Hi guys,
I have an easy one for some of you. I have a G3 with poly mags and a 36.5 arm. I tested it with a 9 volt and it gets real hot. Real hot.
I'm afraid to run it and smoke it.
Thanks,
Tom

If nothing is binding up.
Make sure there’s a phenolic or nylon insulator in front of the commentator.
Look at the brushes in the bulkhead to see if they are running true and the springs aren't twisted.
Clean the commentator with pencil eraser by spinning the armature in your Dremel.

Then NO FEAR.

Hi guys,
I have an easy one for some of you. I have a G3 with poly mags and a 36.5 arm. I tested it with a 9 volt and it gets real hot. Real hot.
I'm afraid to run it and smoke it.
Thanks,
Tom

Really hard to say there's a problem without knowing how hot "real hot" is. 125 degrees is enough to make you flinch, but wouldn't be abnormal for that setup.

Check your clearance, I know I burnt the end of my fingertip a few months ago sim-ply because we let a T1 get too low and it caused extreme heat build up just from the magnets..and I didn't just ouch....lol


Dave

I suggest getting a non contact infrared thermometer. Radio Shack is clearing out this model that used to sell for around $40.00. It works very well (goes up to 400 F) but does not have a laser pointer.

http://www.radioshack.com/product/index.jsp?productId=2103171

If you search for "non contact infrared thermometer" you should find plenty of selection.

This one is a good deal, even with the shipping cost. It goes up to 600 F, which will tell you the temperature of your car after it turns into a molten blob of goo.

http://stores.channeladvisor.com/Digitalet/items/item.aspx?itemid=1738608

If you are running polymer traction magnets and ceramic motor magnets (Mod Class) your car can get very hot very quickly and go "poof." This is worse with L19 and L25 traction magnets. At the very first sign of a problem, e.g. you keep having to increase your controller sensitivity to keep the car responsive, take the car off the track and check the temp. If it is above 160F or so you are getting into dangerous territory.

Note that these cars need to maintain a lot of rpm to stay cool. The more rpm the more back emf and the less current in the arm. Because power is a factor of current squared small changes in current make a big difference in power dissipation. If you find yourself running your Mod at partial throttle through much of the course, go to a smaller pinion or larger crown gear to pick up the motor rpm. All slot cars follow this pattern, it's just accentuated when you are running a 3 ohm or lower arm. Plus, frying a $40 custom wind hurts a lot more than a $5 stock arm or $10 hot stock arm.

I appreciate your replies.
I got a little smoke, just as you described. I think I got it off un-fried.
I tried another custom and all is well.....and fast!
I'll try that arm in another setup and watch carefully.

Maybe I should have described the burns on four fingertips.....haha
I hate the smell of armature in the garage.......it smell like money!
Again, thanks for your replies.
Tom

Cleaning com plates with an arm in a dremel and a pencil eraser is not something you want to do unless you really know what you are doing,one wrong move and you have a worthless 35 dollar arm.In a real big hurry.

When time allows,I will try to post a pictorial how to kind of thing.

Mike

It could be a problem with poor motor brush contact (too strong or too weak contact). If it is too strong, there will be extra friction. If it is too weak you will get extra sparking as the current tries to flow. It could just need a good cleaning. Alos check for any resistance or binding in the driveline.