! But continual failure is not an option, and continual failure at the same point is definately not an option!

And all this design knowledge has to come from somewhere, and its experience. Until we design something and test it in real worls conditions, we have no idea if it is a success or not. We have calculations, books, software and tables we use (or at least I do) to get a grounding or baseline from whence to start, but all this is collective experience too! Not our own, but definately someone elses.

So, what we are saying is sometimes you have to fail to succeed. Do we go out with the intent of building a structurally unsafe subframe - hell no. Do we know to the nth degree the fatigue life of our subframes - not really, but we over engineer to compensate for this. Do we build in a design life for them - yes we do. If we have a failure should we analyse, rectify and redesign - hell yes we should.

Contrary to Matt's view, I dont think we will see mega failures of everyones subframes along the way, there will be a few for sure whose baseline design was not structurally sound, but most will be just fine. There maybe a few afatigue cracks along the way, or cracks due to poor workmanship, but all in all they will be ok. And opposed to what Morris 1100 said, we need to keep a 'failure' in perspective as not a catastrophic failure. BigBad was not a catastrophic failure.

And to answer Morris' other question of the Engineer and whose responsibility is whose, I cant! Every Engineer, like every design, is different. I at least know with my Engineer that he wanted to see loads of data on the design, data on the steel used and wanted to personally inspect my workmanship on every subframe. Until every Engineer asks for FEA on all the designs etc, including torsional, compressive, tensile and shear tests using real world loads, then the call is theres and theres alone to make whether it gets rubber stamped or not, and they rely on one thing to make this decision - EXPERIENCE!!

Cheers,
Tricky

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"Not Speeding Officer..........Qualifying"

I think you've summed it up exactly tricky , the key is to not take each failure as a sign that they are all wrong , and also not to just weld them up again the same but to learn from them and adapt the design to make it better again . The whole mini engine conversion thing is in early days yet (really , come on , with the forces involved in the Honda and oyota engines it will take a while to iron out the kinks) but seriously , people need to be honest with their engineers and not just concentrate on getting them passed (not looking at anyone in particular) .

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well said tricky,,, i salute you,,, It`s very well thought out & written

However,,, i`m not of the view that they all will break,,, just that i`ve seen a few & most of those have broken ,,, That`s my point..,.. a bit like looking down the top of a radiator mate,,, if half the core holes you see are blocked,,, well ,,, you can bet that hal that whole rad is blocked yeah??? but you still havn`t seen the rest of them yet till you rip the top off right???,,, that`s where i was comming from & in no way did i point any fingers or lay any blame (like i said earlier) ,,, just that "all" the jap frames that i`ve seen in the flesh so far i`ve not been happy with & a good few of those have already broken a few times each.

i`m still yet to lay my eyes on yours actually, but we`ll save that for the party yeah?

I doubt that i will be able to critisize yours tho (by the sounds of things) & i will be glad if that is the case,,, then we can agree again,,, i do ever so much like agreeing with you tricky

Mine is still a long way from being finished, (basic layout is done,,, one is semi knocked together) but we hope to have it suit a few jap engines tho, so it really "IS" a major task

anyways,,, i`m off surfing

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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.

Here's an interesting version of a subframe http://www.16vminiclub.com/forums/viewtopic.php?t=15481 This guy has installed a carby 4E-FE (from Corolla). Just wondering whether this design could be considered when you think that the 4E-FE & 4E-FTE are the same block size but different ancillaries hanging off them. He HAS used a Nissan gearbox so maybe the Starlet gearbox is too big to fit within the original subframe?

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-Alan
I blame my dad for my love of minis. I think I was conceived in the back seat of one
I also blame my Dad for me being 6' 1" - not really the optimum height for driving a Mini.

Nice and neat!!

Yes, that Starlet gearbox is a little longer than the Nissan, but not by much.

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"Not Speeding Officer..........Qualifying"

Check out the Starlet motor on a mini gearbox.



These guys are crazy!

Hey guys, I was surprised to come back to this thread and see so much of a response.

The odometer has just clicked over 7,500 kms, so it really hasn’t seen that much time out and about. Admittedly it is only driven on weekends or time off and is therefore more likely to be given a harder time than a daily driver.

As for the sub frame, unfortunately for us there is no “AS XXXX Steel Design For Modified Subframes” (yet…) in which we can follow step by step, tried and proven method for designing a suitable system. Lucky for us there are enough conversions popping up and enough people in this community with extensive knowledge in automotives that we should be able to get the formula right between us.

As for moving forward with bigbad, I am really just considering this to be a free lesson and my main focus now is now is sort out the subframe so it performs its job adequately and safely without being over the top (now as well as in the future, especially with so much potential power in this engine). I am open to suggestions for the most suitable way forward and any further suggestions would be greatly appreciated.
Cheers.

Whoa, carby and all! At least it's got AC!

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1964 Morris 850, 1330 Supercharged - 81.8hp atws.
1975 Leyland Mini S 1100S powered - Nice and reliable.
1977 Leyland Mini LS - Project LS-T

Hmmm, no PCV or breather hooked up yet, guess it gets plumbed back into the air cleaner housing.

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"Not Speeding Officer..........Qualifying"

Interesting way of mounting the Master Cyl and Booster.