249 replies to this topic

[Gator Bob]

Built for the "Balls Out" California Thingie Proxy race - Cars are here
I have not built one of "My Motors" in 20 years.
It's... "Evil"

= = = = = = = = = = = = = = = =

All NOS or new parts

Vintage Mura set-up - Blueprinted assembly.
Champion Yellow Dot magnets
Custom heatsinks

Modern Pro/Slot armature spec:
55 Turns of 28 AWG
.450" x .518" Stack
.012 air gap

Break-in test = 45 minutes total:
.94 amps @ 3 volts
.98 amps @ 6 volts

[slotbaker]

Nice looking motor Bob, it should fly... but I don't think we are allowed heatsinks in the balls out.

[Champion 507]

Nice build, Bob. Some interesting ideas here.

It looks like the heat sinks are made from correct period Mura B-can brush hood base plates. It also looks like the aluminum base plates are also B-can. However, turning the base plates into heat sinks, might cause an issue with the rules, but I'm not the judge. Very nice concept, though.

I agree with Steve. It oughta scream.

[havlicek]

Looks cool to me Bob. Love me some old Muras!

-john

[Marty N]

What brushes are those that have shunts or did you make them?

[havlicek]

Hey Marty. I don't know what Bob used, but drilling brushes to shunt them is EZ. You can even make a "drill bit" for this by just snipping the end on a piece of correctly-sized piano wire. The snipped end should be rough and sharp enough to drill into the brush and the spring groove makes it fairly easy to locate the hole. I just twist the shunt wire at the end and stick it in there, then untwist it and it should hold well enough to install the brushes, after which the spring leg holds them in very nicely. You can also tin the end of the shunt wire before inserting, but I don't bother. I think this works much better than just having the spring arm hold the shunt in the groove...even with vertical shunt grooves.

-john

[Danny Zona]

How I love seeing those old mura motors.

[TSR]

Bob,
Your heat sinks are not period-korrekt..., and I'd be you I would mount my lead-wire clips on the flat surface under the opposite screws... for better conductivity.

[Pablo]

Looks super SANO Bob

One question I have is, with regards to the Thingie Proxy, does it break Rule # 14 ?

[Champion 507]

Champion used to sell shunted brushes in the 26D size and the 36D size. I have some. Champion put 26D size brush holders in their Celcon endbells for the late 507s and 517s and that took care of their 16D size motors. I'm not aware that Champion made the tiny 16D brushes with shunts. Maybe Dokk could komment.

Bob could have used a vintage pair of 36D Champions. What did you use, Bob?

[Gator Bob]

Nice looking motor Bob, it should fly... but I don't think we are allowed heatsinks in the balls out.

Thanks Steve !

[Gator Bob]

Nice build, Bob. Some interesting ideas here.

It looks like the heat sinks are made from correct period Mura B-can brush hood base plates. It also looks like the aluminum base plates are also B-can. However, turning the base plates into heat sinks, might cause an issue with the rules, but I'm not the judge. Very nice concept, though.

I agree with Steve. It oughta scream.

Ding, Ding, Ding - WINNER.
BTG Doug " damn good eye for a Champion guy"

[Gator Bob]

Looks cool to me Bob. Love me some old Muras!

-john

Thanks John!

[Gator Bob]

What brushes are those that have shunts or did you make them?

Those brushes came with the shunts installed, I can't remember who mad them but they were super SANO, expensive and hard to find. I bought them at Zepplin Hobbies in 1989 or 90. I used them in my championship "Outlaw Flexi" class cars. Save 2 pairs for this kind of motor, 1 pair left.

[Gator Bob]

Hey Marty. I don't know what Bob used, but drilling brushes to shunt them is EZ. You can even make a "drill bit" for this by just snipping the end on a piece of correctly-sized piano wire. The snipped end should be rough and sharp enough to drill into the brush and the spring groove makes it fairly easy to locate the hole. I just twist the shunt wire at the end and stick it in there, then untwist it and it should hold well enough to install the brushes, after which the spring leg holds them in very nicely. You can also tin the end of the shunt wire before inserting, but I don't bother. I think this works much better than just having the spring arm hold the shunt in the groove...even with vertical shunt grooves.

-john

Thanks John, I will try this method.

[Gator Bob]

Bob,
Your heat sinks are not period-korrekt..., and I'd be you I would mount my lead-wire clips on the flat surface under the opposite screws... for better conductivity.

I did this trick before I got my first period - korrect? LOL. "B" can plates came before "C" as you know.

My intent was to put the lead wire connectors on the opposite screw but the was interference with the spring and spring retainer tabs.

[Gator Bob]

How I love seeing those old mura motors.

They are so cool

[Gator Bob]

Champion used to sell shunted brushes in the 26D size and the 36D size. I have some. Champion put 26D size brush holders in their Celcon endbells for the late 507s and 517s and that took care of their 16D size motors. I'm not aware that Champion made the tiny 16D brushes with shunts. Maybe Dokk could komment.

Bob could have used a vintage pair of 36D Champions. What did you use, Bob?

Yes, Champ made (sold) shunted 16/26d brushes back in the day. PM me if you need a pair, you da winner.

I have vintage 36D brushes NOS no shunts. These were a hot item after they were replace by a brush for another manufacturer ... these were claimed to be better and some refereed to them as 'pull-outs'.

[Gator Bob]

Looks super SANO Bob

One question I have is, with regards to the Thingie Proxy, does it break Rule # 14 ?

Pablo, thanks for the
I'l go back and re-read rules

[zipper]

I have vintage 36D brushes NOS no shunts. These were a hot item after they were replace by a brush for another manufacturer ... these were claimed to be better and some refereed to them as 'pull-outs'.

Still have a couple of them, "Old Originals" sold just one pair in a plastic bag - and not too cheap.

[Marty N]

Those brushes came with the shunts installed, I can't remember who mad them but they were super SANO, expensive and hard to find. I bought them at Zepplin Hobbies in 1989 or 90. I used them in my championship "Outlaw Flexi" class cars. Save 2 pairs for this kind of motor, 1 pair left.

Isn't that the way it always goes? BTW Bob. Nice motor build!

John, thanks for the tip. I'll try it.

[Bill from NH]

Hey Marty. I don't know what Bob used, but drilling brushes to shunt them is EZ. You can even make a "drill bit" for this by just snipping the end on a piece of correctly-sized piano wire. The snipped end should be rough and sharp enough to drill into the brush and the spring groove makes it fairly easy to locate the hole. I just twist the shunt wire at the end and stick it in there, then untwist it and it should hold well enough to install the brushes, after which the spring leg holds them in very nicely. You can also tin the end of the shunt wire before inserting, but I don't bother. I think this works much better than just having the spring arm hold the shunt in the groove...even with vertical shunt grooves.

-john

John, this has been my way for installing shunts since my wing car days in the early 1970's. I put a minature drill bit in my Dremel & had at it on a low speed setting. I used different bit sizes depending how large the shunt wire was. One advantage of doing it this way is you'll never get a hung brush caused by a shunt wire.

[TSR]

One question I have is, with regards to the Thingie Proxy, does it break Rule # 14 ?

Pablo, thanks for the
I'l go back and re-read rules

Actually Bob, I think that it breaks rule # 15. External heat sinks as you have them only appeared in 1972... and with a wire size like you have, you do not really need them, all you have to do is use one set of the flat Mura aluminum plates because they DID exist prior to December 1970.

[Jairus]

Technically, its not a rule because I am not a lawyer and didn't write a rule for every possible infraction. But I did write it in very clearly as an update in post #5: "that only the aluminum spacer is allowed beneath the copper" brush hardware.

One interesting aspect of this discussion is that Bob never made any heat sinks exactly. And while I have seen more than one motor with a stack of those copper plates under the brush tube... this is the first example of mounting one of those plates offset. It doesn't quite break the rules as the parts are all correct. Just assembled in a slightly different fashion in order to achieve a different effect.
Definitely not in the spirit of the Thingie... but innovative to be sure.

My only concern is that it will leave the brush tubes slightly cocked at an angle to the comm. unless balanced somehow under the other screw.?!?!

[Jairus]

P.S. Bob, I have tabbed brush hoods I can send you if you need a set. Which it appears you do.