vinnievector
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| posted on 29/12/07 at 10:24 AM |
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My advise ,as i am a aircraft sheetmetal engineer is to stick with the steel chassis .
sounds boring i know ,but if you start to get involved into the world of tempered alloys hope you have a very deep pocket and lots of knowledge of
stress engineering .best of luck
sorry to put a downer on it .
Thats why i think for years the kit car inds has stayed with the tried and test steel chassis.
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martyn_16v
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| posted on 29/12/07 at 11:17 AM |
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quote:
Originally posted by JoelP
can anyone guess my other pet hate?! 
People randomly interchanging their, there and they're? Winds me up no end
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RazMan
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| posted on 29/12/07 at 05:04 PM |
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quote:
Originally posted by martyn_16v
quote:
Originally posted by JoelP
can anyone guess my other pet hate?!
People randomly interchanging their, there and they're? Winds me up no end
.... and using a loose when a lose is needed
Cheers,
Raz
When thinking outside the box doesn't work any more, it's time to build a new box
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dave r
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| posted on 29/12/07 at 06:09 PM |
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so what does a steel book chassis weigh in at then ?
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thomas4age
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| posted on 29/12/07 at 11:22 PM |
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quote:
Originally posted by britishtrident
quote:
Originally posted by gazza285
quote:
Originally posted by britishtrident
A welded aluminium alloy spaceframe is very likely to be lethal.
Like this Le Man winning deathtrap..........
Did you know that the T70 was infamous for something called "the Lola Limp"
the lower wishbone pickup in was fully exposed in the drivercompartment just below the knee, in a front-end collision this broke of and hacked right
in the back of ones knee.... ouch that gotta hurt. one than was "Lola Limp" when walking
quote:
But it wasn't built out of 25x25 extrusion a Porrsche went to great lengths to monitor the chassis for cracked welds durring the race.
More than one car was pulled out with cracked chassis.
but that has had to do with the very soffisticated way the alloy round tube chassis was welded at the factory 
foto of original Porsche 917's famous welding
Look at what RCR are doing nowadays with their alloy monocoques, those seem to be very strong. so it can be done
Grtz Thomas
[Edited on 29/12/07 by thomas4age]
[Edited on 29/12/07 by thomas4age]
[Edited on 2/1/08 by thomas4age]
If Lucas made guns, Wars wouldn't start either.
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JoelP
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| posted on 29/12/07 at 11:46 PM |
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quote:
Originally posted by martyn_16v
quote:
Originally posted by JoelP
can anyone guess my other pet hate?!
People randomly interchanging their, there and they're? Winds me up no end
nearly! your and you're (sorry paul  )
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iank
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| posted on 30/12/07 at 12:08 AM |
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quote:
Originally posted by dave r
so what does a steel book chassis weigh in at then ?
Page 53 of the 'and race it' edition has a picture showing Ron waving what looks to be a complete chassis minus brackets and panelling in
the air. The claim is 'about 35lb'.
The spaceframe chassis really isn't the key to massive weight reduction. Maximum saving is only ever going to be a couple of kilo's.
--
Never argue with an idiot. They drag you down to their level, then beat you with experience.
Anonymous
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cossey
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| posted on 30/12/07 at 04:15 PM |
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you can make a aluminium spaceframe work but it will almost certainly require fully chassis heat treatment post welding and if your going to go to
that trouble you might as well go for 4130 steel or similar.
if you want a better chassis use seamless round tube and use a large mix of tube sizes so that each section only uses what material is needed. also
make sure the roll cage if you use one is an intergrated part of the chassis and can be used to reduce the weight of other structures
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02GF74
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| posted on 3/1/08 at 11:10 AM |
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It is a fact of life that nearly all newbies ask this question, even me
Take a look at bicycles - nearly all are now made fgrom alloy (note - not the same as raw aluminium) which has replaced steel.
In the early days, must be about 15 or more years, there was some problems with frame fracture but volume of experience means that is no longer is the
case. I daresay if the same was done with alloy chassis, the situation would be
same.
As said. there have been alloy frames as well as the aluminium robin hood monocoque so it is doable but you would need to know what you are doing.
In short, it is cheaper, easier and safer to go with a proven steel design - the weight saving not being enough to entice more buiders to use alloy,
not to mention steel is easier to DIY repair.
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britishtrident
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| posted on 3/1/08 at 02:19 PM |
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A push bike frame or motor bike frame can easy enough be heat treated -- heat treating an entire car chassis is a bit more problematic.
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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iank
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| posted on 3/1/08 at 03:06 PM |
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quote:
Originally posted by britishtrident
A push bike frame or motor bike frame can easy enough be heat treated -- heat treating an entire car chassis is a bit more problematic.
Indeed, also the aluminium bike frames tend to have 2-3" diameter round/oval tubes for far smaller loads than a car spaceframe made from
1" box will see. Frequency of vibrations will also be an order of magnitude different.
I suspect an average bike will also see fewer than a 1/10th the miles of an average kitcar, and if the frame cracks it's 1. out in the open so
you can see it often as it goes bang, and 2. chances of someone dying/suing are much less.
--
Never argue with an idiot. They drag you down to their level, then beat you with experience.
Anonymous
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Confused but excited.
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| posted on 5/1/08 at 10:28 PM |
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quote:
Originally posted by britishtrident
A push bike frame or motor bike frame can easy enough be heat treated -- heat treating an entire car chassis is a bit more problematic.
So the answer would appear to be; make the chassis out of push bike frames bolted together. This would give plenty of triangulation and make
maintenance easier.
Tell them about the bent treacle edges!
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Triton
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| posted on 5/1/08 at 11:11 PM |
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quote:
Originally posted by Confused but excited.
quote:
Originally posted by britishtrident
A push bike frame or motor bike frame can easy enough be heat treated -- heat treating an entire car chassis is a bit more problematic.
So the answer would appear to be; make the chassis out of push bike frames bolted together. This would give plenty of triangulation and make
maintenance easier.
The Halfords spesh.......
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iank
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| posted on 5/1/08 at 11:36 PM |
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quote:
Originally posted by Triton
...
The Halfords spesh.......
Guy at work calls Halfords bikes BSO's (Bike Shaped Objects) but then he spent more on his bike (he's a triathelete in his spare time so
what's not carbon is titanium) than I'm spending on my car.
--
Never argue with an idiot. They drag you down to their level, then beat you with experience.
Anonymous
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gazza285
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| posted on 6/1/08 at 12:33 AM |
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Push bike snob is he?
Halfords is not the place to buy a performance bicycle, same as it is not the place to buy perfomance car stuff.
But.
A cheap bike probably weighs 28-9lbs.
A £300-400 bike weighs 23-24lbs.
A £800-1000 bike weighs 22-24lbs.
A £5000 bike weighs 21-23lbs.
And just like everything else bullshit baffles brains, how much did he spend on his bike?
DO NOT PUT ON KNOB OR BOLLOCKS!
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gazza285
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| posted on 6/1/08 at 12:37 AM |
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quote:
Originally posted by iank
what's not carbon is titanium
Ask him why the Tour De France boys still use steel frames then......
Steel alloys I know before anybody calls me, but still more iron than anything else.
DO NOT PUT ON KNOB OR BOLLOCKS!
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iank
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| posted on 6/1/08 at 01:58 AM |
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quote:
Originally posted by gazza285
Push bike snob is he?
Halfords is not the place to buy a performance bicycle, same as it is not the place to buy perfomance car stuff.
But.
A cheap bike probably weighs 28-9lbs.
A £300-400 bike weighs 23-24lbs.
A £800-1000 bike weighs 22-24lbs.
A £5000 bike weighs 21-23lbs.
And just like everything else bullshit baffles brains, how much did he spend on his bike?
Oh yes big snob, I suspect over £3k, but I've not asked.
--
Never argue with an idiot. They drag you down to their level, then beat you with experience.
Anonymous
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iank
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| posted on 6/1/08 at 02:06 AM |
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quote:
Originally posted by gazza285
quote:
Originally posted by iank
what's not carbon is titanium
Ask him why the Tour De France boys still use steel frames then......
Steel alloys I know before anybody calls me, but still more iron than anything else.
I suspect like all things the tour guys have special requirements (robustness over days of competition under all weathers, surviving the odd crash,
allowing some repair on the event etc.) For all I know there could even be regulations on what materials you can use.
As a counterpoint the velodrome events seem to all require carbon bikes these days, and a significant number of the triathletes use composite bikes
from what I remember.
--
Never argue with an idiot. They drag you down to their level, then beat you with experience.
Anonymous
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Doug68
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| posted on 6/1/08 at 05:08 AM |
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The Tour bikes are steel for comfort, it's a more 'springy' ride and less harsh than the other materials.
They do use different bikes for different days though and in the mountains I'd expect everyone to be all Carbon.
Back to the subject of Aluminium Chassis frames. Bluntly put just swapping out one material for another and building the same design is either going
to leave you massively over designed or on the way to hospital.
Any design for any load bearing object needs to be designed with full thought to the material its being made from.
So for example if you do a Aluminium space frame you typically will end with much larger cross sections used which therefore have a much higher second
moment of area this is important as tubes will fail in compression before they do in tension and looking at
Eulers Column Theory if you reduce the Modulus of Elasticity (by going from steel to alloy) you need
to increase the Second Moment of Area to compensate or the tube will fail at a much lower load.
If you look at the picture below you can see the large cross sections used, this is the frame for the
RCR Super Light Coupe which is a when respected manufacturer in the USA.
[Edited on 6/1/08 by Doug68].jpg)
Doug. 1TG
Sports Car Builders WA
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crafty
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| posted on 6/1/08 at 01:39 PM |
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I like this a lot... http://www.teamlorenz.com/shannon_s2.htm
Ultima GTR - 600hp Magnacharged LS2
MNR Vortx - Supercharged R1
Porsche 356 - midmounted Audi V8
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crafty
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| posted on 6/1/08 at 01:56 PM |
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... or how about THIS
http://www.gmtracing.com/carsforsale.htm
Ultima GTR - 600hp Magnacharged LS2
MNR Vortx - Supercharged R1
Porsche 356 - midmounted Audi V8
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cymtriks
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| posted on 6/1/08 at 11:34 PM |
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An aluminium space frame is never going to be as good as a steel one.
To be as stiff it will need to be made of tubes with three times the cross section of a steel tube. The aluminium has a density about three times less
than steel so you end up back where you started. But you have spent more money, the welds will be harder to get right (or easier to get wrong) and the
fatigue properties will be worse.
The only way to get it to work, as far as I can see, is to use bonded on aluminium panels to turn the chassis into a semi monocoque. The sheet
material could replace all the spaceframe diagonals if you did this right. It could also be very stiff if the panels were added both sides of the
chassis tubes which would turn them into very deep rectangular cross section beams. However by "bonded" I mean properly etch primed and
glued using the correct kind of glue applied in the correct way, not stuff squirted out of a hot glue gun or, god forbid, bath sealant. You'll
want to pop rivets aswell just in case the glue hardens and cracks over time.
Even then there's going to be corrosion. Aluminium may not rust but it certainly corrodes in salt or in the pressence of steel parts (like a lot
of the cars parts will be).
The "spaceframes" made by mass manufacturers are actually more like multitubes or complex ladder frames (i.e. they are not triangulated).
They get their properties partly from the large cross sections of the tubes and partly from the bonded on body panels. I don't know how much of
the final strength and stiffness is due to either.
By the way a book chassis is nowhere near 35lbs finished, more like 180lbs if you strictly follow the book, which specifies a 16 gauge steel floor.
Even with an aluminium floor and some lee way from the book I'd expect a finished and paneled chassis to be well over a 100lbs.
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iank
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| posted on 7/1/08 at 12:18 AM |
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quote:
Originally posted by cymtriks
...
By the way a book chassis is nowhere near 35lbs finished, more like 180lbs if you strictly follow the book, which specifies a 16 gauge steel floor.
Even with an aluminium floor and some lee way from the book I'd expect a finished and paneled chassis to be well over a 100lbs.
As I said picture that claims 35lb has no panels at all (I include the floor as a panel) or brackets. Since people on here have made floor panels in
everything from 3mm steel though 1.5mm aluminium the range is huge.
I'd wouldn't disagree with your estimate for a fully panelled chassis (without running for a calculator  )
--
Never argue with an idiot. They drag you down to their level, then beat you with experience.
Anonymous
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britishtrident
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| posted on 7/1/08 at 08:26 PM |
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The 35 lbs weight is roughly the weight of a bare early Lotus Seven S2 chassis.
These chassis have a lot less tubes than a Locost (or later Lotus or Catherham) and were made of 1.2mmr round tube.
A very bare Locost chassis is more than twice that, many builbs nearer to 100 lbs.
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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chrisg
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| posted on 7/1/08 at 08:37 PM |
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It's worth noting that the chassis that Ron is holding up in hat picture IS an aluminium space frame - one of the experimental frames made by MK
Engineering.
My Locost frame (with a steel floor) was 94.5 lbs.
Cheers
Chris
Note to all: I really don't know when to leave well alone. I tried to get clever with the mods, then when they gave me a lifeline to see the
error of my ways, I tried to incite more trouble via u2u. So now I'm banned, never to return again. They should have done it years ago!
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