Perhaps two years ago I started on a very similar adventure.

It seems all of the pedal car designs are current as of 1920, or so. Lots
of
the execution is really awful. It pained me to put my young daughter in
such
junk.

So I re-considered my few feet of books on automotive design and had at
making
one of my own. I have several pictures of it, but none posted on line.

The basic idea was to make a safe, good handling glider car. Gliding is
much
less complex than pedaling...

Choosing wheels is the hardest part, and leads to most other design
decisions.
Here is fair warning: there are no _good_ wheels available. Sure, there are
lots
of wheels out there, but there are no light, easy-to-obtain wheels with
proper
offsets. So I went with the small pneumatic wheels sold by Northern
Hydraulics.
These have two 1/2" ball bearings. Careful use of Nylock nuts lets one
secure
the wheels and set bearing preload.

The central spoke design prohibits the use of good steering geometry, and
good
suspension geometry, but this makes fabrication easier. I made my own
spindles
and bushed them with press-in sintered bronze. Kingpin inclination is
calculated
to produced auto-centered steering, about -8 degrees. Layout is front-steer
with minimal Ackerman.

For a steering shaft I used real 5/8 shafting with ball bearing pillow
blocks. Steering
input is by a 10" leather covered wheel mounted via a TaperLock bushing.
Steering
to wheel is by another TaperLock, with tie rods using 3/8 fine Heim joints.

For a seat, I found a used Rhoad Gear child carrier bicycle seat with a
3-point
restrain. This was cut, then mounted. Additionally, a full-width seat belt
was
added, giving a 5-point restraint.

In the back, I took a look at the deflection of small pneumatic tires and
set each wheel at -10 degrees so that during hard steering input grip would
increase until the full contact patch of the tire was applied. I made a
combination
push bar, light bar and roll cage from a single hoop of 1/2" galvy pipe.

The kids have been using it for somewhat less than 2 years. They love it.
Performance is excellent, even for adults. I have a G-Tech acclerometer for
use
in my track car. The little car I made will out-stick anything you can buy
at a showroom today.

Several years ago I designed a semi-independent negative roll solid axel
rear suspension for use in RWD race cars. It has never been built, but as
it happens, I am going today to buy minature shocks (mountain bike
take-offs)
so I can build a small version for the kid car.

"BP" wrote in message
...
I've been reading here for a while and would like to start playing around
as
a hobby. As I will be practicing things like welding as I go I would like
to start with something of Low Stress like a kids pedal car for my son.
Does anyone know where I could purchase a set of plans? I'm mostly
interested in these for things such as steering and drive system design
rather than body design.

Thanks

Barry