I have to chime in that this is a fascinating thread. Makes me want to try an electric car build down the line after a few other projects get done! :)
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I have to chime in that this is a fascinating thread. Makes me want to try an electric car build down the line after a few other projects get done! :)
Go for it, Steve. Playing with these things has been quite an education. For a long time I've been toying with the idea of building a street legal version. I would make it larger so it could be seen in traffic and also so I could haul a small "payload" like a weeks worth of groceries or maybe a passenger. Maybe some day...:rolleyes:
Jim I might just do that. Today I'm cleaning house on a bunch of vintage stereo stuff. I have been delving in electronic stereophnic stuff from the 60's and 70's during the winter, when I couldn't work on my truck project. I actually learned enough on my own and thru forums for stereo equipment that I volunteer at the local hospice thrift store and fix up stereo stuff for them. It's amazing what people throw away when their parents pass on, that they have no concept of quality or value. To date my old Marantz reciever coupled with Epicure Speakers and a magnetic drive JVC turntable delivers a sound that nothing new on the market comes close to unless your paying tens of thousands of dollars, where as I got about 400 into that system. Anyway I digress, but once the extra stuff is cleared out and the truck is road worthy, then something like an electric car/bike project would be a lot of fun to do, plus out local ace hardware is 2 blocks from my house!
Excellent advice on the overlapping welds.
I spend a few hours practicing this weekend. I found that putting eight tacks around a joint and then running a bead from one tack to the next really helped me direct my focus. It still looks a lot like dog poop. But at least the dog is no longer sick :)
I ordered a cheap gokart master brake cylinder for $29 on ebay, It looks like it will work well enough as a proof of concept.
I bit the bullet and ordered a Motenergy ME0909 motor and Alltrax AXE4834 PM Controller. $720 total. Sadly, with the wheels and frame materials, this pushes me ahead for my initial original budget of $1000 per year for two years for the project. I guess I need to revisit the budget :)
@stovens,
I highly recommend the project. Personally, I have never had the time, space, or tools to work on a full sized hot rod. The electrathon vehicle seems to be a good first step. For $1500 and 6 months of evenings it feel like a relatively inexperienced person can put together a vehicle that can a least complete a couple of races. Then if one takes a second season to revise their plans they can have a reasonably competitive vehicle.
The breadth of topics covered is amazing!
That's a good price for the motor and controller. Did you get a special price for buying them together? The Motenergy ME0909 looks like an updated version of the Briggs Etek. I've not seen one in person, yet, and I am interested to see how it performs. If it's as good as my old Eteks you'll be very happy. The good news is, if you like this motor you can use it almost forever.:3dSMILE: When I sell a car and build a new one, I just move the motor and controller to the new car. I've built 10 cars, but I've been using the same 3 Etek motors since 2004 and they seem to keep getting better with age!:rolleyes:
It costs me just under $1,000 in parts and components to build a new car using all new materials. (That does not include the motor and controller.) Having done this enough times, I know what I need and have very little wasted material. It was a different story when I started out, though. I cut that first car up and started over twice! It finally ended up as the orange and silver car seen below.:cool:
Excellent inspiration!
Initially I was looking at the Etek motor. They seem to be the most well understood motor in the sport. However, the market for used Eteks is pretty tight. I take to be a good sign that the motors are high quality and the sport is growing at a steady pace. The ME0909 seems to be the succor to the Etek.
I used the same criteria for the controller. It appears to be very common and well understood. I went with a match set.
I am going to head off a bit into the world of experimentation with the batteries. My intention is to make a 1 KW/H LiPo batttery out of recycled laptop cells (18650) which is the same type the Telsa model S uses. I have worked with these a bit on robots. It should be possible the keep the weight under the 14 lbs as specified in the handbook.
The 1KW/H target keeps me in the same energy ballpark as stock electrathon racers. The upside is they are cheap, about $50 for a 1KW/H module. The downside is they tend to perform poorly when drained at greater than 1C such as when accelerating.
It will be interesting to see if the reduced capacity is worth the reduction of 50 lbs of weight.
Just a quick word of advice... Build your battery trays so that they can accommodate full size automotive batteries. The reason being that you may want to change to conventional batteries later. Here in Florida there are only two cars running in the Experimental battery class. If one of them doesn't show up, the other one is basically making practice laps because there's no class for him to run in.:HMMM: It's not much fun when there is nobody to compete against. Are there other cars running in the Experimental battery class in your area?:confused:
Agreed,
I am trying to be flexible with the batteries so that if they don't work I can fallback to standand SLA batteries.
On the other hand from my limited research it seems that most of the students and teachers involved in electrathon are gearheads :) No one has really looked into alternative batteries past the price and potential danger. A safe, DIY, battery for under $100 might provide interesting options.
If the experimental class becomes boring, I was thinking about implementing some sort of handicap like golfers use. My first thoughts were to self limit the available energy the vehicle uses until it performs on par with other cars.
There may be teams in your area that run in the Experimental class all the time so you'll have somebody to compete against. You'll need to go to an event to find out...:rolleyes:
Actually, the kids involved seem to be a pretty equal mix of gearheads and nerds! When I was teaching and mentoring a team I was always amused by such diverse kids working together so well. Ordinarily the grease monkeys and eggheads avoid each other like they have contagious diseases, but Electrathon seems to bring them together and they end up making new friends.:D
Yes, price can be a critical factor to some teams, especially the high schools. Most of them don't have expendable funds to experiment with, so they stick with the "tried and true". I run Optima Yellow Top batteries. I bought 4 of them in April of 2010 and 4 more in December of 2010. I'm still using them!:eek:
There have been attempts to equalize the different battery types before. Usually, ballast is added to make up the difference in weight. For instance, Standard Battery class is limited to 73 pounds of batteries while Lithium is limited to 22 pounds. Simply add 51 pounds of ballast and the cars should be equal, right? It doesn't quite work that way because Lithium batteries perform differently; they still have a performance advantage. If you can find a viable way to equalize the Experimentals with the Standards I'm certain that Electrathon America would be very grateful.:)
It is great to hear the this project is a place where gearheads and nerds come together to solve problems. I have a foot in each group :)
I spent most of the last two weeks on batteries. The two systems I am testing are building pack out of 18650 cells and pre-built Nissan Leaf modules. I like the Nissan Leaf route because they are about the same capacity and cost as the red and yellow top battery. The DIY pack is a great learning experience.
I ordered 20 100W power resistors to build a resistive load bank to test various batteries against the workloads they will experience in a actual race. They should arrive in a couple of weeks
The motor and controller arrive in good condition. I borrowed a couple of 12V batteries from the garden tractor and a car to test the motor. It spun up right away. Over the long weekend I hope to spec
For the most part the subsystems are coming together nicely :)
My current hiccup is gearing. If I run the motor at 48 volts, it will spin twice as fast as at 24 volts. This would require a driven sprocket of about 120 teeth instead of the standard 60 teeth used by shiftev in their rear hub adapter. It looks like I might have to have shiftev fabricate something so I can use standard 6 hole gokart sprockets with their adaptor.
I just fired up the garage furnace. Hope everyone has a enjoyable and productive thanksgiving weekend.
I will be interested to see what your battery experimentation yields. If it saves money in the long run it could be a boost to the sport.
What kind of sprocket adapter does shiftev make? If they make the ones that hold the standard 5-hole bicycle sprocket ring, you don't want it. Bicycle chains are junk for Electrathon; they stretch like elastic and frequently come off the wheel sprocket. I used bicycle chain and sprockets on our team's first Electrathon car (Blue Sky Aerocoupe) back in 2003 & '04. It did OK in its first two races, both on smooth ovals. In its third event it kept jumping off. I didn't realize that it had stretched to the point that the chain no longer matched the pitch of the teeth on the sprockets!:eek:
If you Personal Message me I can give you the e-mail address for Rodney Schreck in Miami. He makes the sprocket hubs (pictured below) that I use and sells them for $99. He uses an ordinary rear wheel sprocket cassette and adds a sprocket adapter that holds a regular 6-hole go-kart sprocket.:3dSMILE: Rodney bolts the adapter plate to the sprocket on the cassette. When I get them I weld the two pieces together and then discard the bolts, but that's just a matter of preference to eliminate the possibility of the bolts ever working loose.:rolleyes:
I hope the battery experiments yield something useful. As you mentioned earlier, if I run Li-ion batteries, I will probably be in my own class. Rather than keep secrets for a competitive advantage I might as well take the time to make the results public as others can learn from my mistakes:)
Yes, what you picture is exactly what I need. Professional cyclist often use a new chain for each race. Bicycles can get by with such light chains because their rear triangles are very ridge and cyclists lean into the corners so any flex happens in the same plane as the chain.
I am speculating that one of the reasons your frame designs are so reliable (and successful) is your use of curved tubes in the rear triangle and front wheel support. These curves provide a bit a suspension so your vehicles flex rather than bounce or break.
As a result, I am going with a go-kart chain. The product shifttev sells is https://shiftev.com/index.php/compon...ory_id/25.html
Actually, if you study the picture of my latest bare frame design (below) you may notice that almost everything except the front axle is triangulated. The frames I build are very stiff. Flex is desirable in a go-kart frame to provide traction and handling. It is unnecessary in a 3-wheel vehicle where weight transfer is absolute. The EMT conduit I use to build frames will fatigue and crack if allowed to flex. The rear fork in my frame is triangulated vertically on both sides as viewed from the side and rear and horizontally at the bottom as viewed from below. I don't want any movement in the rear wheel as that causes thrown chains.:eek:
The front axle main tube is arched in the center so the ends descend toward the spindle. It is very rigid and the bottom supports are curved mostly for appearance, but will allow the front axle to bend if serious impact occurs. (It's happened more than once!) I don't triangulate my front axles because if the car is involved in a crash I want the axle to bend without transferring damage to the frame.;)
Nice,
The current frame design looks like it has gone through several generations of refinement:)
Yes, it has been improved continuously from use and experience. Since the white car build in the first half of this thread I have changed the front hoop of the roll cage slightly and added the extra triangulation to the bottom of the rear fork. Otherwise, the design is dimensionally the same.
The change to the roll cage was strictly for driver comfort; the white car's front roll cage hoop put pressure on my upper arms when cornering and became uncomfortable after a while. I simply raised and deepened the bends to get the vertical portion farther forward.:)
The extra braces were added to the bottom of the rear fork after I had a problem with frame flex! After I finished the white car and raced it twice I built the black car (which I still own). In my first practice session with the black car I kept hearing chain binding noise in every corner. About halfway through the 3rd lap the chain broke! The rear fork was twisting badly in every corner. The problem never occurred with the white car (different rear forks?), but since it showed up in the black car I have added the extra bracing to all subsequent chassis.:3dSMILE:
I do enjoy looking in from time to time,as Jim said reg bike chain can go bad n dose. I used pro high $ bike race chain n had no probs,but it did cost about 5X as much,very lite car with only 1HP,but as I was also using 6speed set up,the derailer with extra MB spring held very well. In a car with higher lbs n HP may of failed too.
Finally started the frame build... and promptly threw out 80% of what we talked about. It didn’t seem like I had a good enough feel for what I was doing to convert my paper plan into tubing. I am do this frame by eyeball and feel.
The most satisfying part of the week as been building all the jigs to hold things in place before welding.
For this build, I am intentionally leaving things flexible and weak. I wouldn’t want to race it:( But, hope to gain a better feel for where and why thing bend and break by tooling around the parking lot:)
The first week of December when I started my frame build was a wake up call. I had gotten pretty good welding flat stock on a bench. Even the short stubs of tubing I was using for practice were good-enough. However when it came time to weld the frame, everything fell apart. I had not prepared for welding weird angles from weird positions.
It took a couple of days to pick my self esteem off the ground and figure out what to do next. I thought about cutting the frame up and reassembling it with each tube an inch of two small just for the practice :) But the time spent cutting and fitting the tube would be too great compared to the practice spent welding.
Yesterday, I took a piece of 16 gauge sheet metal and cut it into 2 inch by 2 inch triangles. I used these triangles as gussets at each joint. Each gusset required 4 welds of about 2 inches each…. from many different positions.
The key for me is fit prior to welding. It I go slow enough to get good fusion, I tend to blow though even tiny gaps. It is probably a matter of practice :) For now, it means a lot of time on the grinder getting things to fit as closely as possible.
On Saturday the 6th we raced at Middleton High School in Tampa. This year, because of other events taking place at the school, we were moved to a different parking lot than the one we used in past years. The course was a simple oval which is fine, but this was the roughest course we have ever encountered! Most of the track was OK, but there was a patched area in the asphalt (it was turn two in the first race, turn 3 in the second race) that created multiple bone-jarring bumps on every lap.:eek: I tried every possible line through that turn and there was just no good way. The first race was run in a clockwise direction (all right turns) and when it was over my left elbow and shoulder were sore from the beating they took against the inside of my car. The good news is I finished second with my son right behind me in third. Rodney Schreck won by 2 laps driving the car I built for him, so that means Robinson built cars finished 1-2-3.:D:D
The second race ran the opposite direction (all left turns). The bumpy section was now giving my right arm all the torture. I was in pain and I simply was not having fun. On the 43rd lap, as I was exiting turn 2, the car suddenly danced sideways and I knew what that meant. I slowed, limped around the rough turn, and ducked into the pits with a flat rear tire. I was actually thankful that I had an excuse to quit! Changing the rear tire would take upward of 15 minutes and the laps lost would be insurmountable, so I just climbed out to watch the rest of the race...:rolleyes: Late in the race Rodney coasted into the pits; the key had come out of his motor sprocket and it was slipping. I grabbed the appropriate hex wrench and tightened the set screw into the key slot on his motor and got him going, but he lost a total of 3 laps in the pits. My son won the second race:D by about 6 seconds over the Electrocutioners car from Orlando and Rodney finished third, 3 laps down.
At the end of the day my son won the event!:D:D Rodney was second, 1 lap down and I was credited with fifth (6 cars in Open division). The nearest finishing high school car was about 20 laps back! The school kids just can't understand how a bunch of fat old guys keep outrunning them.:LOL: It's all about consistency.
Now to repair and prepare the cars. The beating from that rough course cracked the Lexan covering on the nose of the 94 car around several of the rivets. The 13 car has some broken spokes on both front wheels. I haven't checked it yet, but I suspect both cars will require front-end alignment. The bottom line - if they run that same course next year I'm staying home!:p
David,
I assume you are using a MIG welder or a flux-core wire welder. Either is good. Trying to run a continuous weld bead on thin material is a challenge for the most experienced of welders.:rolleyes: About the time you get a good weld puddle, the metal blows through and you have a gaping hole to fill. Try using a series of overlapping tack welds. That's the most successful way to weld this thin stuff. When you start the weld, watch the puddle. As soon as it gets nice and round (this happens very quickly), stop. When the puddle loses its glow, start again. Do this over and over until you have completed the weld. It will seem like slow going, but actually saves time over having to constantly repair blow-holes. When done right the finished weld looks like a bunch of overlapping circles or "stack of coins". I've been doing this for years and not all of my welds are pretty, but I'll take strength over looks any day.:cool:
Thanks for race report,fun read,High Five for top 3 cars in frist race n super your son's job.
Thanks for posting the race highlights, Jim. I always enjoy your posts!
X's 3, thanks for the updates and congrats on the successes!
Congratulation on your good showing. Is this the start of a dynasty for Robinson Racing.
Last week I chopped up V1 (version 1) in order to start fresh on V2 for the new year. I thought I would share a couple of lessons that might be useful for builders without a lot of experience.
1. Build a decent platform. This platform will be the base for all measurements and fastening jigs. A two foot by eight foot sheet of ½ inch plywood on two sawhorses was not enough. For this iteration I fastened the sheet of plywood to eight foot 2X4s running beneath the plywood like floor joists. This provides a nice solid platform which does not sag that is still light enough to move out of the way if the space is needed.
2. Screw a eight foot measuring tape directly to the middle of the plywood platform. The edge of the tape provides a reliable mid-line and the tape provide a constant frame of reference for measurements along the length.
3. Prepare a bunch of layout blocks. In order to hold things in place for welding you will need fixtures to hold the tubing in place. Rather than scrounge up a suitable piece of scrap while you are thinking about the joint, it is handy to have a bunch of pre-drilled blocks on hand. You will already have enough on your mind when doing the lay out.
4. Set a tolerance. While working is it hard to know what is good enough. Experience must help a lot, but until I have that experience I decide that everything must be within 1/16 of an inch when fitting most parts. Steering and driveline must be a good deal more exact :) This seems reasonable without being too exacting.
5. Set a margin of error of joint fits. After a bit of experimentation I found that having no more than .035 of an inch gap on joints makes for pretty decent welds for someone of my experience level. Anything bigger and I tended to blowholes:(
I look forward to hearing more about your season!
Thanks for all the compliments, everyone. My son's win eased some of the pain I was feeling after the event, but I was still sore for two days after!:eek: I'm probably getting too old for this.., but it's just so darn much fun! Next race is January 17 at Wharton High School. I don't particularly like the track layout, but at least it's tolerably smooth.:HMMM:
David - If you look back at the beginning of this thread, I used a 2' x 8' piece of 1/2" plywood to make my "frame jig" platform. At the time I had it clamped to two work tables in the school shop. That kept it flat and level, but I later put 1" x 4" (on edge) framing under its perimeter and then added "wings" on either side to locate the side pods. I also built a fixture to hold the rear fork in place instead of using the plumb bob and measuring tape. Another fixture holds the kingpin bosses at the correct angle for welding and others hold the rear hoop and roll bars at their correct heights. I cut a stack of 2" x 4" blocks from 3/4" plywood to use for holding the tubing in place on the platform (plus I clamp the bottom rails down) and attached them with drywall screws so they can be moved if necessary. I'm still using the jig and all the fixtures. It's showing a little wear after having built 9 frames, but is still flat and accurate.:3dSMILE: I bend, cut, fit, and tack all the pieces together. Then I weld everything that I can reach easily. After that I take the frame off the jig and roll it over and over to weld all the otherwise difficult areas.:cool:
I just have a center line drawn on my jig, but attaching the measuring tape along the center is a good idea. Speaking of measuring tapes, if you need to measure around corners or a piece that is already bent, get a fabric tape measure from the sewing department at Walmart or a fabric store. I've kept a couple in my shop for years.:)
Good news, folks. The January 17 race is now history and it was another victory!:D:D Saturday's race course was set up as an oval on the Driver Education field at Wharton High School in northern Tampa. It actually was a similar course to the one we ran last month at Middleton, but this one was not a "boneshaker" like that one.:HMMM:
My son wasn't available, so I got an old friend of mine (and former go-kart champion), Jerry Bristow, to drive the #13 car. The cars were lined up according to car numbers, so Rodney Schreck #4 from Miami was on the pole, Bristow in the #13 was outside front row, and my #94 was deep in the field. It was a pretty uneventful race and at the end Schreck finished first, Bristow was second, and I was third. All three of us turned 126 laps and there was a mere 6 seconds from first to third.:rolleyes:
In the second race the starting field was inverted, so I started outside second row. Schreck and Bristow were at the tail of the field. At the start, the two cars in the front row separated coming off turn two, so I shot between them to take the lead. Down the backstretch Bristow managed to pass the entire field to take second behind me. He matched me move-for-move through traffic for about the first two-thirds of the race until Schreck caught and passed him. At 20 minutes to go I dialed up the throttle, as usual. I seemed to have some uncanny good luck with traffic at some points while Schreck and Bristow were struggling to get through it. That worked to my advantage as, late in the race, I caught and passed Bristow to put him a lap down. I had Schreck in my sights and almost caught him, but then the traffic started hindering me and helping him.:( We finished that way. Schreck and I had turned 128 laps; I had about 3/4 of a lap on him and a full lap on Bristow.:3dSMILE:
In Electrathon, the total laps for the day is what matters and when the officials totaled the laps Schreck and I both had 254. The tie breaker then is total time; Schreck logged his laps in 2 hours and 31 seconds, but I did mine in 2 hours and 29 seconds. I won by a mere 2 seconds!:D It is the closest finish in Florida Electrathon history.:cool:
Aside from cars that I built finishing 1, 2, 3 in the Open Class, the car that I built in the first part of this thread also finished second in the High School division. The Tampa Bay points keeper commented that my cars have become the "class of the field" and they are "fast and reliable"...:)
I've been following this thread with a great deal of interest; it's good stuff and I've enjoyed reading it.
And to see you get results and comments like that...well; give yourself a well deserved pat on the back that man!
You've earned it.
:) :) :)
Way to Go Jim. Congrats on the victories! And way to go on your designs too.
X2 on the congrats. When can we expect to see your new Formula E designs?:D
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Times 10 on the congrats! A 1,2,3 finish with your cars is certainly a great achievement and you should be very proud!
I know we here in the club are proud to see the results you've been getting too!
So like all racing.. What's next?!?!?
Thank you all for the compliments. Yes, it's nice when your efforts finally start paying off. I got involved in this sport back in 2002 when my students and I began construction on our first car. At first we had trouble just finishing a race and it didn't matter if I had students driving or if I was doing it myself. When we finally got one of our three cars to run the full hour in a race it was usually at the tail of the field. After a few years of tinkering we got so we could finish in the top 5, then the top 3. I retired in 2010 just as the race schedule began to expand from 3 races a year to 7. Finally, in 2011, with no more students to mentor, more races to run, and intensified focus on what I was doing, the cars I build became contenders for a win at every event. That gives me a good feeling.:3dSMILE:
Formula E? I look for that type of racing to expand rapidly. It may need a few tweaks to really gain fan acceptance, but it's cool. As for me, I think I'm a bit old for any teams to be interested in me.:o
What's next? More of the same for now; I'm still having fun. I'm rapidly approaching the day when I'll probably give up this sport, though, and leave it to the younger folks (I'll soon be 67):rolleyes:. I still have my coupe and roadster to keep me busy.:cool:
34-40 - That's pretty good; "Do it till you're satisfied". The song that runs through my head sometimes when I'm passing those high school kids is Toby Keith singing "I ain't as good as I once was, but I'm as good once as I ever was." I guess it's especially true when we old fat guys beat the kids by 15 or more laps.:LOL:
As for the coupe and roadster: I have a 15 gallon aluminum fuel cell that I'm going to put in the coupe. It fits differently than the old 10 gallon Geo Tracker tank so the increased capacity doesn't take away any more trunk space, but my range will increase by 50%. The roadster will just get driven... a lot.:cool:
Thanks for the reply Jim. The fuel tank sounds like a great idea, especially the increase in drive time / range! More time for doing "it"!! LOL..
I haven't updated in a while, but we've been having a pretty good season.:) In February we raced at USF Tampa during the annual Engineering Expo and, once again, cars that I built finished 1 - 2 - 3.:3dSMILE: This time it was Rodney Schreck from Miami who took top honors. Jerry Bristow, driving my #13 car, took second. I dropped out late in the first race with a blown rear tire:(, but finished the second race with no problems. I logged enough laps in my total for the day to capture 3rd place.
In March we raced at Tampa Bay Technical High School. Late in the first race, Rodney and I got into a "tooth and nail" battle for first place, swapping the lead back and forth for several laps. I finally managed to outrun him off the last turn of the last lap and hold onto the lead, beating him to the finish line by .8 second.:D My son, driving the #13 car was a close third about 6 seconds back. In the second race, Rodney was involved in a mishap caused by a rookie driver and lost 4 laps. Later, with about 8 minutes left in the race my son's rear tire went flat, forcing him to retire while leading. When the day was over I won, Rodney was second and Jim Jr was third. Once again, cars I built finished 1 - 2 - 3 on the day's total laps.:3dSMILE: Post-race inspection revealed that my son's rear tire was worn completely through the casing causing it to blow.:HMMM: My rear tire was showing cord all the way around; if the race had lasted two more laps I likely wouldn't have made it!:eek:;)
Is it just me?? Or. does it sound like you folks have a lot of trouble with tires? Seems like we read about tire issues quite a bit. Or is it that the tires are just being overloaded in this application?
Just curious.. and once again, congrats on all the successes!!!
Congrats Jim. Very impressive engineering and strategy here!.
34-40 - Yes, we do have occasional problems with tires.:HMMM: We are using bicycle tires in a manner which they really aren't designed for. On a 20-inch bicycle, two tires are carrying the weight of a bicycle (usually less than 30 pounds) and a rider (usually less than 160 pounds). The tires and wheels have the added advantage that they are leaned or tilted into corners at a rate that keeps the tread at it's best angle for traction and the spokes in line with the load place upon them while they corner at speeds of 5 to 10 mph. We take those same tires and wheels, load 400+ pounds on three of them, hold them at a fixed angle, and attack tight corners at 20 to 35 mph. If the surface is the least bit abrasive, it will just grind the tread right off the tires (and sometimes break a few spokes) in the course of the two 1-hour races at a typical event.
Having said all that, though, I must now admit that we started the day on used tires!:eek: The rear tires on my two cars had been used at the last race (USF Tampa in Feb.). I thought they had enough tread left to go the distance this time, but I obviously was wrong. I simply misjudged how abrasive this track's surface was. Had I not made that mistake, my son would have beat me by over a full lap.:rolleyes:
Thank you both for the compliments. Looks like I'll probably miss the April race because of an obligation elsewhere.:( The last race of the season is May 2nd in Cocoa, FL. I won that one the last time we ran there:3dSMILE:; I'll be trying for a repeat... with all new tires on both cars!;)
Thanks for sharing the info and the knowledge Jim!!!
I never really thought about the weight factor.. but then I don't race'm.
Tires and what happens to them in any racing,are a super "tell" of what needs the most carefull work & design. Jim's on the money right here for all to learn from.;
"The tires and wheels have the added advantage on my own design that they are leaned or tilted into corners at a rate that keeps the tread at it's best angle for traction and the spokes in line with the load place upon them while they corner at speeds of 5 to 10 mph. We take those same tires and wheels, load 400+ pounds on three of them, hold them at a fixed angle, and attack tight corners at 20 to 35 mph. "
Back when I read the rules then looked at the first race,that Rex had me come to,that was the bacis that was at the root of my racer design. I'm still woundering why others have not refind the design,I came up with? I beleve Rex as crew an my son as driver showed it to work OK. I give you this drawing,Jim get my old racer from were ever it is and build a better one then I did. Two years of racing it and it was never really completed as I designed it,left the body off the hole time,it was not needed at parking lot speeds we could use. Key part of design was keeping tirea loaded as they were designed to load by leaning them and also by moving % of total lbs per wheel from 33% going in a strait line on each wheel, to being less then 15% on out side front wheel in a turn= drop of rolling friction. Thing is Jim pointed out that tires on anything are the first place that the car talks to you an says"I'm good or I'm bad"in racing.