18 replies to this topic

[Flathead]

Hi Chaps.

I have a few Champion 707 motors and all have a magnet shim except my most recent purchase. Everything else seems legit winding,balancing,endbell,arm marking ect. It shows no signs of ever being apart. 

My question being did all 707's have the shim or did some come without?

 

Motor in question, without pinion.

[havlicek]

I don't know the answer to your specific question: "did all 707's come with the shim?".  I'm not sure all of them did, but some of them did.  The shim says that your motors have the Arco magnets.  That means, even with the fragile end bell, you can feel confident the motors will be a bit faster (as opposed to motors with a similar wind and the stock Mabuchi magnets) and still hold together.  Then too, people went all the way up to a #27 and even beyond on the FT36D motors with the Arco magnets.

 

[Flathead]

Hi John.

First off I'd like to say that I've been lurking on slotblog for a long time and your H-Power forum is first port of call when I log on.

 

I fitted a pinion to the new motor so i could turn it over by hand, and it cogs almost as strong as the shimmed 707's (almost no difference) and way stronger than any standard mag 36d's that I have, but the air gap is bigger than the shimmed motors. Could the Arcos be fitted without shim? or were there other equally strong mags that didn't use a shim?

[don.siegel]

Will check the couple 707s I have, but I've always seen these with the shim. We should ask Philippe about the Champion mother lode in the LASCM - there were probably some early models without the shim... 

 

Don 

[havlicek]

Hi John.

First off I'd like to say that I've been lurking on slotblog for a long time and your H-Power forum is first port of call when I log on.

 

I fitted a pinion to the new motor so i could turn it over by hand, and it cogs almost as strong as the shimmed 707's (almost no difference) and way stronger than any standard mag 36d's that I have, but the air gap is bigger than the shimmed motors. Could the Arcos be fitted without shim? or were there other equally strong mags that didn't use a shim?

 

Hi Lee,

 

     Sure, the Arcos could be installed without the shim, piece of cake!    It might have even been "a thing" for some back then to get to higher revs with the Arcos, but it would seem like shooting yourself in the foot to me.  Don is waaaaay more knowledgeable than me about these things, as is Philippe, so I'd look to either of them for a definitive answer.

    Cog isn't a sure fire way to know how strong a set of magnets are, because the shape of the magnets can make them "cog" more.  It may be possible to use a magnet matcher wand on the outside of the can to get some readings and then test those against known motors...both with and without Arcos.

[havlicek]

I'd also say that, the motor without the pinion, which seems to be the one without the shim also has a Champion sticker that at least *seems* as thought it may have been lifted and reset because the edge is all wrinkled/disturbed.  Of course, this might just be a coincidence too.  In any case, the Champion ARCO-equipped motors seem to have gotten really scarce.  For a while, they were easy to get and classes that ran the FT36D motors made those magnets way-popular.  I had found some more modern Mabuchis that had magnets in the same range as the ARCOS, but haven't seen those either lately.  So these two motors are good to have!

[Flathead]

Thanks for the input chaps.

 

As I have no hi-tech way to measure magnet strength. I tried a different method to compare known motors.

 

I used a 1oz mild steel weight and tried to pick it up with the side of the cans of various 36ds, the results were:

 

Cox, Revell, Monogram, Classic etc - no movement of weight.

707 with shim - I could pick up weight if I was real gentle. 

707 without shim - lifted weight clean before contact was made.

 

This made me look closer at this motor, I shone a torch inside and looked through the holes on can end and the mags are shimmed, just not with usual 1 piece shim + the mags are not retained by the pressed tabs on the flat side (they are not tall enough to reach), but by 2 U clips, one each side.

 

So Don, I'm now thinking possibly late 707 rather than early as this alleviates the uneven air gap created by the 1 piece shim.

 

John the wrinkly edge on the sticker is the end of the lead wire "photo-bombing" my shot. sticker is minty   

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[don.siegel]

As an addendum to this. 

 

In the 1967 Champion catalog (which probably came out in late 66), they list the 705 for battery power tracks, with 50 turns of 27, and the Champion 707 (plain or ball bearing on both models), wound with 50 turns of 28 wire for transformer powered tracks. A new 707 Mabuchi case with Arcos does show the shim on the bottom, along with the usual shims behind the magnets. 

 

In Philippe's Champion motor story, he refers to the 707 with 27 wire. 

 

For the revised edition, roughly 1968 I'd guess, the 707 family is no longer offered, just a 707 kit, plus the stock 701, and across 1967, the 36Ds were not so gradually replaced by 16D and 26D rewinds. 

 

Don 

[Mark Onofri]

Glad to see some life in this thread.
First, Flathead, seems like it's a very scientific way to check the magnets. I say that because..... that's what I do.
Second,Don, thanks for the wind gauge and count. I've been waiting to wind up a 36-D arm. After accumulating soooooo much 💩 in files, I can't remember what file or, I'm too lazy to check them all. Take your pick.
Hopefully, there will be more to add to this thread.
PS: another method I employ is ,to see if they stick to the power strip above my dissecting table..... 🤔 Work bench?

[Bill from NH]

Also, the parts are bigger so there's more room to work with fat fingers.     I have a couple old 36Ds to do something with. In the '70s, I bought all of one hobby shop's 36D motors that were on sale for a buck each. I pulled the motor brushes & threw away the rest. I did keep one, I should have kept 6 or 8. But I was only interested in the brushes for wing cars I was running at the time. In the '60s, How-Kill, a Boston area company was selling what were essentially rewound 16D & 36D Mabuchis. When the winds got too crazy, such as their 28/28/29, they smoked easily, but with a moderate wind, both sizes ran competitively & were quite fast.

[Mark Onofri]

Ah, to do it all over again. It's too much funny that I threw away the brush/spring setups and replaced them with buss bars. I thought I had saved them but, father time must have needed them more than me.

[Bill from NH]

Without having a Koford or Proslot around then, those old Mabuchi brushes were the best thing you could get for use in open class motors from the late 60s to the early 80s. REHCO got some new brushes to sell in this period but when I tried them, they dug up the comms from being so hard. I might still have a used pair.

[Geary Carrier]

Big blocks are fun...

33/27

 

[Bill from NH]

Geary, the arm & motor look nice & cleanly wound. I like how you made backing plates & used C-can endbell hardware on this motor. Who are you using to balance your arms these days? Is Bill Bugenis in Brooklyn still available? When scale racing was popular in the Northeast, we used to see Bill at some of the NH races.

[Geary Carrier]

Thanks Bill,

 

Yes this was balanced by Bill Bugenis a while ago, I think he is still balancing arms

[Mark Onofri]

Nice, did you have to extensively modify the endbell?(for the new hardware)

[Geary Carrier]

Thanks Mark,

 

Milled the top of the endbell flat on each side along with the corresponding hardware mounting locations on the bottom side of the endbell.

 

This motor has Arco magnets with the flux yoke.

[Bill from NH]

flux yoke = Champion 1-piece shim for sides & bottom?

[Geary Carrier]

flux yoke = Champion 1-piece shim for sides & bottom?

Yes Sir