Hi guys
This website is great. Now I registered to post.
I need some advice on some 3 or 4 inch square tube frame construction with some triangulation in it.
What would be a nice tube wall thickness: thick enough so it wont buckle and to make it easy to weld, yet thin enough so it won't be too
heavy?
Maybe some rectangular tube?
The 1 inch frame just scares me, looks too feeble to me.
While it may be sturdy enough I wouldn't feel comfortable driving it.
3 or 4 inch tube is truck/housebuilding technology and I've never seen it in anything sensibly thin. It would be hugely heavy even in 1mm. Hot
rods in the US use large size tubes for the frame rails in ladder frame designs as you don't need much triangulation to get a reasonably stiff
chassis.
You can buy 2"x2" in 16swg (1.6mm) which looks huge but is over 8x stiffer than 1" for 2x the weight.
40mmx40mm is 2.5 times stiffer than 1".
Here's some 1" 16swg and 18swg in action - along with a full cage - it's much stronger than you think (tin tops are down to less
than 1mm if you want to compare)
--
Never argue with an idiot. They drag you down to their level, then beat you with experience. Anonymous
Photo Archive
Building: miles of wild uncontrolled grins
posted on 12/6/13 at 05:47 AM
Welcome to the forum. It is an amazing place.
Will respect to 1" box section, I can vouch for the crash & survivability of the standard chassis. Mine was a front end right off but the
passenger & drivers cell were both fine. weakness in the 7 design is side impact strength. So often an extra side bar is fitted as part of the
cage..
If you want to see the damage on my car there are pictures in my photo archive under "oops"
hope that helps
Howard
Fisher Fury was 2000 Zetec - now a 1600 (it Lives again and goes zoom)
Photo Archive
Building: Robin Hood series 3 + new project old Fury
posted on 12/6/13 at 05:55 AM
If you want a car with much bigger tubing the Robin Hood 2b uses large round tube and the chassis is like a complete roll cage
It's heavy and not the easiest to build but if safety is paramount you won't find a bigger chassis in a 7 replica
I eat to survive
I drink to forget
I breath to pi55 my ex wife off (and now my ex partner)
Doesn't the locust design use a couple of 3 inch beams to form its ladder chassis? That's about as close as I can think. Although I would
actually consider that to be less safe than the 'standard' design, mainly because there's no metalwork on the side of you.
When I was buying my steel, I did notice as the size went up, so did the thickness and more importantly the weight. On the list I saw, anything above
2 inches got exponentially heavier. And I wouldn't like to even consider the price!
If you're really concerned about the chassis, do what I'm doing and look at the 'australian mods'. Their requirements are much
more stringent than our IVA, and there is a tested and proven design that still uses 1 inch metal but with additional bracing in key areas.
Interestingly, the document I downloaded also contains a few comparisons to production cars, and I was truly amazed to see a well designed seven had a
higher resistance to twisting than some pretty major mainstream vehicles.
You can also gain a lot of strength and safety for the passengers by adding a good rollcage with side impact bars.
Oh come on really??? This is my first post and I want to use 3-4" tubing in my chassis.... pass me the can of welding spatter to pour back in
to the welder please.
quote:Originally posted by Talon Motorsport
Oh come on really??? This is my first post and I want to use 3-4" tubing in my chassis.... pass me the can of welding spatter to pour back in
to the welder please.
A full FIA spec roll cage for a rally car is only 50mm dia*2mm thick, admitedly of high tensile tube. Do a search on youtube for kit car crash or
caterham crash - that sort of thing, and look at some of the horrendous track crashes in cars will a full cage, that have been filmed and people just
walk away from, should give some confidence!
Regards
Hugh
That was some crash, makes me want a full cage or a taller roll bar as my head is above it.
Just shows how strong the car is, just imagine a corsa or similar.
Think about it, think about it again and then do it.
If doing it all again, I would make the upper and lower tubes from 50x25mm 16g tube aligned vertically making the chassis 50mm taller to make it
easier to fit OHC engines, and make the chassis considerable stiffer
If you can keep you head, whilst all others around you are losing theirs, you are not fully aware of the situation
I'm just trying to imagine what a Locost built entirely with 4" tubing would look like, how it would handle, what type of suspension it
would need etc.
It could demand another reboot of the book franchise
"Build Your Own Sportscar -with pipes the size of sewersl" perhaps
Just keeping this thread alive, I am hoping to build a roadster in Australia mindful of these mods, so no need for a new topic.
Our rules state that there are 2 paths to follow;
1/ A rebodied vehicle, as in a ladder platform to id the base vehicle.
2/ An individually constructed vehicle, conforming to all current design laws.
So people in Australia build hotrods on a Mitsubishi Express frame or a 4x2 Hilux utility ladder frame.
These frames are typically 4 x 2 inch tubes with a 1/8 wall section, now you can understand my interest.
Luckily, if the motor is an non turbo 4 cylinder a 3 x 1 1/2 tube will pass so you can imagine some scope for heavily cutting into a standard 4x2
ladder frame.
Has anybody ventured into stiffening a ladder frame aside from those big, heavy cobras?
Could anybody please share a link to such a build please?
By the way, my build is hoping to be inspired by the 'haigh special' from your country, a tough little auto test style of car.
(we call them motorkhanas here).
quote:Originally posted by suzcruz
Just keeping this thread alive, I am hoping to build a roadster in Australia mindful of these mods, so no need for a new topic.
Our rules state that there are 2 paths to follow;
1/ A rebodied vehicle, as in a ladder platform to id the base vehicle.
2/ An individually constructed vehicle, conforming to all current design laws.
So people in Australia build hotrods on a Mitsubishi Express frame or a 4x2 Hilux utility ladder frame.
These frames are typically 4 x 2 inch tubes with a 1/8 wall section, now you can understand my interest.
Luckily, if the motor is an non turbo 4 cylinder a 3 x 1 1/2 tube will pass so you can imagine some scope for heavily cutting into a standard 4x2
ladder frame.
Has anybody ventured into stiffening a ladder frame aside from those big, heavy cobras?
Could anybody please share a link to such a build please?
By the way, my build is hoping to be inspired by the 'haigh special' from your country, a tough little auto test style of car.
(we call them motorkhanas here).
Suzcruz, I suggest you join the Australian equivalent of this forum, OzClubbies - http://www.ozclubbies.com.au. There's all you
could need to know about meeting Australian registration requirements. And be aware, there's LOTS of Locosts and the like registered in Oz with
their "weedy" 1" tube frames
Hi Suzcruz, yes I have pretty much done exactly as you have described. Over here there's an old fashioned style kit that I have called a Hornet,
this is a wide bodied version of a Locust. These cars have a ladder chassis with a plywood tub bolted to this which is wrapped in thin aluminium. The
car I have was in need of serious tlc as the plywood had rotted away, thoug early on I had decided to rebuild it using 16 gauge 25mm square ERW
instead. Here is a picture of it in red oxide primer,
Still building it at the moment, chassis is all painted fuel tank in, new fuel line in, brake lines in, just trying to make sense of the abysmal
wiring. Have my 2mm floor cut and ready to go in, hopefully next job is to make my new aluminium body panels.
