Tim Keith
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Posts posted by Tim Keith
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Even if it's only a prototype spring, I would like to try.
When I work out the spring rate, I would probably find a shop
to make the springs. The application is a 1,000 pound car based
upon a Lotus Seven. I don't know who might sell torsion bars for
such a light weight car. It would be prohibitively expensive for
me to order custom springs as a "guess". I suppose springs
from a motorcycle might work, but it might be hard to match the
rate needed. Or torsion bars from an junkyard might be turned
down on a lathe, then heat treated?
I figure if I build the car, I'm already taking my life in my hands.
Especially in a 1,000 pound vehicle, more or less the size of a 1948
Crosley. Thousands of "Locosts" have been built with coil springs,
few with torsion bars.
The torsion bars are used to mount the suspension inboard of the
body shell (it's space limited so that coil springs will not fit). The
inboard springs reduce wind resistence. The "Locost" suspensions
are typically hand built, as is also the case in many hand built motorcycles. A lot of folks are risking their life in building these
mini race cars, once tested *most* Locosts have few problems.
I'd probably use an OEM Honda suspension in the rear.
Sorry, not much of this post is blacksmith related - the entire
car is a study in metal working, it's a stressed space frame
with triangulated welded tubes, more like a 1940s airplane than
car.
Tim -
Can a torsion bar spring be made in a simple forge, assuming
I have the correct type of steel? I know little about metalurgy.
In a particular application I would like to use a torsion bar instead
of a coil spring. I figured someone here would know how to make
these. Some torsion bars are hollow, a solid bar is OK for my
use. The spring would be used in the suspension of a light weight
automobile, it would probably resemble springs used in motorcycles.
I try to rely upon parts that I can find in salvage yards. Some
of my design ideas don't have appropriate off the shelf parts, it
can difficult to find a spring with the precise capacity that is
needed.
Tim
making torsion bar springs
in Problem Solving
Posted
I'll probably be safe and stick to someone else's engineering.
From a practical standpoint it's my intention to use existing
components, not simply because they are proven, but because
existing parts are *much* cheaper than dealing with race
car engineering shops, especially when I might have to place
more than two orders to get it right.
There are racing applications such as mini-Sprint cars that fall
into my weight goals. It'll be wiser to do 1-800 credit card,
but I probably have to keep changing rates until the springs
are precise.
A lot of this stuff is sold on ebay. There are some "new" thirty
year old Porsche torsion bars on Ebay with a current bid of
99 cents. I wouldn't want to guess how much a custom spring
shop would ask to make a set. Motorcycle torsion bars are
probably nearer to my requirements. Ich Bin Ebay'r.
I have a neighbor who makes all sorts of non-spring things
from leaf springs from junk cars, a torch with a big hammer.
Springs are pretty good metal to hammer into things.
Thanks
Tim