Thursday, February 22, 2024

The Go-kart

Go kart V1.0

When I was a kid, the Saturday activity was heading to the hardware store and lumber yard - via the train station - to get supplies for the current household project.  My mom and dad were always doing home improvement.  Improving kitchen storage, built-in bookshelves and mantle for fireplace, fininshing the attic.  There was always something going on.

Part of this, was I learned to use hand tools at a young age.  A really cool thing my dad did, was to help me build wooden push-style go kart when I was in the 3rd grade.  Kind of a glorified wagon.  Each day he would leave instructions on the next step, complete with illustrations.  Drill holes and install the threaded rod for the axle.  Install eye-bolts for steering cord.   Every day a new set would await me when I got home from school.  

This project never really got completed as we moved that summer but we did play with it a good bit in the new neighborhood.

Go kart V2.0

Like every kid, the Sears Christmas catalog was THE thing to peruse every fall.  They had every toy you could ever want.  The section that always caught my attention was the go karts.  Not something I could ever afford or even ask for...  However, somewhere, perhaps Boys Life, there were adds for companies that sold go kart parts mail order.  ...maybe we could build a REAL go kart.  My dad agreed provided I pay for all the parts.  So,  ordered the mail order catalog and started saving.  I think he was interested in the design and build challenge.

Somewhere in the 8th grade, we got started. We ordered the parts we needed from the catalog and an engine from the Sears catalog.   A front axle assembly, tires, wheels, a live rear axle, bearings, band brake, pedals, centrifugal clutch, sprockets and roller chain.  He designed a frame made from 1" steel electrical conduit.  We bought the tubing and rented a bender and cut and bent and drilled and bolted and double nutted a frame.  We attached steel (or aluminum?) angles to allow for mounting the engine, seat, front axle, etc. 

The whole thing looked pretty cool.  Did it run?  Mostly.

Here's video of it running around the neighbors yard in the summer of 1969.


Notice the steering wheel is cut from plywood.  Couldn't afford everything!  Everyone had fun taking a turn until the chain fell off.  

The frame flexed enough that sometimes the chain had enough slack to jump.  We tried many ways of stiffening the engine mount.  Never really fixed the problem, though it did get a bit better.

Next problem was the drift pin the mounted the steering wheel to the hub fell out and the kart careened through a bush into a fence.  Scary.  Nobody got hurt.  Pin replaced with bolt.  Problem solved.

Next, the frame design wasn't quite up to the stresses from a kart with no suspension.  The tubing cracked and broke at several places.  We just plated over the breaks with angles to reinforce the weak spots.  That worked...until another break occurred.  Damn low cycle fatigue!

An continuing problem was getting the engine started.  It was terrible.  Even sent it out for a tune up by a small engine specialist.  Always took a whole lot of pulling the started rope to get it going.

A couple of times, we put it in the back of the station wagon and had mom drive us to some nearby trails in the woods around a sand pit. (off Wilson Rd for those familiar).  Had no idea whose property it was...but it seemed like a good idea.  We had to cut the top of the roll bar to get it to fit in the car.

For, um, safety, we had an ancient industrial hard hat - that we spray painted and put STP stickers on -   and a web strap for a seat belt.  Probably totally useless.  

The go kart had a top speed just short of 20 mph, calculated from engine max RPM and drive geometry, but when we drove it on those dirt paths in the woods, it felt like 90!  The engine would wind up all the way to it's limit and we kept the throttle all the way open as long as the path was straight.  It was really, really cool.  And really, really lucky nobody got hurt.  We could usually get a few runs in before something quit and we had to take it back home.

After a few years, the novelty wore off and real driving started happening and I sold the go kart to some younger kids.  They had good luck with it on paved parking lots where some steering would break the rear wheels "loose" (live axle, remember?) and they could drift/steer around the lot.

What a blast!