are they REALLY blueprinted?

[mudhen]

whilst wandering around behind the counter at downtowns' i noticed "blueprinted" 16-d setups from both fast ones and pro-slot. are they REALLY BLUEPRINTED?

ALSO.................... is there an optimal gauss reading,or range of numbers for mags in the different classes? ---16-d/gr.12/ hornet, etc?

xxoo richard MUDHEN marnhout

[Monty @ B.O.W.]

Richard,
If you saw these items in the counter at the raceway, could you not tell if they were blueprinted? I'm not going to get lured into putting down the competition... I mean, I actually don't know just how far the suppliers you mention go to do their blueprinting. I would say, that if you can't tell by looking, and you're still curious - buy it and try it!

Actually, it is the second part of your question that I believe I can help with most. Different winds or classes of motor do seem to work best with magnets not only matched, but sorted for strength. For starters, though, you need to be aware that you will see several different scales being used to express magnet strength. The scientific community uses 'gauss' to express magnetic flux density. This is an actual unit of measurement, and there are a variety of test instruments out there designed to measure it. They all vary somewhat in accuracy, not to mention price, but the differences pale compared to the number of different ways they could be used on a slot car magnet! Gaussmeter probes seal the delicate sensors in a non-ferrous metallic sheath. Most that I have seen look like a flattened piece of brass tubing with a wire going back to the meter itself. In use, various ceramic slot car magnets will read between 500 and 1400, but the range is really less than that. First of all, the difference between measuring a loose magnet and measuring the same magnet in a can is a lot, over 200 units in most cases. Similar huge differences are apparent depending on the distance from the probe to the magnet (even if touching the magnet, the thickness of the sheath will make a difference) and where on the magnet you touch down. Anotherwords, gauss measurements are dependant on the user's ability to make measurements in a consistant fashion. You would have to ask each of the various purveyors of gauss readings as a service to the slot racing community just how they go about it, although I'm reasonably confidant that they are all pretty good at comparing magnets using their own methods. Therefore, if you send X quantity to blueprinter A , they will be accurately ranked agaist each other in the sample. Blueprinter B will likely come up with the same ranking, but come up with different numbers. So, be consistant with who you send your magnets to.
Heres a description of how I do it, and you'll see that it is most likely to be results that can be roughly duplicated by the average racer. I use the 'TrikTrax' magnet matching device. I have modified it to use a battery eliminator instead of the 9 volt transistor battery it was designed for, as this makes for more consistant readings. I often look at the same magnet several months apart, and get the same numbers. The TrikTrax matcher also has a pair of grooves in its face to hold magnets by their tips. This means you can only slide the magnet in a linear motion (one dimension) so you do so and find the highest reading. This reading is accurately repeatable. OK, thats the good part. There are a few negative points to the TrikTrax machine as well. First, you can only measure the magnet outside the can. Second, between two specimens of the meter there is often a noticeable difference in the range they will report. A racer could arrange to compare a reading off their unit to one from another one (using the same magnet), and know that the difference should be consistant. Many of my customers own TrikTrax meters and have made not of how their readings differ from my own. One has even managed to tune his meter to be almost identical to mine, but thats another story. Third, the numbers from a TrikTrax unit are NOT expressed in gauss, but seem to be about 40% of gauss. Anotherwords, if my meter says 400, an accurate gaussmeter should say 1000.
Now, Richard, I finally answer your question! Mura or Mura type (ProSlot Mega II) magnets range from 420 to 455 on my meter. ProSlot SMQ magnets are found in the 340 - 360 range. Parma EP magnets are found from 330 to 400. Parma EPX and FastOnes DM2 magnets (they seem similar) go from 375 - 415. Kelly C can magnets go 480 - 510. Much of the difference BETWEEN TYPES is in the shape and size, NOT in the material itself!
For usage, I find that within each type, its best to use the strongest magnets for the hottest classes on the more powerful tracks. The reverse is also true! Example: High powered King track, Mura magnets - Gr.12, use 445 and up, Contenders 336 to 443, Superwasp 335 and below, Super 16C 338 to 443. Second example: Low powered short track, subtract 10 from the first example, or use SMQ magnets.
Now, after all of that, you are still going to need to experiment to come up with the best parameters for the tracks and classes that you run. Good luck... but then, constant fiddling is half the fun, eh?

[cheater]

Mom, please put a sticky on this one and mark it post of the year.

Thanks, Monty.

[eap9]

Hello Monty!
That was a very good lecture. I hope you will share more of such information with us.
My question is what is a low or high powered track to you? Is it based on the voltage or the total amperage of the track?
For example, our track uses one 13.8 volt power supply attached to 2 8D batteries and on the track's computer, it is showing 13.8 volts as the track power. Would you consider our track as low powered?
Thanks

[mudhen]

thanks monty. as for the factory "blue prints", well, they were bagged and carol wasn't about to let me go ripping them open to check!
and thanks for the magnet/motor dissertation.

but.....why are the readings so different when the mags are in the can? ...and are the readings lower or higher and does this mean that the mags should be zapped OUT of the can ?

and.......within a given class, will the timing of the armature have an effect on the strength of the magnet you should use?

and.... if that ain't enough, what do you recommend for 16-d on a 13.8 volt track?

xxoo richard MUDHEN marnhout

p.s. and how does this relate to Einstein's unified field theory?;)

[GearBear]

Originally posted by mudhen
but.....why are the readings so different when the mags are in the can?

Now you know why Lee Gilbert doesn't worry about matching his magnets! As soon as you put the magnet in the can the magnetic field changes! Then to top it off if you put it on top of a flexi chassis it changes again! Now on a car where the chassis was plastic if might make more difference. Who knows. I guess you can get out and test test test! :)

[Monty @ B.O.W.]

Cheater, thanks for the sentiments. Hey, the man asked a great question!

Eap9, that could be anything from a fairly low powered track to relatively strong. There is pretty good power at the source, but the wiring in between is what counts. Never mind what the computer says, thats just a report of what the trackowner programmed in as a track description. There isn't a meter at the lap counter measuring track voltage. SRT has a nice little routine that allows the computer to display a different voltage setting if you had something like a qualifying power boost that was switchable from the race control area. The best way to assess track power is to use a fast class of car, and compare practice laps while alone on the track to race laps with all lanes running. A high power track will have no real difference. Most tracks will drop off to some extent. If the lap times are off by more than .2 seconds, I call it modest power. At .3, I start calling it low power. At that point, you'll feel it when other cars deslot.

Richard, the readings are always higher in the can because the can contains leakage of magnetic energy to the great outdoors. The readings will be even higher in older, thicker cans. Since that doesn't describe todays fastest motors, thats proof that strongest isn't always better. For your home track, try about 380 on my scale for a 16d. Don't ask me about Einstein. The man never saw a slotcar and I never had visions of subatomic physics.

Gary, the reason Lee can't worry about matching magnets is his insistance on cutting the backside of the can up to run an axle in close proximity. That does wreck the match because the can has lost symmetry. Incidentally, its a fact that most of us refuse to lend Lee a motor at out of town races unless he promises not to cut on it. That goes for Greg, Roy, Myself, and most other likely suspects. He isn't always right, you know. I gladly borrowed Lee's GT12 roller at the Div.II Nats this year for my son when Lee announced he was to busy to make the race. Used my motor of course - no extra notches, and geared a full pinion size taller than Lee reccommended - and ran away from the field. Lee - and I'm trying to be constructive here - needs a local track with real power so he can learn about motors under conditions other than a flat 12 volts.

[Jim Person]

Mudhen, just a word of thanks for asking such a great question. The replies were very informative.

Special thanks to Monty for the information!

[mudhen]

one of the wing guys mentioned something to me about reversing one of the magnets in the can . he was of the opinion that crossing the fields like that created a stronger overall force. so.... yea? nay? maybe?

xxoo richard MARNHOUT marnhout

[Monty @ B.O.W.]

Richard,
Your wing racing buddy was probably talking about paying attention to which tip edge of each magnet was stronger, and then making sure that these stronger edges were set diagonally opposite each other in the can.

He couldn't have meant to reverse the polarity of one magnet. That would make both the same, and the motor will not run at all in that case.

[eap9]

Hi Monty.

How would I know which tip is stronger if I don't have a gauss meter?

[Speedshop]

Well, here we go again Monty. First I have a question. Is it harder to make a motor run on low or mild power or high power? Personally I find that with low power the job is harder.

On your son's win in the Expert GT 12 race at the USRA Div II Nats you used a 36 degree timmed arm so you had to go to the 8 tooth pinion for top end speed. Your gear choice always goes along with the type of motor you use. Alan did a great job of driving in that race making some of the best drivers in the country look like amateurs.

To find out which one of us us right you need to take the Speedshop Challange. Next time we are together on a banked track with good power let's take one of your pratice motors (one you really don't care about that much) and run it in a car checking lap times without any can or magnet cutting. Then we will pull it out, cut the magnet and can until there is only a small amount of can remaining to hold it together, remount the motor in the same position and check laps times once again. This should prove once and for all which one of us is right. The loser buys dinner!

[Monty @ B.O.W.]

Lee,
OK, you're on. I'd say lets do it to one of YOUR motors, but you've probably already cut all of them :-)

[Speedshop]

Monty, we will have to use one of your motors because the whole idea is to find out if "matched magnets" make a difference. I don't match my magnets so it will have to be one of your match magnet motors that we can cut the back magnet and can (unmatch the magnets) after first testing it with matched magnets.

[Ben Taxel]

I sure hope you guys post the results of this testing, i'm really curious myself......ben

[oldweirdherald]

I'm glad to see that you two can be such sports about settling this debate in such a fun and friendly challenge.

You two have provided some lively discussions, raising some interesting opposing viewpoints for years, and it is fun reading and pondering over the merits of each of your arguments. We the readers, always benefit, and I'm sure that MANY readers will be extremely interested in the results of fair and impartially set up challenges that hopefully will reveal some interesting results. I look forward to it.

There are a lot of variables at play here, and it already has my curiosity going. Whatever bad effect notching the magnet may have on motor performance, may also be offset by the improved handling by allowing the motor to be mounted further back (this change should be allowed in the test, since that is a crucial element in the comparison, and the reason for notching the magnets in the first place). Actual lap times on the track should indeed show the overall comparison in the results.

Monty - as far as the prospect of wasting one of your good matched magnet motors goes - I'll offer a suggestion. After the challenge - we can raffle the motor off here on OWH. I'll pay you full value for the motor, and the proceeds can help fund OWH! :D
Of course, the motor may only be of use where notching is legal, but I would expect enough PNW IMCA racers alone would enter to pay for the motor! If that won't work, I'll knock off your ad bill to pay for it and I'll race it! :cool:

So when's the next time you two get together - Western States Champs at Santa Maria? I can hardly wait!

[Dan P]

"(this change should be allowed in the test, since that is a crucial element in the comparison, and the reason for notching the magnets in the first place)".....

Good point Paul, but the object of the test is to determine the effect of notching on the performance of the motor, not the whole car. Mr. Gilbert's suggestion of mounting the motor in the same place is the right way to go. Test results would be more worthwhile.
How ya been, boss? :)

[oldweirdherald]

Good point.

I'd like to see both results though - as the debate has always involved not only whether the notching hurts performance, as well as if moving the motor back improves performance.

I'd say - get some lap times - then notch the motor and put it back in the same place - get some more lap times - then slam the motor back as far as it'll go and get some more lap times.

My prediction would be that the second test might possibly show a slight disadvantage in lap times over the first, but the third test might show the fastest times after slamming the motor back, due to improved handling.

Sure would be an interesting test - and I think it would be well worth it to test all three ways.


(Haven't seen ya online much Dan! New job must be keeping you busy! I've been swamped... I should be able to get all the Enduro de Chico pix (both years) posted on the new OWH Photo Gallery very soon, and will send you those Chapparel pix too!)

[Monty @ B.O.W.]

Paul,
I'll be there, will Lee?... Lee was at the WSC last year, but that was when Greg was managing Uncle Kal's, and Kal's has a flat road course. Foster's does not, but the paperclip is in excellent condition. Hardly qualifies as a high power, longer track though. Probably will prove my point however. Strangely enough, here in the land of swoopier tracks, we often shift motors forward ON PURPOSE, to improve handling :-)

[Speedshop]

Monty, I won't be at the Western States this year because there will be no real Eurosport racing. Come to Rohnert Park for the West Coast Champs. Frank has a King track that would work well. If not then the next time we will be together is most likely the Div II USRA Nats in Penn next year.

With a year's promotion on this Challange Paul could sell tickets and take bets on who is right. We should remont the motor back after testing the magnet theoy so we can also rebunk the "motor foward for better handling" theroy.

[mudhen]

lee, i can really appriciate you and monty having a shoot out to settle things , but what about my question? if magnet matching is of no use to you, then what about the relative strength of magnets for differing classes? do you agree with monty's assesment? or if you disagree then what would be YOUR selections for various course/power supplies?

xxoo richard MUDHEN marnhout

[eap9]

Now this is getting really interesting now. Lee are you trying to tell Monty that even in wing car racing moving the motor back would be more advantageous than moving it forward?

For Monty:

I can see how easy it is to move the motor backward by notching the mag but how to you move the motor more forward that is what I want to know now. Thanks.

[Bill from NH]

eap9, not to steal Monty's thunder, but as you increase the angle of your motor to the rear axle, it shifts the motor's weight forward. Likewise, as you decrease the motor's angle, the weight shifts backwards. I used to hear that on flat tracks you want the weight back, but on the faster banked tracks it was better to have it forward.

[Speedshop]

eap9, there are two reasons we move the as far back in the chassis as we can. First the farther back the motor (weight) in front of the rear axle the more bite you car will have. The second reason is for durability. On flat tracks with G 12 motors on up we use 7 tooth pinions and even 6 tooth pinions on Eurosports. They do mot make angled 6 or 7 tooth pinions so the farther back your motor the less chance you have of stripping a gear. With the small Eurosport motors now we mount our Speedshop motors in Speedshop cars almost completely sidewinder.

Being an old wing car racer myself I can see no reason we would not want all the traction we can get on all ore slot cars.

[eap9]

Hi Lee.

I can see your point specially on our hillclimb track where the first turn is flat, this is where I lose grip even with full hub piranha tires. So I could not take that turn as quickly as I dare want to. If I use a body with more downforce I lose speed in the straights.

Now my question is, how do you cut the mags efficiently since I also do a lot of Gt-12 racing? Can I use my dremel?

[Monty @ B.O.W.]

The motor angle is just another variable that can be used to tune the handeling of your car. It IS true that as the angle gets over 10 degrees or so, a tapered pinion will be required to maintain integrity of the gear mesh.

As we can see by Lee's examples (which I mostly agree with in context), he continues to live in a very small niche where all tracks are flat and most cars use open class motors, even if they are wing cars. Most of us more eclectic types realize that for better or worse, most tracks are at least modestly banked, and there are more racers overall as the motors get slower - even in wing racing.

At the heart of Lee's philosophy is the notion that you can't have too much bite. This is largely true with eurosport cars which have to hook up a lot of power on small diameter tires with no glue and modest, if oversized for scale, wings. On the other hand, I believe that too much bite is a common occurance. ANY car that tilts has too much bite. Any car built for low traction conditions that finds rubber accumulating on the track will eventually suffer from too much bite. A wingcar with tires too soft gets too much bite. Cars using low downforce bodies (i.e., Nascar) usually develop too much bite. Its a matching to conditions problem, usually cureable by proper tire selection and/or modification. However, cutting your tires is an irreversable modification, whereas taping the chassis elements is not.

My comment about moving motor weight forward is based on personal experience as well as observation of certain people. SoCal racers well remember Chuck Panno (Crazy) and his penchant for usually having the fastest production chassied cars around (whether or not he could drive them consistantly!). Chuck was a master tuner - and worked extensively with motor angle. More than a few times, he cured either tilt or chatter on my cars by pulling the motor forward as much as 1/8". Obviously, I'm referring to the center of the motor, as he left the gears meshed...
Another good example, from another type of racing altogether, is the latest batch of Slick 7 Group 12 chassis. The Vampire II and Express III chassis are quite effective (an overage geezer with poor eyesight is leading the SoCal spray glue series with them... me!) and differ from their immediate predecessors mostly with increased motor angle. Hey, its just one of many methods of putting your cars into balance.

Oh, Roy - the magnets we were talking about earlier, that you took a small cut in... they now measure 442 and 439. Just imagine what a real trench would do!

[eap9]

Hi Monty!

Thanks for all the information. Due to the speed that wings cars attack the turn, there are only 2 ways it will deslot when taken to the limit and that is by tipping from too much grip or the tail sliding out breaking its grip.

On our hillclimb, the first turn is flat and this is where most of the de-slotting occurs moreso on the inner lanes? What normally happens is on the inner lanes the car has a tendency to tip and on the outer lanes the tendency is for the tail to slide out losing speed or ultimately de-slotting. But definitely the problem is more on the inner lane where you lose a lot of time.

What I am trying to find is a how I can make the car handle better on the inner lane without compromising its handling on the outer lanes.

[wstender]

Dear Monty,

Thanks in advance for answering this question. I noticed on you last post that you said taping could help control tipping on stamped steel chassis. Since I am fairly new to this (after a 30 year hiatus) I am wondering how you use tape to cotrol bite and tip. Any info you could give, including theory, would be helpful. Anyone else that wants to chime in on this would be fine too!

Also Monty, I would like to thank you for taking the time to talk with me on the phone about a month ago. When you guessed that I was from New Emgland because I wanted unbalanced 16d's you blew me away! You will be glad to know that when i presented your point that balanced american made 16ds made for a more leval playing field, he agreed and changed the rules. The only people that got sore were those who were cheating anyway! I will probably contact you in a while about buying arms. Thanks for all you help and taking time to explain this hobby to newbees

[Monty @ B.O.W.]

Bill,
First, let me start by acknowledging that the absolute master of the tune-by-tape method is Paul Ciccarello. Direct the most specialized questions to him.

Basically, though, tape across the center and onto the pans, depending on placement and size, will reduce the motion between chassis components without eliminating it. There is both side to side motion and up and down motion to be considered. Tape at the front of the car dampens mostly the side to side, and can reduce chatter. Tape more toward the rear will restrict both motions, effectively reducing bite and controlling tilt. Tape also has the tendancy to reduce chassis noise.

Eap,
When a wing car tilts out of a tight corner yet slides in a wider corner, you are suffering from a lack of nose pressure. The inside of the corner is so slow that the body is not helping enough with the wings. Try spreading the wings some, pulling the body forward on the car, shortening the braid (particularly effective if there is too much glue present), and as a last resort, adding weight immediately behind the guide. Do NOT add weight elsewhere on a wing car. If only ONE corner is that flat and difficult, you can also bias the car by leaving the tire wider on the inside of that corner, and/or cutting or taping the spoiler for more downforce on the inside.

For years, I had noticed that those of us who race both scale and wing cars had less 'one corner trouble' than pure wing racers. I came to realize that the scale racers tended to use far more brake than wing only racers. Weight shifts forward during rapid deceleration, and keeps the guide buried in the slot where it belongs. The exception to this scenario is in heavy glue, where the reacceleration after braking will lift the front. The wing spreading will be the most effective cure in this situation.

[Speedshop]

Mudhen, I go along with Monty on magnet strength. Basically, the higher the power the stronger magnet you need and the lower the power the less magnet you need. Also, the milder the arm the less magnet you need.

As Monty said my theory is you can not have too much bite. As I look at these posts it seems that racers are having trouble with "tilt" on flat turns. Monty says move the motor foward to help this. If that ture the we should be running inlines on South Hill Slot's Canadian White Track. People think the White trace is flat but thats not true. It's banked, BANKED the wrong way or OFF CAMBER. How can our cars work with the weight moved all the way back for more traction on an off camber track? On top that that we drive the White like a wing track. If you don't brake and punch the turns you lose.

Tilt is cause be bad car setup. There is no way you can have too much traction usnless you are using a very low power motor like a Falcon. With lots of rubber on the track it can bog the motor and then you will have to narrow your tires.

Finally I use a Dremal with #409 disks to cut the can and magnets on my motors.

[Dan P]

First I want to say thank you, thank you, thank you!!! -- to BOTH of you for taking the time to share your knowledge with us mortals here on the OWH board.
Monty, you said grooving the magnet reduced your match by four points on a Trik Trax unit - shoot, I use one also, and consider a four point difference a perfect match!!! Do you really think such a minor variation makes a difference?

But, this is a great opportunity to extole the virtues of Best of the West products, and give you a little plug! I've bought a couple of your setups and a couple of pairs of your mags, tested them on my TT unit and they were perfect. (different numbers, my unit reads a few points higher but the match was astounding). Frankly, I'm amazed at the accuracy and truth of what you write on the mags. No wonder your stuff wins so many races.

Lee, you say there is no way you can have too much traction unless you're running a Falcon - this may be true for Matt, Neal, Paul C. and others of their ilk but for an average (OK maybe BELOW average!) driver like me, too much grip can and does sometimes happen. More horsepower just reduces the time between deslots!
Granted, chassis tweaks should be attempted first, but when all else fails a narrower or harder tire usually makes my cars manageable, allowing me to make more laps and win a race now and then.

And now the Speedshop plug -

Without a doubt, THE BEST tires I have ever used. (I've never used any of your other stuff, sorry!)

So here's what I think -
On tracks where horsepower is important, matched mags are important. On tracks where handling is paramount, go ahead and cut the can if it helps you through the turns. Simple as that.

One time, Matt Z. took one of my best motors and cut the grand canyon in one side, I could have killed him! But guess what, lap times increased and the car was easier to drive ON THAT (flat) TRACK.----
The following week I raced on a King and I could feel how much power the setup lost (Thanks Matt
:mad: )!!!

I think the results of this challange are pretty predictable.

Lee, the motor WILL slow down.

[eap9]

Hi Monty! thanks for the help. I will try your suggestions however I do not understand what you mean by spreading the wings? Can you please elaborate on this subject. BTW I also like a lot of brake in my wing cars simply because I can take the car deeper before hitting the turn.

[Monty @ B.O.W.]

Eap9,
Spreading the wings means folding them just above the front fenders so that they splay outward. More air will be channelled over the body. In addition, forces acting on the front end of the wings themselves will vector more DOWN than before, increasing nose pressure. Warning: The increased drag will slow the car on the straights noticeably. Of course, once off the gutter lane you can straighten them up again.

Dan,
Four points is a TON! Remember, on my scale, 99% of all Mura or ProSlott Mega II magnets fall between 432 and 452. Four points is a full 20% of the available spread. Please note also, the little message for Roy concerned a magnet that he had barely notched an edge of - perhaps .030" deep and .080" long. I once did a full trench job for a British racer and found the magnet to be a full 50 points lower. Our solution was to groove BOTH sides of the motor, talk about a long job!

For everyone- The easiest and fastest way to cut on ceramic magnets is with a small diameter diamond plated mounted point cutter. Tool supply firms such as Enco sell them in sets for very nominal prices.

Finally, for Lee
Why is it that any experienced wing racer will swear by drilled hubs, hollow axles, magnet wire for the rear portion of the leadwire and other lightweight tricks to INCREASE BITE during qualifying sessions? And, why do those PlaFit powered turbos handle so well with such a light motor? Many, if not most of us, subscribe to the pendulum weight theory of slotcar handeling, holding that weight at the rear of the car DECREASES traction. The exception would appear to be on flat or off camber tracks. I suspect that where one puts weight on a car is tied to a multiplicity of variables. Over the years, your total tuning lore has evolved to favor rear weight. Mine has tended to favor weight in front. To get the same effect, we are probably using different bodies and body dimensions, different tires, different chassis flex patterns, different chassis articulations, and probably other variables that I can't think of at the moment.

[Speedshop]

Monty, when you move your motor forward you are moveing the weight distribution forward and reducing bite. The biggest improvement in slot car came in the mid 60s when Gene Hustings put his motor in sidewinder. This moved the weight back giving him more traction and all racing slot cars have been sidewinders to this day. Gene recognized something; weight equals traction. If you want to see traction check out a MAC truck.

What we are dealing with here is weight distribution. We want as much weight as possible in front of the rear wheels to increase traction. When wing car racers use light weight parts to reduce the rear weight they are really just reducing total weight because with full glue and wings weight distribution is not the factor that it is in scale. Using wing cars as an example doesn't help us understand scale cars.

We want as much weight as possible in front of the rear wheels for bite. If we put weight behind the rear wheels we get the "pendulun effect" you mentioned. A proper weight distribution is what we are looking for. For example, if we put a C Can motor in a current Eurosport chassis we will have far too much weight and have to increse the chassis weight to acheive that proper weight distribution. The reverse is true if we put a mini Eurosport motor in a flexi car. That car will have far too much weight foward and we will have to reduce the over all weight to get that proper weight distribution.

As Dan P mentioned when Matt Z cut the can and magnets and put his 16D back toward the rear wheels the car turned faster lape times. More bite, faster times.

Dan, have you ever wondered that your car may not be handing right because you have too much motor angle and too little weight on the rear wheels. I know of no flexi chassis today that is so light that your motor has to be moved foward. As for your motor slowing down with notched magnets and can I stand by the Speedshop Challange. After that we will be able to put this question to bed.

[Monty @ B.O.W.]

Why does the handeling improve in a production chassis when a PlaFit or Falcon replaces a heavier motor? For many months, PlaFit powered cars actually beat Contender motor cars on Kal's Korkscrew. Oh, you could get a slightly better lap time from the faster motor, but lap totals were stubbornly similar. When the power was improved, the faster motor finally made more laps.

You also feel that wing cars shouldn't respond to theory because they are used in glue. This is not always true, of course, and one of my favorite classes right now is G12 in sprayglue conditions, often no stickier than our scale meets. In my view, a wing car is just a GTP with even larger wings... in any case, the latest Kelly or ProSlot motors handle BETTER than their heavier predecessors, with or without glue. Fact is, GT12 cars handle better with the lighter motors, and so do GT1 cars. As the power diminishes, we tend to run less and less tire (yes, ability to spin tires comes into play here), but those cars certainly don't need additional bite.

[wayne h]

1. light is good. a light car gets its "weight" from down force generated by the body. a lighter car handles better than a heavy car because of the laws of momentum and interia. a light car's "weight" is a function of its speed. that is, the light car develops adequate "weight" as it speeds up. light cars accelerate quicker (a=f/m). lighter cars brake quicker. lighter cars are easier on tires. therefore you can start lower, which also equates to better handling.

2. balanced cars are good. it is not so much a matter of how much the car weighs, but rather where the car is weighted. low c of g is critical. as a starting point for tuning purposes, i think that the car should balance around 2/3 of the way back between the guide and rear axle. body position is also critical.


wayne h.

[Larry Geddes]

Here's an observation that may apply to chassis weight distribution. Call it the "yardstick theory". Imagine two standard yardsticks with metal weights of equal size taped to them. Let's say the weights are 1 pound each. One has the weights at the ends (one at each end), & the other has two weights taped together at the center of the stick.

If the overall weight is checked on a scale, both sticks weigh the same, 2 pounds (the weight of the stick itself is uniform from end to end, is minimal compared to the metal weights, & is the same for both sticks, so it is neglected).

If you support both ends of either stick on two scales, each scale shows 1 pound.

If you balance the sticks on a knife edge, the CG is at the same spot for both sticks.

The difference is that the sticks don't respond the same to outside forces. Imagine holding the stick with the weights at the ends with your hand at the middle, & try to twirl it, baton-fashion. Then imagine doing the same thing with the other stick. There will be much more inertia (resistance to a change in motion) with the stick that is weighted at the ends. The end-weighted stick will feel sluggish & the center-weighted stick will feel nimble.

So what? Well, if the guide represents one end of the yardstick & the rear axle the other end, the same thing that happens with the weighted sticks can happen with the chassis.

In my humble opinion, a rolling chassis where most of the mass is kept in the middle will be quicker & more responsive than one with a massive front end OR rear end. Note that the amount of weight on the tires & guide is EXACTLY THE SAME in either case, & so is the balance point. Although the weight distribution is the same, the mass distribution isn't, & that's what affects inertia.

This may be one way to get enough weight on the tires for traction without increasing the "pendulum effect".

[Rotorranch]

Larry.....what you have described in 300 words or less, is simply known as "Polar Moment of Inertia" ;) A car with a low PMI will turn quicker than a car with a high PMI.

Rotor

[Larry Geddes]

Rotor ----- Ohhhhh, ......... cool! I didn't even know there was a name for it! :p Thanks!

So if a low PMI is a good thing, how does one go about getting it? Steeper motor angle? If adding weight, add it in the middle? Keep the extremities as light as possible? All of the above? I'd say yes.

[Rotorranch]

You actually answered all of your own questions! ;)

Real race car designers strive for low PMI by placing all the heavy components between the axles. Slotcars have sort of an exception, as they pivot from the guide flag, rather than around the center of the car. If adding weight to a slot car, I would try to add it as close to the flag as possible, to maintain a lower PMI. Of course, there are always exceptions to the rule. :rolleyes: Generally, however, the lighter you can keep the total weight of the car, the lower the PMI. More weight at the rear of the car, increases PMI, or "swing weight". There you do get the "pendulum" effect, much like a rear engined Porsche 911, which can be very "tail happy".

Rotor

[eap9]

Hi Monty!

We had our regular boxstock 12 race today and I incorporated what you said and the difference was astonishing! Not only did I win the race, I also had the lowest lap time of the race from the white lane! The splayed wing worked well with the narrow tire on the outside. I have'nt tried moving the weight forward yet but will do so on the next race.

Question, would it be advisable to use an 8/35 gear combo using an angled pinion gear so I can increase the angle of the motor in relation to the spur gear and move the motor forward?

Thank you very much.

[Dan P]

Hi again all, I love this kind of discussion and can't stay out of it!

Since slotcars have so many other different things going on than a real car (namely a guide flag and rigid axle) I'm wondering if a HIGHER moment of inertia might not be beneficial in some circumstances?
Seems to me, if you make the car slide gradually and predictably, that's good. A car that's loaded with the weight up front would be twitchy.
Could this be why, on some tracks, getting the motor way far back is the way to go?:cool:

[Monty @ B.O.W.]

For Lee,
Yes, the anglewinder was a successful, lasting concept. However, anything taken to extremes is usually wrong. Gene got the weight furthur back than an inline, and improved mesh. He didn't slice up the motor.

Larry, Rotor,
100% agreement! Added weight belongs nearest the guide pivot. Weight loss is best when it occurs at the extreme sides and rear, and of course, the top! There is also a polar moment for vertical roll!

Eap,
The hazard of increasing the motor angle is poor or easily damaged gear mesh. Instead of 8/35 (4.37:1), try 9/39 (4.33:1). The slight difference in ratio will be compensated for by the better mesh, and with the larger diameter gears the entire motor will be furthur forward without increasing the angle.

[eap9]

Hi Monty!

Thanks for your advise. I always gear 9/39 but when you suggested of moving the motor forward, I thought that you have to increase the motor angle so the best way to achieve this is to use smaller gears.

On wing cars, is it better to minimize air that is passing under the body? how low do you mount the front end of the body?

Thanks.

[Speedshop]

If the "pendulum effect" was the a big problem we would all be running sidewinders with front wheel drive!

As for wing cars you want the air to go under the body. A percentage of your downforce comes from the "swoop" in the body using ground effects. If you don't believe me take a piece of .010 lexan and seal your car's underside all alone the chassis. You will be looser than a goose.

[wayne h]

have you ever wondered why, with a little practice, virtually anyone can balance a bicycle? it is that gyroscopic effect caused by the rotating wheels. try this: hook up a motor to a power supply and try to move it around. it is relatively easy to rotate it in the direction that the arm is rotating and relatively difficult to rotate it along the armature's axis.

so which motor orientation will give a less tippy car (ie. one that handles better)? it is easy to see that a sidewinder will handle better than an inline arrangement.

pendulum - shmendulum:

yes this is an important consideration. the correct length and weight distribution will depend on the track, motor weight, chassis, etc. as an example, at the AFTW's i ran a jk scorpion chassis in g-10 and g-12. for g-10 (with full c-can/contender motor) the car handled better for me in the "short" chassis position. to get the same handling in g-12 (with a lighter strap 12 motor), the car handled better for me in the "long" chassis position. i qualified 5th in g-10 and 2nd in g-12. there, now my secret is out!! a balanced car is the key to good handling.

wayne h.

[eap9]

Hi Lee!

Thanks for the info on the wing car body mounting. What about for the Gt-12 bodies, would it also be better to let the air pass underneath?

Thanks.

[Dan P]

Wayne, one aspect of the gyroscopic effect that is very important in slotcars is the phenomenon known as precession. The axis of a spinning gyroscope moves in a cone shaped circle and in a slotcar motor, this translates into downforce if the motor is spinning in the right direction.
The more RPM, the stronger the effect, which is one reason euros and opens handle so well.

Have you ever done that experiment with your students where you have someone sit in a swivel chair while holding a spinning bicycle wheel? The chair starts spinning around on its axis. That's precession.

[Dan P]

"on my scale, 99% of all Mura or ProSlott Mega II magnets fall between 432 and 452. Four points is a full 20% of the available spread"...........

That's true, but four points is less than one percent of the total magnet strength.

If I have two magnets and one is, say, 450 and the other is 454, then there is less than a 1% difference between the two, a pretty good match. I consider two percent or less a good match (anything over an 8 point spread means the mags are NOT matched.)

I put the strong magnet in the front (on flexis) figuring it will weaken some when the motor is soldered in.

I am certain the match changes by AT LEAST four points when the mags are installed in the can, and the motor is installed in the chassis. That's why I don't think it's that important to have a "PERFECT" match!

(But, don't change what you do, for heaven's sake! I DO start with a perfect match when possible, and your mags make it possible!):D

[Speedshop]

To all you magnet matchers out there: Because your magnetic field is made up of not only your magnets but also your can (if not we would be running carbon fiber cans) what do you think happens when you flop that exactly matched set up down on top of you flexi chassis? What happens to your matched magnetic field when you add all that flexi car chassis metal?

The answer is simple your matched set up is now quite unmatched. But even with this we are able to build motors that run in flexi cars just as fast as in cars without this added metal. If this were not true then motors raced in GT 12s should be running much faster than one in you flexi.

eap 9 the air on your GT 12 is not as important as in wing car racing. Wing cars are very light and much faster than GT 12s so aerodynamics affects them a lot more. You do want air to exit on GT 12 also otherwise it will create lift under your car and that's the opposite of downforce.

[Monty @ B.O.W.]

Dan,
If you start with enough magnets (I have hundreds!) its actually rather easy to come up with numerically perfect matches. This still doesn't take into account relative tip strength, but its a good start.

I have done extensive testing with the effects of soldering on the motor vs. magnet condition. There is almost no change at all after temperatures return to normal. I do take care to solder quickly and efficiently, which means motor surfaces properly tinned beforehand, etc. I DO use acid flux on motors. I also clean it up immediately afterward.

As far as having the field become unbalanced due to proximity with chassis components, this is unavoidable, but not as extensive an effect as you might think. Actually, the axle has an effect also. You can play with a motor on a power supply by waving various metallic objects at it (such as an axle, chassis brace, even another magnet) to satisfy yourself that there is an effect, but not that gross. The can has quite a shielding action.

Lee, there may be little difference on your short low powered track between GT12 and Flexi 12 cars in sheer speed, but where I race GT12 is faster in a straight line, period. The difference ain't subtle at all. When you were at the WSC at Kals you should have noticed how the better GT12 cars were running the big hillclimb in 3.3 seconds. Two weeks ago I won a SoCal USRA boxstock race on that track... my fast lap was 3.3 seconds! Yes, GT12 cars make mondo horsepower, cause they still don't quite handle like a wingcar! Back when we raced Flexi12 cars in SoCal, the times and totals were nowhere near what we get now with GT12. Sure, handeling is a large part of that, but the unfettered motors have a large part also.

[Zippity]

All my recent reading about magnets/zapping/gauss meters/matching magnets etc etc has been a great learning curve, which hopefully, I will soon be puting into effect :)

Monty/Lee - did you guys ever sort out, let alone settle, the above debate?

I'd love to know the outcome.

Or is the answer - 49? :D:D:D


Yours in learning.......

[kiwiracer]

Just to add my two cents worth to the whole magnet debate.We race 1/32 GP12 cars which for all intenets are a euro chassis with a bigger motor box.There is one chassis manufactuer for the UK that makes the fastest GP12 chassis by far.But to get these cars to handle like a euro (and they do)the motor has had to be run as far back against the axle and at a really shallow angle.The only way to do this is to notch the crap out of the can and magnets so what we might or might not lose in magnet strength is far out weighed by the superior handleing of this chassis.There are two other chassis that come from the UK that are close to this chassis in handling but not quite there,they don't have a notched can or mags so that big lump of a GP12 is sitting futher foward and at a steeper angle.so my point is this sometimes a small compromise in one thing can give you a huge gain in another.Of course these cars work on our tight 4 lane tracks i can't say if this theroy works on big 8 blane speed bowls where you can let horse power cover up a ill handling car but just using straight line speed.
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