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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.

 

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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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Mike Swiss
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Two-time G7 World Champion (1988, 1990), eight G7 main appearances
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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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Mike Swiss
IRRA® Components Committee Chairman
Five-time USRA National Champion (two G7, one G27, two G7 Senior)
Two-time G7 World Champion (1988, 1990), eight G7 main appearances
Eight-time G7 King track single lap world record holder

17B West Ogden Ave Westmont, IL 60559, (708) 203-8003, mikeswiss86@hotmail.com (also my PayPal address)

Note: Send all USPS packages and mail to: 5858 Chase Ave., Downers Grove, IL 60516


#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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Five-time USRA National Champion (two G7, one G27, two G7 Senior)
Two-time G7 World Champion (1988, 1990), eight G7 main appearances
Eight-time G7 King track single lap world record holder

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Note: Send all USPS packages and mail to: 5858 Chase Ave., Downers Grove, IL 60516


#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
IRRA® Components Committee Chairman
Five-time USRA National Champion (two G7, one G27, two G7 Senior)
Two-time G7 World Champion (1988, 1990), eight G7 main appearances
Eight-time G7 King track single lap world record holder

17B West Ogden Ave Westmont, IL 60559, (708) 203-8003, mikeswiss86@hotmail.com (also my PayPal address)

Note: Send all USPS packages and mail to: 5858 Chase Ave., Downers Grove, IL 60516


#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
IRRA® Components Committee Chairman
Five-time USRA National Champion (two G7, one G27, two G7 Senior)
Two-time G7 World Champion (1988, 1990), eight G7 main appearances
Eight-time G7 King track single lap world record holder

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Note: Send all USPS packages and mail to: 5858 Chase Ave., Downers Grove, IL 60516


#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?
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