Thread: Electrathon - A Different Kind of "Hotrod"

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http://www.evmaster.com/
This is the one I was talking about. Not much difference from what you found,is it?

The one I have seen is produced by evmaster.

I finally got the chance to take the car to another race. I missed the race in December, so was pretty determined to make this one. I didn't have any tire problems this time; front wheel bearings proved to be my undoing... I lasted 35 minutes into the first race. My ampmeter was registering 50+ amps in every corner and my front wheels were chattering and wobbling on corner exit. Weird! When the batteries began to fade, I parked the car and discovered the real problem.

Actually, it wasn't the bearings, but the bearing spacers and my ignorance of modern bicycle components. When I got these mountain bike hubs, the factory-installed spacers felt like they were somehow attached to the bearings. I incorrectly assumed that they must be pressed into the wheel bearings. In fact, they were only held in place by aluminum retainer rings pressed into the hubs. The oilite bushings I am using to center the 20mm I.D. bearings on the 1/2" axle never reached the bearings, but were trying to support the wheel by holding only the spacers. Apparently, after just a few laps, the retainers let go and the spacers were no longer holding the bearings. The wheel hubs were riding directly on the outer surface of the spacers. That created considerable friction in itself, but also let the wheels wobble and caused the disc brakes to drag in the corners.

After removing the spacers and retainer rings I discovered that the bearings, which had never really carried any weight, were undamaged. By moving the bushings directly into the bearings, all I had to do is make different, smaller diameter spacers to fit behind the inside bushings, put some washers between the outer bushing & nut, and problem solved. I still need to drill new holes for the hitch pins. Now maybe I can finish the next event I go to...

Well, I finally finished the new car. It's almost identical to the white one that originated this thread except it's black. Here are a couple of pics of it and one of the two cars together. Because of a mistake I made early in the fabrication process, the black car actually turned out two inches longer. The only other difference is the black car has a different brand of front hubs. Next race is February 20 at University of South Florida in Tampa. Weather permitting, I should be there with both cars.

Wow! I like the custom paint jobs. Nice to see the family name on them. Goodluck at the track.

Thanks, Steve. There really isn't much "custom" about them; one car is just plain white and the other is all black. I have my own plotter/cutter, so I am able to do all my own lettering...

OK, in case it wasn't clear what was happening at that last race, here are a couple of pics I was able to pirate from the Tampa website that illustrate the problem. In the first pic, we are getting ready to start the race. Notice that the front wheels look correct. The front end has 7 degrees of negative camber (wheels lean in at the tops) and 7 degrees of positive caster built into it. In the second pic I am making a hairpin turn a few laps into the race. Notice the inside wheel has increased its negative camber to about 12 - 13 degrees while the outside wheel has decreased to almost 0 degrees. If everything had been working correctly, the opposite would have happened - decreased negative camber on the inside wheel and increased negative camber on the outside wheel. Hopefully I have the problem fixed now.

during the latter part of last year i had a download of a fella up in washigton state, an ME who, out of his home garage has been building and developing an all electru=ic 4 dr Nissan Sentra as a dedicated drag car, clockin mid 11 sec ets in succession on a single charge. at last report he was moving to lighter even more powerful and efficient electric motors, he has on at each rear wheel, independantly sprung.
If anyone knows of or has heard of this car or any further progress since last i knew of it, please reply... i was fascinated by it...the guy has a video on YOU TUBE z" electric drag car "

Not sure about that one. Here's an electric vintage Toyota that runs in the high 10's:

http://www.youtube.com/watch?v=BrHXdM9f13k

hey, thats the exact same car i was speaking of, wasn't really firm on exactly what it was outside of RWD and electric,(actually thought i recalled it being a sentra)at the time i 1st saw it it was still in the 11's...ended up runnin mid 11's, so thats a drop of essentually 2 secs since i 1st saw it....as i say, he was in the process of upgrading motors and batteries at that time....thanx...figured someone HAD to have at least heard of the car!!!!

Jim,

I like the write-up you did here. I am going to post a link from the EA forum to here. It is a good learning tool for anyone who has not built a car before.

I do have a couple comments though. You can fix the axle/bushing issue and really strengthen up the car by using 20mm bolts as axles. I have seen a lot of 1/2" axles break (they are stressed where they are welded at the head). Have never seen a 20mm axle break.

Read rule 13.5 on page 9 of the rule book. On your car you must reach outside the car to turn your car off, this is a rule violation. You need to install another switch inside the car or a lot of us add a pull wire to inside the cars. Not a big deal though unless the catch it durring inspection.

I saw a comment about running split brakes. It really seems odd to someone who is used to working on cars, but splitting the brakes really helps on these cars. the braking effort is shared by both hands instead of all on one hand. It also can really help when turning to have the ability to just use one brake when cornering.

Aaron

Thanks, Aaron. If this write-up helps get one person motivated to build a car and get involved in Electrathon, it has served its purpose. Electrathon is just pure fun.

You have been at this longer than I have and you see a lot more racing up in your corner of the country, but I have yet to see anyone break a spindle shaft here. I use grade-8 bolts when making the spindles. We have had kids hit curbs and drain grates and break the centers out of wheels or bend front axles, but never broken a spindle. In fact, we've never even bent one! Having said that, if I had known the problem that using the bushings was going to cause, I would have used 20mm bolts just for convenience. Those suckers are heavy, though. The ideal thing would be to chuck the 20mm bolts in a lathe and bore a 3/8 or 7/16 inch hole through the center to lighten them by about 30%.

I just plain missed and forgot that rule about reaching outside the car! My previous car (the orange one in the early part of this thread) was fully enclosed and had a pull rod inside the car to shut the switch off. Since this car is open and the switch is accessible, I completely overlooked the rule. I will put a rod or cable on it before I race it again and post the "how to" pictures here.

Since I built the white car above, I have changed it from split brakes to a single lever. I also built the black car with a single lever. I have run brakes both ways in the past (our Blue Sky Aerocoupe still has split brakes) and I agree with you about cornering. You can really stuff a car into a corner hard and use the inside brake to make it "turn in". That's a great feature when doing slalom or gymkhana handling competitions. Unfortunately, some of my students complain that they don't like the split system and can't get used to it, so... single levers it is.

Jim,

I totally agree that boring out the center of the bolt would be the way to go. Welding the nut on the spindle and reversing the bolt is good too. That way when you have to pull the tire you do not have to mess with the brakes, the wheel just slides down and off.

I have seen numerous broken axles. Our tracks around here can be very agressive. Between the rough tracks and agressive cornering it does take a toll. One race I remember (John Day, Oregon) had a downhill run crossing a drain "dip" in the road, then a hard turn to the left. I think I saw that course eat more than 10 front axles in one day! Many of them were grade 8 bolts too. I have yet to see a broken 20mm axle though.

We definatly do have a lot more races around here. I think Mike Hodgert and I have the record for people who have attended the most races. I have lost the exact number but someplace around 150 races since getting involved. Our primary season is going to start in a couple weeks, we will have a race almost every weekend for a couple months.

Aaron

The Bat and dmorgan - are either of you guys going to Pensacola this coming Saturday (April 17)?

I didn't make it to this race last year - I'm looking forward to it. Running these cars on a half-mile banked track should feel like running on a superspeedway. Now I'm trying to figure out what gear ratio to run...

OK. I went to Pensacola, but I'll get to that in a moment... I promised that I would fix my main power switches so they are Electrathon America legal before I raced again. Well, I fixed them, but never got around to posting the "fix" here, so...

The legality of the switches was brought into question because Electrathon America rules clearly state that the driver must be able to shut the main power off without reaching outside the car. Even though the switches on these cars are easily accessed by the driver, they ARE outside the driver compartment. So, all I did was bend a loop in a piece of welding rod, drill a hole in the cowling for the rod to reach through, and attach it to the power switch. The pictures tell the story better than my description, but the loop rides against the inside of the cowl when the power is "ON". To turn the power "OFF", the driver merely needs to hook his thumb or finger in the loop and pull inward. Simple.

Chances are these will never be used in a real emergency, but they are enough to make the cars legal and they DO work. An added benefit is they keep the power cutoff "key" from falling out and getting lost.