22 replies to this topic

[Don Wedding]

Just picked up these 2 Mura motors in a box of Vintage slot cars.

 

Both have the Mura sticker on the can.

 

The purple Motor's arm has a tag that reads  Grp 7  and it has been balanced.

 

Blue Motor has a Mura endbell but no markings on arm but it is also balanced.

 

Were these made by Mura as they stand? What age would you put on them.

 

Both were tested and run great. The GRP 7 seems super strong. What performance or class would that motor be run in.

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[TSR]

Don,

the purple motor is a type "B" from late 1969 as it already has the larger brush holders.

The other is a "D-size" motor, does not have the can shim, so is likely a "Group-12" from 1969 through 1972, that uses the older 1968 endbell with pent-roof brush holders, obsolete for open-class Mura motors by that time, but old stock was used on those G-12 motors that had a larger armature of the same diameter as a Mabuchi "26D".

Both are standard Mura motors.

The purple one is stock number M-522, the blue one is M-422. Please note that these numbers remain the same for several variations of these motors over time... with Mura, it's pretty complicated! 

[Gator Bob]

A+B w/stickers = Good score Don ....

 

Dokk, weren't  the earlier Gr-12 class motors un-balanced until it became Gr-12x in the C cans much later for 'Box12'?

 

Just asking ..

I have a short stack Mura 12 (un-bal) and a short stack Mura 12x (balanced) and also the Gr-12 Champion 26D motors were un-balanced.

That lead me to believe it was an un-balanced class.

 

Tell us about the connection between the classes based on retail cost if there really is one.

TIA.

[TSR]

Bob,

per NCC rules, Group-12 were supposed to be unbalanced and not epoxied, meaning, after factory assembly...

Checking the Mura catalogs, the first C-can motors were first sold under the MPP brand (Modified Production Products) from 1971 through 1972. In the first listing, there is only a Group-15 motor (# 049 assembled or 049K in kit form), but not Group-12.
 

These appear in the "Mura II" listing from 1973, in two forms: with D-size cans (so, effectively the old motor recycled and also found in Dynamic and Riggen RTR cars), # RO-16, and in C-can form, # R-O.

Then there is an "Illegal Group-15" (balanced, epoxied, trued), # R-1-X.
 

But no mention of a G-12 also balanced and epoxied. If they are 'short stack", they are from the 1980s, still in the same can but with the shorter magnets. There is such an animal in the 1984 catalog, # RO, but again, no balanced version. However the balanced, epoxied etc. Group-15 is still there, # R1-INT. (obviously for "International G-15" racing).

 

In 1995, the "Mura IV" catalog shows two Group 12 motors, # M1012 with "buss bars" and M1013-P with "high timing, double shaft and buss bars".

 

No mention anywhere of a balanced G-12. Do you have more info on this, or a boxed/bagged  motor?

[Gator Bob]

I have a Gr-12x in a 'Box' car I built back in like 1989. One of 'My Built" motors from a 'stock' Mura C can (#ROA-Wasp)

I ran it in a 'Box15" class as the arm was legal and a was faster than the Mura #R11-INT for me.

 

Here is what I found...

 

Motors  - mid to late 80s Mura.

#RO was an unbalanced 12

#RO-X was the balanced 12 - I used the wrong nomenclature, they are is tagged X-12 (not 12x)

 

Armatures:

#R10 was unbalanced (have a used one somewhere)

#R10-X balanced version ( see photo)

 

I don't believe I have any 80s NOS Mura 12s or X-12s on hand anymore.

Also - there was a statement by .. I can't remember who ... that the "X" stood for High Timed but it was for Balanced / Outlaw as Gr-12 was an un-balanced class back in the day.

 

[TSR]

Bob, that's not a "Group-12" but an "X12", a totally different animal. We use X12 arms in retro pro cars now inside Pro Slot 4002 setups.
I am not sure when the X12 started because it is way past my personal years of interest, but it was in the early to mid 1980s at the earliest. By that time, the original Group-12 concept had long gone out the window.
The X12 arms today are little else than open-class arms with smaller wire. The 1969 Group-12 motors were meant to be simple replacement for the Mabuchi FT16D and FT26 stock, unmodified motors for the lowest possible cost of racing.
 

Group-12 is vintage, from the 1969 NCC rules, X12 is "post-vintage"... and has little in common with G-12 other than the use of the numerals, which just like "box stock" means basically nothing anymore since it is not "stock" and there is no box. 
I am not sure what the X12 are wound with but the stacks are like 1/8" shorter than they used to be, they are smaller in diameter and they are little rockets.

 

Two very different eras...
 

[SlotStox#53]

Very nice find Don A couple of very cool Mura motors . Bolt 'em in and enjoy 'em !

[Gator Bob]

Sorry Don for hijacking.

 

Bob, that's not a "Group-12" but an "X12", a totally different animal. We use X12 arms in retro pro cars now inside Pro Slot 4002 setups.
I am not sure when the X12 started because it is way past my personal years of interest, but it was in the early to mid 1980s at the earliest. By that time, the original Group-12 concept had long gone out the window.
The X12 arms today are little else than open-class arms with smaller wire. The 1969 Group-12 motors were meant to be simple replacement for the Mabuchi FT16D and FT26 stock, unmodified motors for the lowest possible cost of racing.
 

Group-12 is vintage, from the 1969 NCC rules, X12 is "post-vintage"... and has little in common with G-12 other than the use of the numerals, which just like "box stock" means basically nothing anymore since it is not "stock" and there is no box. 
I am not sure what the X12 are wound with but the stacks are like 1/8" shorter than they used to be, they are smaller in diameter and they are little rockets.

 

Two very different eras...

 

 

Dokk,

 

I agree that this two totally diferant eras separated by 15+ years, but Group 12 un-balanced ether survived from 1970 till the mid 90s or resurfaced in that time frame. The X-12 (balanced/outlaw) version took over as the standard in the 12 classification.   

 

That is a C can arm (R10-X) showing and not compatible with P/S 4002 set-ups.. too long. I do have a couple of P/S Retro Pro X12 motors.

I think they called them 'Box' cars because there were RTRs sold "in the box'

Straight out of the rulebook from where I raced. (Track Champ in Gr-10, second in Outlaw-Flexi... BTW)

There was a time when I could drive pretty good 

 

Motors:

Mura #RO or RO-X

Parma #455

Racer Products #K-2 or K-5X

Champion #506 or #509

[SlotStox#53]

Even better they still have their "pin tabs" so perfect for the period Korrect police

[Hworth08]

I'm not much help but I remember Monty writing of the 12 arms changing from 60 turns of 29 to the 55 turns used today. Monty thought the motors would have been better if they stayed with 60 turns. No date the date of the change was mentioned.

[Gator Bob]

Bob, that's not a "Group-12" but an "X12", a totally different animal. We use X12 arms in retro pro cars now inside Pro Slot 4002 setups.
I am not sure when the X12 started because it is way past my personal years of interest, but it was in the early to mid 1980s at the earliest. By that time, the original Group-12 concept had long gone out the window.
The X12 arms today are little else than open-class arms with smaller wire. The 1969 Group-12 motors were meant to be simple replacement for the Mabuchi FT16D and FT26 stock, unmodified motors for the lowest possible cost of racing.
 

Group-12 is vintage, from the 1969 NCC rules, X12 is "post-vintage"... and has little in common with G-12 other than the use of the numerals, which just like "box stock" means basically nothing anymore since it is not "stock" and there is no box. 
I am not sure what the X12 are wound with but the stacks are like 1/8" shorter than they used to be, they are smaller in diameter and they are little rockets.

 

Two very different eras...
 

 

I understand ... 15+ years difference. So ether the Group12 carried into the early 80s as an unbalanced short stack w/ .007 lams or the moniker returned in that 15 year period. The Gr12 I'm speaking to was in an overlap timeframe with (Gr)X12 in the mid to late 1980s.

 

 

I don't understand the 26D size 0.590 dia. arms being used in the "A" can (D size) motors.

Which magnets were used?

[Gator Bob]

Don,

the purple motor is a type "B" from late 1969 as it already has the larger brush holders.

The other is a "D-size" motor, does not have the can shim, so is likely a "Group-12" from 1969 through 1972, that uses the older 1968 endbell with pent-roof brush holders, obsolete for open-class Mura motors by that time, but old stock was used on those G-12 motors that had a larger armature of the same diameter as a Mabuchi "26D".

Both are standard Mura motors.

The purple one is stock number M-522, the blue one is M-422. Please note that these numbers remain the same for several variations of these motors over time... with Mura, it's pretty complicated! 

So back to Don W. new motors .. the Blue "A" can (D size) can't be a Group 12 if it is balanced. Correct?

 

The Purple "B" Gr-7 sure is a nice little Hotty....  

[proptop]

Bob...I've got one of those dark blue A cans with the red and yellow magnets...it has a .525" dia. un balanced arm... (G 12 probably?) it also has sq. brush hoods, like the early B's...

 

Another A can (or 16D size which ever term you prefer) I have has a .590" dia. arm...and the magnets are dark brown and soft, like refrigerator magnets...and about that "strong" (if you could use that word)....

[havlicek]

 

 

Another A can (or 16D size which ever term you prefer) I have has a .590" dia. arm...and the magnets are dark brown and soft, like refrigerator magnets...and about that "strong" (if you could use that word)....

 

 

-john

[Gator Bob]

Tom Hemmes
Insert witty phrase here...

......... the magnets are dark brown and soft, like refrigerator magnets...and about that "strong" (if you could use that word)....

 

 .... I busted out  

Thanks Tom

[TSR]

I don't understand the 26D size 0.590 dia. arms being used in the "A" can (D size) motors.

Which magnets were used?

 

Thin and rather weak ones, recognizable by their colorful  red and yellow markings. It is very easy to pick a Mura D-size Group-12 or Group-15 motor from an "open-class" motor: the G12/G15 do not have the large fully enclosing magnet shim (the "can in a can"), that reduced the diameter of the vent holes on the flat faces of the can. Mura also had a "one-hole" motor, generally black in color, with the G12/G15 arms and no shim:

 

Here is a standard 2-hole D-size 1968-1970 Mura motor with shim:
 

 

And one without shim:

 

 

the Blue "A" can (D size) can't be a Group 12 if it is balanced. Correct?

 

The blue motor IS a G12 or G15, because it does not have the shim. The armature is close in diameter to that of a Mabuchi FT26, and if it shows signs of balancing it will have been done after it was in the hands of its first owner.
 

[Gator Bob]

 

Thin and rather weak ones, recognizable by their colorful  red and yellow markings. It is very easy to pick a Mura D-size Group-12 or Group-15 motor from an "open-class" motor: the G12/G15 do not have the large fully enclosing magnet shim (the "can in a can"), that reduced the diameter of the vent holes on the flat faces of the can. Mura also had a "one-hole" motor, generally black in color, with the G12/G15 arms and no shim:

 

1226.jpg

Here is a standard 2-hole D-size 1968-1970 Mura motor with shim:
 

1252.jpg

cukras-colors-12.jpg

 

And one without shim:

2010-03-01 115.JPG

 

- 007.JPG

 

 

The blue motor IS a G12 or G15, because it does not have the shim. The armature is close in diameter to that of a Mabuchi FT26, and if it shows signs of balancing it will have been done after it was in the hands of its first owner.
 

 

I STILL don't get it!

Blue A can, Red/Yel mags, no "Semi-Can" shim.

 

Dokk, you have said this before "The armature is close in diameter to that of a Mabuchi FT26"  Please ... do you (or anyone have) a the diameter and/or a picture of this mystery arm ?

 

[TSR]

There are two types of these mags, for two arm diameters.
I posted a picture of the one with the thin mags and the big arm here about a year ago but cannot find it now.
 

[Don Wedding]

Gentlemen, Thanks for all the info, Looks like I opened a can of worms on tech specs. SORRY.

 

As always this forum is a pleasure to post on , and to get answers on the world of vintage slot stuff .

 

And Thanks to Dokk for his vast memory before it fades away. He should write a book and publish it .

[proptop]

Don...speaking for myself, (and I think the other guys would agree) it's kinda like Detective work...trying to get things figured out with all the variations of Mura (and Champion, and etc. etc.  ) motors...

 

As far as I'm concerned, it started for me with an article written in SARN in 1994 by Dokk, about Vintage Slot Car Motors...I have that issue around here somewhere, but can't find it right off hand...Dokk, would you be able to post that article you wrote back then?

 

Bob...that pic on the left, in your post #11 looks like a "big" arm?  The arm that came in the A can with the Refrigerator magnets (  )  looks very much like the .525 dia. arm (but it's .590 dia.) that came in my blue motor with the red / yellow magnets.

 

My blue motor w/ the red/yellow mags has a "hole" of about .560 across...so the .590 arm will obviously not fit. The dk. brown fridge mags were in a black 2 hole std. length can, and are a lot thinner than the red / yellow ones.

[proptop]

As far as pics of the rubbery , dark brown / thin magnets, IIRC, I think it was Pablo who posted some pics in one of his "adventures in motor building" segments in one of his build threads? Gonna haveta do some digging...

 

 

 

Edit: Having a problem with the copy and paste...? Anyway, couldn't find pics, but in Pablo's (  ) "Electricity is funny " thread...page 2...starting at post #51...(ya still have those mags Pablo?)

[Gator Bob]

Gentlemen, Thanks for all the info, Looks like I opened a can of worms on tech specs. SORRY.

 

As always this forum is a pleasure to post on , and to get answers on the world of vintage slot stuff .

 

And Thanks to Dokk for his vast memory before it fades away. He should write a book and publish it .

 

Two cans ... an A and a B.

Darn worms ....

 

Don...speaking for myself, (and I think the other guys would agree) it's kinda like Detective work...trying to get things figured out with all the variations of Mura (and Champion, and etc. etc.  ) motors...

 

As far as I'm concerned, it started for me with an article written in SARN in 1994 by Dokk, about Vintage Slot Car Motors...I have that issue around here somewhere, but can't find it right off hand...Dokk, would you be able to post that article you wrote back then?

 

Bob...that pic on the left, in your post #11 looks like a "big" arm?  The arm that came in the A can with the Refrigerator magnets (  )  looks very much like the .525 dia. arm (but it's .590 dia.) that came in my blue motor with the red / yellow magnets.

 

My blue motor w/ the red/yellow mags has a "hole" of about .560 across...so the .590 arm will obviously not fit. The dk. brown fridge mags were in a black 2 hole std. length can, and are a lot thinner than the red / yellow ones.

Absolutely ... about the Detective work, we are helping Dokk out so the book is right and the history preserved.

Yes .. that is a chubby 0.0590 Mura Gr12 arm ... my bigger hammer was out in the garage. The one on the right is to show a 26D fits in the can no problem. 

 

As far as pics of the rubbery , dark brown / thin magnets, IIRC, I think it was Pablo who posted some pics in one of his "adventures in motor building" segments in one of his build threads? Gonna haveta do some digging...

 

 

Edit: Having a problem with the copy and paste...? Anyway, couldn't find pics, but in Pablo's (  ) "Electricity is funny " thread...page 2...starting at post #51...(ya still have those mags Pablo?)

Thanks ... I'll try a search on  "Electricity is funny" and see what comes up ..

 

Then I'll go see what is holding up all the stuff on the sides of the fridge. Sides? Yeah .. we 'had' to have all SS appliances.  

 

I'm thinking modern poly neos in a Semi-Can shim might work .. my wife might get mad if I cut up the ones on the fridge and the papers keep falling on the floor.

"You and those damn Slot Cars ... they are all over the house"  

[proptop]

I took some measurements of the rubbery "fridge" magnets...(that really seems an accurate description...the way they look and feel )

All measurements are plus or minus .005"

I get .600 High X .625 Long X .135 Thick

They look like they were extruded, maybe in a long strip, and then just saw cut to length (you can see the saw marks on the ends...maybe bandsaw?) and the top and bottom edges dressed just a little bit (sanded) for better fit in the can.