NeilP
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| posted on 24/10/08 at 06:30 PM |
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quote:
Originally posted by dhutch
I dont know if anyone here has not seen the photos. But as i commented on the thread before it looks pretty dam scary.
I mean, the bits round the diff, maybe just maybe. Big engine, big power, lots track action, curbs. Whatever.
But the failed front rail members didnt look clever at all. And the repair was indeed a disgrace. Something i would have been proud of if i'd
done it in a pit garage with someone elses welder and some angle iron from the carpark floor. But not factory rectification work standard even for a
wed friday.
Daniel
From my perspective the issue is not one of the gauge of the steel but of the underlying steel quality. Those cracks appeared to have all started at
the welds and in places that wouldn't necessarily get the highest of the cyclic forces that would make the gauge the primary issue i.e. you
would see a ductile tear first. These look like textbook brittle fractures eminating as a result of microscopic material damage from weld heating.
Two ways to overcoming this; a better quality steel or preheating before welding. On the basis that one one manufacturer does this as they braize all
of their joints then it points to the steel quality first, gauge second...
For any involved lawyers, this is of course all IMHO and made as a personal statement without bias on a public forum so go stick your heads up your
@rses 
If you pay peanuts...
Mentale, yar? Yar, mentale!
Drive it like you stole it!
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Paul TigerB6
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| posted on 24/10/08 at 06:40 PM |
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quote:
Originally posted by NeilP
For any involved lawyers, this is of course all IMHO and made as a personal statement without bias on a public forum so go stick your heads up your
@rses
Come on don't mince your words. Just say it!!
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austin man
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| posted on 24/10/08 at 08:55 PM |
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and McDonalds got sued for selling hot cups of coffee which burn when spilt. But its okay to sell a structure that self destructs. Remind me to buy
the coffee and not the structure. Coffee £1.49 potential £1000,000 return,
cost of structure and accessories £10k - £15k return -= potential disaster. Who said caffeinfne is bad for you
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Syd Bridge
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| posted on 24/10/08 at 08:56 PM |
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I managed to see the pics before the Westfield heavies had them deleted.
The repairs are abominable. Something the local blacksmith wouldn't even do in his forge. Again, who was the 'engineer'who specced
the repairs?I bet he doesn't exist.
The failures...To me, they look like brittle fractures, started out due to haz problems, and exacerbated by stress fatigue, with a dash of dodgy steel
thrown in.
All the cracks are in stress concentration areas, so classic failure situation.
Also, I would surmise that the back end, and the front, have never been analysed for stresses. If they had, those cracks would never have happened.
What makes me say what I just wrote? You can get a bit blase about things, so I ran the numbers on a current project with irs, AFTER I had looked at
the diff carrier design. Silly me. The forces on the diff supports are a lot more than a man would imagine. And when you throw in 'drop the
clutch at 7K' starts, then those forces are multiplied many times instantaneously. Needless to say, a bit more metal was added.
Hard mounted diffs also transmit a lot more vibration and local stresses than compliantly mounted items.
I expect to see a lot more of these types of failures as time goes on, and not just Westfields. Just about everything with a hard mounted diff in a
se7en type car is suspect. I've not seen one, from any maker, that looks sufficient after what my calcs showed up. If it's not the mounts
which the diff bolts to directly, it's the bits that the mounts are attached to. The system needs to be viewed as a whole.
Maybe it's just me though, and got a couple of decimal points in the wrong place.
All I know is that you need as many triangles (proper triangles, not gussets) back there as can be fitted in, and the whole back end needs to be
attached to everything in front of it, above it, sideways, in every and any way possible.
Cheers,
Syd.
HAYNES ROADSTER BUILDERS NOTE THE ABOVE CAREFULLY. YES,SERIOUSLY.
BUYERS OF OTHER KITS MIGHT WANT TO ASK A FEW QUESTIONS OF THE MANUFACTURERS AS WELL.
Edit: I'm away for the weekend now, hiding in a bomb shelter, so don't waste your efforts sreaming me down. I can't hear you. Deaf
anyway!
[Edited on 24/10/08 by Syd Bridge]
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tks
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| posted on 24/10/08 at 10:29 PM |
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quote:
Originally posted by Syd Bridge
I managed to see the pics before the Westfield heavies had them deleted.
The repairs are abominable. Something the local blacksmith wouldn't even do in his forge. Again, who was the 'engineer'who specced
the repairs?I bet he doesn't exist.
The failures...To me, they look like brittle fractures, started out due to haz problems, and exacerbated by stress fatigue, with a dash of dodgy steel
thrown in.
All the cracks are in stress concentration areas, so classic failure situation.
Also, I would surmise that the back end, and the front, have never been analysed for stresses. If they had, those cracks would never have happened.
What makes me say what I just wrote? You can get a bit blase about things, so I ran the numbers on a current project with irs, AFTER I had looked at
the diff carrier design. Silly me. The forces on the diff supports are a lot more than a man would imagine. And when you throw in 'drop the
clutch at 7K' starts, then those forces are multiplied many times instantaneously. Needless to say, a bit more metal was added.
Hard mounted diffs also transmit a lot more vibration and local stresses than compliantly mounted items.
I expect to see a lot more of these types of failures as time goes on, and not just Westfields. Just about everything with a hard mounted diff in a
se7en type car is suspect. I've not seen one, from any maker, that looks sufficient after what my calcs showed up. If it's not the mounts
which the diff bolts to directly, it's the bits that the mounts are attached to. The system needs to be viewed as a whole.
Maybe it's just me though, and got a couple of decimal points in the wrong place.
All I know is that you need as many triangles (proper triangles, not gussets) back there as can be fitted in, and the whole back end needs to be
attached to everything in front of it, above it, sideways, in every and any way possible.
Cheers,
Syd.
HAYNES ROADSTER BUILDERS NOTE THE ABOVE CAREFULLY. YES,SERIOUSLY.
BUYERS OF OTHER KITS MIGHT WANT TO ASK A FEW QUESTIONS OF THE MANUFACTURERS AS WELL.
Edit: I'm away for the weekend now, hiding in a bomb shelter, so don't waste your efforts sreaming me down. I can't hear you. Deaf
anyway!
[Edited on 24/10/08 by Syd Bridge]
remember:
the grip level is the weakest point...
so in first gear at 7k rpm and leaving the clutch won't do much harm because the rearwheels whill start screaming/spinning...
if you woud let rest an olifant on the rear of the car and re do it... then the ggrip will be higher and the diff will need to withstand more
forces...
The above comments are always meant to be from the above persons perspective.
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an.owner
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| posted on 24/10/08 at 11:35 PM |
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Guys...
As a westfield owner, a member of WSCC and someone has followed the topic on the wscc boardroom from the start.....
there is an update from WSC MD.
http://boardroom.wscc.co.uk/cgi-bin/ikonboard.cgi?act=ST;f=15;t=67756
imo- asking wscc to supsend the topic whilst investigations take place was a little foolish in hindsight, but i can understand why this would be the
case..... and this might have been the advice from the legal team at their insurance company.
i feel sorry for the owner in question and i believe that wsc will meet any of their responsiblites, and we will see a resolution for him soon.
A Proud Westie Owner
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Paul TigerB6
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| posted on 24/10/08 at 11:40 PM |
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^^ Link not available to non members. Can you copy the text across??
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an.owner
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| posted on 25/10/08 at 05:50 AM |
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quote:
Originally posted by an.owner
Guys...
As a westfield owner, a member of WSCC and someone has followed the topic on the wscc boardroom from the start.....
there is an update from WSC MD.
http://boardroom.wscc.co.uk/cgi-bin/ikonboard.cgi?act=ST;f=15;t=67756
imo- asking wscc to supsend the topic whilst investigations take place was a little foolish in hindsight, but i can understand why this would be the
case..... and this might have been the advice from the legal team at their insurance company.
i feel sorry for the owner in question and i believe that wsc will meet any of their responsiblites, and we will see a resolution for him soon.
A Proud Westie Owner
To all Westfield Sports Car Club Members
It was a difficult decision to have to request the suspension of communication on this issue, but this was to protect the company, WSCC and the
individual whilst maintaining our position with our insurance company. However, it is in no way an attempt to sweep the issue under the carpet. Our
track record while we have been owners of the company has been to ensure that any problems of a safety nature are fully investigated, dealt with,
product communicated and product recalled where necessary. If at any time we believe that other cars in service or being built are at risk, we will
issue a statement and recall. The evidence that we have at this stage, on the issue in question, does not indicate such a risk but once again we need
the whole evidence.
Edited by Julian Turner on Oct. 24 2008,19:08
[Edited on 25/10/08 by an.owner]
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NeilP
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| posted on 25/10/08 at 10:48 AM |
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Better - But still doesn't excuse the, "...has been refered to the relevent legal authorities..." bullshit he wrote the day
before...
If you pay peanuts...
Mentale, yar? Yar, mentale!
Drive it like you stole it!
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Paul TigerB6
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| posted on 25/10/08 at 10:54 AM |
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quote:
Originally posted by NeilP
Better - But still doesn't excuse the, "...has been refered to the relevent legal authorities..." bullshit he wrote the day
before...
Totally agree with Neil. There should never have been any mention of any sort of legal proceedings in this case. A response similar to the above along
with actually working with the owners club to see if it was a one off dodgy chassis or a more widespread problem would have lead to a much better
response from the club members!!
Talk about scoring an own goal!! Risking alientating a chunk of the membership like that!!
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CaptainJosh
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| posted on 25/10/08 at 11:31 PM |
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<quote>
remember:
the grip level is the weakest point...
so in first gear at 7k rpm and leaving the clutch won't do much harm because the rearwheels whill start screaming/spinning...
if you woud let rest an olifant on the rear of the car and re do it... then the ggrip will be higher and the diff will need to withstand more
forces...
</quote>
Surely thats like saying that there is no dynamic stress worries in a chassis at all because the force is transfered to the ground and therefore to
the tires, so you can just trust the tires to slip all the time?
Reality is that the force is seen through all the connecting components, the differential has to create an almost equal and opposite force to that of
the prop shaft (aka engine) otherwise it would just spin in place ( the differential casing wants to spin with its input shaft ).
Anyway, if you looked at the whole process in slow motion you will see that the wheels are actually the last thing to take the force through the
system and the diff will twist on its mounts ( if they are soft, if they are not, the force is still there but its less visual ) as it takes the load
before the wheels even spin in the slightest.
You have to be thinking in tenths of a second, but sometimes thats all it takes.
-Josh
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MikeR
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| posted on 27/10/08 at 12:12 AM |
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this is part of the reason i was thinking of adding a little more steel around my diff mounts to triangulate the forces forwards & add a separate
pan hard bar triangulation to the non pan hard bar side to take the forces rear-wards.
well i reckon the chassis is only 380ish kg at the moment (no body work, no electics, no roll bar, no brake lines, no fuel lines, no ali panels, no
seats, no belts) so it can take an extra kg or two.
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kb58
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| posted on 31/10/08 at 02:59 PM |
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With a Miata drivetrain and IRS, the forces are around 1200lbs at the IRS diff mounting points, and as Syd points out, that's with smooth clutch
engagement. Dumping the clutch or any other type of drag race start will make the forces many times larger. Using racing slicks and/or bigger engines
makes the situation even worse.
Mid-engine Locost - http://www.midlana.com
And the book - http://www.lulu.com/shop/kurt-bilinski/midlana/paperback/product-21330662.html
Kimini - a tube-frame, carbon shell, Honda Prelude VTEC mid-engine Mini: http://www.kimini.com
And its book -
http://www.lulu.com/shop/kurt-bilinski/kimini-how-to-design-and-build-a-mid-engine-sports-car-from-scratch/paperback/product-4858803.html
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