How can you stop this brain drain on your team? Short of paying your crew a good deal more money to prevent them from ever considering an employment change, in reality, you will always have team turnover. You need a better plan than just throwing money at it. You need to develop well-defined documentation on how any given process within your team is accomplished.
This is clearly a danger when a process is people-based and the activities that govern the person or persons within that activity are committed completely to memory. This rote method of process performance is not completely bad; you cannot have each member of the team always looking into a manual to see what their next step is going to be. On the other hand, when a new person joins the team, it is very beneficial to have a description of what their job is and some sort of order established.
This is nothing new. Documenting how things are done is a very common practice. In fact, documentation is one of many steps toward reducing variation within any process. Developing standard workflows or documenting Standard Operating Processes (SOP) should be a prime consideration. This is not that different than developing checklists of all the activities that have to be accomplished prior to the race. A checklist just defines the activity or tasks requiring completion prior to the race, not the job of each crewmember. Checklists do not illustrate the flow of the individual activity.
What I am suggesting is not a new or revolutionary idea. It is just common sense. Using our tire example, it may be as simple as an illustrated process flow map showing the steps that the tire man follows to get the job accomplished. Anybody who has been working with cars for over a month will have seen a manual of some type or another. What I am suggesting is no more than the steps a team member might go through to accomplish tasks on race day or even the activities they accomplish in the shop. Capturing the workflow and some of the more critical details may take some extra effort over the short term, but it will improve overall efficiency. This is the process of developing your SOP. This is not rocket science, but this is the same sort of tools rocket scientists utilize to develop their SOP. It may be as simple as just having someone sit down with the tire guy to go through the specific activity and document the process.
The act of documenting the process may illuminate some ways you could improve that process. You may find some things to be unnecessary or you may find that you are not measuring the process correctly or at all. In fact, as you document the process flow, you may see some activities that were not previously defined as part of this person's normal duty. In the case of the tire man's duties, you have a two-fold process. One part of the process is responsibility at the track. The second is his responsibility at the shop. You may find they are very different, but no less important.
You may not have a paid tire specialist on a typical Saturday night team, but the job is no less important. Defining the activity for each crewmember will help you to better understand how many people you really need. More often than not, you will not have enough help to make your program run smoothly. As you further define this activity, it will be much easier to get a new team member up to speed and working with the rest of the team.