11/03/2011

If one this is certain in this hobby, there is no such thing as a perfect gear ratio. With Pioneer fast becoming one of the most popular brands, swapping out gears to change these ratios or to replace a damaged gear is something many enthusiasts will do.

Although you could replace the axle with a Slot.it or comparable part, to me there is no need to replace it. The Pioneer axles are about as good as it gets.  When I measure the diameter of these axles I consistently get readings of 2.32-2.31 mm. I get the same readings when I measure a Slot.it axle. In other words 3/32nd size. So if the axle is straight and true there is no need to purchase a new one.

The only issue is the knurling that is stamped onto the axle that is there to secure the press-fit Spur gear.

The following is how I go about removing it and installing a new Spur gear.

First, snap the axle assembly out of the chassis. Then lightly twist and remove the wheels. Pioneer axles are thankfully not knurled on the ends.

Stock Gears

Once these are out, use a gear puller and remove the original gear. You will see the knurling that is stamped onto the axle. Of course this causes high ridges that "bites" into the plastic gear keeping it secure.

All you need to do is lightly sand this area flush to remove these ridges.

I like to place the axle in my mini lathe. Then I cut a small strip of very fine grit sand paper (wet sanding) as shown. While the axle is turning at low speed I hold the sand paper against the knurled area. It only takes about 20 to 30 seconds and then you can test fit the gear to see if it slips on easily. If so, you are done.

NOTE: You do NOT need a lathe. You can use a regular drill just as easily.

You can still see the indentations of the stamped knurl, but the high ridges are gone.

For this model I am staying with the stock gear ratio. It is also the 19MM diameter gear that matches the old almost exactly.

On most Pioneer models you have shims already there to use. I use one on the non-gear side and 2 as shown below.

Using these shims gives me the setting for the Spur that I like. almost centered to the pinion without rubbing the pinion flange.

Gear mesh with the stock pinion is very smooth and will not need much break-in time.

Now just install the wheel and you are ready to go.

- Harry

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