249 replies to this topic

[havlicek]

 

 

I have run into that style shim making the hole 'way' small ... but ? this one sat slugged at .560 with 'C' can Mura magnets when I soldered the BB in.

 

Yikes!  I just checked a set of these with the supplied magnets in an FT16D and I got under .520!  Anyway, with those magnets and such a large hole, you have lots of possibilities.

 

-john

[havlicek]

A bump back to the top for Bob.  Resurrecting these old Mabuchis and making them as good or better than they were stock is something that very few take on anymore.  With some attention to detail and skill, the end result can be a (now) unique gem!

 

-john

[Pablo]

Awesome, Bob !!!
I like it bare steel.

[Gator Bob]

Here it is with the Mura 55/30 approx. 30 Deg. arm and the Champion BB endbell basics.

 

These arms rev up great and don't draw a lot of current or make a lot of heat.

 

 

 

[SlotStox#53]

Very nice arm & endbell basics Bob   That's gonna make for a very nice reliable runner !

[havlicek]

Good choice on the arm Bob.  Are you mounting the bearing as shown with the flange on the outside of the end bell?

 

-john

[Gator Bob]

John,

The end bell BB is a 5MM with the flange on the inside, small drop of Loctite 680 on the flange before light press fit in plastic.

Ball B in the can is 5MM not flanged.

 

The picture does make it look like the flange is on the outside.  

 

Pablo and Paul, 

Thanks for looking in on this motor "Hop-Up".     

 

Mura, Champion, Mabuchi stir-fry mash up.  

 

Magnetic field set with arm in place, then glued, with a final bore of .5615

 

[SlotStox#53]

Always nice to see a hopped up Mabuchi come together

[Gator Bob]

I thought you guys might find this interesting.

Champion with shim and mags vs. this Mabuchi/Mura.

 

 

 

 

 

[havlicek]

Not surprising considering the ginormous can bushing on the Champ!

 

-john

[Gator Bob]

Not surprising considering the ginormous can bushing on the Champ!

 

-john

 

Really ... I can't see any reason for such a big bushing unless they were purchased as bargain surplus. Why make a hole just to fill it with a heavier and more expensive material.

 

 The motor is RTR .... I'll take some pics.

[havlicek]

The way they recycled the things, the can was probably originally designed for something larger like some sort of bearing (you can still get these cans without any bushing at all)...but that bushing is BIG!

 

-john

[Gator Bob]

Was thinking of drilling one of those out for a 6mm BB...   Anyone try it ?

[Gator Bob]

Completed:

 

[Pablo]

Very Shweeet    and businesslike

[Bill from NH]

Nice motor Bob! What do you plan to put it in to give in a "track test?"

 

 I can't see any reason for such a big bushing unless they were purchased as bargain surplus. Why make a hole just to fill it with a heavier and more expensive material. .

 

Maybe they thought the larger mass would better absorb heat & vibrations so the bushings would last longer. It was probably an Oriental thing.

[havlicek]

Looks great Bob, and should run just as good as it looks!  The shunts shouldn't at all be necessary, but they're one of those things that are better to have and not need, than to need and not have

 

 

 

Maybe they thought the larger mass would better absorb heat & vibrations so the bushings would last longer. It was probably an Oriental thing

 

Maybe, but more likely than not they just used whatever fit a bazillion cans they had lying around.  

 

 

 

Was thinking of drilling one of those out for a 6mm BB...    Anyone try it ? 

 

Of course, many times!  It's just metal and soft, easy-to-solder metal at that

 

-john

[SlotStox#53]

Top stuff Bob ! Looks like its ready to rip up the track!!

[Gator Bob]

Then ... I'll give it a try when I build a 'black can'.

 

BTW:  

the ginormous can bushing on the Champ 

Weighs in at a porker 1.2+ grams ...

------------ 

 

Back to the 'Murabuchion'

 

Detailed fit and finish assembly (a.k.a. Blueprinting) took hours. The end bell plastic prep for can fitment and alignment of the hoods and plates was a challenge. If you assemble this stuff out of the bag the result would be 'really crappy'. 

 

John,  I went with the 26D brushes running on the big Kirkwood trying to keep it in 67 ... I think 68 is when the little 16s went with the 36D size brushes.

Bill, I don't know what chassis this 'enduro' motor would be good in...? ..  What year would this 'stock arm' motor represent ... 67?

Pablo, I changed the whole business end of this motor around ... lol

Paul, and all .. thanks for the comps!

 

What it be made of?   

 

Mabuchi:

• Can (Russkit 22)
• 26D Brush holders (heat sinks)
• Pent roof holders.

Mura:

• 'Stock 16D replacement'  #R12A armature - 50 turns / 30 wire - .400 stack length, 513 dia., .007 lams, Kirkwood com. late 80s. 
• "SEMI CAN" Magnetic shield / shim. *
•  Stock ceramic "C" Magnets.

Champion:

• End bell Plastic
• Base Plates
• Chrome posts
• Shunted brushes
• Plated 4 coil springs
• Can screws 0-80 undercut FH

 

I have to change out the 4 coil springs ... way to strong.... for Mura light 3 coils before start-up and break-in. The shunts get routed and soldered at the same time as the lead wires when motor is test fit in a chassis. 

 

[Champion 507]

Bob,

 

Nice to see some of that 40+ year old GA stuff (and Mura too) is still being put to good use. Nice job.

[Gator Bob]

UPDATE:

 

Springs changed to Champion 3 coil 'red'.

45 min break in at 3V drawing 1.1A at the start and .99A at the end of the break in period.

15 min at 7V with a mild 1.3A

 

Let cool down for 2 min at 2V

 

The motor runs ultra smooth, Ear tach says 75k plus it absolutely SCREAMS .... but, with the low timed (stock (25deg?)) armature coupled with the 26D size brushes makes the timing a bit more delayed. I think what helps it reach that very high RPM is the reduced brush face area drag and the double BBs don't hurt.

 

From a 2V 'roll' to full punch (12V) the motor does take a long second ( one one thousand)  to hit its 'Peak'. In that time it goes from a siren to a dentist drill.

 

I'm super happy with the way it turned out, it 'runs' like a hot vintage motor.

 

Another "MY Built Motor" ... Mission accomplished.

 

SO Men ...... Would this be a 1966, 67, 68 _{(due to the brush holder plates)} period tribute motor ???

[Pablo]

Great job, Bob. Now built it a car

[SlotStox#53]

Sounds one sweet mill Bob As Pablo says..... Now build a car to put it in!!

[havlicek]

Good news Bob.  Those old Mura arms (any of them) were sweet items...even the "regular old everyday ones" were made out of the same good stuff as the top-shelf ones.  They probably had boxes and boxes of those .007" lams and coms, lord knows where that stuff wound up, but it was high quality stuff!  Good job!

 

-john

[SlotStox#53]

Here's to someone finding that pot of gold/box of .007 lams/arms/comms !