I mentioned we took some old Tycos out and tuned them up, they are still good cars and have great performance. Some asked what we did, so hence this post. You can figure on spending about $8.00 per car in parts, we rebuilt 8 cars total.
We bought new tires, rear axles with crown gear, spur gears, silver shoes and springs and new motor brushes and springs. Also, buy new guide pins. The rest was mostly cleaning, polishing and oiling:
Remove both axles and the motor from the frame. Pull off the pinion/spur gear from the motor if it is worn. Replace the front tires, as the rubber if original will be old and cracked. The HO slot car site has all the Tyco/Mattel and BRP hop up parts, plus silicone rear tires. We use a damp sponge to clean the rear tires for maximum traction. Beware that the older foam tires will usually be no good due to age, once you try the silicone slip on rears, you will love them.
On the Tyco Magnum 440 X2 cars, I put on the silver, or chrome front shoes (pick-ups) and replaced their springs. Polish the brush hoods so they make good electrical contact with the shoes and springs. Remove the axles and get all the lint off, then replace the rear slicks with silicone tires. You can buy a new rear axle assembly with rims and crown gear if your rims are slipping. I also replaced the spur gear on the motor. While you have the motor out, polish the comutator and clean the motor frame. If you have different armatures, there is a narrow and a wide gap, set one car up with each as they are different and you will like one better for short and long tracks respectively. If you have new brushes,(the high silver content brushes are best) replace them and the brush springs, then break the motor in with your power supply set to about 6 volts, or use a 9 volt battery. I use a dab of tooth paste on the gears to break them in, it makes a differance. Be sure to clean off all the tooth paste once you hear the gears quiet down. Use a tiny bit of silicon grease on the crown and spur gear, and a silicon oil on the motor and axles, just a tiny drop. The high silver content brushes are best.Gently twist and wiggle the chassis while breaking in the motor to seat the magnets and bearings, listen for the motor to pick up RPM indicating everything is now in alignment.
You can buy better magnet sets but beware! The stronger neo traction magnets will flex the chassis and make it drag on the track, requiring bigger diameter rear tires. There comes a point where the motor starts getting real hot due to having to overcome the drag of the stronger traction magnets. BRP sells a stiffer chassis, but we have yet to try it. You have to run higher track voltage when using Neo magnets to overcome the drag they cause. We only have one car with neos, the rest are using stock magnets (ceramic).
You can take a round wooden toothpick and carve the end to look lile a flat chisel blade, then glue a piece of 600-800 grit sandpaper over the tip of it. Use this as a comutator polishing tool to gently touch the commutator while the motor is running to polish it back up from any tarnish it developes during break in. You can use your "com stick" as I call it on all your HO slots to tune them up. You will hear the RPM jump when you do this, it's significant and really helps.
Tarnish and arcing at the pick-up shoes, and brush hood, plus the comutator/brush condition are critical for the best performance, so focus on that for power and speed. On one car, I have soldered real fine copper braid from the shoes to the brush hoods to help eliminate the tarnish that develops from the shoes arcing where they contact the brush hoods, and it really helps. The condition of the gears affects the power transfer and side to side slop in the rear axle, so it is also critical for handling and power. Be sure to replace the guidepin, use the newer extra wide one as they really help keep the car from deslotting in the turns.
Be real careful about over oiling, especially the front axle and front motor bushing, as the excess oil will get on the shoes and motor brushes and then cause carbon to form which slows the car down.