This article is about what I encountered and learned so that the IROC hot rods actually ran close. Being built close and running close is a huge difference. I was careful when measuring and assembling the chassis. I used the same chassis, matched top plates, close matched magnets, close arms, same brushes, pick up shoes and springs, axles, wheels tires, front ends... I think you get the picture. Even though I did all this the cars were all different when tested on the track. Some were fast out of the gate... others were mediocre and others were just down right dogs when testing on the track. So now the real work began... how to tune them to run close.

The first thing I did was adjust the pick up shoes. What I found out was the closer I got the wear pattern on the pick-up shoes to match between cars the closer they ran. They were closer but not there yet there were other issues lurking.

After I got maximum pick-up shoe contact and consistent wear pattern I then worked on restricting the shoe travel by bending the front of the pick-up shoe. Well after I did that I had to re-adjust the shoes again in order to create maximum contact and consistent wear pattern... That was a lesson is patience and persistence...  :-)  NOT! But it did yield better and closer performance on the track. 

I had lapped the gears and I had two cars that were more noisy than the other two. So after looking at the chassis really close by turning the rear wheels and just watching what was going on with the gears, arms etc... I found that the front magnets on the two noisy chassis were actually moving (loose) in the chassis. They were moving back and forth much like an antique clock pendulum lever. You could also hear a significant difference between those that had this problem and those that didn't. 

So I had to search for two replacement magnets that were of close strength with the other magnets and that did not move in the chassis. When this adjustment was made I now had three IROCs that were running pretty close on the track. So now I still had one that was significantly slower. Again I took that one car off the track and tried to look at it closely. After a lot of frustration and observation I noticed that the armature shaft was actually touching the body when the chassis was mounted on the body. That said I took the body off the chassis and used my Dremel and remove some plastic from the body so the armature shaft did not touch or bind on the body.

When this was fixed ALL the IROC hot rods were now running pretty close with respect to lap times. It was amazing how their times were close, their responsiveness was close and they even sounded close as they were going around the track.

This was a lesson in how tuning is just as important as building. I would highly recommend building several IROC car sets. The more you build the more you notice and learn!! Happy Building/Tuning!!! :-)  

If you would like to see the race report of their debut M.A.S.C.A.R race click here.

Working hand-in-hand with the armature, this is one of the biggest performances decisions you can make. If you just keep trying different magnets you will eventually find a set you are happy with, but making an informed decision will net much higher performance. Generally speaking, the stronger the magnet the better the acceleration - too strong and your car won't  roll (coast) as far when the trigger is released. This is one of the many places where your driving style can be "synced" with the power of your magnets, armature choice and track design & layout. The most important thing about your car's magnets is that they are Matched. Mached magnets are a pair that have generally equal strength. If they aren't matched, even a balanced armature will be rendered ineffective because the stronger magnet will always pull the closest wind harder to that end of the chassis, creating vibration and potentially unstable operation.

There were many different Aurora magnets made for the pancake motor. The only way to determine the orgin is by their colors, or lack of them. One thing we've learned is you can always be surprised - magnet colors that are historically "supposed to be weak" can sometimes turn out to be stronger than you would guess! We know this through measuring with both our own home-built analog tester, and FRHO gauss tester & BRP comparative tester. Let's take a look at some different magnets by strength. We'll rate their strengths from 1 to 5 (5 being strongest) since that's how our analog meter rates them.

By the way, only tall (White/Red) & (White/Black) Magna-traction & X-Traction magnets rate a 5+. Before you get any wise ideas, cutting or sanding a set down will reduce their strength slightly. Also a pair of MT or XT magnets may be matched before you cut, but may not be matched when you are done. Keep this in mind if you decide to go that route, re-matching if necessary. Remember, actual gauss will vary from meter to meter, so our rating is a comparative rating based on our analog gauss tester.

We know these aren't Aurora, but they are also plentiful and powerful that they have to be recognized. The following "Factory" magnets are listed from strongest to weakest, so we put the JL X-Tractions first. If you want strong magnets for your Magna-Tractions, gat a pair of these. We have tested over 10 pair and they have consistent measurements and the strongest ceramic magnets for the MT/XT you can get. They are basically matche out of the box. We haven't "cut" a set down tor T-Jets yet to see if the strngth is any better than their JL 500 little brothers, but will report our findings here when we do.

If you want strong magnets for your T-Jet, get a pair of these. We've tested many pairs and they have consistent measurements as the strongest non-polymer, non-neo magnets you can get. These too are basically matched out of the box and are becoming more common in most Fray racing classes. They have a slightly different shape than Aurora magnets and fit a little snug in an Aurora chassis. If you think you are going to re-paint a pair and sneak them into an event, a good tech inspector will spot them immediately - don't try it. However, if rules allow for them, use them!

Depending on the rules, sanding or grinding the small rectangular "end faces" will not only produce a nicer fit (resulting in less chassis "twist"), but also bring the magnets just that much closer to the armature.

Also known as "turbo" magnets, these are the strongest magnets Aurora ever produced. Available in the ill-fated A/FX Super II cars and on the aftermarket, these magnets are easily identifiable by both color and a little "dimple" cast into the center of each magnet. The magic of the dimpled magnet is the "full orientation", meaning that manufacturing tolerances were such that these magnets should have a consisten strength across the entire face.

Some or all genuine Super II chassis came with fully oriented parings without the dimples! I don't currently own a Super II (it's been many years since I have) so I can't confirm or deny this, however, it went uncontested in the usually spirited discussion list. It was also reported that there were carded black/red parings offered by Aurora that also displayed the dimple.

We've only ever had 2 pairs of these in our hands. They cam in the Xlerator slotless racing cars that have the "clamshell" tops and were also available in the Aurora aftermarket. they can also be identified by the dimple. There is speculation that these were simply Super IIs with a different color combo. That's probably correct, but the 2 sets I've had since building my magnet tester, they measured just a hair below Super II's in strength.

These were probably the strongest non dimpled true T-Jet magnets ever offered. We have a few "untouched" Tuff Ones and have tested the magnets, so we're pretty sure about the findings here. Green & White could also be found in most early XLerator chassis as well, with strengths in the same range as the Tuff Ones. It had been suggested prevously in the HO DL that Aurora wasted nothing and I believe it. As was probably the case with the White/Orange dimpled magnets, the White/Green XL magnets were possibly the same batch as the White/Green Tuff One magnets.

This is where things gett muddy. If you have a bunch of A/FX parts that got intermingled with your T-Jet stuff over the years, then you can't be assured of any type of match without performing measurements. The strengths varied wildly during the X/FX years with colors that matched T-Jet colors. Some were designed for blue armature specialty chassis, while others were for first, second or third generation A/FX cars - strengths vary wildly.

These are probably the most common magnets you'll find in the "Used" T-Jet market, due to the remaining NOS chassis available being (for the most part) outfitted with these. The strengths aren't bad, but they can vary. The Green/White combination has been reported to be a little stronger than the Green/Orange combination. Supporting evidence can be found on the VHORS site, specifically the results pages. We did find 1 pair of the Green/White combo in our collection of magnets and they did score towards the upper end of our rating system at 3.0

Bee careful when choosing these by color alone due to these colors being available as A/FX too. Pairing a rating 2 magnet with a rating 3 magnet can actually yield a lower performance then two magnets with a 2 rating. did you catch that?

Now someone may disagree with us, but this is what we have found. The earlies T-Jets had multi colored armatures, like the "Christmas Tree" Armature. Later early models had Copper wire/Grey tipped armatures. Christmas Tree Arms came from Aurora with Black/Black magnet combos and they are the weakest of all magnets.

The Grey tipped Armatures magnets came Black/Black as well, but the rear magnet had a white stripe on it. the pairs with the stripe were stronger than the pairs without. So again chance for mismatch due to the front magnets always being unpainted black coming in 2 strengths! Without measuring the chance for mismatch is high.

Thanks to Vincent Piazza, as he contributed much information during his extensive research and personal information gathering. Slugger, as he took the time to snap a photo of his collection of Pancake magnets and provide it to us for this article. Much of the information about out of production pairings was gathered from member of the HO DL.

*** Again HOSlotcarz would like to point out and thank Front Range HO for posting the original article. ***

For this project I will be building 4 hot rods. I had 4 Dash chassis on hand and I ordered some Dash hot rod bodies. The usual colors for IROC bodies are white, yellow, red, and blue if your running on a 4 lane track. If it is a 6 lane track then you will need to add a green and orange car.

One other note on this build. All the cars will be very close in specifications how ever they will not be exactly alike. There will be slight variations in magnet strength, and armature ohms, however, they will be very close but not exactly the same. That said, it shouldn't matter that much due to the fact that each driver will drive all 4 cars during the race.

The 4 Dash chassis are the version 2 chassis that has  the 16 ohm 2 lam armatures. The first thing I will do is to take them apart so I can tweak them as I rebuild them.

Next I check the the chassis for flatness. The great thing about the Dash chassis is they are consistently flat. To check this I use a tech block and some drill blanks. I insert the drill blanks through the rear and front axle holes. I then place this on the tech block. If the chassis is flat, the 4 ends of the drill blanks will be touching the tech block. Note that when checking for flatness the chassis is checked with the magnets installed.

Now I check the chassis and the gear plate. What I am checking here is the armature hole and the driven gear hole matches up between the chassis and gear plate. Again these Dash chassis seem to be consistent here also. And again I will use two drill blanks and a tech block. You attach the gear plate to the chassis and insert the drill blanks into the bottom of the chassis up thru the gear plate. When doing this you should notice a couple of things... the drill blank finds the matching hole and once the drill blank is thru both holes spin it. Is should spin and move back and forth freely. Now lay the chassis sideways on the tech block again all 4 corners should be touching the tech block at the same time. If the chassis and the plate pass these tests I consider them a match.

On a rare occasion the Dash armature will start throwing the windings. So as a precaution I use a drop of super glue on top of the winding. If your interested in this topic there is more about thrown windings here.

​I have used this method on some fray cars and have had hundreds of laps without an issue. It involves a toothpick and some super glue. Take a toothpick and put some super glue on it then put one drop on the winding of the armature pole. Using the side of the toothpick gently spread the super glue over the armature pole winding. You will notice the super glue will wick into the winding. If there is any extra glue then take a paper towel and soak up the excess by lightly touching a corner of the paper towel to the excess glue. Now repeat this process on the other two poles of the armature

Now repeat the process on the other 3 armatures.

Now let's take a look at the magnets. Given I am only using 4 sets I will use my magnet matcher and get them close. They won't be exact but they will be as close a match as possible. Again this should all come out in the end because each driver will have a turn at driving each car. 

Now let turn our attention back to the chassis. There are a couple of more things to address; the pickup shoe hangers and the chassis rivets. If you look at the picture below you will notice on the left you see the bottom of the chassis. Look closely at the pickup shoe hanger, you'll notice it is not straight. These need to be checked and adjusted before tightening the rivets. Also if you look to the right you will see the inside of the chassis... notice the 4 rivets I will need to clean these up by making sure the rivet material is below the bottom of the chassis when tightening the rivets.

I have a rivet tightening tool made by Fast Lane Racing. You can see more about their products here. Its a pretty good little tool to have It's made with two press tools, one for open rivet and one for solid rivet.

Solid rivet press on the left open rivet press on the right.

Next I'll install the new tungsten rear axle and crown gear. The rear gear lash on these are not too bad so it won't take much to shim it out. I have read some discussions on social media that some have started only shimming on one side of the crown gear and let the pinion gear hold the other side of the crown. So I will give that a try on these and see how it works out. So as I indicated earlier it did not take much to shim these crown gears. I only took 1 shim 3 thousandths of an inch thick. (0.003 inch). 

So for this I remove the magnets from the chassis, remove the gear plate, insert the pinion gear and clip the gear plate back on. Even though the picture below has the magnets in the chassis remove those magnets it will make this job less frustrating... Also make sure the pinion gear that you used when installing the crown gear stays with the chassis and that crown gear.

Now I use my home made crown gear install tool, pilot rod, and then use a wheel press to install the tungsten axle. If you would like a more in depth explanation on installing a crown gear you can find that here. 

Bottom of gears polished and installed on the chassis.

The next adjustment I make is to minimize the front to back travel of the pick-up shoe and create a better contact between the shoe itself and the pick-up shoe hanger. I use my pliers and make a very small bend at the back of the shoe. You can see the difference between the bent and unbent shoe in the picture below. The right shoe is the unbent shoe and the left shoe is the bend one. As you can see the bottom has a ever so slight hook. This helps to keep contact with the shoe hanger on the chassis.

So the next thing was to install the shoes. After that I pressed on the RT-HO indy/hot rod wheels and slip on tires part numbers RT-205 and RT-200.

​Then finally installed the RT-HO indy/hot rod front ends part number RT-190

Then I took the chassis and oiled them up and let them run on the break in box. 

And now the fun begins adjusting the pick-up shoes and fine tuning the rest of the chassis. As I said earlier in this article I had purchased some Dash hot rod bodies so I finished and painted them up... I think they turned out fairly well. If you would like to see how I finished the bodies you can see the article here.

I will be referring to different parts of the crown gear throughout this article, so let's get them identified and out of the way. For this article I will be referring to two different parts of the crown gear, the head of the gear and the tail of the gear. See the pictures below.

If you look closer at the pictures above you will notice that the gear on the right has a more prominent head than the gear on the left. The gear on the left is more like the standard crown gear for the T-Jet. The gear on the right is a RT-HO gear. You can build up the head of the standard gear using washers if you like. It usually only takes one. The picture below has two for demonstration purposes only. (See the below picture)

Everyone has their preferences about the the type of crown gear to use, for me, I like the RT-HO because of the prominent gear head. First it protects the gear teeth from the chassis, and second I only have to worry about adding washers to the tail side of the gear when trying to remove gear lash/play.

When I install a crown gear I use a wheel press, a guide rod, tweezers, and a home made guide tool. The guide tool was easy to make. I used a handle from a disposable sponge brush and an AFX Magnatraction front axle with the head ground down just enough to fit through the crown gear. Note: Do Not grind the head away completely.

The high level concept here is I use the guide tool to get the washers and crown gear aligned and in the slot correctly. While the guide tool is aligning the holes of the washers and crown gear it is then used to pilot the guide rod. Once the guide rod is in place I check the gear lash/play to see if I need to add or remove a washer. Once I feel that I have the correct washer/crown gear combination I then use the guide rod to pilot the actual axle.

I insert the guide tool through the chassis hole closest to the crown gear slot. I push it all the way through and then slide my washers  onto the tool. 

I then pull the washers with the tool to the chassis. This is why you DO NOT want to grind the head completely off.

I then snap the crown gear in beside the tool and push the tool forward through the crown gear hole.

I now insert the guide rod in the other chassis hole and use the guide tool to pilot the guide rod through the crown gear, washers and the other side of the chassis. You will have to learn to "feel" your way through this. After a while it becomes easy.

I use a guide rod that is 0.055 inches in diameter. It slides through the chassis holes and crown gear hole easily and minimizes the gear slop when checking for gear lash. When the guide rod is in position then check the lash/play in the crown gear using a pair of tweezers. I turn the crown gear about 1/4 turn and check the gear play. I repeat this until I rotate the gear completely. This is also where you will have to learn to "feel" your way through. This is also where I decide to either add or remove a washer. I have different width washers from as large as 0.015 to 0.003 of an inch.

When all is well with the gear lash it is now time to install the axle. The guide rod will pilot the racing axle through the washers and crown gear. For this process you will need the wheel press. See the picture below to set this up.

Now the last part of the installation is to press the racing axle through the crown gear, washers, and chassis axle hole. To do this you will put you thumb and forefinger together and squeeze the guide rod with one hand and with the other hand you will turn the knob on the wheel press. By doing this you will keep the ends of the racing axle and the guide rod together tightly when moving through the holes in the crown gear, washers, and chassis.

As with anything no one way is the right way. This is how I install a crown gear when trying to remove gear lash/play. Hope this will help some and give some some ideas to move forward. Anyway, may your crowns run straight and freely without any lash!! :-) 

I don't know about you but when I got back into this hobby the technology for these little cars had skyrocketed exponentially. One part of this included pick-up shoes especially with bending and limiting shoe travel. I started looking at one particular tool to bend the shoe from Scale Engineering. At first didn't know quite how it was supposed to work, but with time and help I was able to figure it out. Also when I came back to this hobby I didn't realize the importance of shoe travel. That said, If you're interested in this then click the read more link.

For me, the initial part was setting the tool for bending. I use RT-HO front ends so to adjust the tool so the shoe would bend at the appropriate place I used a 5/32 inch drill bit to adjust the tool. See picture below on how I did this. Base on the front end you use and the size of the tires you have on the front your adjustment will be different. Use your drill bit to set the bend height and then tighten the Allen Screws.

The next step is to put your pick-up shoe in the bending tool tighten the clamp and then make the initial bend on the shoe.

After making the initial bend on the shoe, your shoe should look something like the picture below.

 Then using your pliers and a little trial and error fitting you will adjust the bend in or out to fine tune the travel on the pick-up shoe.

Anyway... for me, I like the shoe to be even with the bottom of the front tire. The reason I like this adjustment is I need all the help I can get with minimizing de-slots. As soon as that front wheel comes off the track I want the power to shut down and the car to settle back on the track. 

By moving the shoe tab you have created out you will lower the shoe and conversely moving the tab in you will raise the shoe. This will help you fine tune the travel.

The next adjustment I make is to minimize the front to back travel of the pick-up shoe and create a better contact between the shoe itself and the pick-up shoe hanger. Again I use my pliers and make a very small bend at the back of the shoe. You can see the difference between the bent and unbent shoe in the picture below. The top shoe is the unbent shoe and the bottom shoe is the bend one. As you can see the bottom has a ever so slight hook. This helps to keep contact with the shoe hanger on the chassis.

Here's a great video on this subject from slotking22 also known as Mike King. Take a look at his video below. It will be time well spent!

After adjustment you should get a wear pattern on the shoes similar to the picture below. Plenty of contact the full length of the shoe to maximize contact and therefore maximize current going to the armature.

Anyway guys... happy bending and adjusting!!! :-) 

First, before we get started I would like to thank Scott Udave for sharing the following information. This info is a combination of a friend of his that was a jeweler and Scott himself who polishes brass professionally. Had I not posted the original article with some errant information on social media he would have never shared the following information. I am appreciative of Scott's information.

The following statement is what started it all. "The first thing I do to a mass produced gear set is de-burr the gears using my Dremel and brass wire brush wheel. I do not want to use anything harder than the brass gears therefor the brass brush wheel." This is where I found out NOT to do this if at all possible because it leaves scratches on the face of the teeth that causes more harm than good.

Lap the gears, yes. When the gears have been lapped and worked in together, then polish the wear side of them.You want to remove the burr on the bottom of the gear surface that rides on the top plate. You also do NOT want to remove any brass from the top of the gears because you want to keep them as thick as possible so they run square with the next gear. Next, never polish the idler hole or gear axes hole. It's a wearable surface let's not speed that along. Let the gear wear to the top plate.

Before I start polishing I like using the Brasso as a start. It cleans and brightens the gears at the start. But that's just me. (FYI guys thats about the only sentence remaining from the original article)  :-) 

The following information concerns polishing. This is where Scott's knowledge as a professional polisher of brass comes into the picture. On only one side of the gear (the side that will ride on the gear plate) you will need to swipe it across 400, then 800, then 1200, then 2000 grit sandpaper. At this point is should be a mirror. If you would like to go further then finish with 2500 grit. Remember only on one side (keeping the gear as thick as possible). Also be sure to  polish the gear on a hard flat surface using a single layer of paper (No folds).

Scott then indicated that he had polished gears as thin as the rules allow and those gears did not run as well as the gears that were kept thick. This was because the thinned gears would not run on a flat plane. It created a compound angle which means compounded friction.

Scott then proceeded to politely state that the author of the original article might of meant well but basically did not know what they were talking about. That author was me and after reading his reply on social media he was correct. All that said, I have learned from this and it will make me a better T-Jet builder... after all that's what this hobby is all about!!

​Thanks again for sharing Scott Udave!!  Much appreciated!!

 Happy Polishing!! 

Originally available on the third generation "Tuff Ones" series of cars, these arms were also available on some of the earliest AFX cars as Aurora transitioned from "screw-on" Thunderjet 500 bodies to "snap-on" AFX bodies & chassis.

The Tuff Ones also introduced the 14t Cluster Pinion which was carried over to AFX chassis throughout their production run. These arms produced a fairly good mix of top speed and low end torque; and when run on 20V with the proper amperage these can really come alive. The early Tuff Ones arms had copper colored wire with later models having green. To the best of our knowledge, only the green wire version made it into the AFX. Aurora decided to re-introduce the (Copper|Red) color combination on most of the AFX magna-traction (MT) cars throughout their production runs.

Use an ohm meter as your guide, as you don't want to confuse the earlier (Copper|Red) Tuff Ones armatures with the latter, lower performing (Copper|Red) magna-traction arms.
​

Take into consideration that AFX magna-traction cars came with very strong, dual purpose magnets that not only powered the arm but also provided the vehicle traction. The stronger magnets are probably why these arms ohm so high for Aurora's final pancake offering. Not really a good performance choice in anything other than a MT car; although fair performance in a Thunder-jet 500 can be had with stronger AFX Super II or Johnny Lightning magnets.

As previously mentioned, don't confuse this arm with the similarly colored but lower better performing Tuff Ones arm.

An unusual version of this armature was available in European A|FX magna-tractions. This version had a printed circuit type commutator that sported a resistor or capacitor on each pole. It was suggested by Jim Sgrignioli of Yellow Jacket Performance that this was due to Europe's power not being as clean as U.S. & Canadian power. Cars equipped with this armature might also be found with a capacitor soldered between the pickup shoes, probably to even out the A.C. voltage ripple and prevent surge damage.
​

Designed for high RPM operation, this arm (like the rest that follow) is of the typical Bi-Laminate design. The Green|Green version was available on some of the AFX cars, with some purists believing generally better results can be had with the Aurora version. It is meant to be used with the stronger AFX Super II magnets but you'll find they also run well with Johnny Lightning magnets in an Aurora Thunderjet 500 chassis.

Usually available as a separate item through American Line NOS (Copper|Green), this arm, when properly balanced, can attain very high speeds but is best suited for lighter weight cars T chassis due to it's torque profile; cars that have been lightened or use lighter bodies (like Cheetahs, Falcons, Lola's, GT40's or some of the lighter aftermarket resin racing bodies) benefit most from this arm.

If using weighted rear wheels, avoid using ones too heavy if road racing on technical tracks requiring you to dramatically slow down and speed up repeatedly (like a track with many 6" curves). Complete NOS AFX gearplates from American Line containing the Green|Green version are still available and it is widely thought that they contain the genuine Aurora parts.
​

Usually found on AFX and/or early AFX magna-traction cars. There is some speculation on which cars contained this fairly rare arm, with some suggesting Canadian origination after Aurora's U.S. facilities had closed.

Whether intentional or not, the 4 Green (I think you meant Red?) Devil arms we've inspected all have the communtator plate slightly rotated counter-clockwise by 2-4 degrees (if viewed from bottom) leading to a slightly retarded timing curve, suggesting higher top end. This better than average arm can perform well when matched with either AFX Super II or Johnny Lightning magnets and a 14t cluster pinion.
​

These are found in the AFX Specialty cars like Dragsters and Funny Cars. These cars had longer chassis that had a total of 4 gears and were usually pretty heavy.

Heavier gauge wire was used, so this arm tends to run hot. Stronger magnets and chassis or body colling considerations are a must if used for Enduro Road Racing. this arm can typically be used in heav customs or performance projects using weights or weight pans. apopular application is in HO Drag Racing, since the main characteristic is low end torque.

​When road racing, this arm will launch your from a dead stop, but others will soon be pasing you due to its lack of top speed. You might consider it for road racing when on a very technical (lots of turns) track since it can really barrel out of a turn. You should realize that the A|FX specialty chassis this arm was found in came with large diameter wheels, with dragster tires having an O.D. of .500 (half an inch), so even though this arm typically isn't capable of high RPM, the taller tire provided the higher top end speed. If you are going to road race this arm, check our gearing discussion and consider going to a taller gearing profile to compensate for its lack of all-our RPM.
​

This arm is probably the most sought after Aurora factory arm. It is VERY fast (68,000 RPM @ 15V) and is unique as compared to the other available armatures, netting excellent top speeds while still providing low-end torque. This arm gets its name due to the fact that it has 4 laminates (lams) while other from Aurora offered 2 or even 1 lam.

Initially available in the early 1970's on the ill-fated and under-rated AFX Super II car, which also came with a special edition Aurora Black Chassis out-fitted with brush cups, chassis weights and unique armature gear plate, braided shoes and special guide pin straight from the factory.

The armature as Aurora produced it also sported a "double-wire wind", speial advance curve and had a special silver-plated commutator plate; all for $12 - $13 at the time! No longer in available as NOS, they still pop-up used on eBay every once in a while with complete cars going for around $200-$400.

A variant of this armature was used in the XLerator cars. Precision replicas of this armature are available via AG&G Hobby.

The Quadralam, built for the long straights!
​

Again, I would like to thank Front Range HO for this information.

These were usually found in the earliest Thunder-jets, the type with the solid rivet, or "button" chassis

They typically OHM pretty high, fairly uneven and tend to run hot when used with stronger magnets. If you have some of these, you may be better off putting them in your older keepers along with a solid rivet chassis and set of matched black magnets to retain their originality and value.

However, if you can find that rare one with equal resistance winds, a good pair of weaker matched magnets can make for a fairly responsive racer.

There were some variations of this arm; You may find some with (Green|Red|Green) colored poles or even (Red|Green|Red).

Typically, arms with 2 similar colored poles seem to have steel instead of copper center shafts; they also seem to have fairly decent ohm tolerances as compared to thier tri-colored brothers.

Performance part? Rarely, but they could be readily found in the early days of the Fray...
​

You bet. At first blush, you probably would't choose one of these for a racer (due to the higher OHM ratings) however these are actually pretty good arms and just happen to be the type of arms found in T-jet fray-style racing, try to keep pole-to-pole ohm tolerances to +/- .1 and use matched magnets for best performance.

There is an article on the VHORS site reviewing magnets; it suggest that stronger Super II and JL magnets didn't provide any better performance than medium strength matched magnets.

Current fray rules allow for Johnny Lightning magnets, due to the strength matching being very consistent. You might be surprised at what one of these will do! These will still yield better "Seat of the Pants" results in a T-jet than a lower ohm magna-traction arm in most cases.
​

At first glance these arms seem to have the characteristics of potential, but for some reason fall short. We've never taken the time to pull one apart, but it can only be due to the wire thickness, amount of winds or a combination of both.

They seem to run hot and don't respond as readily to stronger magnets. Easily confused with higher resistance early T-jet Arms due to the color combination.
​

As the predecessor to the "Mean Green", this arm was intended to be used with the 12t pinion contained in the original Aurora Hop Up kit and could be found in some of the Wild Ones cars.

Also available as a separate item for a limited time through Auto World. Like its "Tuff Ones" big brother I demonstrates good top speed with jus a slightly lower torque profile. Best suited for cars that have been lightened, or use some of the lighter bodies and wheels
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Available on the Aurora Thunder-jet Tuff Ones series of cars, these were the fastes armatures produced by Aurora for the Thunder-jet style chassis.

Tuff Ones were produced after the Wild Ones and offered increased performance (advertised at 760 scale MPH!) and a few new body styles. The Tuff Ones also introduced the 14t Cluster Pinion which is probably why these arms produce a fairly good mix of top speed and low-end torque. When run on 20V with the proper amperage, these can really come alive... tuff Ones arms were also available on some of the earliest AFX cars as Aurora transitioned from "screw-on" T-jet to "snap-on" A|FX bodies and chassis. The early Tuff Ones arms had copper colored wire with later models having green wire. Unfortunately Aurora decided to re-introduce the copper and red color combination on most of the AFX magna-traction cars throughout thier production runs.

Use the ohm meter as your guide, because you don't want to confuse the earlier Copper|Red Tuff Ones arms with the later Copper|Red magna-traction arms if performance is your goal
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When repairing the thrown windings you have to gently move the wire(s) back onto the armature pole. I gently pull the wire back toward the center of the armature. to do this I use a disposable micro-brush. The fine bush like bristles are able to gently pull the wire without causing any damage to the wire.

Once you have tightned up the winding by moving it towards the center of th armature, then take a toothpick and put some CA (super glue) on it and put one drop on the winding of the armature pole. Using the side of the toothpick, very gently spread the CA over the armature pole winding. You will notice that the CA will wick into the winding. If there is any extra glue then take a paper towel and soak up the excess by lightly touching a corner of the paper towel to the excess CA. While you're at it repeat the process on the other two poles of the armature to prevent the windings on those two poles from doing the same. (Being Thrown)

As stated above you can perform this process on the Autoworld and Dash armatures before running them to prevent thrown windings from ever occurring. This process did not appear to affect the balance of the armature. I think the balance was unaffected because I repeated the gluing process on the other two windings as well. I will update this post on how durable this repair is and how well it performs.

Of course the first thing I do is try to find the most electronically balance arms. By this I mean those that have the closest Ohm reading between the three armature stacks. Once I have narrowed that down I then work on the physical balance. To start the process I take my sharpie marker and mark the stacks with no marking, one mark and finally two marks. Below is a picture of the stack with no marks.

The next picture show the one mark. Notice the black mark on the right side of the arm stack in the picture.

The next picture show two black marks on the end of the stack

Once the armature is marked I then mount the armature into the balancer. If you would like to see how I made the balancer you can click here. When mounting the armature into the balancer I put the arm between the two magnets and turn the caliper until both magnets are just lightly touching the two ends of the armature shaft. See picture below to include the caliper reading. You will notice the caliper reads about 0.6465... half way between 0.646 and 0.647.

I then back the caliper off about 0.001 and 0,0015 of an inch this usually allows the armature to spin the most freely. You can experiment yourself and see what I am saying.

I then use a straw to spin the armature... take a look at the video below.

When spinning the armature I keep track of which marked stack goes to the bottom and how many time. If I have another stack that goes to the bottom that helps me determine where I notch or remove material from the arm stack. Below you will see how many times I spun the armature and which stacks went to the bottom 0 = no mark, 1 = 1 black mark, and 2 = two black marks

You will notice that the stack with no marks ends up on the down side 7 times and the stack with 1 mark ended up on the bottom 1 time and the stack with 2 marks  did not end up on the bottom on any of the 8 spins Given the results I will remove the material from the stack with no marks and I will remove the material from the center of the stack. Should the stack with 1 one mark end up on the bottom a couple of more time I would remove the material from the 0 stack on the side closest to the 1 stack.

After I remove the material by notching with the Dremel I then spin 8 to 10 times and see that the arm is balanced and that no one stack consistently goes to the bottom. Finally I then clean up the dremel cut with a Jewelers File.

Hopefully some of you will give it a go!! Practice on some bad armatures first. It's a combination of Science and Art!! Good Luck!!