[cbwho]

One of my family heirloom AFX MT cars smells unpleasant of burnt plastic/electrical. I took it apart and noticed the clip was indented so it rubbed badly on the idler gear. I fixed that and made other adjustments. Now it runs much better.

What is the best way to clean the car to get rid of the stink? Cold it doesn't smell but once warmed up...

 

[RichD]

When you get a smell of that sort it is because the car is running too hot. Cars run hot because they are pulling too many amps, if that goes on for very long the motor may be permanently damaged. Running the car with a power supply that has a built in amp meter would tell you if it was running properly. At 18 volts the car will pull about 0.2 amps. There could still be some extra drag in the gears, etc., or the armature may be shorted and will have to be replaced. Lacking any way to measure the amps you could swap in a gear plate/armature assembly from a car that does not stink. The earliest Magnatraction cars came with a 6 ohm armature, but most of them have 14 ohm armatures. 6 ohm green tip gear plate/armature assemblies are readily available from JAG Hobbies and Lucky Bob's. Slot Car Central has the red tip 14 ohm assemblies.

 

[cbwho]

I better measure the ohm's of the arms

 

[model murdering]

As a rule, the damage is likely done. While the undue friction has been fixed, abused or fatigued winds generally dont heal themselves after the fact.

Ive never found anything to get rid of the pungent stench, short of throwing the burnt winding/component away.

The 6 ohm swap improves the Magna's giddy-up considerably.

 

[cbwho]

MM, I think you are right.
The arm reads 12.3, 14.4, 14.7 ohms... So not within 0.1 tolerance

I took the chassis complete, and bathed it in Windex, rinsed in hot water, then in weak hydrogen peroxide, rinsed and final rinse with alcohol. The stink seems very faint. So took it to the track and the stink is starting to come back a bit.

So a new arm is needed. I think I'll put a Dash arm in.

 

[RichD]

When you measure the ohms you will be reading all three poles at once. In this case it looks like one pole has a partial short across the windings. With a three pole armature, if the poles have equal resistance, the resistance of each pole will be 3/2nds of what you will read with them connected together. If the armature was a 14 ohm one you could use a JL/AW armature. I don't know if the gear plate/armature assembly would be a perfect fit in an Aurora chassis. If you wanted to race your car a certain ohm value might be called for, otherwise you can use whatever you have handy.