The Motorized Lawnchair




An almost word-for-word duplicate of this page appeared in automotive column Curbside April 01, 2000

You may use any part of this page for your own purpose – but don’t plagiarize: give credit.

How it got started

After riding a Motorized Barstool Racer in Prince George in the summer of 1998, I just had to have one of my own. One of the things I didn’t like about the barstool racer, was the high centre of gravity. If you were to hit something, the bottom of the stool would stop but the top would keep going, and you with it. I decided to fix that. The basic lawnchair is powered the same as the barstool – Toyota Starter motor, and deep-cycle/RV battery.

I found a plastic kiddie’s lawnchair at Value Village, and proceeded to design and build a rolling frame for it.

I set the chair on the floor, and determined where everything was going to go so that it would look right, and took measurements. I wanted the track and wheelbase fairly square for stability, and a very low centre of gravity. The result is a very low, small car.

Frame Construction

The frame was made out of 1″ steel tube, built to support the chair, since the chair was plastic and starting to break (people insisted on trying to sit in it).

The front axle is 1″ tube, with fully functioning steering, including Caster, Camber, Steering Axis Inclination, Toe (with adjustment) and Ackerman (Toe-out on turns). I used Spherical rod ends in the steering, as I didn’t want any play and the steering axles don’t swing in a straight line because of the geometry.

The wheels were Boat Trailer Wobble Rollers, and I machined aluminum hubs for them. Offset for the rears, with bolts to secure the wheels to the hubs, and small hubs in the front with pressed-in sealed roller bearings. The rear axle is 3/4″, supported by steady bearings (bushings).

Starter Motor Power

The motor was originally a starter from my old Pontiac Firefly, but it proved unsuitable due to excessive current draw and heat. It would last about two minutes and then start smoking, slowing WAY down.

The next motor was a gear-reduction starter from a Toyota Cressida or Supra or something. I modified it heavily for improved cooling, and now it just goes and goes without overheating.

The original gears were 16/28 drive/driven for the Firefly motor, which produced quite a nice top speed, but acceleration was limited. The new gears were 10/28 for the Toyota motor, which ended up being only slightly slower in top speed, but it got there almost instantly.

The starter is connected by a Ford-style solenoid, and the power is applied through a fuse (smart!), a key switch (so my students don’t take off in it), and a push button. I went through a few push buttons. Get something made of metal, that can handle at least 6 amps and 240 volts.

The Riding Experience

There is no reverse, and no brakes.

After running around with it at school and at home, I found out a few things: The car will corner far, FAR better than your body can actually hang on. I have to really lean over to stay on it.

Also, if you aren’t leaning forward a lot, the front wheels will sail up in the air. This creates difficulty in steering.

Also, on a slight incline, those wheels don’t always stop. I found this out the hard way when (in showing off to some colleagues) I flipped the chair onto it’s back. It broke one of the cooling fins off, popped the fan off, and bent the key.

Wheelie bars were then attached using 1″ tubing, and two roller-blade wheels (you can buy them in packages of four – I assume they wear out??). A helmet would be a good idea…

By the way, the school liaison officer threatened me with a ticket for

  1. Driving an unlicensed motor vehicle
  2. Riding without a helmet
  3. Speeding in a school zone