Although nearly all our classes are described as ‘box standard’ there are still subtle things you can do to a slot car to maximise its performance.
Once the magnet has been removed the handling of most cars will improve if there is a degree of movement between the body and the chassis: ‘body rock’. This might be as simple as just loosening the screws a turn but sometimes a little sanding of the areas where the chassis and body come into contact is also required, to stop fouling. Scalextric cars frequently have odd mouldings that can restrict independent movement of the body.
Also, many models now mount the motor in ‘pods’ that can, with loosened screws, float independently of the chassis.
Some manufacturers’ tyres are better formed than others and sanding the tyre whilst it’s mounted on its hub can flatten off bumps and increase the contact patch.
With the sandpaper still out, gently rounding off the edges of the tyres can prevent the car digging in and de-slotting when cornering.
Running on inevitably bumpy plastic track it’s best to lower the profile of the front tyres to lessen their contact with those bumps.
Check and ensure that the fronts really rotate freely. In addition, they can be glazed with nail varnish to lower their grip coefficient and stop them from grabbing if they’re put under load when cornering.
Some brands make it possible to raise the front axle using grub screws in the chassis.
Don’t over lubricate but do put a drop of oil on your motor’s bearings.
The motor and gears will always benefit from a period of running in to free things up and mesh them together. A little toothpaste on the gears, for a short period, aids the process.
Motors can often be screwed, or else hot-glued, to the chassis or motor pod to prevent twisting under load.
A drop of oil on the bushings helps reduce friction in the axle.
Sometimes a spacer might be needed to stop excessive lateral play in an axle.
Similarly, Scalextric axle bushings have a much bigger diameter than their axles allowing all sorts of vagueness. This can be cured by dropping some oil in the bushings, jacking the chassis up and setting the axle turning and very carefully putting a drop of super glue on to the spinning axle by each bushing. Capillary action should draw it in. Keep it turning for a few minutes while the glue hardens and that lateral movement should be gone.
It isn’t uncommon to find you’ve got a slightly warped chassis. This is most noticeable once the magnet is out and you barrel into a corner, as you brake a warped chassis can push the rear of the car out of line.
There’s detailed instructions in this PDF on how to restore your chassis’s balance.
Final Word on Tuning
You can do all of the above and still the best tuning you can achieve is practise. Nothing beats practising.