Jump to content




Photo

Hawk 7 two-speed "wall" syndrome


  • This topic is locked This topic is locked
221 replies to this topic

#26 Cheater

Cheater

    Headmaster of the asylum

  • Root Admin
  • PipPipPipPipPipPipPipPip
  • 23,128 posts
  • Joined: 14-February 06
  • Gender:Male
  • Location:Norcross, GA

Posted 14 November 2017 - 07:23 PM

Will, I was racing slot cars when you were in diapers. And I have burnt up my share of motors, believe me. I recall one enduro in South Georgia where we burned four or five motors just in practice for the race and decided to DNS.

I am not defending anyone. There may be a problem with the motors or there may not be, I have no opinion.

But what I do have an opinion on is the standard of discussion in my little house. Ridicule and insults don't sit well with me, nor, I am pretty sure, with a large portion of the members here.

Keep in mind that this isn't Facebook.

Gregory Wells

Never forget that first place goes to the racer with the MOST laps, not the racer with the FASTEST lap





#27 Brinkley47

Brinkley47

    A winner is a loser who gave it one more try

  • Full Member
  • PipPipPipPipPip
  • 845 posts
  • Joined: 18-August 12
  • Gender:Male
  • Location:Murfreesboro, TN

Posted 14 November 2017 - 07:27 PM

So jumping on the OP is OK? Got it. Your playground, Greg. Just dont be surprised when you are the only one in the sandbox.
Will Brinkley
willbrinkley@gmail.com

#28 Cheater

Cheater

    Headmaster of the asylum

  • Root Admin
  • PipPipPipPipPipPipPipPip
  • 23,128 posts
  • Joined: 14-February 06
  • Gender:Male
  • Location:Norcross, GA

Posted 14 November 2017 - 07:32 PM

So jumping on the OP is OK?


Show me where that occurred, Will. I don't think you can.

Gregory Wells

Never forget that first place goes to the racer with the MOST laps, not the racer with the FASTEST lap


#29 Noose

Noose

    Grand Champion Poster

  • Full Member
  • PipPipPipPipPipPipPipPip
  • 21,364 posts
  • Joined: 08-November 06
  • Gender:Male
  • Location:Denville, NJ

Posted 14 November 2017 - 10:16 PM

I had the two-step dance with Rs and putting them on low voltage (2 volts) for around 20 minutes cured the problem.

I know motors blew at the Fall Brawl but I cannot say all were 7Rs. I will say that the Simple Green method works but great care to thoroughly clean it out is a must. Thus one can conclude Haste makes Waste if not done properly as one tries to hurry to get motors broken in.


  • tonyp, DOCinCocoa and bbr like this

Joe "Noose" Neumeister
Sometimes known as a serial despoiler of the clear purity of virgin Lexan bodies. Lexan is my canvas!
Noose Custom Painting - Since 1967
Chairman - IRRA® Body Committee - Roving IRRA® Tech Dude - "EVIL BUCKS Painter"

"Team Evil Bucks" Racer - 2016 Caribbean Retro Overall Champion
The only thing bad about Retro is admitting that you remember doing it originally.


#30 Kevin Donovan

Kevin Donovan

    Mid-Pack Racer

  • Partial Member
  • PipPipPip
  • 120 posts
  • Joined: 05-December 16
  • Gender:Male
  • Location:Alden, NY

Posted 14 November 2017 - 11:16 PM

I had some of these two-speed issues and fixed it by putting a drop of superglue on the leadwire tabs.


  • Cheater likes this

#31 slotcarone

slotcarone

    Posting Leader

  • Full Member
  • PipPipPipPipPipPipPip
  • 3,380 posts
  • Joined: 23-January 07
  • Gender:Male
  • Location:Dutchess County, NY

Posted 15 November 2017 - 12:01 AM

Thanks for the info, Kevin. I will find a two-stepper in my box and give your method a try!

Mike Katz

Scratchbuilts forever!!


#32 NSwanberg

NSwanberg

    Checkered Flag in Hand

  • Full Member
  • PipPipPipPipPipPip
  • 1,057 posts
  • Joined: 01-April 09
  • Gender:Male
  • Location:Canton, MI

Posted 15 November 2017 - 02:37 AM

On my chassis dyno, with a complete car, I quite often find cars that will be smooth at near 4 volts and then buzz like crazy until I get to 7 volts where the car will suddenly smooth out. The current draw of the motor will drop and the output voltage of the dyno will suddenly increase as well. I attribute it to harmonics in the drive train, including the motor, that cannot be accounted for. The final test should always on the track. 
 
How can we expect non-epoxied winds to stay in place and an armature to remain in balance through an RPM range? Most armatures are never in prefect balance and will have a critical RPM where the unbalanced condition is apparent. Getting that imperfection out of the usable RPM range for these cheap little sealed motors seems almost a crap shoot to me with the winds flapping in the breeze.
 
Switch oil and see if it changes.
 
You can bet I am going to try super glue on the tabs to see if that helps!


  • tonyp likes this
Remember the Steube bar!
SUPPORT YOUR LOCAL RACEWAY!!
"The denial of denial is the first sign of denial." Hank, from Corner Gas
Nelson Swanberg

Peace be with all of us and good racing for the rest of us.
Have controller. Will travel. Slot Car Heaven

#33 Zippity

Zippity

    Posting Leader

  • Full Member
  • PipPipPipPipPipPipPip
  • 4,677 posts
  • Joined: 05-March 06
  • Gender:Male
  • Location:Wellington, New Zealand

Posted 15 November 2017 - 04:21 AM

Please remind me.

 

Are we talking about $12 motors here, or have I missed something?


  • Cheater likes this

Ron Thornton
 

 


#34 raisin27

raisin27

    On The Lead Lap

  • Subscriber
  • PipPipPipPip
  • 425 posts
  • Joined: 11-March 13
  • Gender:Male
  • Location:Garden City, MI

Posted 15 November 2017 - 05:49 AM

Although super gluing the tabs or windings is probably undetectable wouldn't that be considered illegal for sealed motor racing?


Michael Garrett

 

Proud to drive an American car, from an American manufacturer, assembled by American workers.

 

 I own a car from each of the big 3, I have a Ford, a Mercury, and a Lincoln.


#35 Racer36

Racer36

    Race Leader

  • Subscriber
  • PipPipPipPipPip
  • 796 posts
  • Joined: 09-October 11
  • Gender:Male
  • Location:St. Catharines, Ontario, Canada

Posted 15 November 2017 - 05:56 AM

Superglue on the wire tabs fixing the problem just confirms what I stated earlier. Too much heat when soldering the wires melted the nylon bushing and destabilized the brush arm. With proper prep and clean work it should take less than a second to solder wires. Any more is just asking for trouble.

Dennis Dominey

Lifelong half-assed slot racer


#36 Kevin Donovan

Kevin Donovan

    Mid-Pack Racer

  • Partial Member
  • PipPipPip
  • 120 posts
  • Joined: 05-December 16
  • Gender:Male
  • Location:Alden, NY

Posted 15 November 2017 - 06:02 AM

Although super gluing the tabs or windings is probably undetectable wouldn't that be considered illegal for sealed motor racing?


It's easy to see the superglue on the tabs so I guess thats up to the interpretation of the tech guy.

What bothers me the most is that I don't remember these issues with the old Falcon 7 or earlier Hawk7.
I never had one two-speed and they didn't require such elaborate break-in.
I remember just running them in on the track and they usually ran great.
Supposedly the brushes are harder now but I dont think the new motors are as good.



#37 Kevin Donovan

Kevin Donovan

    Mid-Pack Racer

  • Partial Member
  • PipPipPip
  • 120 posts
  • Joined: 05-December 16
  • Gender:Male
  • Location:Alden, NY

Posted 15 November 2017 - 06:12 AM

I think the tabs are loose and the leadwire movement causes the problem.
The car speeds up and slows down in the same sections of the track lap after lap.
I’ve never seen this running a motor with conventional endbell.

#38 slotcarone

slotcarone

    Posting Leader

  • Full Member
  • PipPipPipPipPipPipPip
  • 3,380 posts
  • Joined: 23-January 07
  • Gender:Male
  • Location:Dutchess County, NY

Posted 15 November 2017 - 06:52 AM

Superglue on the wire tabs fixing the problem just confirms what I stated earlier. Too much heat when soldering the wires melted the nylon bushing and destabilized the brush arm. With proper prep and clean work it should take less than a second to solder wires. Any more is just asking for trouble.


This happens even before the motor has been installed in a car!! No heat on the tabs!
  • Jim Lange, NSwanberg, Matt Sheldon and 1 other like this

Mike Katz

Scratchbuilts forever!!


#39 havlicek

havlicek

    OCD Rewinder

  • Subscriber
  • PipPipPipPipPipPipPipPip
  • 10,299 posts
  • Joined: 20-August 07
  • Gender:Male
  • Location:NY

Posted 15 November 2017 - 07:18 AM

My "take" on all this after watching the video is that this is a *very* common thing.  I've frequently seen this sort of behavior with motors from:

1) Slight bushing misalignment (can sometimes be self-corrected by running-in the bushings).
2) Dry bushings
3) Armature imbalance (again, even slight)
4) Brush/spring problems... hung-up (not the case with this type motor because the brushes aren't located within hoods), brush "bounce" (can be caused by different things like weak springs, out-of-round comm, or sufficiently "untrue" shaft; in this type motor, loose spring arms).
5) Too much end-play and/or arm not centered in the field (tightening the end play on sealed motors by banging the can or pushing the bushing and then trying to "reset" the bushing can make this better or worse).

I may be forgetting some possible causes, but it's also quite possible that more than one of the above is in play here, and how the motor is installed could make the behavior more noticeable or not. I honestly think this sort of thing is probably way more prevalent than many people might think with "all" inexpensive sealed-type motors. Motors with actual endbells *might* be more easily improved depending on the skill of the person and what the cause is but here's the thing:

On motors (more $) and in racing classes where the motors are meant to be opened and checked/worked-on, a lot of the basic "tuning" steps a builder might do would normally take care of this sort of thing. The behavior of the motor in the video is the same as you would see with some older, less expensive motors from Mabuchi, Mura, Champion, etc. As you got into the more expensive motors from any of those manufacturers, you *hopefully* got motors that needed a drop of oil and not much more because of tighter tolerances/specs, but even then racers just opened-up the motors to get things as right as they could.

 

While I believe this behavior is probably way more prevalent than people might think and is really to be expected from such low-cost motors just because of "chance," that same "chance" means that the presence or absence of the general type behavior and to what extent it's there almost definitely will vary from production run to production run. To put it simply, it's mostly just "the nature of the beast." 

 

All of this type motor and those with an actual endbell are made to a similar general spec because they have to be! The biggest mistake would be to think that one brand or the other has some sort of advantage, when they're all subject to "chance" from production run to production run. The other way to state that is that they're all exceptional performers... all things considered.

On a side note, I get asked to make "special" motors all the time (of course, I don't do that... ever) because there's the impression at least, that some people have a motor "advantage." This kind of motor would naturally be more difficult to "improve" in a way that's hard to notice, but I have to assume that some people have figured ways to have at it. Personally, I think that it's far more likely that people work around these variances by buying a whole bunch of motors, and there goes the whole "even playing field" and/or "taking money out of the equation." The answer to that is just hand-out motors, but everyone already knows that. There will still be some "cherries," but at least everyone has the same chance of getting one.


John Havlicek

#40 Kevin Donovan

Kevin Donovan

    Mid-Pack Racer

  • Partial Member
  • PipPipPip
  • 120 posts
  • Joined: 05-December 16
  • Gender:Male
  • Location:Alden, NY

Posted 15 November 2017 - 07:21 AM

Never had the two-speed issue on a Falcon 7. Soldered the same way with them.



#41 havlicek

havlicek

    OCD Rewinder

  • Subscriber
  • PipPipPipPipPipPipPipPip
  • 10,299 posts
  • Joined: 20-August 07
  • Gender:Male
  • Location:NY

Posted 15 November 2017 - 08:00 AM

Personally, and having seen motors do this many times, none of what I think might be causing this has to do with "user-error." The soldering thing "might" be the case for some people (I wouldn't know honestly), but with the very thin brass brush arms in these motors that probably does happen sometimes. 

The superglue thing seems like something to try anyway because it's easy to test.
John Havlicek

#42 John Streisguth

John Streisguth

    Johnny VW

  • Full Member
  • PipPipPipPipPipPipPip
  • 4,862 posts
  • Joined: 20-November 08
  • Gender:Male
  • Location:Bangor, PA

Posted 15 November 2017 - 09:57 AM

I have seen the 'two-speed" phenomenon, and IMO John H probably has explained most of the possible reasons. Cheap motors, lots of variation in production. They are what they arre.

 

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.


  • tonyp and Samiam like this
"Whatever..."

#43 JerseyJohn

JerseyJohn

    Posting Leader

  • Full Member
  • PipPipPipPipPipPipPip
  • 3,910 posts
  • Joined: 05-September 07
  • Gender:Male
  • Location:Northern NJ

Posted 15 November 2017 - 11:01 AM

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.

 

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


  • Samiam likes this
JJ TRADE MARK BANNER copy.jpg

John Chas Molnar

"Certified Newark Wise Guy since 1984" (retired)
"Certified Tony P Chassis God since 2007"
" Internationally Know Slot Car Racing Celebrity "
https://www.facebook...nchassisworks/#
Email me
 


#44 Fast Freddie

Fast Freddie

    Race Leader

  • Full Member
  • PipPipPipPipPip
  • 641 posts
  • Joined: 04-March 08

Posted 15 November 2017 - 11:39 AM

I've had several of these two-speed motors and I concur with Jersey John. Once the brushes are fully seated the two-speed effect is gone, at least that has been what happened on all of my HR and H7 motors. 

 

One other thing that has happened on several of my motors is that when the two-speed effect goes away the magnetic "cog" seems to increase. I only have 20 motors so that is only what I have experienced with my limited supply of motors.


  • Cheater likes this
Fred Younkin

#45 JK Products

JK Products

    Mid-Pack Racer

  • Subscriber
  • PipPipPip
  • 154 posts
  • Joined: 12-December 15
  • Gender:Male
  • Location:Carson City, NV

Posted 15 November 2017 - 11:59 AM

Thanks, John(s), and we know this is done often.

 

A gear ratio of 2.7:1 or 2.8:1 is really tall gearing and significantly outside of the recommended 3.3-4.2:1 operating range for these motors.

 

Can you do it? Sure.

 

Will it work sometimes? Yes.

 

Will you blow up more motors as a result? You bet.

 

Is this a defect in the motor???


Tim Homola
JK Products

#46 willy wonka

willy wonka

    Race Leader

  • Full Member
  • PipPipPipPipPip
  • 627 posts
  • Joined: 18-January 10
  • Gender:Male
  • Location:NE OH

Posted 15 November 2017 - 12:27 PM

I've seen this many times, even with the older versions. I usually marked it and just keep trying them and over time some would come around, some would not.

The smoke show at the Brawl I would say was either because over-gearing or the car on too soft of tires causing a lot of heat in the motor.
William Custer
To finish First you must first Finish

#47 Fast Freddie

Fast Freddie

    Race Leader

  • Full Member
  • PipPipPipPipPip
  • 641 posts
  • Joined: 04-March 08

Posted 15 November 2017 - 12:51 PM

I noted this on the other thread but which has the most effect on the motor gear ratio or FDR (final drive ratio)?  A gear ratio of 13/36 with .720" tires has a FDR of 3.85. The most popular gear ratio in Retro racing is 9/28 with .8125" tires and the FDR is 3.83. I have run an HR motor with that first gear and tire set-up, in a major race, with no adverse problems and the car ran very good. I have also run a HR motor with a 10/35 gear set and .760" tires. The FDR in that case was 4.61. Since it was virtually impossible to hit a good FDR with such a small pinion gear I relied on the overall gear ratio in this case.
 
Like John pointed out above 10/28 or 10/29 is the wrong gear ratio for .8125" tires. Both 9/28 and 10/31 yield nearly the same gear ratio and FDRs of 3.83 and 3.82 respectively.
Fred Younkin

#48 willy wonka

willy wonka

    Race Leader

  • Full Member
  • PipPipPipPipPip
  • 627 posts
  • Joined: 18-January 10
  • Gender:Male
  • Location:NE OH

Posted 15 November 2017 - 12:57 PM

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


9/27 for me.
William Custer
To finish First you must first Finish

#49 Pablo

Pablo

    Builder

  • Subscriber
  • PipPipPipPipPipPipPipPip
  • 13,754 posts
  • Joined: 20-February 06
  • Gender:Male
  • Location:Johnson Bayou, Mississippi Gulf Coast

Posted 15 November 2017 - 01:05 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.


  • NSwanberg and JK Products like this
Paul Wolcott

#50 John Streisguth

John Streisguth

    Johnny VW

  • Full Member
  • PipPipPipPipPipPipPip
  • 4,862 posts
  • Joined: 20-November 08
  • Gender:Male
  • Location:Bangor, PA

Posted 15 November 2017 - 01:05 PM

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

 

I didn't race Coupe, but it seemed that's where people were taking the risk, if they had a motor that didn't have good speed. Not sure about Can-Am, I wasn't paying attention as I had my own problems LOL.


"Whatever..."





Electric Dreams Online Shop