3573 replies to this topic

[havlicek]

Hi Ken,

I got your message and sent you a reply.

-john

[Old pink can guy]

thanks John either day is fine!!!

[havlicek]

Here's something I've wanted to do for a while and have only gotten to it now because, well...because I knew it was going to be a pain-in-the-patootie and it definitely was. Before that traditionalists and/or the period-correct police get nuts, Philippe showed this very mod sometime ago that was done "way back when"! Anyway, the idea is to do something about the bushing in the otherwise fine Tradeship endbell. I mean, the posts can be protected and you then have an endbell made of a much better material than the auto-melt Mabuchis...but that tiny bushing is a problem. For one, it makes a direct replacement with a ball bearing impossible, it's also not a particularly snug fit from what I've seen, and should a replacement bushing be needed in the future, where do you get that without buying a whole endbell?

So I tried to figure out a way of solving all that without making things worse than they were (been there done that). So I:

1)Cut off the protruding part of the endbell flush that carries the bushing, but left the remainder of the bushing in place to use as a "center".

2)I then fabricated a "strap" from a piece of tool steel with the endbell mounting holes in place but no hole for the new bushing/bearing. I figured that brass wouldn't be nearly strong enough after I whittled it down, but of course this made things difficult as this steel is very hard and drilling/shaping it is a bear.

3)I then mounted the strap to the endbell with some #2x 3/16" screws and, using what was left of the original bushing to center the new bushing hole. I then flipped the endbell over and ran a diamond engraving point (that just happened to fit the old bushing perfectly) through the old bushing to put a "centerpunch" where I needed to drill the new bushing hole.

4)Using carbide drill bits alternately with cone-shaped grinding points, I drilled a hole opening it up slightly after each pass until the new bushing was a "snap-fit".

5)I then assembeld the can/endbell/arm to see if everything was OK so far and seeing that indeed it was, I soldered the bushing to the carrier strap.

6)Up until now the strap was left long so I could hold onto something, but it was time to cut it to shape and smooth it out as best as I could so it didn't look like a total catastrophe. I mean, it's nice if stuff works, but it's even nicer if it also looks OK. After a bunch of shaping and then polishing...it was ready to mount for real.

7)When final mounting the thing, I put a touch of JB Weld around the back of the strap and then slowly tightened the screws trying the arm as I went to make sure it wasnt binding, and when I got it fully seated wiped of the excess with some acetone. While the JB Weld won't really bond to the endbell material, it will form a hard surface behind the strap for it to sit "true" on.

Like I said, I knew this would be a bear and have put it off for that reason. Total time...almost three hours It would have been a little easier with a 2mm x 5mm bushing, but all I have is 6mm. Anyway, now there's a nice tight bushing and I can easily install a bearing should that come up.



-john

[Champion 507]

Hey John,

That thing looks like it would survive a nuclear direct hit!

Nice job and expert craftsmanship...as usual.

Can't wait to see that as part of a motor build. I like shunted brushes. They're cool.

[havlicek]

Hi Doug,

Thanks. it's a nice solid mod alright and one that was actually done by at least some back then so I'm just following the trail that others had already blazed Of course if I had a drill press, I could have cut at least an hour off of the fabrication time..maybe more because my only methods of drilling/fabbing tool steel are caveman-crude. Oh yeah and I forgot, between steps 4 and 5 above, I had to cut off the bearing retainer portion of the endbell completely to mount the steel bearing strap

-john

[Champion 507]

HAVLICEK QUOTE:

"Of course if I had a drill press, I could have cut at least an hour off of the fabrication time..maybe more because my only methods of drilling/fabbing tool steel are caveman-crude."

*****************************

John, I was at the right place at the right time a few years ago. There is a tool store here called Re-Tool. They buy and sell new and used tools of all descriptions. You being a woodworker will recognize the name Shop Smith. They've even had a few of those over the years. Anyway, shortly before Father's Day one year they had gotten in several desktop referb drill presses...for only $25 each! SOLD! To me they looked like new. It's precision isn't to within a millionth of an inch, but it's close enough for what I use it for. I used it just last night to balance some arms. So I feel very fortunate to have one. I hope you can find a bargain on one for yourself soon.

[TSR]

Thanks. it's a nice solid mod alright and one that was actually done by at least some back then...

Indeed, this is one of my own that dates from... 1966!



yes, it is a bit rough because despite all this armor, the endbell began melting from the heat generated by the 25-single arm fitted in it, and it shows here...

Champion also used a similar setup in 1969 on their production motors, and while the idea was great, the endbell was a disaster because there was not enough plastic to retain the screws without them stripping instantly, and the hole for the bearing was awfully loose.
The biggest problem with such a setup of course is... the motor mounting in a chassis. Unless the plate has been permanently epoxied on the plastic, which is not an easy task as the plastic had polypro in it, a compound that refuses to be attached by anything in the adhesive world. This 1970 Champion "Group-7" shows the plate with the soldered bearing, screwed into the endbell with two self-tapping #1 screws.



Fitted in the Champion RTR cars, one can remove the motor by simply... prying it off the chassis, and it does not take much effort to do so!



it was not uncommon while using these RTR models, to have a minor shunt with the wall and when the car was re-slotted, find out thet there was no more drive because the motor had wandered inside the chassis, being barely retained by the body, now being comprehensively ground by the pinion under applied power...

[Old pink can guy]

Sweet. Nice stuff again. As for the bearings I wonder if Master Thigpen could carve some out if you can find the oillite stock. He has all those tools we all would like to have.

[Bill from NH]

I don't didn't know you could buy oilite stock, but Beemer Precision in PA sells it. I'd rather use bearing bronze myself because I already have a piece.

[TSR]

Actually you can make motor and axle bearings from hardened brass stock, it really is good stuff and has very low friction coefficient against steel.

[Old pink can guy]

Thanks Bill and Doc. I forgot about new tec. LOL.

[TSR]

Ken, in vintage anything, new tech sucks.

[havlicek]

Thanks Philippe for proving the "period-correctness" of the mod. Now what I want to know is how on god's (small g) green earth did you get the cojones to put a 25 in that motor And people think I'm sometimes "over the top"(!?), you've got us all beat, and by decades too!

-john

[TSR]

We did not know any better.

[Bill from NH]

John, ask him about the 15T of 22 ga. arms.

[havlicek]

Hi Bill...15T/22awg? YIKES, did they require a special permit for those things? Please Philippe...Do tell! I did a couple of #23 rewinds on modern D can arms and coms with soldered tabs and regular Devcon epoxy when I was getting started again. I guess that at least makes me a wide-eyed optimist

-john

[TSR]

John, he is pulling your leg.

[Hworth08]

. Now what I want to know is how on god's (small g) green earth did you get the cojones to put a 25 in that motor

Simple! The person that won the week before used a 26 wind. How everything gets bigger, faster, slower, smaller...

[Champion 507]

HAVLICEK QUOTE:

" I did a couple of #23 rewinds on modern D can arms and coms with soldered tabs and regular Devcon epoxy when I was getting started again."

**************************

John, did they last? How did they hold up? Details please. Thanks.

[havlicek]

Hi Doug,

Along with all kinds of other winds on all kinds of blanks (anything I could get my grubby hands on), I did a bunch of 23s and aside from getting the wire on there straight and even, a big problem was getting enough room at the com tabs (unless it was a Kirkwood or modern Mura com) to attach that massive wire. Most all of the early arms I did I either gave away or tossed as I was most interested in finding out what worked and simply at getting better. The 23s would spin like nobody's business and draw a hefty amount of current, but they were pretty crude. As I did more winds, I got a better balancing block (than you RGEO!), better epoxy (Duralco 4461) and better ways of terminating the wires at the com tabs. With those early 23s, I would spin them up all the way to 12V and I never had one blow simply doing that, but I doubt they would have lasted long on the track(?). I haven't done a 23 since then as nobody has asked me to, but just recently did a 24 that came out just great.

-john

[Prof. Fate]

Hi

As I said, there was a lot of money in racing in my circles in the day. And I never did a motor that was expected to last more than the 50 minutes that qualifying and racing took. That said, I did a few 23s, but I wasn't driver enough and didn't have controller that would handle them.

But even a 25 or a 26 would be completely rebuilt in the day every race.

Well, to be clear, when last running flexies with super 16ds for "my team"... I rebuilt the "stock" super 16ds, a mere 28 every race. The bushings in the can were only good for 3 races, the brushes 4 and the arm, because of the soft com, 3 races.

I did convince them ONCE to let me wind up some medium stack 29s whose purpose was to just have some quality bits in the motors, but they didn't like it, ultimately, as a well done 29 with quality stuff is a lot better than a sloppy 28 in a Parma! So I tried talking them into a 30.

Grin.

Fate

[idare2bdul]

A lot of racers think that if a little bit is good, more must be better. I often ran less hot winds to insure that the motor would last and would hook up the tires. The difference between a group27 time and the open G7 was usually pretty small. When we finally got cobalt magnets you could run a 23 with the expectation it would last but before that it was pretty tricky.

[MrWeiler]

When we finally got cobalt magnets you could run a 23 with the expectation it would last but before that it was pretty tricky.

My best G-7 OMG moment was running your C-Can cobalt double 25 at Crash and Burn, putting the car down in front of me as Dan was passing me, punching the trigger and blowing past Dan on the drivers straight (before he reached the bank) like he was nailed down and having him stop and look at me and ask:

WHAT IS THAT????

That monster was the fastest motor I ever ran 'till it got too hot and spit the pinion off..

But then there was that skewed blank "thing" that Big Jim tested and on the first lap (it never made a lap) it was going so fast it launched in the bank and hit the back wall of the shop....He just stood there looking at the controller like it did something bad...

[HarV Wallbanger III]

Hey Mike I have a legal skewed blank GP27 that I got from Jim when we were still using can cobalts (before straps) and that thing would just freight train the bank at Valley Rwy! They were never USRA legal but it did have the right # of turns and it was so smooth and fast.

[MrWeiler]

Wow!!!

That car would have flown 50-60 yards if the wall had not stopped it. The chassis was TRASHED. As far as I know he never ran that motor anywhere again. I have NEVER seen another slot car go down the straight faster than that BJ car did that night. I would have LOVED to try that motor on an Engleman.