lexi
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| posted on 11/1/06 at 12:10 AM |
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My floor is 16g steel as is trans tunnel and bulkhead. Won`t make no difference to my car as I hope to lose three stone before it`s SVAd . My wife
will be riding shotgun and if she happens to drop that purse of hers on an ally floor..
Alex
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C10CoryM
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| posted on 11/1/06 at 12:34 AM |
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Pretty well all cars here are just spot welded together. Stronger/lighter than rivets but weaker than bonding.
Ive never seen a spot welded car come apart at the seam and I have twisted the hell out of a few of them .
Had a camaro that tore the quarter panel, tore out the door striker, and twisted the car enough the dome light stayed on but there was no damage to
the spot welds. Little too much power/traction for the stock body.
Spot welded steel will be just fine. having said that, I intend to use SS structural rivets and also bond the aluminum to the chassis. I want to
leave the sides bare aluminum. Havent decided what to do on the tunnel though. The thought of using aluminum there and having a u-joint fail scares
me. Not a V8 car though so less likely than I am used to I guess.
Cheers.
"Our watchword evermore shall be: The Maple Leaf Forever!"
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locost_bryan
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| posted on 11/1/06 at 01:58 AM |
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Cymtriks recommends welding a steel panel under the nose as part of the torsional rigidity improvements.
I've been considering using the roof off my donor Suzuki van for the floor (as suggested by Uncle Ron) - it has stamped ribs running down
it's length, so would be nice and stiff. 
The original 7 was a little on the flexible side - I'd like mine to be a little stronger around my vital bits (and don't mind a bit of
extra weight closer to the ground) 
... and I'll save some weight by going for an axle, gearbox and all-alloy engine that are heaps lighter than Ford's 
Bryan Miller
Auckland NZ
Bruce McLaren - "Where's my F1 car?"
John Cooper - "In that rack of tubes, son"
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Philippe
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| posted on 11/1/06 at 10:03 AM |
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quote:
Originally posted by C10CoryM
Pretty well all cars here are just spot welded together. Stronger/lighter than rivets but weaker than bonding.
Ive never seen a spot welded car come apart at the seam and I have twisted the hell out of a few of them .
Had a camaro that tore the quarter panel, tore out the door striker, and twisted the car enough the dome light stayed on but there was no damage to
the spot welds. Little too much power/traction for the stock body.
Spot welded steel will be just fine. having said that, I intend to use SS structural rivets and also bond the aluminum to the chassis. I want to
leave the sides bare aluminum. Havent decided what to do on the tunnel though. The thought of using aluminum there and having a u-joint fail scares
me. Not a V8 car though so less likely than I am used to I guess.
Cheers.
R-Thanks for your reply.
Indeed spot welds need dynamite to be separated. I am currently rebuilding the body of my Suzuki Samurai and I could not separate the plates around
spot welds. I had to plasma cut 1" holes around them. So I am confident that welding light gauge sheet steel on a Locost tube frame will be the
strongest bond possible. Your idea of using SS rivets/aluminium plates is good too. I would still introduce a bonding agent (epoxy) though in order to
provide the skin to chassis bond more integral strength and prevent water penetration in steel tubes.
I hope these thoughts are usefull.
Take care.
Ps. I like the photo of your sister on the left.
Philippe
[Edited on 11/1/06 by Philippe]
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02GF74
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| posted on 11/1/06 at 11:12 AM |
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quote:
Originally posted by Philippe
Indeed spot welds need dynamite to be separated.
[Edited on 11/1/06 by Philippe]
maybe nowadays but I recall a story about Marina or some other BL car from the 70s. The owner would go to the countryside and park the car. He would
hear a strange pinging noise once in a while - turns out it was the spot welding coming apart!
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Peteff
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| posted on 11/1/06 at 11:19 AM |
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I could not separate the plates around spot welds
Get one of these they're good for splitting panels.
I've used them or just drilled through the welds and peeled them with grips or split them with a chisel but that tears the metal so you need to
be careful if you are reusing it. You can reweld in a different place to recycle panels though.
yours, Pete
I went into the RSPCA office the other day. It was so small you could hardly swing a cat in there.
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NS Dev
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| posted on 11/1/06 at 11:56 AM |
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quote:
Originally posted by Philippe
quote:
Originally posted by britishtrident
quote:
Originally posted by NS Dev
The problem will be that using 0.5mm steel (as opposed to 1.2mm ally) will mean that the steel will wrinkle when welded, almost impossible to stop
this happening with very thin section sheet steel.
R-I was refering to sequential spot welding. This is the way the industry stitches car bodied together. Punch holes all around the perimeter of your
panels, turn the amp at the lowest on your mig welder, weld one second hole at the time, etc.... No distorsion, no buckling, perfect.
Philippe.
Yes ;-) it buckles or to put it anotherway because of the greater thickness an aluminium panel is stiffer in bending than a comparable steel panel
-- which is why aluminium and magnesium alloys are such excellent materials for making road wheels.
You mean what I would call plug welding, i.e. puddle welding through punched holes with the MIG.
I use this technique a lot, but it still wrinkles 0.5mm steel sheet, in fact it still wrinkles 0.8mm sheet, even when pretensioned.
Retro RWD is the way forward...........automotive fabrication, car restoration, sheetmetal work, engine conversion
retro car restoration and tuning
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NS Dev
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| posted on 11/1/06 at 12:07 PM |
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quote:
Originally posted by britishtrident
quote:
Originally posted by 02GF74
is it not possible to spot weld the thin sheet to the square tubes or the difference in thcknesses too great?
using steel has anther disadvantage - rust! so you need rust treatment and paint = more weight!
the question is how much rigidity you gain by a more solid join of sheet to the frame, if you knew that, then maybe you could use lighter tube so shed
some weight there.
Lotus or at least Arch Motors used 1.2 mm round tube for the spaceframes. 1.6 RHS is easier work with.
Early Lotus space frames were a lot sparser than the Locost --- somewhere on the net is a picture of chunky Chapman holding up an Eleven chassis--
just try that with book chassis.
With the Seven Series 2 Chapman tried to take even more weight out cutting out nearly all of the diagonals -- the result was a lot of broken chassis
(mainly fatigued brazed joints), with the late Series 2 and Series 3 the missing members were re-instated. Locost are about twice the weight of a
Lotus Seven S2 chassis.
Chasing grams on the chassis isn't worth it, the chassis dosen't way a lot compared to the bits bolted on to it.
The last line of the above is one of the best observations made on here for a while!
Retro RWD is the way forward...........automotive fabrication, car restoration, sheetmetal work, engine conversion
retro car restoration and tuning
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Philippe
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| posted on 11/1/06 at 01:08 PM |
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quote:
Originally posted by NS Dev
quote:
Originally posted by Philippe
quote:
Originally posted by britishtrident
quote:
Originally posted by NS Dev
The problem will be that using 0.5mm steel (as opposed to 1.2mm ally) will mean that the steel will wrinkle when welded, almost impossible to stop
this happening with very thin section sheet steel.
R-I was refering to sequential spot welding. This is the way the industry stitches car bodied together. Punch holes all around the perimeter of your
panels, turn the amp at the lowest on your mig welder, weld one second hole at the time, etc.... No distorsion, no buckling, perfect.
Philippe.
Yes ;-) it buckles or to put it anotherway because of the greater thickness an aluminium panel is stiffer in bending than a comparable steel panel
-- which is why aluminium and magnesium alloys are such excellent materials for making road wheels.
You mean what I would call plug welding, i.e. puddle welding through punched holes with the MIG.
I use this technique a lot, but it still wrinkles 0.5mm steel sheet, in fact it still wrinkles 0.8mm sheet, even when pretensioned.
R- Thin steel in my experience will buckle if the welding sequence causes it. I believe that I can limit the buckling effect by welding away (in a
sequential fashion) from the center of the work. But you are right there is always a bit of distorsion on thin steel no matter what you do. Nothing
that could not be flatened out using a torch or in the worse case body filling.
Philippe.
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Alan B
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| posted on 11/1/06 at 01:15 PM |
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quote:
Originally posted by NS Dev
quote:
.......Chasing grams on the chassis isn't worth it, the chassis dosen't way a lot compared to the bits bolted on to it.
The last line of the above is one of the best observations made on here for a while!
I'll add my 100% endorsement too....there are many, much better places to save a few pounds.
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David Jenkins
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| posted on 11/1/06 at 01:23 PM |
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For me, I must lighten the nut holding the wheel (yes, I know I've said it before... quite recently in fact!)
David
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NS Dev
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| posted on 11/1/06 at 01:27 PM |
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Surely that one Nyloc doesn't weigh THAT much does it?????
Retro RWD is the way forward...........automotive fabrication, car restoration, sheetmetal work, engine conversion
retro car restoration and tuning
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kb58
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| posted on 11/1/06 at 03:39 PM |
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"Chasing grams on the chassis isn't worth it, the chassis dosen't w[eigh] a lot compared to the bits bolted on to
it."
But only if that is followed through - I find it's actually the opposite. I think instead the thought "it's just a few ounces, it
won't hurt", happens to just about every part of the car.
It's just like dieting where people cheat, "it's just a little bit." That thinking, carried to its logical end, results in
overweight people - and cars. I realize we don't have the buget for carbon this or titanium that, but it's still important to always be
asking, can I make this (and every) part lighter.
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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TheGecko
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| posted on 11/1/06 at 11:35 PM |
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It's well worth reading "Driving Ambition" by Doug Nye (and Gordon Murray & Ron Dennis) about the design and manufacture of the
McLaren F1. Murray set a 1000kg weight target and was fanatical about chasing every spare gram. In the end the road-ready car weighed (from memory)
1100kg, amazing for a 3-seat 5 litre V12 autobahn weapon! Murray said that only setting the (probably unachievable) 1000kg target had kept the
design/development team focused enough to reach the (still impressive) 1100kg end result.
Now, none of us are building 300km/h+ supercars (well, I'm not - anyone else want to claim otherwise?) but, as Kurt points out, it's
possible to let a "Near enough is good enough" attitude compromise the end result significantly. So, I say, think about those extra
grams, even if you decide in the end that it's not worth saving them. At least then it's an informed decision rather than a "swept
aside, too small to bother about" dismissal.
Will my car be heavier than it could be. Absolutely! Will I cry tears of blood over that? No because, wherever possible, I have considered the
factors and made a decision. In a lot of cases, that decision was that I would accept a (probable) weight penalty in exchange for ease of
construction or availability of materials or peace of mind about strength or any of a hundred other reasons.
To try and drag this polemic back on topic, my car will have bonded (sikaflex or equivalent) and riveted aluminium skins. I'm not too concerned
about corrosion since I intend not to park the car underwater any more than neccesary. Living on the dryest continent on Earth helps but, that
said, we've had 75mm/3" of rain this year and it's only the 12th of January.
Anyway, enough rambling from me. I'm back to the garage to make some more informed, considered decisions about engine bay tube sizes. I think
I see a way to save about 4kg!
Dominic
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Peteff
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| posted on 12/1/06 at 12:36 AM |
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puddle welding through punched holes with the MIG
That would be a button weld
yours, Pete
I went into the RSPCA office the other day. It was so small you could hardly swing a cat in there.
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NS Dev
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| posted on 12/1/06 at 12:41 AM |
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I'm tired so a short reply!
Yep, in order to achieve the ultimate we need to do everything to the
ultimate................................................................................................................................but then we
must not over complicate things!
Keep It Simple Stupid, as they say!
Look at the Ultima GTR (to current demo car spec)......vastly quicker in a straight line than the McLaren, quicker around a track, less than 1/10 the
cost, nearly 200kg lighter, 100 times simpler and uses an ancient engine design that still makes more power!!!! There is no stressed carbon fibre on
the car, a steel spaceframe chassis, pop-rivetted alloy panels etc etc.................................................................... Simple is
Quick, Colin Chapman taught all of us that but nearly all have forgotten it completely.
Simplicity is the reason that to save weight in my 7, I am simply not bothering with things that I don't need! Maybe I can save a few grammes on
the chassis, but having no instruments saves a lot and why do I need them???? What does trim do exactly???? Don't need that. No windscreen, no
heater, no wipers, no washers............nothing that I don't need in order to use the car for what it was meant for...FUN!!
Retro RWD is the way forward...........automotive fabrication, car restoration, sheetmetal work, engine conversion
retro car restoration and tuning
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David Jenkins
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| posted on 12/1/06 at 08:39 AM |
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quote:
Originally posted by NS Dev
No windscreen, no heater, no wipers, no washers............nothing that I don't need in order to use the car for what it was meant for...FUN!!
My sentiments exactly!
David
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Mark Allanson
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| posted on 12/1/06 at 02:27 PM |
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quote:
Originally posted by Peteff
That would be a button weld
Or even a plug weld!
If you can keep you head, whilst all others around you are losing theirs, you are not fully aware of the situation
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NS Dev
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| posted on 12/1/06 at 03:41 PM |
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quote:
Originally posted by Mark Allanson
quote:
Originally posted by Peteff
That would be a button weld
Or even a plug weld!
I know, I'd call it a plug weld to anybody in the UK!
I used the "nondescript" terminology on seeing that the person I was answering was not from our shores and may not understand our
terminology.
Retro RWD is the way forward...........automotive fabrication, car restoration, sheetmetal work, engine conversion
retro car restoration and tuning
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Peteff
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| posted on 12/1/06 at 06:36 PM |
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It had already been called a spot, plug and puddle weld, I just thought I'd throw another one in there
yours, Pete
I went into the RSPCA office the other day. It was so small you could hardly swing a cat in there.
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NS Dev
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| posted on 12/1/06 at 11:37 PM |
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lol
Retro RWD is the way forward...........automotive fabrication, car restoration, sheetmetal work, engine conversion
retro car restoration and tuning
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locost_bryan
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| posted on 13/1/06 at 04:10 AM |
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quote:
I think instead the thought "it's just a few ounces, it won't hurt", happens to just about every part of the car.
I realize we don't have the buget for carbon this or titanium that, but it's still important to always be asking, can I make this (and
every) part lighter.
Wasn't that Mazda's approach with the new MX5 - shave a little bit of weight off every component (even the door handles!)
Bryan Miller
Auckland NZ
Bruce McLaren - "Where's my F1 car?"
John Cooper - "In that rack of tubes, son"
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cossey
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| posted on 13/1/06 at 04:33 PM |
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has anyone tried epoxying the floor on rather than using pu glue which isnt rigid so wont kelp with the stiffness of the chassis?
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NS Dev
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| posted on 13/1/06 at 05:22 PM |
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no but epoxying it on is a much better idea!
Would have done but for the expense of the epoxy!!
Retro RWD is the way forward...........automotive fabrication, car restoration, sheetmetal work, engine conversion
retro car restoration and tuning
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smart51
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| posted on 13/1/06 at 05:56 PM |
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Epoxy can be a bit brittle and doesn't stick to its full potential unless the surfaces are impossibly clean.
PU is very sticky and is flexible. it is less likely to brake or come loose even though it is perhaps less strong.
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