I expect that most of you have systems to address these questions. Just this morning I had an exchange of emails with O'Brie about this topic. Over the years I've developed a simple but pretty effective system of my own, resulting in my cars slowly becoming better with time, which I passed on to him today. I thought I'd share it with you all for what its worth.
My Method
I seldom if ever take notes trackside on race night. The real testing takes place during the races and there’s no time for note-taking then. I try to take notes the day or night after racing, or the Saturday after while everything is fresh in my mind. I use an iPad for recording these notes because of its ability to search and return information immediately, however you can use a computer or other electronic device, or simply an old-fashioned notebook and pen. The key thing is to make notes that can be referred to later.
The initial and most important notes I take refer to how fast the car qualified (available in the race report on the forum), who was on pole (available likewise) and with what time (for an idea of how far off I was), how the car felt - its handling, acceleration and top speed compared to the fastest car in the class, my driving errors, etc. These are represented by the first paragraph in blue in the example below. I then add thoughts of what may address the shortcomings (red below). These may not be added immediately - they're often added over the period before the class comes round again. The first and main thing is to get the record of what transpired with the car in the races (the blue section). Here’s an example for my Zakspeed Capri, almost exactly how I wrote it at the time:
Over time you end up with a full development history of each car you race which can be referenced to see what may or may not have improved its performance. You'll also know what components are currently in use on the car (e.g..motor, tyres, wheels, gears, etc).Slot car notes 9/11/18
NOTE: Track seemed slightly down on power and everybody's times suffered as a result.
Modified Production
Zakspeed Capri:
… Car was sluggish with times of 5.2 to 5.3 sec. Handling was excellent with XX tyres, but reverted to previously installed taller YY tyres so that added weight could be removed. Eventually qualified at 5.152 sec, 0.345 sec off Ramesh's Subaru's pole time of 4.807 sec.
… Idea 1 (No, I'm not giving away setup secrets! They're lots of other tips to help you out there).
… Idea 2.
… Idea 3.
… Idea 4.
… etc.
In summary, you absolutely have to note down the blue portion for each car you raced within a day or two of the races, otherwise you’ll never remember five to six weeks later when the class rolls round again and you'll just have to be guessing.
So this is my technique. Perhaps you can mention yours in the comments below.
(As a footnote, I just very recently used an iPad database app to develop a more automated system, however the method described above has worked very well for me.)