Thread: Electrathon - A Different Kind of "Hotrod"

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Thanks Earl. All you need is a friend to build one along with you and you can have a race. People see you having fun and, the next thing ya know, there will be a bunch of you all out there having fun.

Next step in my build was to complete the roll cage. All this requires is another hoop bent from 3/4 inch conduit to the same approximate radius as the first one. I trimmed and fit this one so it attaches to the top frame rail about half way between the main hoop and the rear of the frame. I also bent the little hoop for the headrest from 1/2 inch conduit and attached it to the upper rear crossmember. At the top, the roll cage hoops are about 4 inches apart and tied together with another piece of 3/4 conduit.

It's Ez to say cut to fit,but??? OK here;
Going to try and add one of my drawings to help,this should help even with other stuff some rodders are doing on here,this is a way to cut fishmouths with just a strait hacksaw and a little layout work;
As when you make a angle cut acrossed any round tube ,it makes a rounded cut anyway,we're using this as a way of getting a fishmouth,but with only cutting strait.

Thanks Bat. I have used a similar process with a chop saw (double mitering the ends to achieve a fishmouth). In some situations, like radical angles, it is actually better because most fishmouth jigs with hole saws only go up to 45 degrees...

The following pictures contain a wealth of information, but I must apologize for them. I went to school on that particular day without my camera. When it came time to work on the car, I couldn't very well tell the kids "We can't do any work today because I don't have my camera". So, we proceeded with the day's activities and I had to take these pics the next day...

What we're seeing in the first pic is the frame with the top & bottom center crossmembers and the vertical uprights in place. All those are in the vicinity of where the front axle will go. Notice that the top piece is arched slightly. This helps to hold the shape of the body later and will become the support for the steering shaft. Also visible are the diagonal aluminum side supports. In my previous car I made these from more conduit, but since they are always in tension, I have used aluminum this time. The 1/16 X 1 aluminum flat stock weighs about 1/3 of an equal length piece of 1/2" conduit.

The second pic shows the seat-back supports and the temporary seat back made from 3/16 Luan plywood.

In order to put those aluminum supports in place I had to have something to attach them to. I got some #10 fender washers at the local hardware store and welded them in diagonally opposing corners. The rear ones are placed at the base of the roll cage hoop where it attaches to the lower frame tube (1st pic); the forward ones are at the junction of the forward vertical member and the upper frame tube (2nd pic). Aside from providing an attachment point for the aluminum strips, the washers also form gusstes in those corners.

To install the aluminum and get it tight, I needed to pre-stress the frame. To accomplish that, I placed a 3/16" thich strip of wood under the frame at the bottom seat crossmember (visible in the 3rd pic) and then clamped the frame down to the table on both ends. Next, I cut and drilled the aluminum to fit, riveted it in place with large-head 3/16" rivets. When I released the clamps, the frame sprung back to its original shape and pulled the aluminum tight.

Looking good Jim, keep em coming.

Very cool Jim! Keep photo's coming. This might be a fun project for after the truck is completed.

I've never had it before! Gee thanks. Now I have Closterphobia.

Looks cool.

Dave G

Thank you all for the compliments.

HRD - Fear not; there is plenty more to come...

Evolvo - The link isn't working here, but our computers here at school have so many firewalls, etc. that may be the cause. I'll try it at home...

Stovens - These things are so much fun that I'm afraid, if the government ever finds out, there will be some kind of tax enacted on them. This is the cheapest racing I've ever done. Three or four sets of tires for my old stock car would pay for this whole car and all the tires and electricity I need to run it for a year!

Stovebolter - If you're claustrophobic you DON'T want to get in one of these cars! It's like putting on a body glove with wheels. Here's a pic of me getting ready for a race a couple of years ago. There ain't much extra room in there...

Next on the agenda is to mount the rear "suspension". (I put it in quotation marks because this car really has no suspension; it is rigid.) The rear wheel is mounted using an ordinary bicycle front fork. In this case I am using the fork from a 26 inch beach cruiser, simply because that's what I had on hand.

I prepared the fork by opening the axle slots up with a file to accommodate a 14mm diameter bolt because the wheel I will eventually use here has a 14mm axle. Then I cut the neck off the fork with a hacksaw.

To mount the fork, I set the frame on blocks at the intended ride height. Then I put a 20 inch wheel in the fork and propped it up in its approximate position. I put a slight bend in a short piece of 3/4 inch conduit and then cut it to fit between the rear roll cage hoop and the top of the fork. It also connects with the top of the headrest hoop. With everything fit in place, I tack-welded the conduit piece in place.

Using a mix of tape measure, combination square, and "calibrated eyeball", I got the rear wheel and fork pretty well lined up and put a healthy tack-weld at the top of the fork. I then removed the wheel and hung a plumb bob from the center of the fork and used the tape measure to make sure the fork was centered and vertical. When I was satisfied with that, I then measured from each side of the fork to the center of the front of the frame. I was already really close on this, but I tweaked the fork until both measurements were exactly the same (as close as could be determined with a tape measure - less than 1/32" difference) and then added two more tack-welds at the top of the fork. Finally, I cut two lower struts from 1/2" conduit and connected the bottom of the fork to the frame at the lower corners. With the struts in place, I checked the measurements one more time and welded everything solid.

In the last pic above and below here, the center seat back support is visible (arrow). I added this because the motor I'm using (Briggs Etek) requires a face mount that must have a top mounting bolt. I will add the bracket later. If it was just a flat base type mount, I would have used an aluminum strip for the seat back support.

The next part of the build is probably the most difficult part - the front end. Up to now we've been putting pieces together to form the frame. Everything has been welded or riveted and, if it was a 32nd or even a 16th of an inch off, no big deal. The front end, however, includes the steering and we are now dealing with some moving parts that affect steering geometry and rolling friction.

To begin, I put the frame back on the jig and spaced it up off the table to the intended ride height. I then used a 20 inch wheel with a bolt through the center to determine where the spindle shafts and, therefore, the ends of the axle would need to be. The way this car is configured, the driver's legs will pass under the front axle. Because of that I had to keep the axle as high as possible in the frame. In order to keep the axle high enough but still get the ends low enough, the axle would need to rise in the center. I put a slight bend in the center of a 34 inch piece of 3/4" conduit, inserted it through the frame and clamped it in place. This would become the main axle tube. After centering it by measuring from both ends to the frame, I welded the tube in place.

The next thing I did was build a small fixture to hold my king pin bosses in place at the proper height and angle. The bosses are made from 1/2" O.D. 3/8" I.D. tubing that I got at ACE Hardware. The fixture was made from scrap 3/4" plywood. I tilted it in 7 degrees to give me a 7 degree king pin inclination. I also cut the blocks so the kingpin boss would be installed with 7 degrees of caster.

With a kingpin boss clamped in the fixture, I moved it into position and determined where I needed to notch the top of the axle tube. I notched the axle tube with tin snips and then tack-welded the kingpin boss in place. I repeated the proceedure on the opposite side and then welded them both completely.

To finish the axle, it needed to be braced. The front end of these cars sometimes take a beating from bouncing off of curbs, running over parking lot drain grates, and an ocassional collision. To add the appropriate strength to this axle assembly I bent two pieces of 1/2" conduit to about 60 degrees and then trimmed them to fit between the lower part of the kingpin boss and the vertical frame member. I took care here to make both sides as identical as possible. When I was satisfied with the fit I welded both of them in place.

Jim this is cool! I'm learning a bunch just following along!

Frame is looking good. My only concern is the bracing of the front axle. You have it well braced in vertical, but the fore and aft integrity depends on the bending strength of the axle tube. When I raced karts I remember seeing a number of front axles sheared off during impact.
What about a triangulated brace of the lighter tubing running from the axle end back to the junction of the dash hoop. It would add considerable strength when "bouncing off of curbs, running over parking lot drain grates, and an occasional collision."
The main consideration would be avoiding the steering linkage.