3573 replies to this topic

[havlicek]

????well, that's pretty much what I said there Jairus. I had guessed this was an early Green Can and that the notch was added later. Anyway, this guy will be getting a cool motor I guess!

-john

[Pablo]

I like the news about the 13uo because I just won 2 13uo motor brackets on ebay yesterday Maybe I'll have you build one like that for me someday

[Jairus]

right.
read your post too quickly then. never mind.

[Russell Sheldon]

Beautiful workmanship, as ever, John.

I absolutely love 13UOs. Back in the 1970s, the Brits were cutting out the sides of the can and installing Mura ‘B’ Production magnets, in the never ending quest for smaller and lighter motors.

Soft polymer cobalt magnets came in the late 1970s and the logical development was to cut them to size and install them inside the can, along with turned down Mura ‘B’ Production endbells with 36D hardware. 13UO-size Johnson 111 cans were preferred, as they don’t have the large gimbal bearing and could be easily drilled to take a ball bearing.

If you want to use ceramic magnets, SCX makes a 13UO-size motor with very good ceramic magnets.

This article, written by a then 15-year old youngster by the name of Ross Brawn, was published in the April 1970 issue of ‘Model Cars magazine:-






Ross Brawn is of course a very talented engineer and after college he follwed a career in motor racing. He has since engineered nine motor racing World Championship titles; once with TWR Jaguar, twice with Benetton, five times with Ferrari and once with BrawnGP. He is currently the Team Principal of the Mercedes Grand Prix Team and still keen on slot cars:-

See: Purple Haze, Ross Brawn's Big Cat

With kind regards,

Russell

[havlicek]

Hi Jairus...no worries...but I DO appreciate the info. At least the collector will be getting a slightly more interesting and rare® motor...although after I'm done with it, the "collectability" factor may have gone down a notch or two

Hi Russell,

Yes on the SCX. It's a very cool little motor in it's own right and I've torn apart and otherwise done violence to a whole bunch of them I have also used those magnets in other builds and they are excellent ceramics alright. For this "13", I actually used magnets from an earlier "mini motor" (Falcon???) before they switched to neos. The strength is right there as well and they gauss surprisingly high for such small/thin magnets. Unfortunately, they're not an exact fit and did require some trimming/fitting with a diamond wheel. I also flattened the can tabs that hold the bottom of the magnets in and epoxied them in with a pair of wedges ("parallels").

I would think the folks who are really into the vintage stuff would find one sentence in particular very interesting in Brawn's article. He states he will be looking into building a suitable chassis for the "13". This would clearly have been a fairly lightweight and good handling chassis for the time, and would make a dandy project for those into reproduction...IF...he ever followed through and built it!

-john

[havlicek]

I got started on the early Mura Green Can project for a blogger. The can was in pretty awful shape with a load of solder, rust and pitting as well, probably from using acid on it. After stripping what was left of the paint and then sanding it to get the pitting out, I worked the can on a piece of #220 grit paper laid on my glass work surface for the flat sides and bearing strap. After I got it all flat (I also did the end bell end to true it up a little), I sanded the curved sides by hand with the same #220. I then shot a first coat of white and after curing in the oven, had at it with some water and #600 paper. Then I shot a second cover coat of white and baked that. Pretty well satisfied with the way the old girl was looking, I assembled the lams, drill blank shaft and Bugenis com for the armature I'll be winding, as well as a nice new and tight 2x6mm can bushing. That was enough work on this thing for now...next up, I'll take apart the end bell and clean that up so I have a setup that I can space the arm for.



-john

[Alchemist]

Wow John!

All your motors you build are exceptional! I find the white colored and red colored cans to be the most attractive - hot and cool!!

Ernie

[Jairus]

Very pretty but, who is the blogger?

[havlicek]

Hi Jairus...I forgot to ask him if it's OK to use his name (usually I do). I'll see if it's OK.

-john

[havlicek]

I finished off the arm (a #27S with a Bugenis com and a drill blank shaft) for the neat-o early Green Can Mura going to Ken Butterfield in the UK. It comes in at a healthy .130 Ω per pole , and should provide plenty of "oomph" for his period scratch-built inline. I like Ken...he basically said to just make him a nice Mura...not "too hot"...but hot enough! That left things wide open for me to do my thing, both with the arm and motor setup, as well as with the "look" of this nice old Mura. I've got the end bell mostly done, so now I only have to make some shims, install the magnets, assemble the motor and give it a spin. Anyway, neatness counts (a LOT) ↓


-john

[Peter Horvath]

Beautiful work, John.

Wait until you see my next batch of Muras. They look pretty bad as well!!!

[havlicek]

I'm all eyes Peter...love me those Muras! (and Mabuchis and Champions etc etc.)

-john

[havlicek]

I finished Ken Butterfiled's Mura...another screamer! This thing draws about 3 amps after a short break-in and sounds and acts a lot like a "race" motor. After installing the shunts, the motor revs higher and draws more current. To me that means this motor (even though it's "only" a #27) definitely "needs" them .



-john

[MantaRay]

I received my motors from John. They are works of art. When John sends out the motors he also writes down all of the particulars of the build on the bag. He is a true craftsman.

[Don Weaver]

...... He is a true craftsman.

X2

Don Weaver

[havlicek]

Glad they got there safe Ray...and thanks guys

-john

[havlicek]

I haven't posted any "start" pictures for a while, so I figure this is a pretty good to use. The Mura is in better shape than most (at least the ones I get here)...well, at least the end bell is. After I strip it all down, it should be a honey of a motor. It's going into the first chassis this blogger ever bought, and it will need to be timed CW...but first there's a bunch of work to be done to get this baby all purdy and up to snuff. No worries...old Muras have more lives than even old Mabuchis, and that's saying something!



-john

[havlicek]

Here's that Mura all done up to run CW. I did a #28 wind as the Blogger wanted something zippy but not too crazy. I adjusted the wind to accomodate the modern stack with a thinner winding leg/inner profile and wound it "hemi" style. It comes in at .237 ohms per pole and sounds pretty slammin' even though it only draws about 1.5 amps. Since the can already had a bearing installed when I got it, I installed one in the end bell also as the end bell bushing had a tiny bit of slop.



-john

[havlicek]

When you do a lot of motors, there's sometimes one where the stars seem to align and a particular motor just comes out slamming. Such was the case with a Russkit "23" I just finished for a Jairus project. The can was a little beat up and somewhere along the line, someone had drilled a hole right through the Russkit sticker for a screw. I stripped the can down and went at it with solder and acid to fill the hole. Then I flattened the magnet retainer tabs on the bottom and removed the magnet rear spacer tabs. Since I had the solder and acid out, I filled the flattened magnet retainer tabs and then sanded everything down nice and flush. Next, I removed the blind can bushing and installed a spare end bell bushing in it's place. I've been not digging the gold paint I've been using for Russkits as it never seems to get very hard. Just handling it makes a mess of it after a while, so I switched a little while back to the same color in a "hammered finish" because those paints get hard as epoxy, with a great gloss to boot. Lastly, I (of course) tossed the stock "23" magnets in favor of a pair from a later Cox Mabuchi. These are a solid upgrade from the originals and not too far off from Arcos, so I figure they would be just about right as an analog for then-available aftermarket mags. Anyway, 2 hours later... the can looked great and I was ready to attack the endbell.

The end bell that was on the motor had been sanded or ground or something on one side, so I salvaged a cleaner example and took it apart to give it a good cleaning. While it was apart, I tinned the underside of the hoods and the top of the brush heat-sinks...then I soldered the heat-sinks to the hoods upon reassembly. Next I installed a set of spring post protectors and installed a less-worn end bell bushing. To finish, I clearanced the underside of the endbell to be sure it didn't hit the com tabs. Just for that "little bit extra", I wound up a pair of three-coil springs for this bad boy out of .015" stainless steel guitar strings as they seem to work really well for a few reasons.

For the arm, I stripped the "23" and epoxied the fiber stack insulators to the top and bottom of the stack after installing a new drill blank shaft. After curing, I trimmed the stack insulators pretty flush (still a bit proud) to the stack. It got topped off with one of those great Bugenis coms, because I just don't trust Tradeship coms after having a couple blow up just lightly spinning a motor up. For the wind, I was instructed to go a bit on the milder side, even though Jairus' build will be a semi-replica Team car. I did 57T of #29 using a special pattern I developed a while back, welded the com and the arm balanced right up after tieing and epoxying. How does it run?...sweet as all get out. It may not be the hottest "23" of all time, but it will live fine with the Mabuchi end bell, it sings a mighty sweet tune and seems to have torque for days. Even though this car isn't destined to be raced, the motor would no doubt love to be run hard!

Anyway, like I said, sometimes everything just seems to come together...the planets and stars align and you get a really great motor. There isn't any one thing I could point to as a reason, more like an accumulation of a bunch of smaller reasons. The result is----------------------------------------->


-john

[Pablo]

[Jairus]

Stunning!
Chassis for that is done, just waiting on the rear wheels from an ebay seller who is... kind of slow.
Thank you John, the motor is beautiful.

[havlicek]

Thanks Jairus, the motor should arrive over there in a day or so

Another Russkit "23" project started for Chris Walker . He tells me they run a vintage series on a shorter road course, so he's looking more for driveability than sheer horsepower. I sat at my bench staring at parts and combinations for a while and came up with a plan (sometimes a dangerous thing) for making a solid Russkit that fits his needs. This one is a bit of a gamble, but I can always wind him another arm if I don't like it before I send it to him. Here's what I got so far...it's a #29 wind, but very different:



-john

[havlicek]

Done! This is a pretty wild "23", drawing only just over an amp, but it wants to twist itself when you hold it and spin it up I think Chris is going to like this old Russkit!



-john

[slotbaker]

...it's a #29 wind, but very different:

Please explain...

Great looking motor.

[havlicek]

Hi Steve,

Well, the obvious thing is that it's a big dia. arm, about .560". I shortened the stack a bit and then did my super-secret special pattern wind. It's sort of a "semi-hemi" with an additional twist, but then on top of that...the number of turns just sounds stupid "on paper". It works out to be about .5 ohm (my ohmeter crapped out again, so I'm using a regular multimeter for now) wind, but it spins up with real authority.

-john