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Hawk 7 two-speed "wall" syndrome


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#51 Half Fast

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Posted 15 November 2017 - 01:12 PM

One guy ran a 10/26 in Can-Am! His motor did not blow.

 

Cheers,


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#52 willy wonka

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Posted 15 November 2017 - 01:24 PM

Tried it in Coupe but didn't want to risk it so put a 27 on.
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#53 Gator Bob

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Posted 15 November 2017 - 01:25 PM

One guy ran a 10/26 in Can-Am! His motor did not blow.

 
Is that fake news?
 
Not possible... didn't you know the issue has been resolved again.
 
It's the: 'Free-Revers' hitting the wrong note, 'The Gear Jammers" singing 'Below The Threes Blues', and 'The Simple Greens' played 'We're Not Washed up.'
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#54 Matt Sheldon

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Posted 15 November 2017 - 01:32 PM

Technically I think that gluing the brush arms at the insulator is illegal with regards to IRRA® events.


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#55 Pablo

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Posted 15 November 2017 - 01:45 PM

So we have two schools of thought here:

- free-revving them while dangling them by the brush leads like string puppets and flicking them like a bug.
- gearing the piss out of them with 13/16" wheels in hopes of winning a race.
 
:laugh2:
 
That's what I like about vintage - I can make my motor as perfect as I want. :dance3:

And if it goes "poof" I only have myself to blame. :D
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#56 MSwiss

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Posted 15 November 2017 - 01:54 PM

Ask anyone at the Brawl how many 7Rs burnt up on Friday. Probably the most I have seen at a Premier event. No worries, nothing wrong here... LOL.


Look's like your friend, "The Most Feared Man in Retro racing," has an explanation for you, in this thread. LOL.

And at the Fall Brawl, I know that some people were pushing the envelope of gearing to gain an advantage on the big Engleman track, so that may explain some of the magic smoke escaping LOL.


Of course.
 

A lot of 10/28 and 10/27, John.


Run a 10t and all bets are off on motor reliability.

9/27 for me


9t for the winner.

The smoke show at the brawl I would say was either because over-gearing or the car on too soft of tires causing alot of heat in the motor.


I seldom watch video foootage of racing, but somebody had a good video, up on Facebook, of the start of one of the Mains.

The cars were all bunched together, and I was surprised they didn't take each other out.

Anyway, looking at the cars going around the track, to me, they seemed like they were on rails, not fish-tailing enough.

One thing I notice at Retro races, and non-wing races in general, is racers unwillingness to adjust their traction level mid-race.

In the Sano Can-Am A Main, after getting off of red, in fourth place, with a pair of scissors, I clipped off a bit of the inside of one of the tires.

I won the heat, running fast time, so I clipped off a bit more, for the next heat on blue. I again won the heat and ran fast time.

With finishing on purple and black, I left it. Somewhere I moved into second, and managed to hold on to it, though finishing on black.

I'm 98% sure, I would have wound up forth, if I didn't risk loosening up my car.

Bottom line, with the norm these days running Retro on real sticky tracks, racers should really stay on top of not being too locked, as awesome as it is, for the car being easy to drive.
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Mike Swiss
 
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#57 dalek

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Posted 15 November 2017 - 01:59 PM

The video may well show the best method to turn a good motor into a "two-speed" by abusing it.

 

Would you rev a race car engine to redline in neutral under no load?

 

Ever if the rev limiter didn't prevent it, they aren't designed to perform that way.

 

The motor that you're referring to is one of three that I bought at my local raceway a couple of weeks ago.

 

I put a 10t pinion on each of them and broke them all in the same way – a few minutes at 5 volts on a power supply then easy laps, cooling with fan if needed, and looking at the brushes every 30 laps or so until the comm is dark all the way across.

 

Then, running laps with each of them installed in my one and only JK Indy car. two of them performed as expected. The other one (the one in the second video) was laughably slow around the track. Occasionally, maybe every tenth lap or so, it would suddenly increase speed halfway down the track's longest straight.

 

Now I ask you, what did I have to lose by putting it on my power supply and running it up?

 

And frankly, until I see evidence suggesting otherwise, I wonder if all of the comments against running the motors with no load briefly up to 12 volts is simply knee-jerk reactions based on myths and incorrect assumptions.


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#58 MSwiss

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Posted 15 November 2017 - 02:25 PM

How you kidding?

Along with the expert racers, the manufacturer, has expressly told you not to do it.

It's been explained to you.

The motor free-revving, at 12Vv is going to rev much higher,than it ever will in the race.

In your video, even at 9.7v, the motor was screaming like a trip to the dentist.

What exact benefit do you think you are enjoying by running the motor at RPM it will never achieve in a race?


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#59 Brinkley47

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Posted 15 November 2017 - 02:37 PM

What exact benefit do you think you are enjoying, by running the motor at RPM, it will never achieve in a race?

 

You should ask the "Most Feared Man in Retro." He does it a lot. I also spin them up. That is the best way to identify a motor with a transmission.  ;)


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#60 MSwiss

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Posted 15 November 2017 - 02:59 PM

Will,

Hopefully both of you are wearing some sort of eye protection.

The point is guys should be aware if they push their equipment, there is a chance it will fail.

This is called slot car racing. Racing, and stuff failing, goes hand in hand.

1/1 guys blow up $25K races motors, and are less upset than some slot racers, running $13 motors, with turbine-sized blade, pinion gears.

The problem here is Tim has tried to address the issues.

Jerry never posted on the 'net, and when complained to, would usually answer, "So what?"


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#61 Gator Bob

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Posted 15 November 2017 - 03:03 PM

Dale,

 

Listen to your 'superiors' and love these motors or you will be ostracized.


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#62 Gator Bob

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Posted 15 November 2017 - 03:05 PM

... guys blow up $25K races motors, and are less upset than some slot racers, running $13 motors, with turbine-sized blade, pinion gears.

 
 How do you know that?


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#63 Danny Zona

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Posted 15 November 2017 - 03:09 PM

Looks like a blogger is getting their overall total posts up again. 😉
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#64 MSwiss

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Posted 15 November 2017 - 03:18 PM

Bob,

It's a safety issue.

I've seen racers hit in the eye from laminations.

At the '93 Slugfest, I was standing in the bank, was hit in the chest, by a comm segment from Lee Gilbert's motor.

It melted into the carpeting, after bouncing off of my chest.

If a racer wants to post an unsafe practice here on Slotblog, I feel obligated to let the readers to know it's a bad idea, with zero benefit.

Mike Swiss
 
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#65 dalek

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Posted 15 November 2017 - 03:20 PM

If you're entering you slot car in a big race (cash prizes, huge bragging rights, etc.), wouldn't you be extra thorough in you motor prep?
 
Let's say you expect the motor to max out at 40K RPM at the end of the longest straight. I think it would be a good idea to spin it at about 44K for a couple of minutes to make sure nothing is going to shift or come apart at 40K during the race.
 
The track at our local raceway has a non-adjustable 13.8 volt power supply. I'm assuming that a motor on my power supply at 12 volts no-load will not spin all that much higher than it will spin when in a lightweight, low-drag slot car at 13.8 volts.
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#66 MSwiss

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Posted 15 November 2017 - 03:27 PM

Dale,

You keep using the word "assume."

Like I just posted to Bob, if you post about doing something unsafe, with myself doing this for the last 36 years of my life, the last 32 years at 50-80 hours a week, I feel obligated to comment about it.

Mike Swiss
 
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#67 MarkH

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Posted 15 November 2017 - 05:49 PM

One possible reason the motor behaved as it did in the second video could be an oversized bushing.

 

I have seen it in machinery running shafts and bushings. Under light to no load conditions the shaft can follow the wall of the ID and travel about its diameter instead of staying centered. We had to replace the bushing with new/tighter bores and they would stop vibrating. Applying a side load or bumping the shaft with a soft faced hammer a couple of times was the normal method to isolate which end of the shaft was the problem while the machine was running. Eventually all the bushings were replaced with ball bearings.

 

All I am saying is maybe.


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#68 Gator Bob

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Posted 15 November 2017 - 05:56 PM

A good post.

 

A harmonics/vibration is being set-up somewhere and that would be a good theory on where it could start. Thing is they do it in the car with a side load also.


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#69 MarkH

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Posted 15 November 2017 - 06:01 PM

Maybe it is the other end???

 

Hard to say, just throwing stuff on the table to look at.


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#70 Gator Bob

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Posted 15 November 2017 - 09:01 PM

A statement was made to the effect of "it goes away when the brushes are fully seated."
 
Is it true?
 
IMO, The current fast 'break-in routines are a patch for the brush radius being in the wrong orientation.


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#71 NSwanberg

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Posted 16 November 2017 - 03:02 AM

"In the Sano Can-Am A Main, after getting off of red, in fourth place, with a pair of scissors, I clipped off a bit of the inside of one of the tires."

 

Demonstration video please.


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#72 MSwiss

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Posted 16 November 2017 - 09:37 AM

Nelson,

You can see it in post #8 in this LINK.

There's not a ton of contrast with the picture taken on one of my black pit tables.

It's the outside tire (in a King donut).

Mike Swiss
 
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#73 JerseyJohn

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Posted 16 November 2017 - 10:19 AM

Beyond all of the issues regarding this motor, it's still just a mass-manufactured cheap 12 dollar motor.

At the Fall Brawl, the A and B Mains were 4.8 to 4.9, C and D mains 5.00s, on the Engleman. Custer went through every motor in his box to find the right fit. He also did a 4.8 on the Engleman in GTC Coupe with a hand-out! The A guys are all on the track all day, testing, testing, testing. Going fast requires a lot of work. Do you? I don't.

 

I dont recall all of this when you bought a Puppy Dog for 50 bucks and it was a dog... just saying.


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#74 Brian Cochrane

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Posted 16 November 2017 - 01:39 PM

The best way to prevent a motor from getting a terrible vibration that causes it to have the two-speed "wall" condition is to be very careful while breaking it in.

 

Many people let the motor hang on the lead wires while breaking it in. I don't recommend that. These motors are tempermental,y ou do wrong to them during break-in and they are ruined for life. After you do your water or Simple Green initial brush seat-in make sure the motor is totally dry and there is no dampness on the brushes. Then oil the bushings and hold the motor as if it is in the car and run it slow as you are holding it. This will dampen any vibration that the motor has and it will keep brush bounce to a minimum.

 

After you have run it a while you can give it one or two quick snaps to 10 or more volts if you like.T his will tell you if it sounds fast and has any snap. The final test is to put it in the car. Drive the car say 20 laps then let it cool off. After it has cooled run it again and then let it cool again.

 

Hanging a motor with the lead wires of your power supply causes the oil to run out of the bushings and may also get oil on the comm and brushes.


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#75 Shiggy

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Posted 16 November 2017 - 05:33 PM

Tim,
 
Where can we find technical information for JK motors? I do not see anything on the website.

We run the Hawk 7 on our track and to be competitive you need to run 2.7-2.8:1 gearing, not factoring in tire size (.720" and smaller tires).

So are the recommended ratios with or without tires? Spur/pinion or spur/pinion x tire dia?
D. "shiggy" Person

#76 Eddie Fleming

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Posted 16 November 2017 - 06:48 PM

The question changed. never mind. 


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#77 CoastalAngler1

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Posted 16 November 2017 - 07:14 PM

I race with Dale.  I wish I could be as smooth as Dale...His cars are almost silent - and very fast. 

 

I believe Dale, and have also noticed the same 'phenomenon' and I posted about these 'surge duds' a while back.

 

I don't know about puppy dogs - before my time but they sounded evil when I started out - at $50 a piece.  :huh:  

 

Two words: motor program  :ph34r:  


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#78 Gator Bob

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Posted 16 November 2017 - 10:24 PM

Go, Dale.
 
Yes Charlie, you've brought it up, others have brought it up and these threads seem to end in one of two ways
 
1 - "Locked-Up" due to arguing/name calling, etc..
2 - It drifts off to gear ratios, tire size, Puppy Dogs, soldering... hold it upside down, shake it, dip it in whatever the fast guys use, buy more, angled pinions, more testing... etc., ect., etc. :bad:
 
As said before, this is not new. Even I remember getting two-speed FKs and I quit racing these like four or five years ago.
 
What actually gets solved or resolved?
 
Kicking the can down the road. LOL.
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#79 dalek

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Posted 17 November 2017 - 12:06 AM

I took the motor apart today to try to find out what was wrong.

 

Before I took it apart, I ran it on the power supply and saw that the arm ran against the end bell bushing. 

 

There was a time I would run new motors at a few volts and check to see if the arm floated between the bushings. I found that many, maybe most, run against one bushing or the other so I quit even checking them.

 

Anyway, to get the motor apart, I had to tap on the motor shaft to get the endbell out of the motor and when I put the motor back together, it had more end play than before. I guess I drove the bushing deeper into its pocket.

 

When I checked the motor on the power supply, the arm was floating between the bushings. Also, the motor ran up just fine – no more problem like in the video.

 

I'll put it on the track tomorrow and post the results.


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#80 Fast Freddie

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Posted 17 November 2017 - 11:26 AM

Dale, just so you know for next time.

 

Try gently tapping each end of the arm shaft against something very solid and stable; I usually use one of my drill vises. It seats the bushings if they are loose or not aligned. I say do it "gently" because you don't want too much play in the arm. 

 

One more thing you can do to see if the arm is centered or tending to one end or another is to run the motor at about 2-3 volts on the power supply then push the arm shaft from one end then the other. If it moves when you push it from each end then the arm is probably centered but if it only moves when you push it from one end and not the other it's tending to the end where you don't have movement. 

 

Sometimes tapping the arm shaft on the opposite end will gain some movement without excessive play and sometimes it won't and you'll just have to live with it.


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#81 JK Products

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Posted 17 November 2017 - 03:31 PM

Where can we find technical information for JK motors? I do not see anything on the website.

We run the Hawk 7 on our track and to be competitive you need to run 2.7-2.8:1 gearing, not factoring in tire size (.720" and smaller tires).

So are the recommended ratios with or without tires? Spur/pinion or spur/pinion x tire dia?

 

Hi Shiggy,

 

We made the specification for the typical worst case scenario, with an 0.820" tire. The lower gear ratio spec (tall gearing) is really the one that hurts the motor, and you can tell when you are pushing the motor hard by how hot it gets.

 

While you can go beyond the normal specifications for the motor (as nearly everyone here has regularly), any inconsistencies or weaknesses that might not have shown up in the normal performance range of the motor are likely to be revealed and magnified the more you push the motor. Most racers know that, yes, you can be faster if you really push the motor, but that also increases the chances of a problem, up and to, including poof.

 

Tim


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#82 Bill from NH

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Posted 17 November 2017 - 05:21 PM

Tim,

 

Do you ever converse with Ron Hershman? During this week's Thorne-Hershman YouTube  show, he said he had torn into several JK motors that had the "two-shift" occurrences.

 

He said it could be caused by one of four things or a combination of more than just one of them. He didn't elaborate on the show what these items or circumstances were. He did say they weren't anything that could be "racer-corrected," but that he was open to talk to, if contacted by their manufacturer. I'm just passing along something I heard.

 

I own some early Falcons, but the last local commercial raceways here closed before the Hawks came to market.


Bill Fernald
 

My wife says I don't pay enough attention to her, or something like that.  :unknw:


#83 tonyp

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Posted 17 November 2017 - 06:40 PM

Guess I’m lucky I have never experienced this.

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#84 Gator Bob

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Posted 17 November 2017 - 06:45 PM

We made the specification for the typical worst case scenario, with an 0.820" tire.

 
This is unclear to me.

Are you saying the recommended ratio listed on the package is with 1" tires... but .820 (multiplier) is the typical worst case scenario?
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#85 The Number of

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Posted 17 November 2017 - 07:04 PM

Guess I’m lucky I have never experienced this.


You are a lucky guy, Tony, living in Florida and all. :)
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#86 dalek

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Posted 18 November 2017 - 10:24 AM

One more thing you can do to see if the arm is centered or tending to one end or another is to run the motor at about 2-3 volts on the power supply then push the arm shaft from one end then the other. If it moves when you push it from each end then the arm is probably centered but if it only moves when you push it from one end and not the other it's tending to the end where you don't have movement.

 
That's what I did, and was referring to, when I said "Before I took it apart, I ran it on the power supply and saw that the arm ran against the endbell bushing."
 
Yesterday, I ran laps with my Indy car using the fastest Hawk 7 I currently have. Then I put the bad motor in the car and it ran laps about a tenth slower (than my best motor), so as it turns out, that previously-known-as-bad motor, is an average motor. 
 
Works for me – at least I didn't flush $13.50 down the toilet when I bought it.
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#87 havlicek

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Posted 18 November 2017 - 10:43 AM

Yeah. As I mentioned earlier, there are several different reasons this kind of thing happens... or maybe a combination of them, but it's all about building a motor to sell at a price point. Almost anyone who has... or does still build motors would normally do things that preclude this from happening. I've seen it in modern and vintage motors that cost a lot more than these do, but it's really just the nature of the beast. 

When you get a particularly fast motor, the joy should be tempered by the knowledge that it won't last that long and it might be a while until you get another one.  :D  (Unless you buy and test these things by the dozens.)


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#88 Kevin Donovan

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Posted 18 November 2017 - 01:25 PM

I ran into the two-speed problem running 10/37 gears and .750" tires in a JK ready-to-run car.

#89 chasbeeman

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Posted 19 November 2017 - 10:34 AM

Could a spade connector sized for the Hawk terminals reduce the chance for overheating the plastic bushing? And a 90-degree spade connector sized for the Hawk for flexi cars?

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#90 Gator Bob

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Posted 19 November 2017 - 11:12 AM

Yes.


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#91 JerseyJohn

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Posted 19 November 2017 - 12:38 PM

OK, here is my take on revving the Hawks up on high voltage.

First almost all electric motor devices we us are free revved with no load, Both AC and DC powered. Electric drills, radial saws, Rotozip, battery-powered leaf blowers, Dremels, etc. 

IMO where you get into trouble with any hobby motor is buzzing it up before the brushes are fully seated!!! Lots of arcing and plasma particles flying around chewing up the comm.

Once the brushes are fully seated, rev away... the seated brushes will keep the comm safe and sound unless of course it's outta round... then you're screwed!!!...

 

JJ


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#92 havlicek

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Posted 19 November 2017 - 01:06 PM

Not really at all the same thing, John. 

First off, many AC motors are relatively slow... waaaay slower than these little DC motors. The ones like the Dremel and simillar can spin up to as high as 20K, but try doing that for any period of time and see how long they last, and that's still slow relatively speaking. Battery-powered leaf blowers are self-limited by the voltage they get, and I sure as heck doubt that any of them are all that fast in terms of RPM. Even high-speed tools like a Rotozip and a router are usually no faster than 20K and those have good solid industrial type bearings, have multi-pole motors with good natural balance. Really not comparable when you consider how fast even these type slot car motors are and that their design specification is NOT for free-revving at the stated voltage.

Still, all of this is really a side issue as to the whole "two-speed" thing, which itself (in only my opinion) is really no issue at all.


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#93 zipper

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Posted 19 November 2017 - 02:33 PM

I suppose out of round comms and bearings with play or bad balanced arms may cause this - when raising voltage slowly on a free spinning motor you may hear the revs not going up evenly but then doing a jump when more voltage is applied. But the clearest two-speed motors were Koford G27 arms some 15 years ago as they tended to break the wire, usually near the comm tab. Some time they went with two, then with three poles and back to two until the contact in the break was totally lost.

 

And free-revving was my special trick to check Gr 7 arms 45 years ago. If they could spin at 12v without blowing (just a battery charger) they were good. Some weren't... Nowadays I keep my revving at 9 -10 volts max; every motor after break-in seems to handle it.


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#94 JerseyJohn

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Posted 19 November 2017 - 03:18 PM

FYI most the Fawl Brawl A Main guys were spinning therir motors at 12v or better after break-in... and won. My friend who stayed at 3 volts before a load did not. Just an observation.


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#95 MSwiss

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Posted 19 November 2017 - 03:29 PM

As already mentioned (in one of these threads) these low power motors, will probably handle it.

 

The point is, for what?

 

I don't see how zinging a cold motor, with no load, simulates anything that is going on in the race.

 

Does the rare FK motor, that throws a wind, do it at the start of the heat or well into it, after the motor has heated up?


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#96 JerseyJohn

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Posted 19 November 2017 - 03:33 PM

OK, John, got it.

However what would be the proper minimum load to test the motors? Again I'm thinking the only difference between no-load and load is the strain it puts on the motor, causing it to draw more current and create more heat....

There are a lot of variables. Are the amps high at V because its binding or higher arm resistance same as if i pushed on the arm shaft the amps rise? Is it low amp at same V because it's working efficiently? Obviously the real test is put it on a track. 

I have taken  readings at 3v and 12v motors that ran slow and compared them to rockets. The results show that dogs at any compared voltage pull less amps and lower rpm when compared to a fast motor. Example reading A on a 5.9 sec motor on Engleman at 3v .5 A, at 12v .75 amp, 47k RPM on 5.3 motor 3v .65, at 12v .97A at 53.5K.
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#97 JerseyJohn

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Posted 19 November 2017 - 03:34 PM

Motors are run in for 25 mins at low volts before revving up. Never cold. IMO these motors are like a two-stroke motor; they need to scream to make power.

You can't rush the break-in process; they require lots of foreplay to find the spot. A quick break-in doesn't cut it.

There are things you can do to ruin the motor and also to get the most the motor has to offer.
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#98 MSwiss

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Posted 19 November 2017 - 03:39 PM

To be clear, this whole "run them at 12V", and the suggestion not to, was based on the person using it a diagnostic procedure, and taking readings.
 
Way different, than Willy giving the motor a few quick zings to see if it "feels fast."
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#99 JerseyJohn

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Posted 19 November 2017 - 03:57 PM

Reading volts and amps and RPM I believe is taking ready. A few zings is good to check balance of the motor at high speed. 

I think the Hawk Retri is the best thing to come along. There is nothing wrong with the new motors, just requires the right foreplay LOL.

Have a good day, Mike. I believe I'm done commenting.
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#100 Kevin Donovan

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Posted 19 November 2017 - 04:11 PM

I think all these motors with no endbell and hidden springs are junk. You guys can spin your story anyway you want.
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