By Michael Ashton
I am a fan of the red plastic angle winder gear set that NINCO has used in the Sport line of slot cars for ages. I have at least a dozen NINCO GT cars that use this gear set and they are all fast running, good handling cars — among my favorites. These gears can be somewhat noisy at first, however, they break in relatively quickly and eventually become smooth and quiet.
There is one downside to these gears that I am not a fan of: the pinions tend to develop stress cracks. This happens most often over time although I have had several cars that came this way out-of-the-box. When the pinion develops this type of crack it is unmistakable. Gear mesh sounds terrible and the negative impact on performance is quite obvious. I would estimate that this has happened to least 25% of the cars that I have with this gear set. The following photos show how the crack usually appears. They are barely visible to the naked eye, however, the effect is fatal to the car's operation. The white arrows in the two photos below highlight the location of the crack.
Once this happens the pinion cannot be repaired and must be replaced. Unfortunately, the pinion is not available as a separate part. So, the only way to obtain a replacement pinion is to purchase the entire axle set and use the pinion from the set.
The NINCO red plastic angle winder gear set is not expensive. And if you have a use for the spur gear axle assembly and/or the second axle and bushing that come with the set, then buying the entire set is probably worthwhile. If not, then the extra parts are just wasted. In this case there is another option available: the NINCO #80249 ProRace V.03 pinion. This is a brass pinion that is held in place by two set screws, which make it very easy to install and adjust. The cost is slightly less than the complete axle set. In my experience, when adjusted correctly, the ProRace pinion meshes perfectly with the red plastic spur gear. The advantages of the ProRace pinion are no wasted parts and you are never going to see a crack in this pinion.
The original plastic pinion is a 12 tooth, therefore, a 12 tooth ProRace pinion is selected for replacement in order to maintain the same gear ratio. If a change in gear ratio is desired then a ProRace pinion with 11 or 13 teeth may be substituted.
Now, for those who have never taken the body off a slot car before, it must be noted that there are a couple of tools that are needed to perform this type of repair. These are tools that I believe are among those that represent an absolute minimum requirement for anyone who plans on performing even the most basic slot car maintenance, repair or tuning. They are: a gear press/puller for installing and removing press-on type drive train gears; and a 0.9 mm hex driver for the M2 set screws that are used to secure set screw type drive train gears and wheels in a wide range of slot cars.
There are many available from a number of manufacturers with a wide range of prices. Good quality versions are not expensive and they all perform the same basic functions.
The first step is to remove the defective pinion from the motor shaft. To do this properly, the motor must be removed from the chassis. When removing a motor, I always pop the rear axle assembly out first in order to avoid any damage to the motor shaft during motor removal. If you are fortunate, the crack will have compromised the plastic pinion structure to the point where the pinion can be pulled off the motor shaft by hand. If not, the gear puller must be used.
The following photo shows the orientation of the motor shaft in the puller section of the tool. The motor shaft is placed in the slot between the pinion and the motor's can. The shaft at the end of the threaded turn bolt fits inside the hole at the end of the pinion, contacting the end of the motor shaft. The bolt handle is then turned clockwise, forcing the motor shaft down and out of the pinion hole.
Eventually, the pinion will separate from the motor shaft. It may be necessary to pry the pinion off the turn bolt shaft with a screwdriver blade or by backing the bolt all the way out to the top of the tool.
When installing a set screw type of pinion on a motor shaft I find it best to first reinstall the motor without the pinion and before reinstalling the rear axle.
Insert both set screws into the pinion with a few turns, then slide the pinion onto the shaft, approximating its position where it will contact the spur gear. Tighten one of the set screws so it is just snug.
Now reinstall the rear axle.
There are a number of documented tricks that are used to obtain optimum gear mesh in an angle winder set up. For example, placing a slip of thin paper between the pinion and spur gears, adjusting the gears for a tight fit, then removing the paper. I have always obtained good results through trial and error, feeling the mesh as I go.
Using the 0.9 mm hex driver, loosen the set screw that was previously tightened and move the pinion slightly on the motor shaft until the faces of the two gears' teeth are centered. Tighten the one set screw, then turn the wheels in the forward direction feeling and listening to the mesh. You are looking for a smooth feeling with no binding or skipping. Repeat the process, moving the pinion in or out by a small amount each time, checking that the set screws do not make contact with any part of the chassis, until the smoothest feeling of the mesh is obtained. Tighten both set screws.
Next, lubricate the pinion teeth with some plastic-safe grease and run some laps. Listen to the gears and check lap times. If the mesh does not seem smooth in the running car or the car is noticeably under performing, repeat the previous adjustment process until the best performance is achieved.
The new gear combination will require some time to break in. But if the installation and adjustments are preformed correctly, the car's performance should return to the identical level prior to the demise of the plastic pinion.
__Michael Ashton
