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In the last pic above:rolleyes: 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.:HMMM:
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The next part of the build is probably the most difficult part - the front end.:whacked: 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.:eek: 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.:3dSMILE:
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.:cool:
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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.:3dSMILE:
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Jim this is cool! I'm learning a bunch just following along!:cool:
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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.":LOL::LOL:
The main consideration would be avoiding the steering linkage.
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Thanks, Resto. And that's a very good question that maybe I should have addressed already.:o It is purely a matter of personal preference. The reason I don't put lateral bracing on the front axle is because, if it hits something hard enough to cause damage, I would rather just bend the axle tube than transfer the damage to the frame.
In the pic below you can see the front axle in this car only has vertical bracing. I was cut off going into a corner one time and simultaneously tangled with the other car and the curb.:eek: The left end of the axle was pushed back two inches, but the wheel was undamaged and I was still able to finish.:HMMM: Between the day's events, I was able to straighten the axle and went on to win the second event of the day!:D Had the axle been laterally braced, it could have caused damage to the frame that might have sidelined me for the rest of the day. As I said, it's a matter of personal preference, but Electrathon usually isn't as "rough and tumble" as Karts (I've raced those, too).
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Reasoning understood. Just wondered.
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Your build is going great!
To cut down steering frictoin in Kingpin bose on mine,i may of over did it using small PCV as a inter bushing with graffight and some small flat bearings at the base. But I was going for a power steering feel,seems to work well.
I did use ackerman for steering arm lay out,if thats helping any one.
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OK, I was gone for a week on Spring Break. I spent the entire week painting the outside of my house...:rolleyes: Anyway, we're back at school now and I can continue.
Having built the front axle, the next logical step is to fabricate some spindles. For the knuckles I used 3/16" x 1 1/4" flat steel. The first piece I fabricated is the steering arms. These pieces also form the top piece of the spindle knuckle. No rocket science here, I merely drilled the appropriate holes and then cut & ground the pieces to the shape I wanted. The hole for the tie rod is 1/4", the hole for the king pin is 3/8", and the other holes are 1/2" and are just for reducing weight. Notice I bolted the pieces together for grinding. That way the two pieces are identical.:3dSMILE: The other pieces are pretty self explanatory. The long piece has a 1/2" hole near the bottom where the spindle shaft (a 1/2" x 5" bolt) will be welded later. The little piece is just the bottom piece of the knuckle.
To assemble the spindles, I cut a scrap piece of 2" x 2" lumber on the miter saw. I was careful to make sure the saw was squared so it would cut nice square ends. I then cut the wood 1/16" longer than the kingpin bosses on the axle (kingpin bosses are 3 3/4"; I cut the wood piece 3 13/16"). I bored a 3/8" hole through the wood so I could bolt the knuckle pieces in place and then positioned and secured the outer piece with a clamp. After welding the outside, I removed the knuckle assembly from the wood and welded the inside. I simply repeated the process (using the same wood block) for the other spindle knuckle being careful to arrange the pieces so it would make the opposite side.:whacked::D
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jr I was wondering if ackerman angle matters on 3 wheel cars ....ted
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Yes, Ted, the Ackerman principle is the same as on a 4-wheel vehicle. As you will see when this car is finished, there is some Ackerman angle built into this setup. It isn't as critical here as it would be on a heavier vehicle that uses wider tires, but since friction and rolling resistance are definite considerations in Electrathon competition, I try to build some Ackerman into my front ends.:3dSMILE:
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Hay we're all big shots:LOL: we made April 09 "AutoWeek" mag,heres the page.
I'll add a small thing about ackerman; On a race car or any car that's driven hard,the front tires have a slip angle to each wheel that is not the same on each side becuase of def load,under hard driving to the real way that there pointed,this varys depenning on speed and is why ackerman can be a bit less then perfect to design as layed out in book[that is great for normel driving].:cool:
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Cool! We need all the publicity we can get...:rolleyes: I wonder if there will be any coverage on the event at Pensacola (Five Flags Speedway yesterday):confused:. Ten cars showed up; Rodney Schreck from Miami won both races...:D:D
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The wheels I am using on the front of this car had to be specially assembled for me.:HMMM: 20 inch wheels with hubs that accept disc brake rotors are almost non-existent. At the local bicycle store, the proprietor and I selected a mountain bike hub that has sealed bearings and disc rotor mounting holes. Then I picked out a double wall alloy rim and the bike shop guy called his supplier and ordered them for me. $85 per wheel (:CRY:) and two days later I got these. The hole through the center of these is about a half millimeter larger than 3/4". The disc and brake caliper are not included in the $85:eek:; they are sold separately.
At the local ACE hardware store I found some bronze oilite bushings that are 3/4" O.D. and 1/2" I.D. The perfect solution for putting 3/4" hole bearings on 1/2" diameter axles. I failed to take a pic of them separately, but the bronze shoulder is visible here behind the nut.
This quick trial fit revealed that the 1/2" x5" bolts I had for the spindles would not be long enough.:( Fortunately, I had not welded them to the knuckles yet. I exchanged the 5" bolts for 5 1/2" and solved the problem.
To weld the bolts into the knuckles and assure that they are straight, I used a short piece of conduit as a sleeve and tightened the spindle nut firmly against it. Then I welded the head of the bolt to the back side of the knuckle. The sleeve not only assured that the bolt was installled straight, but also protected the bolt & threads from the welding spatter.:D:D
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Steering is next!:3dSMILE: A lot of Electrathon cars have twin-lever steering because entry and exit of the car would be difficult or impossible with any type of steering wheel in the way. In this design, however, a steering "wheel" is not only possible, but preferred. It works just like the steering seen on most Go Karts; a shaft, "wheel", pittman arm, and tie rods.
The first step is to locate where the steering shaft will go. To do this, I used a piece of conduit about 4 feet long. I put one of my students in the car and determined the approximate height and angle needed for the shaft. Then with the long shaft propped in place with a piece of flat stock and a folded rag, I was able to tack-weld the upper sleeve in place.
Next, I fabricated the pittman arm from 3/16 x 1 1/4" flat steel. I have to admit here that I actually made this piece three times before I got it right.:whacked: The one in the unassembled pic is the first one and it was too short. The second one was also just a bit too short. Finally, on the third try I got it long enough. I also cut the conduit shaft down to a useable length.
The tie rods are fabricated from 1/2" O.D. tubing (bought at ACE Hardware) with a 1/4-28 grade 8 bolt welded to the end.:rolleyes: At this point, the pittman arm is still not welded to the shaft.
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Awsome looking front wheels and brakes,disk do stop great:D:D:cool:
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With the major components all fit, it only takes a couple more steps to finish the steering. I first welded the pittman arm to the steering shaft. I only welded it on the side away from the sleeve so that it won't grind into it and cause unnecessary wear and binding.;)
Next, I fabricated the "wheel" (actually more of a bar because of space limitations) from a piece of 3/4" conduit cut to 14 inches in length. I notched it in the center so that I could bend it about 10 degrees and welded it. This serves two purposes. First, it helps to keep the ends of the "wheel" inside the cowling when turning. Second and more importantly, it makes gripping it more comfortable.:3dSMILE: After climbing up on the table and slithering my fat self down into the chassis:rolleyes::LOL:, I held the steering "wheel" where I felt it was comfortable and marked the location on the shaft. Then I climbed out, removed the steering shaft, cut it to the marked length, and welded the "wheel" to the steering shaft. Care must be taken here to make sure the "wheel" is perpendicular to the pittman arm.
Finally, I reassembled everything and then drilled a 1/8" hole horizontally through the shaft and secured it with a hitch pin (arrow).:D
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Brakes are next!:eek::LOL: Electrathon rules state that brakes are required on at least two wheels on the same axle. On a tricycle car it is easy to use ordinary rim calipers on the rear wheels. It becomes a bit more difficult on a cycle car because there is no fork assembly or framework where a rim caliper can be mounted on the front wheels; the brakes must be mounted at the spindles.:HMMM: In the past we commonly used Arai drum brakes on these cars. Unfortunately, Arai stopped making those over a year ago and they are no longer available.:CRY: The obvious alternative is some of the newer (and more effective) disc brakes...
After assembling the discs to the wheels and the wheels on the spindles, I held the brake calipers in place, one at a time, to determine what kind of brackets would be necessary. A little rummaging through the junk cabinet netted an 8" corner bracket that is made of 14 gauge steel - perfect!
The bodies of the calipers are cast in an offset configuration to accommodate the fork mount on a bicycle. Therefore, in order to get the calipers in their correct positions on opposite sides, the brackets are different. I started by making patterns from poster board. The one for the right side was easy and accomplished on the first try.:3dSMILE: The left one was somewhat more difficult; I configured and cut it out four times before I got it right...:whacked:
Once the bracket patterns were transferred to the steel, holes drilled, and shapes cut out (with a hacksaw and grinder), I bolted them to the calipers. Next challenge was to hold them in place and mark their locations on the spindle knuckles. Once satisfied with my marks, I disassembled the calipers from the brackets and the wheels from the spindles. Then I was able to clamp the brackets in place according to the marks and weld them in place. Finally, I reassembled everything and checked for smooth operation.:cool::D
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Well, it's finally on its own 3 wheels.:D Next up... motor mounts!:HMMM:
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OK, first step to mounting the motor is to mock it up in position. I am using a Briggs & Stratton Etek motor here (Yes, Briggs & Stratton makes electric motors!:eek:). After situating the motor where I wanted, I added two crossmembers in the frame to support it. The rear one had to be contoured slightly on the ends to get it back far enough.:HMMM:
After the crossmembers were welded in place, I next fabricated the bottom mounts from 18 gauge perforated angle. Yes, this lightweight stuff supports the motor just fine; electric motors don't vibrate like gasoline engines, so metal fatigue is not a problem. I cut these pieces so they are mirror images of each other, notched them to fit the crossmembers, and then folded the bottom edges upward at a 90 degree angle. The fold adds strength and also keeps the bottom edge from hanging below the frame.:) I mocked up the motor in place again with the mounts underneath to assure the fit and mark which holes would be used. While the motor was in place I fabricated a tab for the top mounting hole; it's a piece of 16 gauge steel, drilled, and a 5/16 -18 nut welded to it. Then I elongated 4 pairs of holes where the motor bolts down to allow for chain adjustment (I put a red outline around the elongated holes so they would show for the picture);).
I mocked everything up again, this time with bolts in place. I squared everything up with a try-square and measuring tape, and tack-welded the mounts in place. Then I removed the motor and welded everything solid. Finally, I reinstalled the motor and bolted it down.:3dSMILE:
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In order to use an electric motor, an electronic motor controller is necessary. Without some type of controller, the motor would either be full-on or off; there could be no intermediate speed, no smooth acceleration, no real control.:HMMM: A mechanical potentiometer big enough to handle the amperage of two Optima batteries in series would be HUGE and heavy. Electronic controllers do the same job, but are substantially smaller and lighter than a mechanical potentiometer. They use a very low power electronic circuit to control the main power circuit. Although controllers can get expensive, the one I am using here is a remanufactured Scott controller that I bought a few years ago for $160.:3dSMILE:
I located the controller near the motor, but far enough away so if I ever throw a chain it won't be likely to whip the controller.:rolleyes: Mounting it was simple; I just fabricated a couple of tabs that match the bolt holes on the controller and welded them to the rear crossmembers.:D
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I would be interested in learning how you decided on that particular motor for this build. I remember that you said that "BAT" used a 1 hp Scott motor in his. How does the Briggs & Stratton motor compare to this and what other choices are available?
I imagine that there is a balance between the power output and energy consumption so that you can maximize speed without draining the battery too quickly. Have there been any studies made on various motors to find out which are the most efficient?
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Where did you get the motor, and about how much does one set you back?
The car is looking good! Ive mentioned this to a few friends, but no takers yet. Im gonna get somebody to make one with me, then we can race each other.
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OK,I'll tade Jim,HA Ha,mine for your Etek,actuly we got the old Scott from Jim,he told us it was the trick motor to use only about 4 or 5 years back or more,tell these new Etek came out and some others at much high cost.
As for the Scott,most efficient?no,but the cost was just right $00000 and I would of give 2X that HA HA $0000000000:LOL:
Our controller is a old golf cart one that Rex [head part of our 3 man team Rolling Thunder] got from some one for free too.
Yet were winning now and then again the big dogs motors:whacked:
Sure looks good,as this build gets better all the time:cool:
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[[In order to use an electric motor, an electronic motor controller is necessary. Without some type of controller, the motor would either be full-on or off; there could be no intermediate speed, no smooth acceleration, no real control.]]
The full on or off reminds me of a minibike my Dad made when I was about 10. He used a bare frame and added a 12v starter motor out of a Mustang, converted to belt drive with a 12v car battery on the frame and an on/off switch. It was wicked fast but that thing was dangerous. Either 'on' or 'off' No brakes either, looking back I'm pretty happy I never got hurt on it.
Cool build - I'm enjoying it very much!
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Motors are as many and varied as there are people who use them and I am certainly no expert.:whacked: I originally built my orange car and the silver car (pictured previously) with Scott 1hp motors. The Scott 1hp (also sold under the NPC brand name) is probably the most common motor in use in Electrathon because it is reasonably priced (about $260 new), plentiful, and reliable. Using 24 volts, it puts out 1hp continuous at 2800-3000 rpm. It is capable of up to 3 1/2hp under load. For its size and weight, it's a pretty efficient motor.:)
Several years ago, Briggs & Stratton bought the rights (from Lemco, I think) to produce the Etek design that has a radial armature. They made a production run of them and they originally sold for about $395. As the supply started to dry up, the price began to escalate and I saw prices as high as $675 at one point.:eek: Fortunately, they are being produced again and the price now is in the $469 range. I bought the one I have 4 years ago for $425.:rolleyes: At 24 volts the Etek produces 3 1/2hp continuous at 1728 rpm. It is capable of 8hp under load. It is also an efficient motor.
I am using the Etek here because I am overweight for Electrathon (me personally, not the car:o) and the higher torque of the Etek gets my lard moving without power-spiking the batteries so bad under acceleration. I also have a couple of Scott motors and, although I didn't mention it above, they will fit the motor mounts in this car if I ever want to run one.
The motor that Dana (The Bat) has is an old Scott that was traded to me a few years ago. It was probably 8 or 10 years old then and had dozens of races on it. I gave it to them so they could at least get on the track "until they could get something better". Dana's partner cleaned it and put a new set of brushes in it and they have been soundly thrashing all the competition ever since. Their success is a testament both to the reliability & competitiveness of the Scott motor and to The Bat's car-building extertise.:cool:
Horsepower isn't everything, either... The car pictured below holds the world record for distance/speed in a sanctioned Electrathon event. It traveled 58 miles in one hour using a 1hp Lynch motor. Someone correct me if they know, but I think that Lynch L200 motor costs about $1600.:eek: For those of us on a budget, that's pretty steep for a motor ($425 just about broke me!). Occasionally, motors can be found in surplus stores and on Ebay for much less than new prices.
I once considered trying to use a starter motor, but I was told that they won't live through this kind of use. Starter motors are built to produce very high torque for short bursts and burn themselves up with constant running. I don't know... I'm still tempted to try it someday...:3dSMILE:
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RestoRod - I'm sure some of the folks who have been doing this longer than me have done detailed comparisons.:confused: There might be some results online somewhere, but I have never researched it myself. Many Electrathon teams have websites with tons of info. There are links to some of them on the Electrathon America website (www.electrathonamerica.org).
HRD - Motors are available from several places including National Power Chair, EV Parts, KTA Services, Pentad, Robot Marketplace, Cloud Electric, and others. (Just do a search for one of those or go to the Electrathon website for links to some of them) I have done business with most of them and all have given me good service. Prices are all over the spectrum. I bought a brand new Scott (NPC) from National Power Chair a few years ago for $180 on sale. On the high end, the sky is the limit.:rolleyes:
Bat - I'll trade motors with you if you make your driver gain a hundred pounds and disconnect one battery.:eek: Then I MIGHT have a chance of outrunning him...:LOL::LOL::LOL:
Signshop - How did that Mustang starter hold up on your old minibike? Did it ever get really hot? I have a friend who owns a salvage yard; he will give me starters if I want them...:3dSMILE: How far are you from Berlin Raceway (Marne, MI)? They have some Electrathon races coming up there in just a couple of weeks.
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Very cool aero body
For every ones prospective;
The super Fancy aero bodied car in photo post #67 is some very cool work indeed,but there record speed for one hr. was done on a super speedway,so it did not need to make turns like we do in most of our races here in Fla.
Turns like we have would drop that cars speed a lot closer to what we are doing,that is if that car can even make turns as sharp as we're running ?.
I think it's a big gain to have nice aero body if av. speed is above 25mph.;)
OK,no deel then on the Etek,I think we need both bat's,nuts!
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Very cool speed car. Reminds me of some of the cars out at Bonneville!
Jim this is a very cool thread. Looking foward to the rest of the mechanicals, wiring and accelleration linkages!
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The starter we used on the minibike never seemed to get hot but we never really rode it a long distance. It had no way to control the speed - 50mph on a minibike is spooky so we just rode it in bursts on to accelerate off to coast...
If you're worried about heat you could always duct some air directly in there too.
I'm about an hour from Berlin. It's a nice facility (for a short track of course)
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Stovens - Since you mentioned Bonneville, check this out: http://www.speedace.info/electrathon...tober_2007.htm 89+ mph at Bonneville in 2007.:D
Signshop - Whenever the motor is enclosed, we duct fresh air to it. Notice the scoop on the side of car below; it's a direct vent to the motor...:) I looked at the Berlin schedule; that race runs on a Friday during the day. I guess it's for people who don't have to work for a living.:mad::rolleyes:
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Jim cool Bonneville car. Jim I noticed you sit way back at a fairly steep angle. Is it hard to drive for long periods of time like that, and how hot does it get in there?
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Running a car at Bonneville would be a blast! Did you look at any of the videos on that site? I liked the in-car video.:)
The reclined position is actually pretty comfortable once you get in. The cars are fairly tight inside, so they make you feel pretty secure (see pic below). The most important thing is finding a helmet/ headrest combination that supports your head comfortably. Without that, on some of the parking lot courses we run, your head will be lolling around like a bobble-head doll after just a few laps (been there, done that!):whacked:.
The fully enclosed cars can get pretty hot inside as they have little or no ventilation. Ventilation creates wind resistance, so... One of my kids lost four pounds during a race on a 91 degree day!:eek: The open cars may be slightly more comfortable because of fresh air, but open cars require long sleeves, gloves, and full-face helmets. If it's hot out, the driver is going to suffer a little regardless of which kind of car he/ she is driving. But hey, it's only for an hour at a time...:rolleyes:
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Jim, I went back and watched a few videos including the cockpit view. Boy it gives you a great perspective of how much bobbing around is going on that close to the ground at those high speeds. I also watched his walk through video of the car. Very cool design. I might have to see if there are any local competitions and volunteer or at least go to a few races! I like the crew boss too!
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Heh, heh, yeah Steve, the salt flats ain't exactly flat, huh?:3dSMILE: Imagine what that ride would be like in a car with rigid suspension!:HMMM: The walkthrough of that car shows what is possible with a few more bucks. Kirk is obviously very serious about this sport. Fortunately for us poor boys, most of the cars aren't quite that high-tech.
The Oregon and Washington area is a literal hotbed of Electrathon activity, so maybe there is some activity in northern CA. I know that Petaluma is in northern CA; there used to be a team in Sacramento (Cordova High School), but I don't know if they still exist or if there were/are races held there. The event calendar on the EA website doesn't show anything past May, so I don't know what's coming up in your area.:confused:
No wonder Mr. Swaney went down the salt so fast; he was in a hurry to get back to the pit boss!:LOL::LOL:
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I wish I had a cutie like that to work on the truck, it would have been done last year! :LOL:
My wife is helpfull sometimes though. Yesterday she held a wrench on a bolt coming up through the fire wall where I bolted the emergency brake cable clip too!:)
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Never been to the saltflats,but it dose look like from info on the net that salt has good hard and bad soft days for racing the clock,some what like our Daytona Beach was. Wounder how much red tape cutting it would take to do Daytona again.
Hay Jim,can we brake that record on the Beach?:eek::D;):cool: foooy on going way out to BFE to run :LOL:=must be a eastcost thing:HMMM:
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Hi Bat. I don't know about Daytona Beach; that would probably almost take an act of God.:rolleyes: However, there is a place a lot closer than Bonneville; Maxton, North Carolina. Do a search and check out the East Coast Timing Association. They use the same rules and classes as Bonneville, but the trials are run on a one-mile paved course. It's actually an unused airstrip at the back of an airport.:HMMM::3dSMILE:
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On the silver car and orange car pictured previously, I used 18 gauge perforated angle to make the battery trays. For this car I decided to try something different (and lighter?)...:HMMM:
I bought some 1/16" wall, 1" aluminum angle at the local ACE Hardware. I don't have access to a TIG welder, so I used 3/16" pop-rivets. I cut a piece of angle long enough to go around the perimeter of the battery bottom, allowing 1/4" clearance both directions, plus an extra inch for overlapping the ends. I drilled a 3/16" hole through the fillet of the angle where the bends would be and then made a cut from the edge of what would be the bottom to the hole (see pic). Then I made the bends in a vise with the bottoms of the corners overlapping, overlapped the ends, and riveted them. After checking and adjusting for square, I also riveted the botom of all four corners.;)
I made eight mounting tabs (four for each tray) from 1/8" x 3/4" flat steel. I drilled and riveted the tabs to the battery trays and then welded the assemblies in place from the bottom of the chassis.:3dSMILE:
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Becase of the weight of the batteries, the bottoms of the side pods need additional support along the outside.:rolleyes: In this case I used 1/8" steel round stock (welding rod) to make a pair of diagonal struts for each battery pod. The forward ones are welded to the outer bottom rail in front of the battery tray and to the top rail near the steering wheel crossmember. The rear ones are welded to the outer bottom rail behind the battery tray and to the main roll cage hoop.:)