Thread: Electrathon - A Different Kind of "Hotrod"

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Front end alignment is important on these cars to keep rolling friction to a minimum. To get the toe set correctly, I use this method that I borrowed from my stock car days. I made this pair of alignment boards in just a few minutes to use here, but they can be used on any car.

I began with some old shelving I scrounged from a renovation project here at school. This is 3/4" birch-faced plywood, but I could have used any flat material. I cut two rectangles the same size (11" x 24"). I screwed them together temporarily so I could cut them the same. I used a screw, string, and pencil to mark a half-circle on the top piece (Yes, I marked it twice. The first time wasn't big enough). After cutting the half-circle out on the band saw, I marked and bored two holes equal distance from the bottom corners. I used a 2" Forstner bit, but this could also be done with a hole saw. With all the cutting done, I removed the screws so I then had two identical pieces.

To set the toe, I put one of the boards against each front tire sidewall, secured with masking tape, and put a pair of identical tape measures through the holes. Now the toe could be set by comparing the readings on the tapes. I use 1/16" toe-in on this car.

These boards also work on full-size cars; I have used this method on my coupe and recently gave a set of these to a friend to use on his Model-A coupe, also.

Now very close to being able to take this thing for a test-drive, I just need some circuitry for the motor and controller. The first part is mounting the main power switch through the triangular panel on the left side pod.

After that, I was able to run the battery cables. I didn't take any specific pics of this step because it's just a matter of cutting the cable (# 4 AWG) and soldering on the ends.

With the cables installed, next step is to install and wire the "dead man switch" and potentiometer. The "dead man switch" is required by Electrathon America. If the driver lets go of the controls, either deliberately or due to some sort of incident, all power to the motor is cut off. In this case, I used a little microswitch located on the left bar of the steering "wheel". When the driver's hand is on the controls, the upper part of the left forefinger holds the switch closed. If the driver's hand lets go of the steering, the controller cuts off power to the motor.

The throttle in these cars is a 5K ohm potentiometer which signals the controller. There are several options available for this including foot operated "pot box" assemblies and twist-grips similar to what is found on motorcycles. Everyone has their preferences, but I like a hand operated throttle. In Electrathon, consistency is important to battery life and having a throttle that the driver can "set it and leave it" helps to promote consistency. For this instance, I made a bracket from 1/16" wall 1" aluminum angle. I drilled and shaped the bracket and riveted it to the right bar of the steering "wheel". I positioned this so the potentiometer is accessable with the driver's right thumb. Roll the knob up to accelerate, down to decelerate.

If you remember from back near the beginning, I cut a "temporary" seat back from 1/4" luan plywood. It's light enough and rigid enough to be made "permanent" so here's what I did. First I riveted two strips of 1/16" x 1" aluminum across the seat back area (arrows). Next, I split the "temporary" seat back down the middle. After painting both halves (both for appearance and preservation), I hinged them together with duct tape. Now I can easily remove & replace it for access to the motor & controller.

In an Electrathon race, success and survival is all about battery life. In order to monitor how much juice you're tapping from the batteries, an ammeter is necessary. In this case I am using a digital unit. I made a little aluminum panel to hold it and riveted it under the cowl. The wiring feeds through a hole in the panel and into the back of the ammeter.

OK, all major components are in place. It's time for a test drive. I took it outside and tooled it around the parking lot after school. I discovered very quickly that I had forgotten to tighten the nuts on the rear axle. Quickly fixed that... Otherwise, the test was without incident. The car is extremely smooth and quiet. This was Thursday evening (May 7th). Pic is the car as tested.

Today (Friday) I forgot to take my camera. My kids and I did a little thrashing to get some last minute things buttoned up; I have a race tomorrow! We made the lids for the battery side pods, adjusted the brakes, made a seat pad from 1/2" foam sleeping bag pad, and installed an electronic bicycle speedometer. Hopefully, after tomorrow I will have some action photos to post here...

If you are in the Tampa area and see this in time, we will be running at Tampa Tech High School tomorrow (Sat. May 9th). Races are at 11:00 AM and 2:00 PM.

Been following your build, very nice. Good Luck

Jim, you slipped those brake levers in without mentioning it. Am I right to assume they are of bicycle origin? Front and rear operating separately?

MikeB - Electrathon is BIG in your part of the country. Have you seen any events?

Resto - Yes, the brake levers are of bicycle origin. Nope, no rear brake on this one. Right and left brakes are operated individually.

Go get'm Jim and class,Team Rolling Thunder not going to make it this sat.,cu still don't have tow car,but soon.
Wish ya luck,that's a super job well done.

Bat - Sorry you guys won't be there. Thanks for the well wishes. I'm on the road in just a few minutes...

Evolvo - It kind of depends on the situation. It's better to hold the dead man switch on and roll the potentiometer up & down as needed (very rarely run full power) to maintain constant speed. Sometimes in traffic it is necessary to do some on & off the switch driving, but each time is a power spike on the batteries and shortens the life of their charge.

There's a lot of ways to do much of this stuff,to work 2 front wheel barkes,I used a twin pull lever I got off a old BMX bike,it's kind of like this one;
http://www.niagaracycle.com/product_...ucts_id=402826
But made by some other Co.?looks a little def but close,idea is I set balance between front wheels with the cables,that way ya don't have to have both hands doing the same thing.
OK ,How bad did Jim and his gang beat the others??????,

Originally Posted by The Bat

There's a lot of ways to do much of this stuff,to work 2 front wheel barkes,I used a twin pull lever I got off a old BMX bike,it's kind of like this one;
http://www.niagaracycle.com/product_...ucts_id=402826
But made by some other Co.?looks a little def but close,idea is I set balance between front wheels with the cables,that way ya don't have to have both hands doing the same thing.

Those look like they would be much easier to use as long as they are properly balanced. I imagine braking with two levers on two wheels might get a bit hairy esp. panic braking in a sharp corner while adjusting the potentiometer .

I'm sorry to say... I should have stayed home!.. Well, actually I'm glad I went, but the day was NOT a success from a competitive standpoint. It's always risky to take an untested vehicle to a race. Everything started off well. The car drew a LOT of attention; it would easily have won "best appearing car" or "best engineered" if there had been such awards.

I drew the last starting position and at the drop of the green flag I was trailing the field, waiting for them to get strung out. On the straights I was dialed up to pull 23 amps. Strangely, however, in the corners the ammeter was reading 38 - 39 amps when it should have been 25 - 27 amps. Seven minutes into the first race, my right front tire went flat! I limped to my pit, pulled the tire & tube off and discovered two cuts on the inside area of the tube. I wrapped a strip of duct tape around the rim, replaced the tire, installed a new tube, pumped it up and got back in the race. I lasted about another 6 minutes and the same tire went down again! Pulled the tire off again and discovered another cut on the inside near the rim.

Between races I went to a local bike shop and bought two more new tubes, one with Green Slime self sealing fluid in it. I chose to line up last again and got off to a good start. I had passed two other cars and was cruising smoothly, still wondering why the high current draw in the corners (hadn't had time to investigate because of tire woes) when, six minutes in, the right front tire went down again!!! I limped to my pit and removed the tire again. After 15 minutes of cleaning up Green Slime, I discovered that it was cut on the inside again. I put another layer of tape on the rim and re-installed the tire with my last new tube. By the time I got done, there were only a few minutes left, but I climbed into the car and made two more laps before the checkered flag flew. My total laps for the day: 35 (Should have been around 200 if I had finished both races).

After the races I finally got to research the current draw problem in the corners. It appears that my front wheel bearings were "seating in" and allowing the wheels to move slightly on the spindles. This in turn caused the brakes to drag in the corners.

Hopefully I will have some pictures of the event to post here in a day or two. Meantime, I will take some pics of the stuff I missed Friday and post those.

Jim what a frustrating wheel experience! Still you managed to complete 35 laps on your real first maiden voyage, fresh from a shop build, not bad!

Did you find out what was causing the tire problem?