Our SC class requires that only Slot.It parts be used and there are wide variety of options available that are legal for the class, so much so that it can be a bit confusing (even daunting) for Slot.It newcomers to come to terms with. For this reason, this post will try to clarify things for those new to Slot.It and may even be helpful to experienced SC racers. You can also refer to this previous post when setting up your SC car.
Eligible Cars:
As mentioned above, our SC class is based on Slot.It versions of the Group C cars that were the pinnacle of LMP racing from 1982 to 1993. Only the following Slot.It cars are currently legal for the class:
As more Group C models are introduced, they will be added to the list.
Our SC class rules can be found in the FRC Class Rules 2019.
Key Items:
When preparing an SC car to be as competitive as possible, the key items for performance tuning are your choice of:
- Wheels (rear in particular).
- Tyres.
- Motor pod (to get the minimal ground clearance when combined with rear wheel/tyre diameter).
- Magnet.
- Axle gear (to get the best gear ratio for the track).
- Guide flag.
Wheels:
You have a wide choice of alternative wheels, however the ones which came with the car are quite likely all you need. Here's a reference:
Tyres:
Although you can use any Slot.It tyre (the markings on the sidewall identify that it is a Slot.It tyre, as well as the compound), we have found that Slot.It silicones work best at FRC. The following chart shows all the information you need to know about Slot.It silicone tyres:
Motor Pod:
These are the three inline short-can motor pods eligible for the class:
Offset refers to how far off the axle and motor shaft alignment is with the specific pod. Zero offset means that the axle and motor shaft are exactly aligned. The greater the offset, the closer the pod will be to the ground, so this is an effective way of both lowering the car as well as getting the magnet closer to the track. Here's a diagram:
The ground clearances shown are based on the combination of motor pod and rear tyre diameter. The diameters are the Slot.It silicone tyre dimensions shown in the section on tyres above. Avoid ground clearances shown in red.
Magnet:
The class requires the use of only the currently-available standard Slot.It "non-race" magnet (the one with the grooves, part # CN06). When selecting wheels, tyres and motor pod, your objective should be to get the magnet as close to the track as is practical. Generally-speaking, this should be somewhere around or just under 1.0mm. Anything less than this may cause the magnet to make contact with the track rails, slowing the car significantly. UPDATE: If your magnet isn't giving the "downforce" you need with your car's ground clearance at the minimum, it's not a bad idea to have a few extra magnets to choose from, as some otherwise identical magnets are stronger than others. Note that the magnet and all metal parts that can potentially make contact with the rails must be covered with insulation tape of some sort (this applies to all FRC classes).
Axle Gear:
Slot.It crown (axle) gears range in teeth from 23 to 30 and the gears increase in diameter with the number of teeth, so you have to be careful to not install a gear that is too close in size to the diameter of your rear wheels/tyres, otherwise it will make contact with the track and create problems. These gears are available with either brass (heavier) or aluminium (lighter) hubs. From experience, a ratio of about 3.2:1 is usually in the ball park, although this can change with other variables such as rear wheel diameter, motor performance, etc. Trial and error is the best way to get the ideal ratio for your specific car and setup. UPDATE: It's important to note that Slot.It also makes "offset" gears which are required for 1.0mm offset pods. Unlike the standard gears which are colour-coded by number of teeth, all offset gears are white.
I've included 10T and 11T pinions, however its highly unlikely you'll ever want to use them at FRC.
Guide Flag:
The one that comes with the car is fine. Over time as you fine-tune your car, you can look at getting what I have found to be the best Slot.It guide for plastic track (part # CH85):
Chip:
Whatever car and setup you use, you'll need one of these (part # SP15b):
Finally, here's a link to the most recent Slot.It catalogue:
http://slot.it/Download/BROCHURE/SLOT_I ... 6-2017.pdf
Its a PDF, so you can download it and keep for reference.
So, get yourself a high-quality Slot.It Group C car and join us at FRC!
