# metering the armatures



## wyatt641 (Jan 14, 2012)

so now that i have been given great info on removing armatures..next i need info on metering the armature..what am i looking for in ohms????where specifically am i reading from on the armature??also is it easier to rewind or just replace the armature should one side read less/more than the others.is there a website that has the armature color codes and their respective ohms range???do not worry guys after this the next question will be installing back onto shaft...first thing first as i take notes...last question on metering is who is the best source for new armatures..runners/racers...but mostly for runners..:thumbsup:


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## Jisp (Oct 19, 2008)

Wyatt, try here for info on the various t-jet arms. Here for AFX and MT.

Take your ohm readings from either the 3 brush contact areas on the bottom of the arm or the small soldered tabs on the edge of the plate. On my MM I set the ohn range to 200 and measure area 1 & 2, 1 & 3 and 2 & 3.
The closer the readings, in theory, the better. A single reading that is off the chart from the other 2 usually means a thrown wire.

If you can find the end of the thrown wire you can sometimes unwind it by just one wind to give you the length to get it back to the tab for soldering. My experience doing this has been very hit or miss.

There is some info for rewinding in the links above but I don't bother, I just grab another arm....

Cheers,
Michael.


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## tjetsgrig (Nov 1, 2009)

Here's a VERY rough drawing, but it gets the point across.


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## Ralphthe3rd (Feb 24, 2011)

Wyatt, for the common T-Jet arms, look for readings in the 16-18ohm range sometimes a little higher, but consistent among all three poles.
Now, the High performance(Aurora) Arms have readings in the 6-7ohm range from the factory. These will be your Mean Green arms(Green wire/Green tip OR Gold Wire/Green tip), your Wild Ones Arms- Green Wire and either Grey tip or Red tip, then there is the Blue Drag arms, they have Blue tips and Gold wire(maybe some have Green wire too?).
Some of the early Aurora Arms will Ohm in the low 20ohm range, and that is normal and ok, as long as all three poles are close.


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## Ralphthe3rd (Feb 24, 2011)

PS- if you have bad arms, it's actually alot more cost effect to just replace the Arm itself with a NOS Arm, there are still tons out there in ALL the color combos- 'cept for the earliest Aurora types. As an example, lookie here- Aurora T-Jet Parts from JAG and until recently, the had both Wild Ones arms in stock, which IMHO are just as good as most Tuff Ones Arms. Also check this page -AFX Parts/arms from JAG which shows Mean Green Arms as Well !
Also


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## Ralphthe3rd (Feb 24, 2011)

*Slotmonsters Arm Guide*

BTW- there is alot of mis-info/labeling on those pages, and they were never amended. The color combos listed are wrong on some arms listed, and the reason some Wild Ones arms run hot and/or slower, is that there was some binding in the cluster gears, as a bad batch of clusters found their way into a larger run of Wild Ones Top plates- just an FYI, as Wild Ones Arms are GREAT otherwise 


Jisp said:


> Wyatt, try here for info on the various t-jet arms. Here for AFX and MT.
> 
> Take your ohm readings from either the 3 brush contact areas on the bottom of the arm or the small soldered tabs on the edge of the plate. On my MM I set the ohn range to 200 and measure area 1 & 2, 1 & 3 and 2 & 3.
> The closer the readings, in theory, the better. A single reading that is off the chart from the other 2 usually means a thrown wire.
> ...


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## Jisp (Oct 19, 2008)

Yer not wrong Ralph, there are a number of clashes but I've never come across a more accurate guide online. On the limited number of occasions where I had a bunch of arms to try and ID, I printed the pages out and sat them in front of me with the arms. Combining the info, pictures and ohm values usually results in a positive ID. Do any of the "slot bibles" have a more accurate guide? I was outbid on a Bob Beers bible just a few days back.....

Cheers mate,
Michael. :thumbsup:


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## wyatt641 (Jan 14, 2012)

so what i am getting here is that what causes the overheating and smoking is bad cluster gears or armatures going bad...help me out here before i start tearing apart chassis..the symptoms are slow moving chassis and they start smoking and overheating...a couple have melted the comm.brush cups..i was thinking bad arms or magnets..help me out here..what do i need to do to get them going at a good working condition again...that is why i wanted to meter arms..am i looking in the wrong direction??


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## alpink (Aug 22, 2010)

checking arms is a good thing.
also you need to disassemble partially the chassis and check for binding any where it might occur.
once you have eliminated all shaft binding, then check that the gears on the gear plate are meshing well. a little time there smoothing the gears can go a long way to a smooth running car.
also, without the idler gear in place, run the car and put a little load on the armature gear with your finger or a popsicle stick to see if it tries to pull under load or just dogs out.
there are many other things you can look for such as excessive spring tension on the brushes .......


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## Ralphthe3rd (Feb 24, 2011)

Wyatt, yes- like alpink and I have mentioned, binding and/or friction is a killer on these little motors. And an otherwise brand new arm that's perfect, can be fried like bacon if it overheats due to binding/friction.
Always be sure you can thumb the rear wheels and feel a smoothly turning over drive train- with and without the idler gear in place. It really doesn't take much friction/binding at all to damage an arm. And when thumbing the rear wheels on a complete drive train, use light pressure, and feel if there is any coast in the wheels(although very strong magnets can also be the cause of less coast and a tighter feeling drive train).


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## TGM2054 (May 14, 2011)

I would suggest taking the mags and brushes out to check the chassis for binding. if you feel it, take the idler out and spin the arm to check it to see if the shaft is binding. If not turn the back wheels to check there. If all that checks out, I would move on to brush tension and checking the com.


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## Jisp (Oct 19, 2008)

Wyatt, I admire your determination to stick with it. You'll find the problem. TGM just offered about the most concise process of elimination I have ever read. He nailed it. Grab a beer, sit down with the little critter and follow that method. Let us know how you got on please.

Cheers,
Michael. :thumbsup:


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## brownie374 (Nov 21, 2007)

Wyatt come by my house sometime and I will give you a tjet basic class.


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## wyatt641 (Jan 14, 2012)

sounds like a plan brownie...then i can apply that to the afx chassis that need tuning also as they are similar in function..will bring my glasses as i can hardly see the little pieces anymore.........and a note book ...


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## brownie374 (Nov 21, 2007)

Sounds good we you will have to come out and spend a day in the basement.There is a lot I don't know but I would be happy to share what I do.And as you know I always buy in bulk and always have extra parts.


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## wyatt641 (Jan 14, 2012)

hey brownie..thanks for taking my back when i had log-on problems..told the wife about your offer on t jet rebuilding..she says i go the kid goes with me..lol..hope there is something you have for a 7 yr old to be pre-occupied with..the nintendo ds only lasts so long.....ha ha ha.


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## brownie374 (Nov 21, 2007)

Better buy him a gameboy on the way out.


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