Tech Tips for AF/X Magnatraction
If anybody has any good tips on how to tune your Magnatraction for racing, post them here!
I only have a question: if I install a pair of the BSRT polymer magnets for the Magnatraction, should I be upgrading the armature (perhaps to a MeanGreen)?
AFX Dragster arm troubles
So, I wound up with a thrashed-looking Furious Fueler, which I repainted a glorious metalflake red, re-did the decrepit chrome with silver paint, colored the helmet, seatbelts and steering wheel, painted the drag chute and stuck a new fuelie injector on top of the motor.
Then, I found that intitial looks weren't deceiving: the motor won't run. The 4-gear chassis looks to be in proper mechanical and electrical order, and is now clean, but won't turn at all on 9 volts.
Does anybody have ideas how I should check the light blue dragster armature?
If it's dead, will a Tjet or MeanGreen be adequate to propel this thing down the track?
Should I put neo dots underneath and race it on my road course?
Re: AFX Dragster arm troubles
1st ohm the arm, make sure you have equal(or close) readings on the 3 poles. Ie a mean green can ohm from 5.7 to 5.9 on average.
if all 3 are the same, put the car together and ohm the pickup shoes, then the plate hat holds the shoes and lastly ohm the brushes. (Note the car is together) this way you can find if anything is not making contact.
Racers wanted in Rocester, NY
For HOPRA rules racing
Post-Op on the Furious Fueler
Slotking, thanks for the methodical approach to de-bugging my AF/X. I went through it carefully, and discovered that the armature was bad.
It looked okay, but the ohmeter said otherwise and I found that more than one strand was severed, up under the poles and above the fiberglass com plate. I also found a poor connection between the pickup shoe and the chassis on the passenger side.
So, surgery began:
--popped the armature pinion off the dead boy
--installed it back into the car, with a brand new dragster armature (Neil's Wheels). I had to Black Max the pinion onto the arm axle, though.
--installed Super II magnets
--installed NOS copper AF/X shoes
--cleaned and replaced the stock silver brushes
--applied magic red oil and touched contacts to a pair of leads running up to a metal rod mounted atop the belfry.
With the first lightning strike, we had life!! Strong sounding life, too.
Now, I'm waiting for a set of AF/X Dragster silicones, en route from Tom Hiester, so that I can run this fella. At this point, it will sure spin the old, dried out tires!
Re: tech tip
If you want to get some more speed out of your magnatraction with a 'cheap' tip try taking the commutator brush springs and stretching them just a little. Make sure not to go too far. It takes a little more time trying to get the arm back into the chassis but it makes quite a bit of difference in your speed overall. Also if you shim the rear magnet with a small piece of metal (like a track rail) it will make your magnets 'stronger'actually giving you downforce in the turns. It takes away from your top end speed so I usually do these together to even out the modifications. I race in a modified class without poly magnets and my fastest car will actually stick to a piece of track upside down like a super g car will.
Re: tech tip
Excellent tip on the brush springs!!
I used to run cut-down pick up springs (cut end up or they 'unscrew' out the bottom) & silver brushes.
Also--
If you run on a track with battery power or similar, make sure the shim behind the magnet does not contact both rails at once!
Either split the shim so it can't conduct rail to rail, or keep the shim up high (inneficient & dangerous)
It's a great way to make the Mag/Traction handle. BTW you can also add a thin shim to the front of the rear magnet, this one only comes into play when the car 'drifts'!
Re: tech tip
I run my fastest Magnatraction without brushes! Copper T-Jet pickup springs will make a Magnatraction fly. Probably not legal anywhere but a hugely observable difference in performance The trick about shimming the magnets with steel is dead on. We shim both magnets and use old Model Motoring track rail. Bend it around a big Magic Marker to get close to the radius you need.
Edited by: Rev at: 2/26/01 4:40:59 am
Re: tech tip
YES...my bad! I should've mentioned the shim being up high enough off the track so no arc welding of the home track occurs. I usually keep my shim up just high enough to clear the bottom of the magnet. Really need to watch the thickness of the shim too so it doesn't warp the chassis. I used to use tyco track rail but have found some thinner metal that is much better if you cut out the bottom of the magnet perch to lower the magnets. Then I glue in the magnets with a little 'jet' on each corner to keep them in place. Sometimes even taping the top side of the pickup shoes and trimming off the excess is needed to keep the front shim from arcing there. We are needing to rewire our local track and replace a piece of track that got too hot from someone not being careful with shims. It is not too expensive since we use tomy/afx track but it would be quite a bit more pricey if we had a buck track or something of the sort. Next sunday is my 'volunteered' time to help with the maintenance since it was one of my loaner cars that burned up that corner piece! No longer do I loan out unfinished modifieds with pans or shims!(another one of my-bads). I didn't have the bottom of my pan clear taped since it was in the building stages.
Todd
Re: tech tip
Never heard of the 'no brush' technic before but I am a believer. It lowered my average lap time in 76 feet of track by a full second! Thanx for the GREAT idea Kevin! Does anyone have any ideas for metal besides track rail that they use. I have been experimenting with paint,hairspray,and misc. cans with some good luck but there has got to be something easier and less messy.
Todd
Warning: If you do a 180 spin with brush springs for brushes do not stay on the power as sometimes the springs will catch on the com segments if the motor trys to run the other direction.
Re: Shim Material
Yes, I've used the top of some cans. Usually .012"-.015".
The inside shim only needs to be .040" -.050" high & fits inside the inner curve of the magnet. This shim can protrude slightly (.003" approx) because it cant short, but it can hang-up on a rail if too low. The back shim I glue onto the back of the magnet with Black Max & cut with a Dremel after it's set to prevent both rails shorting on it. Without the danger of shorting you can lower the shims right onto the rails for max downforce.
Re: Shimming the magnets
Actually shimming the magnets are for the extra magnetism.(is that a word?!) I was told that the extra piece of metal boosts the magnet's pull thus making a GREAT handling magnatraction in the corners. If that is right or wrong someone please let me know. It doesn't hurt that you are shimming the magnet TOWARDS the arm but I have not seen a noticeable difference in doing so. I have one car that I used a thinner piece of metal and the magnets were tight to begin with. I got more downforce from the metal without lowering the magnets but just notching the metal to be lower in the chassis. I lowered the metal alot, notched the shim, then ended up cutting about a 16th of an inch out of the center of the shim. Now I have no worries about shorting out the track by being too close. The metal is thin enough and with the help of my trusty dremel(can't live without it anymore) I now have the closest possible shim to the track without hitting.
Just one last thought...I check all my chassis for the best downforce in magnets in the stock form first and work with my. Out of my collection I found about 20 or so that had ultra strong matched magnets to begin with. I didn't do this first and spent alot of time modifying a couple of cars that don't handle any better than a stock car...go figure. Hindsight is my best teacher.
Hope this helps a little with your questions.
Todd
Re: Shimming the magnets
My bad, shim=flux clollector in my old brain!
Ever looked at the "magnetic closure" on coffee table doors or small cabinets? It's basically a garden variety magnet with two HUGE flux collectors sandwiching it. The concentrated magnetism gives amazing holding power!
This same idea is what we tried to do to the motor magnets in the Mag/Traction. The thicker the shim (of the same material) the stronger the pull. You run into space/location problems if you go too big, you have to cut plastic at that point.
You can get plenty more downforce than stock by using even a thin shim, & sandwiching the magnet with a low shim on the inside. This works well & is almost undetectable if done right! Using the MagnaTraction chassis without the outer magnet lips will let the magnet come down to the rails.
No the Ceramic magnets don't short on the rails by themselves. With the split shims the limiting factor on lowering will be the electricals- specific the rivet!
BTW we got more noticeable results sandwiching the rear mag rather than the front, because by the time the inner front gets to the rail the car was usually past recovery.
Re: Shimming the magnets
GREAT explanation that I could even understand Geezerotti. As you can tell I am not a great 'teacher' when it comes to explanations but do like trying to help with tips. One question though is what works better for the arm...one shim or both shimmed? Meaning I guess does it make the arm run harder/faster with one or both shimmed or does it not affect it noticeably? I like your explanations since they are easier for me to relay them onto the next person when they ask at the track.
Todd
Re: Shimming the magnets
I saw a drawing of a Magnatraction car that had the magnets retainer radius cut. Then the magnets were shimmed on both sides and at the back. The shims split at the center of the outside magnets radius. The result was two shims that tied in both magnets. I've never tried this but was told it was an effective mod. Anyone tried it?
Edited by: Rev at: 3/2/01 5:00:46 am
"brushless" Magnatraction cars
Great tip, Rev!
I torn down, cleaned, polished and rebuilt one of my MT cars last night. I first built it up with brushes freshly cleaned and cooked out with the soldering iron and good condition AF/X brush springs. Then I removed the AF/X springs and brushes, replacing them with copper Tomy SG+ pickup springs cut down to 6 coils. The set-up using only springs was much faster.
After discovering that the springs will easily screw themselves out (as mentioned), I went back in and tucked half the tail back into the coil (now 5.5 coils long) and solved that problem. I'm using the "finished" end of the coil for contact with the commutator, since there's a bit more material there.
The formerly slowest MT in my box will now keep up with my Mean-Green'ed MT using the NOS silver brushes (not for long!).
REv, how has the com on your car held up to running without a brushpad?
Edited by: EBasil at: 3/5/01 2:48:50 pm
Re: "brushless" Magnatraction cars
The only time I have ever had com damage was when I did a 180 and stayed on the power. The spring hooked on the com segments and damaged the com beyond salvaging. If you try copper T-Jet spings you will have a finished spring on both ends. The com looks clean all of the time with this arrangement.
Re: "brushless" Magnatraction cars
This post should probably go in the Non magnet car section, but the discussion is here, so the comment is here too.
I just tried the "brushless" idea on a t-jet. I flattened out the copper contacts where they enter the bottom of the chassis so the springs would have a nice area to sit on, and also be less likly to "wind" themselves down out of the bottom. Results so far? 3 rockets! The fastest is one where I took some springs that had wound themselves together creating "double thick" springs. I'm not sure if I'll tell my local race group about this idea just yet. It's probably not legal, but then, why not? I'm not using any illegal parts after all. T-jet pickup springs are stock parts for t-jets. Hmmmmm, an ethical delema, but an ellegant solution to the age old problem of t-jet brush tension.
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