How to Replace Worn Out Pinion Gear

[Ned]

The pinion gear in my car is worn out. I suppose it is not surprising since I run it on a track permanently located outside in a dusty and abrasive environment. The spur gear appears to be in good shape. No noticeable wear.
I have a new pinion, new spur, and a new axle with a new spur mounted on it. Should I replace both gears or only the pinion?
I have never done anything like this. Should I hold the axle with pliers and pull off the wheel farthest from the gears just using my fingers? Will I be able to reuse the wheel? Or will it just spin on the axle when pressed back on? How do I remove the pinion from the motor shaft without damaging the motor? And how should I fix a new pinion to the shaft?
Any tips would be very much appreciated.
Ned

[rex craemer]

hi ned, i would replace both gears, because i think they are both worn.its more on the little gear. i am afraid you will worn the new gear very fast if its not perfectly runs in the old spurgear.you can pull the piniongear from the motoraxle with a little violence.it will not hurt the motor .the new gear will hold by itself, there is not much tourqe going on the axles.for long living of the gears ,a perfect adjustment is very important.not to hard or not to much air between the gears.i hope i could help you greetings from cologne markus

[WesR]

The wheels and pinion gears are just a push fit on the axle so easy to remove. The motor pinion is also a press fit. Use a small screwdriver to prize it off by twisting the screwdriver.

[WesR]

Thinking further Ned, if the large pinion is ok, then leave it. Perhaps the rear axle bearing has worn
and the gears have come out of mesh. You can push the axle forward by gluing a plastic plate behind the axle on the inside of the bearing upright. Drill a 2mm hole in a piece of plastic and file it to a c shape to fit round the axle. I have done this. Much easier than re- building the car.

[Ned]

Thanks gentlemen. Upon careful inspection with a magnifying glass and comparing the used spur gear with a brand new one, I have determined that there is a little wear on the spur gear so I think I'll replace both gears. Also, I'll check the rear axle bearing and adjust per Wes's suggestion.
Many thanks.
Ned