These motors will all be used in a Losi xxx-s touring car. I have only raced about 15 times total (just got into r/c two years ago), about half of that was with a touring-converted HPI Rally. So...I'm usually about a second or slightly less per lap slower than the fastest guys, so I have a bit of work to do there. When it comes to straight line speed I'm very close - it's just the whole driving thing I am sorting out. Mostly all I really wanted was to know that I could be competetive when it comes to power, the rest is just getting more driving and set-up experience...

Denney

That's basicly the reason I bought my dyno... I wanted to know why I was getting beat on the straights... now that I'm up to speed on the straights, they just go by me in the corners... I do know for sure that I'm not getting be by motor... and I still have fun, so that's all that matters...

Actualy, I easlily see a couple tenths per lap on a fairly small increase in power... but it's only like on my best lap... all my other laps are still pretty crappy.

Thanks for the help. I'm new at using a dyno and I was primarily using it to track changes that truing, and changing of brush & spring combos would make. I've been running an ROV with power in the 65+ 21,000-24,000 rpm .935-.953torque and 48-50% eff. (everytime it sees the dyno I see a slightly different #'s) This motor loves a small pinion. It never seems to run out of speed on the straights and the smaller the pinion the faster the corner speed seems. While not the fastest I consistently run in the top three if no bumps or crashes.

I have a GM3 64.5,19,933,.958,52% I think I want to try this weekend.
Having a better grasp of what to look for will certainly help- thanks again.

The only place I have run an MVP in the last 6 months is in touring car. I'm not taking BJ's side, but say what you want about the MVP's or "I won't a race a motor under X watts!" LoL Some people really crack me up. What are you gonna say when I pass you down the straight with an MVP that sucks? I think some of you are so far into thinking every race is won with a motor and a dyno that you have forgotten to see what things feel like on the track. I think we all need to take Glenn's advice, and starting working more on the car and our driving rather than getting another watt out of a motor. :p

Don't get me wrong, Dyno's are an important tool for going fast, but I still agree with a lot of other people, WE DON'T RACE DYNO'S! So go ahead, say what you want about the MVP and how it looks on the dyno. If I had never raced some of my motors that don't look good on a dyno, I would be missing out. Put a few runs on a "bad" motor, and sometimes they improve on the next re-build.

Glenn, why should I buy another MVP when most people think they are crap and will give them to you for free? :) I think the 4 I have is plenty, I only ever bought one.

Here's the race report from last night (we run a Thurs night series, with 2 heats & a main):

First heat I ran the GM3 (belongs to a friend), geared 90/22 (Losi xxxs). The car was really fast. At least as fast as all but the Pro-match sponsored guy that was there.

Next heat I ran the MVP, geared 90/23. Not quite as fast as the GM3, but I needed more gear...so for the main I ran 90/24 & it was better, but I think I can go 90/25 & be as fast as the GM3 or faster, but I didn't try gearing up the GM either. Either way speed is not an issue, the 6-8 smacks into the boards are slowing me down more than any power deficiency. Also, the MVP at 90/24 was no hotter than the GM3 after the race either.

Denney

My info was based on what is working on my local banked oval.
I only have to go fast and turn left 4 times per lap!:thumbsup:

Bascily... I find it hard to belive that motor is more then about 10% of the total picture in road course racing.

In oval it might be 20% or maybe slightly more...


Basicly I think there are many many reasons why people go faster or slower with one motor vs. another motor, perticularly in road course and even more so in off road. I beleive it's entirely possible for typical club level driver to actualy go faster with less power in road course or off road... there are so many variables involved in that forum of racing, I personaly wouldn't use it as a judges of actual 'power' of a motor.

In oval... the same is basicly true, but to a lesser extent. Here beleive that a good driver can pretty easlily see even small changes to motor proformance in a oval situtation... It's like off center says... you have two straights, and two corners... (Offcenter says 4 corners, and I guess you could call it that...) Basicly I think in oval it's much more likely that motor proformance will be seen on the track... even so... I still say it's probably at best 30% of the big picture in oval racing. Motor is probably slightly more important on a banked oval, then on a flat oval.

Right now... I think my dyno's most valuable use is in helping me to switch from one motor to anohter and still be confident about getting the gearing close. That, and continuing to re-enforce the fact that my motors are not causeing me to go slower then the fastest guys...

Sorry for getting into the conversation a little late. I have a MVP and it does about as good on the dyno as my other motors, it is just a little off. On the track, it is not up to speed. I do race touring and I cannot gear high enough to go fast. I've taken it off the track at over 250 degrees. I've also geared it lower, no help. But my Monster kicks its butt every time, but it only does a little better on the dyno.
But I should say that my Dad loves the MVP. I believe it is because he goes so slow and hits the wall so much, that having a power curve like the MVP is very benifical. Now don't get me wrong, I don't think that the MVP is for people that suck. The fastest guy at our track occasionally uses his MVP and beats us all. I just find that my dyno data usually backes up my performance. Execept that my Monsters seem to do a little better than what they say on the dyno, but I believe that has to do with the fact that I gear them tall and they don't over heat.

what i'm looking for is what kind of #'s should i be looking for on a ce dyno on a 19t arcor motor in a 4 cell class.i know the fantom "s but not on a ce dyno.

I don't have ARCOR motor numbers on a TurboDyno, but do have some memory of 5 volt 30 amp numbers for Chameleon motors... 116 watts at 30 amps, 5 volts, is all I remember... It's not much, but that might give you something to go by.

My best guess is that the ARCOR motors would be a few watts less then a really good Chameleon... I base this on seeing both ARCOR and Chemeleons on my Robitronic dyno... On my Robitronic, 90 watts is about as good as I've seen for a 19 turn Chameleon, ARCOR motors have always been lower then the Chameleons I've dynoed, perhaps 85 watts or slightly higher.

Denny: I remember the file :) I cut out 6 runs and pasted into excel sheet for you on the TD data I have. I added the 6 v files to the viewer and included in the zip file. IF you want to see the remainder of the excel files on the motor let me know. I have about 100 runs on that ssheet.

Glenn, I know that Mels C1's pull 119 on Keith's TD. :)

Yeah? those are likely cranked C1s... Not acusing anyone of cheating... but my understanding of all the C1s that get used around here arebascily all cranked. I guess the fact is, with the way we run around here, it's not considered cheating... but then people don't generaly use them unless they are just having fun... Even so... I wouldn't think it's unheard of to achive 119 watts even without changing the timeing a bit.

I'm positive they weren't cranked! He can tune a 19t like no ones business! I think he only has one that is cranked, it wasn't cranked until after I saw the numbers. I saw these numbers in late nov/early dec. :p

Thanks 300M!!

I know this might not be the best place to ask but the results I saw were on a dyno so..... Has anyone ever heard of a brush deglazer. I watched a motor pull another 10 watts and several thousand rpm gain after one drop. I don't know what was in the bottle but it definatly showed some higher #'s. Could it have been water, or denatured alchol? it appeared clear. The guy wasn't telling what it was. Maybe someone out here knows. It wasn't comm drops.

I wasn't going to comment because I have no info on the type of product your asking about. However since no one else has yet to respond I'll make a comment or two about what I see as being related.

My experiance is that some motors will look really good on a dyno when first built/tuned, yet after you run them in a race they will come back and be down on power by 10% or more. A really good motor will not see this kind of decrease, or is less likely to have this kind of decrease. I can't say for sure what all is involved if/when a motor sees this kind of proformance decline after use.

Other motors will run really well before and after a race, these motors will generaly will work well time and time again. Often comm drops do very little to improve the proformance of a good motor like this, basicly they are just really good motors.

Back to the topic at hand... If a motor gains 10 watts by just putting some liquid on the brushes and comms, it probably was one of these motors that didn't run consistantly well. I seriously doubt that you'd see this kind of behavior on a motor that was truely in top notch conditon as far as tuning goes.

I am currious about the liquid, but I suspect it's not as miraculous as it may sound. I don't mean that as an insult to you OffCenter, or to anyone, it's just that generaly when a motor is REALLY good, things like that just wouldn't be likely to happen. At least not in my opion.

FYI... There is a Robitronic dyno up for bids on ebay right now. Opening bid is like $475... I don't know the person or anything like that, I just thought if someone is interested in a Robitronic dyno at this time, there might be an opertunity to get one at a reasonable price...

Based on the photos this dyno appears to be in good condition, and if I didn't already own one, I'd be interested in it.

I hope I didn't get anyone into a bidding war on a item they already knew about... but since there are currently no bids, I'll assume it's not been seen by any who are truely interested in it...

I make no claims about the condition of this dyno, other then the photos make it look like it's all there and in good shape.

I think what you may be talking about is a product called "conducta" which was clear and sold by a compamy called "aero tech' if my memory serves me correct. If it is the same I dont think it is sold anymore.
I used it for years with success it really added to efficiency #'s.

Originally posted by Mayhem
I think what you may be talking about is a product called "conducta" which was clear and sold by a compamy called "aero tech' if my memory serves me correct. If it is the same I dont think it is sold anymore.
I used it for years with success it really added to efficiency #'s.

You can get it Tower Hobbies. It's made by "Aero-Car".

http://www2.towerhobbies.com/cgi-bin/wti0095p?FVPROFIL=++&FVSEARCH=conducta&FVPROFIL=++

Thanks for the info. We got people here that think Comm drops are Windex, So if this was some simple homemade stuff I thought that someone out here would know.
Unrelated to this but on the subject I ran a G3 which hat lower Fantom #s than my ROV but with the right gearing turned out to be a happier combo for the track I race at.
One thing mentioned here I have noticed is that after a practice, 3 qualifiers and a Main with only a spray out before the main I dyno my motors after a day at the track to record #'s before a teardown and comm cut and the #'s are higher than before my day of racing. They actually go down slightly after truing and cleaning. I use the dyno as a guide, and the track to gain results.:roll: :roll:

Offcenter.... I see simmilar things on my dyno... Well... notthing to do with your GM3 with lower numbers out proforming the ROV (what is that? I'm assuming Monster?)

What I am seeing is that when I have a fressh cut comm, I get lower RPM and good peak power, after a run the RPM may go up, power may go down just slightly, then after another run, power may even come back up and RPM go up as well... Basicly what I'm seeing lately is that a fresh cut comm may not be all it's cracked up to be... I think sometimes a motor will run at it's best after at least one run, and maybe even better after 2 or 3 runs... My experiance is with 4 cell oval racing...

So far I have not found out exactly how many runs I can make before the proformance declines significantly. Mainly becsuse I basicly will cut the comm the night before a race day, and rarely have more then 4 runs on any motor.

I have run my EX-Spec motor for as many as 8 runs and noticed no indications of proformance loss. But this is a standup brush with low timing.

I'm trying to follow this killer thread. Ton of info.

One question.... What is an ROV?

That would be the "Revenge of the Monster" but do to my spelling I chose to abbreviate. Also, I had also seen the monster referred to as a ROV elsewhere in here and wanted to look more hip with the proper jargon.
Dyno, I agree and do the same, I would really hate to find out it only had one more good run before a tuneup since I usually don't drag a lathe and dyno to the track. I also am far better at tuning at home with more space to work and the pressure of the next heat etc.

I vaguely remember ROV... but wasn't it ROM? I don't remember... ROM would be the way I'd refer to them... but sometimes I simply use M... M1, M2, etc... So far I only own 2...

I did notice something that is somewhat odd... I still am strugling to get a Monster motor to run how I really like it to... I am like 98% a 4 cell oval guy. The best I can get out of my Monsters is about 59 or mabye on a good day 60 watts. This is not bad... but I like at least 60 and prefer 62 if I can get it...

Well what I noticed is that one of my Monster motors puts out 130 watts on the 7.2 volt setting of my dyno... Typicaly 125 is the start of a good motor, 128 being what I shoot for... 130 is the best I've personaly been able to acomplish. I do have some Paradox motors that do 130 as well, but my surprize is that when I tune my Monster for it's best output at 5 volts, it really doesn't impress me that much, but when I happend to test it at 7.2 volts, I was somewhat amazed that it ran as good or better then most any other stock motor I have. I've tried everything to make one of these exceed 60 watts on my dyno at 5 volts, but I just can't do it.

I wonder if maybe these are better suited for 6 cell racing for some reason.

See what I mean about spelling. I don't know where ROV came from, hell the " V " isn't even next to the " M " I meant to write ROM. I too run 4 cell (ARCOR packs)in an open wheel SK modified class on a 190' banked track. The ROM ran good and the smaller the rollout # the better, but the G3 with proper gearing seemed like a happier combo. The guy to beat also runs a G3. I did also note that tires on the fast cars are very low profile. I run mine now at about 2.15 - 2.175 and though they wont'last as long this seems to be how the fast are fast. I still am playing catch up with them and I attribute 1/2 the difference in my driving, but there has got to be some more speed in there somewhere. I have gone to teflon coated pviot balls up front and freed up the rear and smoothed out the diff with better balls, and rings. I'll see the results this weekend.

The fastest guys at are local track are still running GM3s, I have seen a few trying to run Monsters but as of yet haven't seen anyone really fast using them in 4 cell stock. I did loan my first Monster to one of the guys who's generaly one of the fastest 4 cell stock drivers in our area. I did so after dynoing his motor, and I was confident that my Monster was as good as his GM3. I told him what to gear it at compared to how he was runnig his GM3, and he had identical lap times with both motors. Later he brought his GM3 back to me, and he had it tunned up a little, and it was showing better then my Monster at that point. He TQed with my monster motor that night and ran his GM3 in the main... he won by 2 laps over another guy who is also extreemly fast... the other guy was trying a monster... (it was not as good as my monster however).

Bottom line really is that there is nothing magical about a Monster motor as near as I can tell. It's not a bad motor, it's just not what some people have attempted to make it out to be. At least that's my opion.

Mine have always worked great in 6 cell touring.

Well... like I say, my second one is showing pretty good 7.2 volt numbers, as good or better then most any other stock motor I've tuned... but I just can't get it to do the same with 5 volts applied to it.

I'd like to request the help of some fellow dyno owners... There seems to be some confusion about what happens to a stock motor in relation to spring tension. For a long time, the general idea has been that sping tension reduces RPM and increases torque... or at least that's what I heard back a couple years ago when I first started learning about motors, and I keep hearing others that have that same idea...

Well my testing shows otherwise. I've tried to document this before, and have previously shown my work. However, it seems some doubt what I am saying.

So, it seems to me, that one of the only ways I could defend my posistion without just simply saying... 'trust me'... is to ask others to conduct tests and share there results with us all...


What I recomend for a test is this... take a modern stock motor... I believe anything from a P2K2 to a Revenge of the Monster stock motor will work. Get three sets of springs... two greens, two reds, and two purples. Make a dyno run with the greens on the motor, record the data. Next put the red srpings on the motor, record the data. Finnaly do the same with the Purple springs...

Idealy you should find some way to measure the spring tension, because springs can often vary greatly in their tension even when they have some perticualr color... Also make sure you control your tests pretty closely... let the motor cool between tests, and give each test the same conditions... or at least as close as you can get.

Report back with the data...


My posistion is that the red springs will yeild RPM that is higher then the green springs. Purple will likely yeild higher RPM then the Red springs, when doing 7 volt (6 cell testing), but at 5 volts, you may not see the increase in RPM and may either be very simmilar then the Reds, or slightly lower.

Better yet... use the fiddle stick to measure the spring tension of the three sets of springs you use... In my testing I started out with springs that were about 4.5 on the fiddle stick, medium springs were about 6.5, and stiff were about 7.5... Purples springs are like 9... and I personaly never use purple springs or tensions that high, and also don't recomend it... but most of all my own personal testing never used springs higher then 7.5 on the fiddle stick. I fully expect that at some point exsessive spring tension will indeed cause RPM and power to go down... but in my testing I never saw this, because I never used springs that were that strong...

http://www.wiltse.net/springs.htm


I really would like for others to conduct tests and report back... I think we need to clear up the confusion and what I beleive is mis-information. However I really don't expect people just to take my word for it, and it would be very good to have others conduct simmilar tests.


By the way... my test showed that a P2K did not change much at all with my variation in springs... The higher RPM motors responded to a larger degree then lower RPM motors.

Glenn, talk to Jamie this weekend. He is a firm beilever that the lighter the spring the faster the motor in 4-cell. :)

All my testing was done on a Fantom dyno, I believe it is at 5 volts Your mileage may vary! All power #'s were 62-65, Rpms were 19,5 to 24,000 (ROM) and eff was in the 48 to 52% range for both motors. Unfortunately the records of these tests were lost but the best combos are on the motors now. Have you expierimented with holes or cuts in the brushes? I've been using Zubak Speed juice with better results.

Dyno, I think my first post got lost. I have done what you had just suggested with a G3 and ROM. The G3 worked best with a black+ silver- and the ROM has a purple+ silver- I don't know the tension #'s, But all the numbers across the board were highest with these combos.
I tried Red Green (almost as good on both) red red, green green, purple green, black silver, etc. My P2K is such a slug that nothing helps it.

Fastest on the track is not what I'm looking for here... Fastest on the track has too many variable... like for instance gearing, and many other factors...

What I'm looking for here is RPM of the motor as it relates to spring tension. Any other data that can be provided would be even better...

What I really would like is actual dyno data. Howver if you don't have the data and just want to report to us what the data said, that is fine...

I would however like to avoid just pure speculation on what happens.


Jammie can go fast with anything... including a motor that I personaly tune... My motors all have spring tension that is between 6 and 8 on the fiddle stick... I have never found any reall need to gou outside of this range myself.

I'm sorry my results are not available but i do recall that green on the + side was alot less rpm than red or purple on +. I couldn't try silver on + because I have one for that side. purple + gave the best results with a silver but only slightly better than with a green. Red red, did nothing, green green was no good, red green was the second best. The results were similar with both motors except the G# liked the black + better than it did a purple. With every improved RPM change power seemed to improve as well. Efficiency varied but my concern was for Rpm and power,. The computer puked and had to get reloaded so those tests were not saved.

OffC... I've experemented with a few brush cuts, but basicly I use just one at this time. I cut a couple notches in the side of the brush, basicly what is called a H-cut. I also trim the trailing edge of nearly every laydown brush I use. Even in Monsters, or P2Ks... or what ever... The P2K doesn't seem to care much what the cut is... other motors seem to like trimed brushes... basicly to reduce brush overlap and increase efficeincy...

What I do to trim a small amount off the trailing edge. Dyno... if I feel I still could get better numbers I might trim a little more off, and dyno again. If the power starts going down, I know I've gone too far. Not much you can do at that point, except maybe start over... mostly I just try not to take too much off... about 1/16 or less is what I end up with.


More on the test I'd like to see... I'm not looking for what is the 'best' combination... what I want is to see the trend that takes place when you use progressively stiffer springs.

Aside from the tests of progressively stiffer springs and what happens....


I have found that nearly every motor I play with prefers slightly differnt springs. I also find that springs dirctly from the package rarely have tensions that are consistant with what they are suposed to be. For instance, you can often find green springs that are just a strong as other red springs, and red springs that are often just as stiff as purple ones... etc... if you don't have some way to measure the actual tension, you're really just hoping that the spring is what you think it is... The fiddle stick is not perfect, but at least it's somehing to work with... If you practice with it, you can get pretty consistant results.

Differnt brushes also seem to like slightly diffent springs as well... There are many many variable that go into the perfect spring package for a perticular motor. It seems to me that the higher the RPM the more picky the motor is about springs...

As far as brushes go I am at the mercy of what is available at the track on Sun when I race. I've got Putnam green/high silver in the G3 now and Trinity 4499 in the Monster. I'm just starting with cuts and so far just a vertical down the brush about 1/8 was what had been suggested. It doesn't seem to do much on the dyno but I have yet to note whether it will improve racing. I played with the timing trimming of the brushes as I had read about somewhere and definately lost significant rpm/power #'s on the dyno.

I think I've resolved the issue of the spring tension and RPM with the person (Tempest2000) that was questioning my comments and/or findings...

It turns out that I think he and I basicly agree with one another. The sticky point being that there is a point where too much spring tension does indeed decrease RPM. My findings were based on 7.2 volt dyno testing on my Robitronic and 7 volt testing on a CE TurboDyno... Tempest's observations were on a Fantom dyno. Basicly he indicated that yes RPM was lower with lighter springs, but that anything above a red lowered RPM... or something close to that...

Anyway... I don't really dispute his observations and I dont' think they conflict with my observations at all. The reason I was able to see higher RPM with even stiffer springs I attribute directly to the voltage differances in the testing. Higher voltages require and/or will allow for higher spring tension before you get to that point where too much spring tension will start to decrease RPM and power....

I think I may eventualy do some further testing, where I do one set of tests with 5 volt setting, and another set with 7.2 volt setting.... I think it will become more clear then, that motor setups for 6 cell will work better with slightly stiffer springs then are needed for optimal power at 4 cell voltages. This will likely help make this issue more clearly defined.

voltage would definately have a direct effect on the results. The higher voltage would definately vary the results pertaining to spring tension, RPM, and power/torque. All it really says is that with more voltage there is less RPM loss with heavier springs than with 5 volts. At least I think that is what we determined. :thumbsup:

For sure... the gray/blurry line is what is too much spring, and what is too little. Clearly there is a point at which light springs cause RPM loss due to loss of input current, and another point where too heavy a spring causes RPM loss from too much friction.

The point where the spring is just right is what we all are looking for I think.


Just recently I sent a motor to a guy to test... He dynoed it on his TurboDyno, and the numbers were not impressive. On my Robtronic at 7.2 volt setting it looked pretty good. It also looked quite good at 5 volts on my dyno. Basicly I felt it was perfect for 4 cell racing and thought that it was likely to be good for 6 cell as well. Based on the new data I have, I'm thinking that for 6 cell I needed stiffer springs on this perticular motor.

I really am now very curreious and determined to figure out just how much differance there is between the ideal spring for a 4 cell motor, vs. the ideal spring for a 6 cell.

Basicly I'm moving to a new point in my learning as a result of this discussion and other recent observations I've made.

I don't know for sure when I will get a chance to do more extensive testing at a variety of voltages... probably at least a week off, maybe more. However it's basicly going to be my next motor project to figure it out.

I mainly run 4 cell so 5V is perfect to test with for me... I can see where 7v would be beneficial to 6 cell racers.

Dyno, Unless you think there is something wrong with your dyno stick with using it. Trying a motor on different dynos will net different results. I'll bet you already new this but I couldn't resist.:eek:

Well what I mean is that I sent a motor to a guy to do some track testing with... I had several of his motors myself for awhile... anyway... my motor didn't show to well on his dyno compared to other motors he has... yada yada yada... He's going to do some track testing and then wei'll go from there trying to figure out why the dyno says what it says.... I have my theroys... He runs both 12th scale and Touring car, so he has a need to have motors that run well for both... I felt farily confident that the motor I tuned for him to try would actually work well for both. However now I'm not as sure as I was.... I know my motors work great for 4 cell... but I don't have much experiance with 6 cell... but I really want to be able to know what it takes to tune for both types of racing... so I'm going to do what ever it takes to figure it out... that's what I have fun doing... well that and racing, but I really want to figure this out. Given some more time and some more testing, I'm confident that I can figure it out.

Dyno: There is a differance. I run both TC and 1/12, but I use different motors. If I use one of my 1/12 tuned motors in TC they will arc at the high loads. Punch is down. I tend to use lighter springs on the 4 cell tuning than I do on 6 cell. About 1/2 FS unit in general, but most are motor specific. Working on a monster now for 4 cell just to see for myself. Best motor is still P2K2. This one has the best power numbers and pulls well.

Pretty new to this rc thing and even newer to a dyno, though I have recently got a robitronics. I have a couple of questions/observations

1.When you cut the brush trailing edge, how much? I think I read a couple of posts back, 1/16" though that seemed quite a lot to me. Do you always cut both brushes?

2.When I dyno a motor (P2K2, 6 cell, TC) with new brushes #4499 I get a particular graph and results, naturally. After 5 min race the serrations are all but gone and if the motor is dynoed again the graph is markedly different, usually a gain in power in the low amp numbers and a near equal loss in the higher amp range (25 ish). When both results are put into goldens dyno viewer the gearing usually changes by upto 2 teeth, and the resulting rpm plot is near identical. Thus I assume that the gearing change would result in two pretty identical motors (I realise it is the same motor, but you know what I mean). Therefore would you assume that the 'gearing' of the new brush motor would change during a race and that it may be more consistant to not reserrate the brushes?

3.Would a hole in the center of the brush have similar results to the serrations and any info on how this works with a cut trailing edge? I was going to try it but incase someone already has.

Sorry for the ramblings but if you don't ask you don't .........

You've asked some very good questions, it seems you are also very observent, all good things.

I generaly break in a set of brushes for quite a long time, I like to get some visual indication that the brushe is indeed making contact with the full surface before I dyno anything. If brushes are only partialy broken in, the dyno results will change. Even 90% broken in is not good enough. 95% isn't really even good enough... This is not a direct reponse to any of your questions, but you should be aware that dyno results will vary a great deal as the brushes get seated.


Motors that have higher RPM will show lower power at low amp rates... at least in a general sense. If your motor picked up power at low amp rates, it was likely becuase the RPM went down. Don't ask me how or why this works like this, becaus I don't know why. It's not just something to do with the Robitronic either... You'll see the same thing on a CE TurboDyno if yo look at it closely.

What your seeing seems odd to me. In someway's it makes perfect sense, but it's not really like what I see most of the time on the motors I call good. To me, a motor should run just about as good after one run as it did before the run. I personaly see my motors pick up a little RPM, and loose a very small amount of peak power. What I see and what you are descirbing are almost just the oposit. I don't know if I've ever seen my motors change so much that a two tooth gear change would be in order.

My observations have been that even when the RPM changes, the gearing really doesn't change on the same motor I'm working on. This is hard to understand maybe, but it really boils down to the fact that the motor really is the same as it was before, it just has slightly more or less power and RPM. I guess there are cases where this isnt't true, but my feeling is that something is wrong if that occurs.

I'd like to see your data. Maybe I could offer more comments if I actualy had the data.


Triming the brush.... I break in the brushes fully first, dyno... to get a benchmark. If the motor looks like it could use a little more efficiency, then I will trim the triling edge by about half the thickness of a dremel cutoff wheel. I'll dyno again, and if I'm still not happy, I'll take the other half the thickness of the cuttoff wheel.... (to get one full thickness trimed off) My estimate was that this was 1/16th... I've never actualy mearuesd it... I'll do that now.... hold on...

Opps.... I'm sorry... my mistake my cuttoff wheel is just .025" of an inch I guess I have to re-state my measurments... A 32nd of an inch is about the most I ever tak off... I start with about .015 and go up to maybe .030

Sorry... I really never measured, and obviously my estimation and memory of what a 16th was like were way off... Glad you aksed the question....

Take a little bit off at a time, if you see peak power drop, you've taken too much off. In my opion, if you want to learn about dnyos and what numbers mean, what happens when you take a small amount of material off the brush etc.... work with brushes that don't have serrations left on them, or very small amounts of serrations left... If you try and work with serrated brushes while your doing dyno work, you'll constantly be fighting with consistancy problems related to the serrations and/or brush breakin.

I can make a non serrated brush work just as well as a serrated one, and to me, the only value in serrations is to allow quiker brush breakin. On the dyno, serrations are just a pain in the you know what to work with.

does anyone break in motors while dipping in water anymore? i have heard this is a very fast way to break in the brushes and get them seated very quickly?
do you just hook up a 4 cell pack to the motor and dip the endbell in some water?

It will eat up your brushes in less than a sec. Try it once. I did it on an old motor with hard brushes once, and it actually worked quite well. But remeber that all our newer brushes are very soft as far as brushes go for electric motors. We may call them hard in the RC world, but they are actually soft.

Also, I hear it works for those spec motors with hard brushes.

4 volts should work, and you shouldn't be able to shock anything at that low of a voltage.

I've done it recently on a Ex-Spec motor. I do it with a old Tekin Dyno, at 5 volts,... my Spec motor was pulling about 18 amps when the brushes were fully broken in. I have had stock motors pull more then 20, and had to turn the voltage down to keep the amp bellow the 20 amp limit of the Tekin.

Depending on the brush, a couple minutes or so will get them fully broken in, even with realtively hard brushes, and a great deal of differacne between the contour of the brush and the commutator.

Just hook em up, dip them and check them once in a while.