Jump to content




Photo

Mura 'Green Can' Group 7 motor


  • Please log in to reply
12 replies to this topic

#1 Zippity

Zippity

    Posting Leader

  • Full Member
  • PipPipPipPipPipPipPip
  • 4,321 posts
  • Joined: 05-March 06
  • Gender:Male
  • Location:Wellington, New Zealand

Posted 18 September 2016 - 07:52 PM

Due to ill health, a friend of mine is selling his entire slot car stable.

 

Amongst the goodies, was this motor.

 

Is it of any value?

 

 

 

MuraMotor.jpg

 

MuraMotor2.jpg

 

MuraMotorTag.jpg






#2 Samiam

Samiam

    Posting Leader

  • Subscriber
  • PipPipPipPipPipPipPip
  • 3,526 posts
  • Joined: 18-January 12
  • Gender:Male
  • Location:Long Island, NY

Posted 18 September 2016 - 10:19 PM

Hell Yeah!

Too bad someone hacked up the can getting one of those pins out. I cut a slot in the head and simply unscrew it.
Sam Levitch
 
When the only tool you have is a hammer, everything is a nail.
Support your local raceway, or you won't have one.
Slot cars are quad-pods.
Support your "Local Racer."
:laugh2:

#3 Bill from NH

Bill from NH

    Age scrubs away speed!

  • Full Member
  • PipPipPipPipPipPipPipPip
  • 7,858 posts
  • Joined: 02-August 07
  • Gender:Male
  • Location:New Boston, NH

Posted 18 September 2016 - 10:41 PM

The can cutout should be at the back of the motor in order to provide some measure of axle clearance. Ron, it's a nice old motor worth hanging onto. The value will depend on what magnets & arm were used.


Bill Fernald

When chemists die, they barium.


#4 Zippity

Zippity

    Posting Leader

  • Full Member
  • PipPipPipPipPipPipPip
  • 4,321 posts
  • Joined: 05-March 06
  • Gender:Male
  • Location:Wellington, New Zealand

Posted 18 September 2016 - 11:31 PM

So the can screws were not the original hardware?

 

The motor does not appear to have been ever used, nor had a pinion or lead wires soldered to it.



#5 Bill from NH

Bill from NH

    Age scrubs away speed!

  • Full Member
  • PipPipPipPipPipPipPipPip
  • 7,858 posts
  • Joined: 02-August 07
  • Gender:Male
  • Location:New Boston, NH

Posted 18 September 2016 - 11:44 PM

I don't know if the screws are original or not, the button heads could be, but I'd sooner think pintabes were originally used..  The endbell hasn't been properly mounted to the can. Even if unused, the motor has been opened up.  Is the arm tagged or engraved with any markings?


  • Roy Lievanos likes this

Bill Fernald

When chemists die, they barium.


#6 Zippity

Zippity

    Posting Leader

  • Full Member
  • PipPipPipPipPipPipPip
  • 4,321 posts
  • Joined: 05-March 06
  • Gender:Male
  • Location:Wellington, New Zealand

Posted 19 September 2016 - 07:14 PM

Reluctantly, I have just opened the motor to take a look inside. I don't think it had ever been opened before.

 

The armature has no tag nor engravings on it:

 

MuraArm.JPG

 

A piece of the silver Mura label on the can has been broken off and there are highly visible scratch marks (had someone tried to open it?) around one of the screw holes:

 

MuraCan.JPG

 

Looking at the commutator and the inside of the motor, it is obvious that this motor has never been used before.

 

The magnets feel very strong and the armature shaft was very tight against the double ball races.

 

 

 

I have had a couple of PM's from racers expressing an interest in buying this motor.

 

As I mentioned earlier, I am selling it on behalf of a friend - who has medical bills to pay :(

 

Could someone please give me a rough idea of what this motor's value is in US $$$$ as I have no idea. The prospective buyers are wanting me to name a price.

 

Thanks for viewing :)



#7 Bill from NH

Bill from NH

    Age scrubs away speed!

  • Full Member
  • PipPipPipPipPipPipPipPip
  • 7,858 posts
  • Joined: 02-August 07
  • Gender:Male
  • Location:New Boston, NH

Posted 19 September 2016 - 09:22 PM

Ron, you probably don't care, but that Mura label was put on the can upside down. That could be the reason why the can is mounted upside down & the label partially scraped off. If you look at the end plate on the can where the bearing is located, you'll notice it's placed offcenter on the can with more room given to the edge nearest the can cutout. This was done to provide chassis clearance on an anglewinder chassis, which is what most of these C-cans were put into. If someone puts this motor in an inline chassis, mounting the can upside down isn't going to make any difference

 

The arm appears to be machine-wound rather than hand-wound. The comm has not been cut. The slight brush tracking on the comm was done when the motor was powered up to see if it would run. I estimate this motor to be worth in the US $45-$55 range.,Had the arm been  hand-wound,, the motor would be worth more.


  • macman likes this

Bill Fernald

When chemists die, they barium.


#8 Mbloes

Mbloes

    On The Lead Lap

  • Subscriber
  • PipPipPipPip
  • 426 posts
  • Joined: 19-April 12
  • Gender:Male
  • Location:Los Angeles, CA

Posted 20 September 2016 - 02:56 PM

Really?  I would say it's obviously been opened.  I've never seen a Mura can / endbell combo without the pintabs, so my guess is that the pintabs were removed and replaced with the allen head screws.  This, the damage around the screws and the fact that the endbell is mounted upside down all point to it being opened.

 

Finally, I would say this comm has been run.

 

Bill, I don't think that the label was put on upside down.  The Mura arrow would have been pointing "down" in Ron's photo, so if you flip the can over for proper can drive placement, the arrow will be pointing in the correct rotational direction.


Mike Bloes

#9 Bill from NH

Bill from NH

    Age scrubs away speed!

  • Full Member
  • PipPipPipPipPipPipPipPip
  • 7,858 posts
  • Joined: 02-August 07
  • Gender:Male
  • Location:New Boston, NH

Posted 20 September 2016 - 03:46 PM

Mike, if you flip the can over so it's oriented corrrectly to the endbell,, the word MURA on the label will be upside down. I wasn't considering an arrow, that doesn't show. :)  .It's always possible that the arm now in the can isn't the original one. No question whether the motor has been opened or not, but the arm shown hasn't been powered much. I doubt the motor brushes are even broken in, if we saw them. Whoever removed the pintabs didn't know the fingernail clipper trick. Both the can & back heatsink were scratched. If this motor got blueprinted, the owner would have a fine looking vintage C-can motor..


Bill Fernald

When chemists die, they barium.


#10 havlicek

havlicek

    OCD Rewinder

  • Subscriber
  • PipPipPipPipPipPipPipPip
  • 8,477 posts
  • Joined: 20-August 07
  • Gender:Male
  • Location:NY

Posted 20 September 2016 - 04:16 PM

It seems pretty clear to me that the can has been opened (as per Mike Bloes) and the motor has definitely been run...not even a question.  The arm is nothing special at all, which is not to say it might not run well.  The stack and com seem to be Mura, but there are two weird things about the arm that caught my attention:

1)The material used to tie the com looks like fiberglass!  I never saw Mura use that, but I could be wrong.  Whatever it is, it sure doesn;t look like the regular material they used.

2)I'm surprised nobody mentioned the balancing holes.  Mura used what I think were spot-weld drills that produced a very shallow angle (wish I could find the ones they used!).  These seem to have been done using a regular run of the mill drill.

 

3)The actual winding is sloppy and ugly...pretty much how all the Muras were done, could have been hand wound, could have been machine wound...but if it was hand wound, it wasn't done by anyone of note...which is borne out by the lack of engraving.  The label says Group 7, but the coils *seem* to be #27-ish wire (which would be roughly group 20).  Without a good meter, it would be hard to tell.  In short, I wouldn't be surprised if this wasn't the original arm.  I bet Philippe could clear all this up.

 

Like Bill, I would guess that the motor is worth maybe $40 or more.  It depends on whether or not you hit the right buyer.

 

-john


John Havlicek

#11 Mbloes

Mbloes

    On The Lead Lap

  • Subscriber
  • PipPipPipPip
  • 426 posts
  • Joined: 19-April 12
  • Gender:Male
  • Location:Los Angeles, CA

Posted 20 September 2016 - 05:23 PM

Mike, if you flip the can over so it's oriented corrrectly to the endbell,, the word MURA on the label will be upside down.

 

Correct.  I see what you are saying, though.  I meant, the sticker is showing the correct rotational direction, just based on my experience.

 

Check out my photo.  If these motors are oriented correctly, the sticker is either upside down (facing the front of the car) or right side up but facing the rear.

 

I've never seen a Mura sticker right side up, facing the front - the arrow would be going in the wrong direction.

 

mura sticker.jpg


Mike Bloes

#12 Zippity

Zippity

    Posting Leader

  • Full Member
  • PipPipPipPipPipPipPip
  • 4,321 posts
  • Joined: 05-March 06
  • Gender:Male
  • Location:Wellington, New Zealand

Posted 20 September 2016 - 05:24 PM

Thanks for all the feedback :)

 

I will open the motor again, measure the gauss of the magnets, get the timing, and polish the armature and commutator.
 
The brushes have no wear on them.


#13 Zippity

Zippity

    Posting Leader

  • Full Member
  • PipPipPipPipPipPipPip
  • 4,321 posts
  • Joined: 05-March 06
  • Gender:Male
  • Location:Wellington, New Zealand

Posted 20 September 2016 - 08:39 PM

The gauss readings for the can (using my Spin Doctor Magnet Meter) read 1187 South and 1300 North.

 

The armature's timing is 30 degrees. Diameter .510" and the comm is .203"

 

The stack length is .479"

 

Windings.JPG

 

Comm.JPG

 

Bottom.JPG







Electric Dreams Online Shop