Want to start ho drag racing

Hi, I'm new to this game to. My track is 24 ft. long.Last year my 1/4 was 171/2ft long. And anything over 30mph just got destroyed!No madder what I put back there. So I moved my 1/4 back to NTRA 16ft and I need a brake. Just something to think about. If I find something Ill let you know.

good luck: Iowajeff

Hi Iowajeff,
Check out hodragraceregistry.com for info on other tracks and how they are operating. My track uses 1/8th bar stock for the shutdown area with each bar shorted across to the other bar in the same lane. Dynamic braking occurs then. Has not damaged any tires or cars, they just stop quicker. If you are wanting a portable track, I recommend hot gluing your snap together track onto two 1 X 4's with one ten foot long and the other about 6-8 foot long. Wire your ten foot track for the timing with the starting line 9" from the end and the finish line 3" from the other end for a 1/75th scale 1/8th mile track. That way it's totally portable if you screw two more 1 x 4's to each side of it to make it look like an "H" shape when viewed from the end. Takes the flex out, hides the wires under the "H" crossbar and makes the top of the "H" look like and work as guardrails. Set them up on a table, sawhorses or wall "L" Brackets when needed and store when not in use as two pieces. I made one like this a few years ago and it worked fine. Doesn't take up too much space, very portable and if you use wall warts, you easily can power up one for each lane. I don't recommend you go with high voltage unless you have decent shutdown to work with or something thicker than the snap-type track wire for magnets to grab and slow the cars down. Just my preference and others may have ways that work for them. We have a couple of tracks like this being put together for additional tracks in the Orlando area now! Whatever way you go, just don't forget to keep it fun.
Phil

I have a couple of ideas bouncing around my cranium, concerning track length. Specifically finding enough length. The first idea is pretty simple. If you can find a space to accomodate it, perhaps a REMOVABLE SECTION of track to get the length you need is a simple solution. Say you have room for a sixteen foot 'run' but the next six feet of territory is shared by the family barge, or a washing machine access. A 'portable/removable section can fill the bill, allowing enough length to accomodate your other wise 'too large" track.

The second idea is bound to be much more controversial, and I'd love to have a discussion on it. For road racing, it used to be common to use 'third wire braking." The third wire was a reverse voltage (usually 1-2 volts.) When the rheostat hit the 'zero position' the reverse circuit was completed.This would bring the cars to a slamming stop for cornering. Now while l don't propose going from 24-28 volts forward to 2 volts reverse instantaneously, I am toying with the idea of say a three foot magnetic brake area (unpowered double steel rails) then a two to three foot area of reverse polarity braking. Electric motors, by their design are much like a "fluid coupling" and the shock load would likely be much less than you would assume. Also, after a couple of feet of magnetic braking, much speed has already been scrubbed off. The only real shock load would be to the drive train, and with such tiny masses involved, I dont anticipate any damage. The final braking section would always be 'hot' at 1-2 volts reverse. ( maybe an intermediate section would be better.) Any way its something I'll be experimenting with in the future and pass along.....I'd love to hear some comments on this, yay or nay...... ( the negative comments are often more fun!)

Your aren't gonna talk me outta this one quite so easily! lol

I know exactly what you mean about the 75 mph reverse trick in a full size car..............Im not convinced these tiny masses would be likewise affected.............in other words....how much actual momentum ( mass times speed) in a pinion spinning at ...by the way how many rpm are we talking?? Ill have to do the math.............. let me see..........75 mph divided by the rollout travel of one wheel turn......... who knows the answer hmmm?

[first one who can tell me me how many RPM a standard T jet chassis car (15 tooth drive pinion) is cranking at 75 mph......wins a prize that Ill figure out when i see an answer I like!!! lets assume a standard tuff ones rear slick circumference....do the math and show me your work..... ;D ;D ;D]

after that we can weigh a pinion and armature to see how much mass (weight) they have, heck, weigh the whole car, and see how strain there is under an instantaneous halt. I may be way wrong in practical application, but the theoretical fascinates me anyway!

As to the generator equation, that one makes much more sense to me.....the motor is being 'driven' by the wheels and gear train and that WOULD produced a voltage output......but.........

ONLY as long as the motor itself turns.......if the motor is STOPPED--- as in the case of reverse voltage.....the production ceases...now the car is slowing on locked rear slicks...just like slammin' on the brakes........Im not saying its the way to go.......................Im just not convinced it wont work...Ill get back to you when i smoke a few armatures!! lol (actually you guys probably think armatures are exactly what im smoking)


P.S. The fire engine sitting downstairs as I type this, is 1999 Pierce triple-combination. Weighs in at close to 20 tons.....and uses the magnetic braking you mentioned. The drive shaft is surrounded by a hefty armature. Electricity applied when you use the service brake (air brakes, of course) activates the electro- magnet and attraction beteen the driveshaft and the magnet slows the beast.

no you didnt really have the fire enging thingie wrong.............you were pretty close


True dynamic braking is what diesel train engines use.... In order to avoid having a 'solid' coupling between powerplant and the huge mass to be moved., diesel train engines are actually diesel- electric. The diesel drives a generator which in turn appl;ies voltage to motored trucks. When they switch to 'dynamic braking, the electric motors are disconnected from the power source and the weight of the train spins the motors (now acting as generators) and the voltage produced is converted to heat which is dissipated throuigh cooling grids. Kind of a slightly different curve!

if i follow your logic..........and i certainly might be the weak link you are looking for.......the magnets will not "fight' anything......the motor will merrily turn in reverse with the same magnets if you apply reverse voltage. The only fight is the forward momentum of the motor and weight behind it versus the "new" motor....the one that wants to go the other way....all the strain is on the drive train......i'm still not saying its a good idea.........I am just enjoying the logic discussion involved!! I will be testing this out tho!!! (ill wear dark sunglasses to avoid 'arc burn' to my eyes.)

P.s. if the tires are glued.....(no skid) the argument is the same.......the car stops even faster! the question is: "does the gear train break?"

It's not really relevant to your "how to shut em down" discussion that's interesting but giving me a headache. But your earlier comment regarding the length of the track and how it fits in all of our homes and garages that I want to comment on.

Last year I purchased a neat portable track from Rev. Kevin Barnsdale that uses 4 seven foot long sections for the track. the timed length is 21'-6" if I remember correctly and we have toyed with the idea of taking the middle powered section out when needed to be able to use it in locations where length is limited. I'm in FL and I prefer air conditioned race tracks without rain. Sam, I know you like those snow races (where do you get the snowmobiles to race?) From my regular built in routed track to the two tracks I've seen in St. Louis to Sam's Psychoslots Raceway, I've concluded that I don't need a 25 to 30 ft. long track to have a lot of fun.

I don't have the NHRA reason for shortening it in that we don't want to have anymore people killed from the excess speed and short shutdown probably demanded with longer timed length. However with their shortening of the distance for the Pro cars and the IHRA 1/8th mile races that have gone over successfully and also the new ADRA 1/8th mile races, length is not so important on full size tracks anymore either.

Yes, I probably need to walk the longer distance to get the car back, but I'm so lazy I built in a powered return road for my 1/8th mile HO track so that doesn't come into play either. My premise is this. Build what works for you and don't worry about it. Just get it done and have fun. Real scale 1/4 mile is cool too but the deal is get'er done. The real need is for more and more people to be able to race on our small tracks and see how much fun we are having. You are having fun aren't you?