13 replies to this topic

[Old Pilot]

Hi everybody,

I'm trying to identify, restore, etc., cars from Aurora and K&B (1/32 and 1/24), and have some questions I hope someone could help me with them.

I got some loose yellow mabuchi 36D, even in different yellows (I suppose all are Bobcats, Royal or not). Also I got a couple of Lotus 30 Charger 1/24, a Sebring Chaparral kit and a couple of Auroras in 1/32 Pontiac GTO and a Mustang.

As I can read from the book of Thomas Graham, Bobcat could it be 9 or 12 volts.
The Lotus 30 Charger mounts the 9 volts, as he stated in the book that it is a Royal.
I'm interested in mounting a 12 volts. How can I know diference between Royals of 9 and normal Bobcats of 12?

Referring to the Auroras, I suppose all 1/32 Mustangs and GTOs mount the 12 volts Challenger.

The Sebring Chaparral kit contains a Super Challenger 6 volts. Any option to install a 12 volts motor?

My idea is to use them in commercial 12 volts tracks without turn them in little holocausts.

Thanks a lot in advance.

[TSR]

Jesus,
The K&B yellow Mabuchi FT36 came in two styles. The first was without brush heat sinks, the second with heat sinks. I would use the later type in any case. Most are endbell-side drive.

The K&B Challenger motors were found in all the Series 1 kits as well as the 1/32 scale kits these have a disc-type commutator and they are a bit slow. The later Super Challenger is more powerful and has a tubular comm.

I never figured out how these motors can be rated by voltage. For me the only thing that ever counted is the torque curve from zero RPM to maximum achievable RPM at 12 volts.

[Old Pilot]

Thanks Dokk,

I'm afraid I don't know how to see what you say, all my 5 motors are identical, except for a couple of different yellow tones.

If you find a pic I will thank you, but not in a hurry, my possibilities are only to use the best unit for now.

Thanks again.

[Gary Bluestone]

Try not to worry about burning out a motor, as this happen very rarely and is usually due to binding in the gear mesh or rubbing tires, and not usually from normal racing. I did melt a commutator on a 16d racing a Monogram Mercedes 540K, so it was just overworked.
I think at one time they tried to classify motors using a voltage rating but that practice faded away. The basic idea was that a motor with a normal (cool) winding would be 12V and the hotter the wind , the lower the resistance, the lower the volt rating.
A long piece of thin wire would have a high resistance. A short piece of thick wire has a low resistance. A Monogram 36d with 90 turns of #30 wire(.011") was rated at 6V. The same armature with 75 turns of #29 wire (.013") was rated at 3V. I found a listing that show the Royal Bobcat as 6V. I did rewind a yellow K&B using 75 turns of #29 wire and it has survived unscathed for at least a decade. You should be able to test the resistance with an ohm meter right at the commutator segments and they will read around .5 ohms . The higher the resistance the cooler it will run and the higher the voltage rating. It is possible to test at the pickups, but you have to compensate for the added resistance of the brushes, springs, lead wires, brushes and connections. Make sure the commutator is clean.
The challenger motors have two brass tubes sticking out from the side, opposite the gear, the super challenger motors have a large round black thimble shaped protrusion instead and there are two brass clips that hold the wires to the internal brushes and springs.
It is hard to see if the super is in fact faster, better or cooler. We run all these together in the same 1/24 class and they are all pretty much equal and we have never burned one out, using 12V car batteries or power packs. In 1/32 class they seem to be pretty much the earlier challenger motors and the are one of the fastest vintage classes in that scale before the anglewinders appeared.
Enjoy your racing cars, have fun with them , they already outlasted their original life expectancy by about 45 years with little or no care, so they will probably last indefinitely with a little common sense .

[Horsepower]

Jesus,
The K&B yellow Mabuchi FT36 came in two styles. The first was without brush heat sinks, the second with heat sinks. I would use the later type in any case. Most are endbell-side drive.

The K&B Challenger motors were found in all the Series 1 kits as well as the 1/32 scale kits these have a disc-type commutator and they are a bit slow. The later Super Challenger is more powerful and has a tubular comm.

I never figured out how these motors can be rated by voltage. For me the only thing that ever counted is the torque curve from zero RPM to maximum achievable RPM at 12 volts.

Wasn't the 12 volt version the "Bobcat" and the 9 volt with heat sinks was the "Royal Bobcat"? Both yellow of course. I think the 1966 and 1/2 Auto World catalog shows that. It's here on Steve O'Keefe's Independant Scratchbuilder site........http://www.theindependentscratchbuilder.com/2.%20Vintage%20Articles%20and%20Info/1.%20Catalogs/Auto%20World/1966.5%20Auto%20World/AW%201966.5%20pg%2094.jpg (copy and paste the link)

[Prof. Fate]

Hi

I wish it were that simple. There was no standard to the classification in the day (much like the modern racers in 1/32 rtrs who are obsessed with rpm ratings).

As above, I have "8" and "6" volt and other ratings that have been in cars in use since new 40 plus years ago. No one THEN was building for the market the sort of "one race and rebuild " stuff that we were actually racing in the day.

You can find 34s winds and 32 winds on the 16d motors, all the larger 36ds seem to have the same wind and are about 2 wire sizes hotter than the other stock 36ds. With a 36d, lifespan doesn't become an issue until you get into 29 winds.

Unlike modern motors, however, these things are all rebuildable. So, again, even with aftermarket parts...doen't sweat it.

Fate

[Horsepower]

Yes, but there was a standard with the K&B motors. Bobcat was rated 12 volts (mild wind) and the Royal was 9 volts (hotter wind). Certainly there was no set standard as far as voltage ratings across the board. In fact, I remember articles about the voltage rating of motors basically meaningless as a ratings guide. The concensus was that they all should have come with ohm ratings instead. It would have given a more accurate idea of the armatures power or possible RPM.

[Old Pilot]

Thanks guys...

With all of that I can obtain a closer view.

[Lone Wolf]

I agree with the others. I run vintage cars all the time and I run them hard. The Royal Bobcat in the Lotus is a very fast motor in my opinion. And you have to love that "clamshell" sound when you drive one. The Challenger motors have great torque and love to lift the front wheels on my 1/32 cars. These motors are very strong and if you fry one you can get one NOS on Ebay for about $15-$20 bucks. In my opinion slot cars are like real cars, there will always be "freak" stock motors that run faster than hot ones. Just race them and have fun .

[Old Pilot]

Yesss...

I'll try.
My idea is always get a couple of units of each model, one in perfect status to preserve and another to be restored and decorated. So I can feel free for using and change the second, because I'm not Chris Clark/Bosmeck or JM Piot, and I'm always afraid of doing not so well.

When I finish the models and if they are merely suitable to be exposed, I'll post again with pics. Otherwise I'll post only comments about their performance in the vintage races, although I have not the quick fingers of Dokk.

Thanks.

[sportblazer350]

in my racing experience with K&B motors, any of the 1/32 scale cars are very fast to my surprise, and i have won races with them, as well as have lost to other K&B cars! The 36d yellow can Bobcats are very popular with our vintage club racers in 1/24 scale classes. I bought spme yellow can K&B 16d motors, and they were all total dogs! . Overall i like K&B motors. I have been steadily racing them in 36d classes without any failure for several years now, enjoy!

[don.siegel]

Whether they're rated at 6, 9 or 12 volts they're all still designed to race on standard 12 volt power packs and should last a long time.

The Challenger motors are very inconsistent: some of the Super Challengers are as fast as as good 36D and others not! The regular Challenger is generally pretty slow, but they're all very easy to control. Brakes are often not very good, but that may be because of the old magnets too... Speaking of which, on some of the cars the Challenger will provide a magnetraction effect if you're using Carrera or similar plastic track.

Have fun!

Don

[Old Pilot]

Due to my poor knowledge about motors, I was afraid of using that motors on wrong volts. But now I'm sure it can be a good race day.

I'll tell you after the 20th....

Thanks a lot for all.

[Prof. Fate]

Hi

The only problem with the Challenger/superchallenger is, really, that the magnets are ordinary iron. In the day, it was one of the few motors that benefited from zapping....and that ment WEEKLY.

The "doggie" part of the challenger was for this reason. They would bleed off very quick. The replacement, new in the box motors have gauss ratings that are, in essense, background from being iron.

If you have access, zap them.

As for the 36ds, I think their popularity in the retro races is that, simply, REH had tons of them NOS!

Fate