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View Full Version : How to tech stock motors for legality?


danjoyy25
2012.12.25, 03:17 PM
:eek:I am starting to see a few PN 70turn motors go as quick as a 50 turn motor in our straight. What is the quickest way to tech this motors to see if they are still legal :eek:

DanDan
2012.12.25, 03:40 PM
At big races, our motors come with the brushes epoxied on and marked with nail polish.

For club races there's no really good way to tech motors. You could remove the armature from the can and measure the resistance of the wrapped wire. In NorCal, we abandoned the Pn70T as the standard. Variance between motors could translate to a full second per lap on the track.

Specification racing is supposed to be affordable and fair, so we went to the Pn50T (with a fixed final drive gear ratio of 5.8) as our stock standard. Before if you wanted to be competitive in stock it was necessary to buy many Pn70t motors, use the best and throw away the rest. If people questioned the legality of your motor, you had a good one. Rather than continuing pouring money down the drain on inferior product, we chose a better product to use :cool:

Felix2010
2012.12.25, 09:19 PM
To check whether timing has been advanced on the armature:

Take a bright,small LED light and shine it directly in the area inside the motor endbell on the commutator (The copper cylinder the brushes sit against);
Look specifically at the 3 tabs on the comm, they are inward towards the armature coils. The small comm tabs should line up directly in the center of he gap between the the 3 armature poles/coils. If the tabs are closer to one coil (Meaning the comm has been twisted slightly) the armature timing has been tweaked. 5-10 degree timing advance = Big advantage. Hope this helps.

imxlr8ed
2012.12.25, 10:21 PM
Straight from HFAY:

"If you are cheating, you are the one that has to live with the knowledge that you couldn't cut it like everyone else!"

See how simple that is?! :D

Batteries make a huge difference too, I finally gave in and purchased
a few new sets because trying to keep up with a racer that has some of the best and most cared for cells out there proved to be too much of a challenge. We all joke with the guy about his magic 70turns, but then you start to remember that he's running with 4 cans of lightning clipped into his car and how his cars handle incredibly well... that's when I just try to drive smoother and get into less wrecks. And aside from a dry break-in, he does nothing to his motors. After the break-in, he pops them into his car and runs them. No comm drops, no oil... I've never seen him do it once.

There are variances between all breeds of electric motors, I've never found one that doesn't have faster and slower motors within a batch. I think the only reason the 70turn gets a bad rap is because it is the most popular one out there.

Yes, I have had some 70turns that were dogs as well but I have two that were re-born after a good run-in. I'm pretty sure that the pressure on the brushes has someting to do with it in these cases. Maybe they just got worn to a point where the brush seated better?

If a manufacturer found it cost-effective to match motors it would be a whole new ball game but I don't see that happening.

imxlr8ed
2012.12.26, 12:54 AM
The timing is the thing most guys mess with because it gets the greater result, the LED inspection is the easiest way to do it, but you can't always blame the racer for doing it because it may have been a factory fluke. Now if the solder is all new and the tabs on the can are all scratched up, the guy could have messed with it.

Painting the tabs, engraving, sealing with a sticker that gets destroyed when trying to remove. All of those are good methods to prevent tampering. I think the fragile sticker seal is the best way. If they made a sticker that would wrap over the endbell and brushes, and only the vendor would be able to apply them, that would be the best way to go.

lfisminiz
2012.12.26, 01:30 AM
Come on ED.....i oil my motors.;):D

imxlr8ed
2012.12.26, 02:11 AM
Really? Never seen you do it... you treat your motors like I treat my real cars! :D

Either way, I guess the general point I'm trying to make here is... Cheaters suck! Another point is, a faster motor won't help many racers... driving skill (and luck) is what gets you the wins.

Anyways... how are you so sure I was referring to you? And what are you doing up at this hour?... Lemme guess, cycling cells? :rolleyes:

briankstan
2012.12.26, 09:25 AM
I haven't ever gone through more than 1 motor to select a fast one. the last 5 or 6 that I have ran came right out of the bag into my car. no break in or anything. I keep them oiled and run good batteries. I haven't noticed a big difference in speed of my car vs. other in our club in a straight line. now exit on the previous corner has a lot to do with speed on the straight, especially if it's a short one like the HFAY tracks have.

are they runnign comm drops on them? that can affect the speeds as well.

egonzalez
2012.12.26, 10:26 AM
We had a similar issue at MHS with the 70turn class… What we decided to do was run a series for 10 weeks and right in the middle of the series we all took are motors out and randomly swapped with other racers. You will be surprised to find that the guy that is fast and not cheating is going to be just as fast with any motor. These motors should have properly seated brushes and cleaned after every race. A fast car has a lot contributing factors, good setup, motor, batteries, and the driver. That being said, advancing the timing will make your motor faster and could be the difference between first and second place with pilots of equal setup/batteries and driving ability. We only run open motor now… :)

NoBrainer
2013.02.20, 05:56 AM
To check whether timing has been advanced on the armature:

Take a bright,small LED light and shine it directly in the area inside the motor endbell on the commutator (The copper cylinder the brushes sit against);
Look specifically at the 3 tabs on the comm, they are inward towards the armature coils. The small comm tabs should line up directly in the center of he gap between the the 3 armature poles/coils. If the tabs are closer to one coil (Meaning the comm has been twisted slightly) the armature timing has been tweaked. 5-10 degree timing advance = Big advantage. Hope this helps.

Nice description.
Does all 3 have to be moved or just one?

I just done some cleaning of a PN70T and one of the comm tabs are scew, but that don't matter does it?? The other two is aligned correct.

I have use a bit of oil on the bushing and I have sanded down the endbell so it's smooth. Maybe this motor will run fine now.