9 replies to this topic

[mam2f]

Hi...

 

A few months ago, I bought a NOS M-522 Mura 'B' Production" stock motor" on eBay.

 

This is the original version of the 'B.' with the two-hole can and the rectangular opening over the comm.

 

Does anyone know what armature wind was used in these? The armature is balanced.

 

I built a car with this motor. It's pretty fast on our local King.

 

Any info is appreciated!

 

Thanks,

 

Mark 

[dc-65x]

B-motors... they are quite a collection of versions from mild to wild. Sounds like your motor is the first version with the can on the left:
 

Here are the five basic B-cans I am familiar with:
 

 

 
From left to right, the first version has .040" thick sheet metal, 2 small vent holes per side and one square hole near the comm:
 

 
The second version changes to one rectangular vent hole per side only. It still uses .040" thick material:
 

 
Now things get more interesting. The third version gets the top or the top and bottom milled down usually to .020" thickness:
 

 
Here's a comparison of the standard and "20/40" milled can showing the difference in height which is pretty dramatic:
 

 
The fourth and I guess final attempt at making a successful Pro motor was the "circular milled" can. It is also milled but to .030" top and bottom and goes back to 2 vent holes per side. Vents in the sides of the can for brush cooling were also added. They also added an axle clearance cutout and releaved some of the back of the can on one side for can drive applications. I think this version was the last ho-rah for the "B" in the Pro races:
 

 
The cool thing is the milling of a .560"+ diameter feature inside the can inline with the armature to increase clearance between it and the can:
 

 
The last version I have is what I call the "C-can of B-cans". It has a lot of features the famous Mura 2-hole C-can has. It's made of the same .030" thick material. It has the nice axle clearance cut out and the bearing support area on the back of the can is much smaller. I thinking this one might have been more of a "Group" motor like the NCC 20 this can came from:
 

 
Another big thing is the can is shortened quite a bit from the previous 4 versions .995" length to about .945". Here's how much shorter the final version (in the middle) is:
 

 
A disclaimer : This is just my small sampling of B-can evolution presented for entertainment only .

[dc-65x]

Here's a Mura B-Production motor with the can you described. The arm in my motor looks pretty "healthy." Your "stock motor" version might be milder:
 

 Next is a little-used Mura B Production motor, first generation I believe:
 

 
It's had a soldering iron melt into the end bell and the can is all scratched up. I think it will be a good candidate for a complete NOS type restoration. Let's crack her open:
 

 
All the parts are ready to go with new brushes and endbell. The cans stripped and ready for a coat of gloss black paint and to have the Mura sticker applied. The armature looks like new. It's a single wind of pretty big wire and meters .2 ohms:
 

 
Next...

[mam2f]

Hi Rick,

 

Yes, absolutely my motor is the first version.

 

Everything I have learned about Mura "B" motors came

from your many posts. Plus the MRJ articles and a few

other sources over the years.

 

It all started with "World's Fastest B-Motor Slot Car"

 

My motor came in the original case(!) and was never opened.

 

I put it into a plated Riggen/Mura anglewinder chassis.

End bell drive of course.

 

Thanks, Mark

[mppicione]

Sounds like a "bad" little car!

Like many of us who are still racing today, I used to race those old cars with Mura B can motors. For those of us who didn't have the means, we would sand the top and bottom of the can, plus cut the hole open.

I am still hoping to get down to Spartanburg someday to check out the tracks there.

[zipper]

I had a s 24....due to our weak powers it didn't burn but hot it was!

[Mark Onofri]

I purchased a inline Cobra and I had posted a comment about it having the loudest scream of any of the(old)16d's that I own. Probably because, (as I was informed here)it's a B motor.

[MSwiss]

I put it into a plated Riggen/Mura anglewinder chassis.

End bell drive of course.

 

That was the combo I used as a 14 year old, that I refer to in this video at approx. the 27:00 mark.

 

FWIW, I used what I would call the traditional Riggen version, vs.the iso-fulcrum one.

 

I thought it was can drive.

 

The motor was referred to as a "B special" and sold for only $6.98, as it was a "second", with the armature stack having a misaligned lam or two.

 

I replaced the standard 2 hole, notched can,  with the silver rectangular hole, non-milled can, Rick T shows in his post.

 

[mam2f]

Hey Mike...great stuff...good 'ol "horsepowah" from "B" can...

 

Thanks, Mark

[mam2f]

Here are a few pictures of the car...

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