71 replies to this topic

[One_Track_Mind]

TSRF24 said

Jeff,
Those are 16D brushes on them end bells.

The Thorp are better quality really.

one_track_mind said

But doesn't this mean that it's not an original motor for a RTR car? Thorp was an aftermarket arm to hop up the rtr cars?

Thanks for the clarification on those Mura color list. It doesn't tell us anything but the arms are pretty much worthless,b/c of being machine wound,and machine balanced.
So instead of paying Mr.Ohren big bucks to re-condition those two arms,would it be ok?just to clean them up,with a slight turning of the comm? I know a friend, who knows a friend with a comm.truer.

[Steve Okeefe]

Dokk,

I suppose it should have dawned on me immediately, but I can be slow sometimes.

The B production motor has brush hoods, but the hoods and the brushes are 16D size.

Did the B production motor EVER have 36D size hoods and brushes? :? (I ASSumed it did... maybe not.)

Another question:

Did the late model (1970) Mura "A" can endbell (after Mura switched from brush holders to brush hoods), ALSO start out with 16D size hoods and brushes? (I'm thinking it did NOT... they were 36D size.)

Inquiring (historical) minds and all that... :mrgreen:

[Jairus]

All "A" can motors that I ever owned or worked on were equipped with 16D sized brushes.
I converted one 16D over to the 36D brush tubes in my time but I am fairly sure that Mura didn't start using the larger brush size until the "B" can was already being produced.
I have found two different sized brush tube hardware on various "B" can motors; for both the smaller 16D and the larger 36D size.

Both pieces of hardware were found on Gp20 motors with square holes and were painted lime green.
Respectfully submitted,

[TSR]

As far as I know, no PRODUCTION "A" or "B" motors ever got FT36-size brushes.
However and just before the advent of the "C" can, some pros had switched to the FT36D-size brushes by using the older pentroof brush-holder retainers and old FT36 brush holders from a myriad of unsold K&B yellow FT36D motors. When Mura began production of their "C" can motors, the brushes were actual Mabuchi items and remained such until 1974, after at last, the guys at Mura were able to concoct a mixture that would not eat the comm and this after 3 tries, one of them costing me a national championship, thank you, Bob Green!

Every single pre-"C" can pro-racing motor in our collection (Mabuchi, Champion, Hemi and Mura cans), all hand wound by the likes of Bill Steube, Bob Kean, John Cukras, Pete Zimmerman etc. all have FT16D-size brushes. All "C" can motors have FT36-size brushes. We do have ONE Mura-Cukras fitted with the larger brushes but it was obviously modified with larger vents in the can, cut end bell etc., so it cannot be considered a production item.

Mike Morrissey describes in a 1969 issue of Model Car Journal how some fellows are now using the FT36D brushes by retrofitting old brush holders. This is when it began, but it never reached production on both Mura and Champion motors until the advent of the "C" can and new brush holders.
I have not found any counter evidence EXCEPT that some older "A" cans were retrofitted with NEW FT36-size hoods, but after the advent of the "C" cans.

[Steve Okeefe]

Jarius wrote (and illustrated):

Quote

I have found two different sized brush tube hardware on various "B" can motors; for both the smaller 16D and the larger 36D size.

That answers my first question (thank you!), the B production motor started out with 16D size brush hoods (tubes), and later was "upgraded" to 36D size brush hoods (tubes).

To help with the second question, some background (please correct me if I don't have my dates right):

Late 1967: Mura introduces the dark gray "Unmeltable" endbell, basically a clone of the Mabuchi endbell done in higher temperature plastic:



It used stock Mabuchi 16D hardware (brush holders) and 16D brushes.

Late 1968: Mura introduces a newer "white endbell", coinciding with the introduction of their new "A" can motor setup. Sorry, I don't have a photo handy... It ALSO used stock Mabuchi 16D hardware (brush holders) and 16D brushes. If I'm wrong about this, please tell me!

Mid 1970: Mura introduces yet another new "white endbell", this time with brush HOODS and NO spring posts. Again, if I'm wrong, please correct me!

What I want to know is, were those brush hoods (on the mid 1970 product introduction) 16D size, or 36D size?

UPDATE: Sorry about the disjointed order; the above TSRF post answers my second question. The mid 1970 Mura "white endbell" had 16D size brush hoods. (Thank you!)

[Jairus]

TSRF24 said

As far as I know, no PRODUCTION "A" or "B" motors ever got FT36-size brushes.

I've got a NOS pink "B" can Mura here, untouched and not run, with 36D-sized brush hoods! How do you explain that? Or are there three sizes of brushes out there?

[TSR]

Some of the pink ones (like on that large batch that was sold on ePay about 6 months ago) were issued after the "C" can just to liquidate stocks. By that time they were receiving the new "C" can brush hoods.
But none was fitted as such before the "C" can came out, because the 36D brush hoods were made FOR the "C" can.

[Pablo]

If you send them off to be reconditioned, be sure and mark:

"NOTE-THESE ARE VINTAGE ARMS, DO NOT CUT THE SHAFTS"

[One_Track_Mind]

pablo said

If you send them off to be reconditioned, be sure and mark:

"NOTE-THESE ARE VINTAGE ARMS, DO NOT CUT THE SHAFTS"

Pablo...Yes! 4-sure...I know this from your experience! Thanks for the reminder!

Since everyone has been great help in identify and restore tips of the other three motors, here is the last one I own that need some TLC. Any idea? Manufacturer, period made, etc., etc.? Worthy to take apart? Or just leave it be?!





Many thanks to all . . . It's been wonderful . . . :up:...

[TSR]

Brian,
This is a standard production Champion motor for their RTR cars with the infamous brass plate on the end bell, dating from about 1970. It apparenltly spent much of its life at the bottom of a pond, I guess...

[Jairus]

Ouch! :|

[One_Track_Mind]

TSRF24 said

Brian,
It apparenltly spent much of its life at the bottom of a pond, I guess . . .

Philippe, my thoughts exactly! . . . One of the bottom-feeder Chumpions!

No, really I had not a clue? Thanks for informing me. I take it we don't need to see the guts on this one :?:

J.W., you got to admit, it was a pretty clear crusty picture!

[TSR]

A beaut of a picture at that!
Here is a similar motor that did not make it to the pond:

[One_Track_Mind]

:doh: The Champion story that's listed here on Electric Dreams! I recognize that picture!

Sorry to bother you, Philippe, the answer was right here all along. I have failed miserably at comparing the water-break-in-for-36-years motor to yours!

[One_Track_Mind]

Bill,
With all due respect to the person that I feel should remain unnamed publicly, this was like you have said, a once in a lifetime mistake! Both parties felt real bad about the occurrence of 1 arm that Pablo had sent to be cleaned. Just my two cents worth?

Pablo, would you agree? Sorry to bring up bad memories. I should have let sleeping dogs lie.

[One_Track_Mind]

Bill from NH said

Brian, you have to take that thing apart & find out what's inside.

Nahh..there are no markings on arm, maybe I can donate to the museum? This would show what has happened to a lot of the history of our 'loved hobby'. All the more reason why it should be preserved properly. Not at the bottom of some pond!

[Pablo]

Hi, Bill,
It was an honest mistake by an honest craftsman. Like Brian said, it would serve no purpose to name the person.

[TSR]

I think that we could organize a showcase with a pond where we could put all the dead remains of once glorious cars, something like this:



:mrgreen:

[Hworth08]

pablo said

If you send them off to be reconditioned, be sure and mark:

"NOTE-THESE ARE VINTAGE ARMS, DO NOT CUT THE SHAFTS"

I'm not familiar with what happened but it's pretty simple to change a shaft with a nice 2 mm drill blank shaft. A lot of the pro-built motors in the '60s had been "shafted".

[don.siegel]

And let's all hope there's no such thing as brass poisoning . . .

Don

[Jairus]

Hworth08 said

I'm not familiar with what happened but it's pretty simple to change a shaft with a nice 2 mm drill blank shaft. A lot of the pro-built motors in the '60s had been "shafted".

Really? How is that accomplished?

[Hworth08]

Jairus said

Hworth08 said

I'm not familiar with what happened but it's pretty simple to change a shaft with a nice 2 mm drill blank shaft. A lot of the pro-built motors in the '60s had been "shafted".

Really? How is that accomplished?

Start with a 2 mm extended shaft drill bit and a block of about 1.5 inch hardwood. Drill a 2 mm hole through the wood then use a bit close to the size of the arm and drill about the depth of the stack, just making a jig to hold the arm vertically. Cut off however long you need the new shaft and use the new shaft to push the old one out. I used a drill press to push the shaft in but you could tap it in with a small hammer.

Changing shafts in electric motors is an everyday thing. Due to expense or lack of parts it's common to push out a bad shaft, have a new one machined, and re-install it.

On a Mabuchi motor try to get some Loctite on the comm and lams; they had a problem with shifting.

[Hworth08]

Bill from NH said

Don, do you recall what Loctite product you used? Was it red or one of their retaining compounds?

No idea! Hey, that was 40 years ago!! I may have been using Elmers glue?? Actually I changed the shaft before re-winding and did use "plenty" of some kind of Locite to keep the comm from shifting. The Mabuchi just had that little tab sticking in the insulator that would also move to hold the comm. Sounds like the Slick 7 motor today?