# Technical brush questions...



## lenny (Feb 29, 2000)

I have some questions on brush composition...

I'm looking for a rough idea on copper content percentage and 'remainder' material percentage for original and aftermarket T-Jet brushes. If anyone knows, it would help greatly.

Aurora original
JL/RC2/AW T-Jet brushes
Wizzard
Slot Tech
JB Thunder Brushes
Copper Comm (a new entry in the brush market??)
Any I missed?

Anyone use pure copper?

Regarding size, the AW brushes are metric, 3mm in diameter. JB's are 1/8". just an observation... Do JB's work in AW cars without opening up the brush holes?


Also, I'm asking for opinions on what your favorite T-Jet brush, and why...


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## Ralphthe3rd (Feb 24, 2011)

Oh my Dan, I don't think the average lay person or even T-Jet racer would know the actual content percentage, of copper and various other material in a comm brush. I'd think that would be a guarded company secret.
Anyway, I personally like both JB's and Wizzard, although I haven't tried any others besides factory Aurora Silver(NOS) and Factory JL/AW....which really aren't too bad either. There has been some talk about the AW Brushes being merely crappy carbon, but from what I've seen under heavy magnification of worn brushes, is that they appear to have high silver content - or some silver colored metal in them?
The reasons I like JB and Wiz, is because they make my cars run faster, and don't dirty up the comm plate as bad as stock old carbon brushes.


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## Bill Hall (Jan 6, 2007)

I liken electric motor brushes to brake pads. The more metallic in the blend the harder they are on the rotor. As the percentage swings the other way performance is affected.

I prefer JB's because they provide a good compromise. Performance is enhanced with no appreciable comm segment wear. Additionally, and too their credit; I've never had a dud or a misshaped unusable mutant. Every one has been picture perfect.


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## win43 (Aug 28, 2006)

I like the JB Thunderbrushes for their consistent performance.


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## lenny (Feb 29, 2000)

Ralphthe3rd said:


> Oh my Dan, I don't think the average lay person or even T-Jet racer would know the actual content percentage, of copper and various other material in a comm brush. I'd think that would be a guarded company secret.
> Anyway, I personally like both JB's and Wizzard, although I haven't tried any others besides factory Aurora Silver(NOS) and Factory JL/AW....which really aren't too bad either. There has been some talk about the AW Brushes being merely crappy carbon, but from what I've seen under heavy magnification of worn brushes, is that they appear to have high silver content - or some silver colored metal in them?
> The reasons I like JB and Wiz, is because they make my cars run faster, and don't dirty up the comm plate as bad as stock old carbon brushes.


there's no silver in the AW brushes... I believe they are 70% copper and the remainder is carbon and binder material. 

The 'problem' with copper brushes is that when you start combining other materials with copper, the conductivity drops dramatically (depending on the other materials). 70% copper sounds like a lot, but it's really not. 90% copper sounds like a great amount, but it depends what the other 10% is which helps determine how conductive the brush is.

An electrical contact made out of 96% copper and 4% graphite has less than half the electrical conductivity of pure copper...


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## lenny (Feb 29, 2000)

Bill Hall said:


> I liken electric motor brushes to brake pads. The more metallic in the blend the harder they are on the rotor. As the percentage swings the other way performance is affected.
> 
> I prefer JB's because they provide a good compromise. Performance is enhanced with no appreciable comm segment wear. Additionally, and too their credit; I've never had a dud or a misshaped unusable mutant. Every one has been picture perfect.


Bill, just out of curiosity, have you ever tried pure copper brushes?


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## partspig (Mar 12, 2003)

Dan, yes, I have some here somewhere. They work, but nowhere near as well as JB's Thunderbrushes, and as Bill said, are the best I have found, offering a good compromise between comm wear and performance! pig


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## Ralphthe3rd (Feb 24, 2011)

partspig said:


> Dan, yes, I have some here somewhere. They work, but nowhere near as well as JB's Thunderbrushes, and as Bill said, are the best I have found, offering a good compromise between comm wear and performance! pig


 Yes, I've also gotten very good service from JB Brushes. which if I remember correctly, were always advertised as having the higher "Silver" content, as opposed to brushes like Wizzard, which were advertised as higher "Copper" content? ....all I know is what I read, if that's wrong, then I dunno what to believe.


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## swamibob (Jan 20, 2009)

I build and race a lot of T-jets and have raced JB's, Wizzard's and Slotttech brushes. My preference is Slottech. In back to back testing they did outperform both JB's and Wizzard brushes. All three are excellent brushes, good quality, reasonable price, but I believe the Slotttech's to be the best all around.

Tom


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## Bill Hall (Jan 6, 2007)

*Happy medium*



lenny said:


> Bill, just out of curiosity, have you ever tried pure copper brushes?


No, sorry Dan, I havent, I have used, Slot-tech, JB's, Wizzard, and of course I've mixed and matched all the factory offerings. 

I'll gladly run some for fun if you want.


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## ajd350 (Sep 18, 2005)

I could be wrong, but pure copper com brush would inherently have too much drag and have high wear on the comm. I would suppose the carbon to act as a slipperier substance to reduce the drag, and the mix would have a point where there is an acceptable balance between the two main components.


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## wheelszk (Jul 8, 2006)

I use slottech in all my T-jets, SS to stock. It really does make a difference.


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## lenny (Feb 29, 2000)

ajd350 said:


> I could be wrong, but pure copper com brush would inherently have too much drag and have high wear on the comm. I would suppose the carbon to act as a slipperier substance to reduce the drag, and the mix would have a point where there is an acceptable balance between the two main components.


I sent Alan Galinko an email regarding his silver brushes, but he hasnt responded yet. Does anyone use these, like these, know what the silver content and 'remainder' content is?


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## alpink (Aug 22, 2010)

I have used em drag racing. I don't think they will be good for long time running though. people keep telling me silver is softer and doesn't cause excessive wear on the comm. I have used silver content brushes exclusively in pancake and inline drag cars where allowed and the wear on the comms is quite noticeable. no one seems to know what has happened to Alan. his site is no help, no answers from phone messages left. he has an ID here, but don't know if he ever checks in. hope he is OK as his buddy Rocky passed a little while ago.


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## slotking (May 27, 2008)

on brush performance we did a bit of dyno testing to determine the best brush for simple speed. The numbers were big enough to make big difference on the track.

Slotech out performed the others.

this was with multiple cars and multiple car owners. 

On the silver, in the inline world, they seem to cut the com faster than copper brushes.

I will head down in a bit to test the silver galinko's vs the slottech


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## lenny (Feb 29, 2000)

slotking said:


> on brush performance we did a bit of dyno testing to determine the best brush for simple speed. The numbers were big enough to make big difference on the track.
> 
> Slotech out performed the others.
> 
> ...


what if the brush was made from a copper or silver 'tube', with a shaft of graphite inserted in the middle for lubrication? That way you don't adversely alter the chemistry of the copper material with the impregnated graphite (the way they are made now), you still get the full conductivity of the copper and lubrication via the graphite tube (or tubes).


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## partspig (Mar 12, 2003)

Why all of this BS about racing performance now?? Are you building a "racing" chassis now Dan?? Just asking! To answer your question about JB's brushes fitting in an AW/JL chassis, yes they do, but it is a tight fit! The Galinko silver brushes were made for racing, i.e., high voltage, high amps, lots of current flow. They are a bit on the soft side and will give you only a few runs before they destroy the comm. Have a good day! pig


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## lenny (Feb 29, 2000)

partspig said:


> Why all of this BS about racing performance now?? Are you building a "racing" chassis now Dan?? Just asking! To answer your question about JB's brushes fitting in an AW/JL chassis, yes they do, but it is a tight fit! The Galinko silver brushes were made for racing, i.e., high voltage, high amps, lots of current flow. They are a bit on the soft side and will give you only a few runs before they destroy the comm. Have a good day! pig


If you've followed my various posts on like everything regarding this chassis, I'm looking for top quality components, regardless of whether they fit the bill of racers or home users. The brushes I can get from the factory have a max copper content of 82% copper. The rest is graphite and binder material. I dont want to make junk. If 18% graphite/binder material gunks up the comm plate and has substandard 'performance', I want to avoid making them. If the stock brush is junk and people will be replacing them, I'd rather start with what the replacement item would be.

Don't read anything into my questions. I'm looking for the biggest bang for the buck. thank you for your response.


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## Bill Hall (Jan 6, 2007)

I'll wade in just below the top of my boots.

Correct me if I'm wrong, but the graphite isnt what gunks up the comm, it's the lubricant slung from the bottom of the arm shaft. Heated oil creating tar by combining with WHATEVER particulate is available in the comm pit.

All the modern brushes run cleaner than the old graphite piles providing lubrication is correct. 

My overall observation has been that; many if not most of the vintage T-jet comms using old school brushes that I've encountered, are in very good unmarred, serviceable condition. Other than neglect the carnage really started about the time that we saw hopped up brushes, beefier lever springs and of course lower ohm arms with taller tires/gear ratios and the ridiculous idea that these new generation hot rods were going to survive on down graded power supplies like wall warts. 

Regardless of what brush you put in your new baby, its inevitable that somebody is gonna pry them open and cram in something else. We saw Aurora go over the top on the brush performance equation with the AFX notched domed high silver content brushes; and they later pulled in their horns with accelerated comm wear, heat fatigued springs, burned out brush guides, and detonated armatures. Whoopsie! They changed back to a more conservative style brush and higher ohmed arms. Reliability became more fashionable than a few thousandths on the clock. 

So we saw the entire evolution, misguided mods and improvements and the eventual devolution of the brushes and the final correction of the brush carriers in the Magnas 

For now, I'd stroke it right down the middle of the fairway and develop the hi-po package down the road as you mentioned previously. Seemed totally logical. :thumbsup:


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## slotcarman12078 (Oct 3, 2008)

Unfortunately Dan, every answer will be dependent on what each person does with their cars. Whatever the stock Aurora brush compound was is fine with me, because I don't race them, I don't hardly run a slot car above and beyond test drives, and other than standard performance all I want is reliability. 

Ask a road racer type and he'll give a totally different answer than the drag racing types, which is totally different than the putt putt around the track types. I understand you want to please as many of us as possible with your major undertaking of a project (THANK YOU), but I wouldn't over think the small stuff. You'll drive yourself nuts trying, and there will always be someone who isn't thrilled with your choice. Best to keep it as close to a bone stock Aurora chassis as possible. That keeps the cost lower, runs consistently good like a T jet should, and let the guys who are going to tear out the stock stuff put in what is best for their type of usage. 

If you can't figure out what works best, I would suggest buying a few samples of each, put them in NOS chassis, and see which performs better. After so many laps, tear down each chassis and look for abnormal comm wear or dirt build up, overly worn or cockeyed worn brushes, and note the performance of each. Then swap another set in different chassis and repeat. 

One other thing you can do is start a new thread with a poll, giving everyone one vote. This will at least give you a quick reference rather than counting posts for each suggestion.

I agree with Bill Hall's observations!! :thumbsup::thumbsup:


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## alpink (Aug 22, 2010)

I jus wanna pancake car that dusnt cost 2 much and runs for awhile


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## Grandcheapskate (Jan 5, 2006)

slotcarman12078 said:


> Unfortunately Dan, every answer will be dependent on what each person does with their cars. Whatever the stock Aurora brush compound was is fine with me, because I don't race them, I don't hardly run a slot car above and beyond test drives, and other than standard performance all I want is reliability.
> 
> Ask a road racer type and he'll give a totally different answer than the drag racing types, which is totally different than the putt putt around the track types. I understand you want to please as many of us as possible with your major undertaking of a project (THANK YOU), but I wouldn't over think the small stuff. You'll drive yourself nuts trying, and there will always be someone who isn't thrilled with your choice. Best to keep it as close to a bone stock Aurora chassis as possible. That keeps the cost lower, runs consistently good like a T jet should, and let the guys who are going to tear out the stock stuff put in what is best for their type of usage.


I agree completely. You will not please everybody. But I believe you will please the most people by using a brush which does the least amount of damage to the comm. You know racers will replace them with their favorites, but others will still have a brush that is reliable, yet easy on the comm.

Seems like the worse thing you could do is use a brush that wears out the comm in exchange for better performance. Racers probably accept that tradeoff, but basement runners would not. You don't want to create chassis which is "designed" to wear itself out, nor would I want to buy one.


Joe


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## wheelz63 (Mar 11, 2006)

If you can't figure out what works best, I would suggest buying a few samples of each, put them in NOS chassis, and see which performs better. After so many laps, tear down each chassis and look for abnormal comm wear or dirt build up, overly worn or cockeyed worn brushes, and note the performance of each. Then swap another set in different chassis and repeat. 

you would think this would be a normal view for most people,
Richard


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## sethndaddy (Dec 4, 2004)

Dan, If Autoworld asked HALF the questions you ask they would have a far greater product. 

Keep up the questions, keep up the great bodies and the keep up the run to this great tjet chassis.


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## ruralradio (Mar 11, 2011)

I've ran both Wizzard and JB Thunderbrushes in my A/FX gravity/brass road race cars, really haven't noticed much diff in my builds, both in comm wear or performance. Cars are set up with brass brush cups and coil springs, arms range from mean greens to low ohm yellow jackets and home winds. I don't like tons of tension, I adjust the tension by sanding the brushes down to reduce their height. I know a lot of guys don't like to do that, but to me it's better than cutting a coil off a spring.


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## Dslot (Sep 2, 2007)

*Tube-construction Brushes*



lenny said:


> what if the brush was made from a copper or silver 'tube', with a shaft of graphite inserted in the middle for lubrication?


Dan,
Thank you for your old-school conscientious concern for quality.

Since none of our tech wizards have responded to that question, I'll take a crack at it.

Just on the basis of cross-sectional area, a 1.5 mm nonconducting core in a 3 mm copper brush, will cost you 25% of the brush's conductivity. If you can get the core down to a tiny 1 mm filament, you'll only lose 11%. (I've got some long-ago hobby manufacturing experience, but I'm not an engineer or electrical professional, so I encourage tech-savvy members to check my math.)

In practice, there will be more losses. Since wear, chips, rounding, bevels and irregularities usually occur at the edges (the conductive part) of the brush, they'll cause a greater percentage loss in conductivity than to a solid brush. 

The construction of the cored brush is more complicated. More extensive testing and development will be needed (How big a core do we need? How small a core can we make? What materials to test?). Greater precision will be required in manufacture (because, unlike a solid brush, any doming, high spot or slight roughness in the center of the brush will mean no electrical contact at all). I believe these factors would result in a substantial cost increase per brush, I'd guess double or more the cost of a solid composite brush, probably for a only a marginal performance increase.

I suspect that you'd get more performance and consumer-satisfaction bang for the cost-and-development buck elsewhere on the car, perhaps lightening the gears, tweaking the profile and travel of the shoes, creating an easy on/off axle system, or a guide pin that has the normal screw hole but also pops in firmly enough for test-running the bare chassis without the front screw.

My preferences are pretty much like Alpink's and Bill's and Joe's (Grand Cheapskate). I'd prefer a slightly slower, long-wearing, all-around brush for the basement runner, to a high-performance racer's special that might increase wear or costs twice as much. Even if your new brush is better in one way or another, I suspect many hard-core racers are going to pop in their own favorites anyway, to suit their specific style of racing, or out of habit, or because they just like to tinker and try for better than the stock equipment. 

That's my 2-cents. Thanks for listening. I wish you the best of success on this project, both financially, and in personal satisfaction.

-- D


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## shocker36 (Jul 5, 2008)

Dan try and get a hold of Bearsox he had someone making brushes for him and is very knowledgeable on the subject. I do remember him telling me some numbers but dont remember the exact ones.


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## lenny (Feb 29, 2000)

sethndaddy said:


> Dan, If Autoworld asked HALF the questions you ask they would have a far greater product.
> 
> Keep up the questions, keep up the great bodies and the keep up the run to this great tjet chassis.


Thanks! Just trying to approach this with an open mind... Not happy with the status quo if it can be improved intelligently and cost effectively


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## lenny (Feb 29, 2000)

shocker36 said:


> Dan try and get a hold of Bearsox he had someone making brushes for him and is very knowledgeable on the subject. I do remember him telling me some numbers but dont remember the exacts ones.


I'm good, thanks


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## lenny (Feb 29, 2000)

Dslot said:


> Dan,
> Thank you for your old-school conscientious concern for quality.
> 
> Since none of our tech wizards have responded to that question, I'll take a crack at it.
> ...


Great answer! Thank you!


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## slotking (May 27, 2008)

I know with inline cars 80% copper was a norm for race brushes
For t-jets I am not sure

As far as a brush with a core ( taking a shot ) I would think a soft core would ware off while the copper is still making contact.

then after a while more core hits, then just copper again.

plus you have the angle the bush sits in the car? could be no core hitting at all?

with silver being softer, would a 80% copper 5% silver 15% graphite/binder be better?


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## slotking (May 27, 2008)

any luck yet?


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## tjetsgrig (Nov 1, 2009)

Galinko silver brushes were supplied to him by JB's. I prefer the JB's, silver used solely for drag racing!


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## slotking (May 27, 2008)

I have used Galinko silver brushes in our mini enduro in the past.

I may have to retest the silvers vs the slottech's brushes, I can not remember which provided better performance


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