In this post we’ll look at re-installing the intercom so that driver and passenger can communicate much easier, what google thinks is a good time at Thruxton would be. I’m thinking about whether to keep on taxing and insuring the car or whether to make it track use only; and we’re going back to Thruxton to play.

Intercom

The intercom packed up about two track days ago. We find it quite useful because MX5 NC’s are inherently noisy when driven with spirit and were forced to shout and use hand signals to communicate as we blast round circuit.

As we’ve seen you can spend significant sums on this equipment. At the cheaper end of the market the Zero Noise Valiant amp and headsets give good service but at £93 to replace the previous amplifier unit and another £73 to replace both headsets, they are not cheap.

I stuck the amplifier rubber housing to the transmission tunnel with 3M Duraloc heavy duty velcro.

Gearbox Heat Shielding Removed

I’ve noticed that the original heat shielding that sits over the gearbox had begun to sag and hang down below the frame rails. Closer inspection reveals a foil outer, fibre middle and cloth backing. I elected to pull it out by cutting the two remaining wings with plastic mounts. Whilst not easy to remove and very dusty and crumbly (so mask and goggles are advisable) it was not hard and took about an hour once I’d got the car up on blocks.

What effect this will have on noise and heat transmission we’ll see but it was in a pretty dilapidated state. I’m not planning to replace it but I will if necessary.

Oh no I’ve found some rust bubbles.

It’s an old MX5 so it will rust, but I’ve found some bubbles on the chassis rails under the Y shaped chassis brace so I’ll have to have a think about whether to repair this myself or get it done professionally. Fortunately the season is nearly over so hopefully it I can wait and be done in the off-season.

How do I know if I’m getting better?

Every provider I’ve used says you are not allowed to time yourself on a tract day, yet most cars seem to have some way to do this. For many its from the video GPS data or mobile phone apps. I’ve also seen Racebox and Racelogic on cars. I often use an AIM Solo2 DL and my GoPro, I don’t use them for overt timing. MySolo2 DL is set to a three segment screen for lap number, calculated gear and RPM functions and is used mostly for the RPM change lights to help me optimise my gear changing. It is placed at the base of the windscreen as a head-up-display so that I don’t have to take my eyes off the track to check these details by looking down at the speedo area.

Over time two things have occurred simultaneously; firstly, I’ve gained confidence in my handling of the car as I’ve explores its capabilities more fully over similar tracks. Secondly, as I’ve got more into the track day lifestyle I’ve invested in the car to tackle some of the flaws I believe it to have.

For both you would expect to see improvements in terminal velocity, the average speed over the lap and reductions in lap times at the same circuit. and generally this has proved to be the case.

Thruxton Lap times

• August 2025: 2.02.806
• July 2026: 1.44.191
• August 2026: 1.44.207

Although there is also an argument to be made about the law of diminishing returns where investment in the car ceases to yield substantial improvements and the limitations of the driver begin to be exposed.

One of the advantages of videoing laps is that you can begin to analyse your driving and pick up on where you might push harder brake differently, etc.

So whilst I felt on my last trip to Thruxton things where more stable and my terminal speeds were higher clearly I was not faster overall than in July, which shocked me as I wrote this post. Given my surprise I asked Google what a good lap time for an MX5 NC would be at Thruxton it said:

• Elite Drivers /Track Car: 1.30 – 1.33
• Fast Track Day: 1.34 – 1.37
• Moderate Mods: 1.38 – 1.42
• Standard Car: 1.43 – 1.46

Clearly I need to think about where I can get more time and the answer must start with not bottling it at Church corner (adverse camber right hander), easier said than done (see video below). This will allow more speed t be carried through the the final chicane.

Data Logging and RS3

Whilst I record all my sessions and back them up on a PC. I really don’t use the data capabilities of the AiM equipment and RS3 software that much but I do often check optimal lap against fastest lapt time to see how they compare: and often watch the fastest laps on the map to see where my best lines are located for future use.

Whilst I had originally been quite keen to add sensors, PDM and Dash this soon passed when I soon realised the data logging I have already (Solo2 DL & RS3) has more performance than I really need at present.

Go Pro (Hero13 Black)

Recently to simplify the conversion of video into RaceRender compatible data begun using just the GoPro video and XML downloads from GoPro Quik to give me Race Render Track Map, G force, Speed, and Lap Time overlays, as below.

In the off-season I’ll run a post on how I convert GoPro to RaceRender and On to our YouTube channel.

Should I keep it taxed and insured?

This month will see the car need insurance for another year and it is likely to require modified car insurance beyond what you can achieve on line for yourself, especially if I adopt a more aggressive approach to modifications.

MX5’s of this age are expensive to tax £360 py and insurance is around £240 py in standard form. This is a lot for what was only a few thousand miles a year.

Now it has to be said in the blistering heat of a British summer then it is perfect as long as you can keep your hat on; and frankly it is a lovely form of transport with the top down on a summers evening or at night (so long as the cows and farmers fields are being sociable), but in truth it has been used more for track days than socially (no room for the dogs).

Part of me has been thinking about whether it would be more straight forward to forgo road use all together and save the Insurance, Tax and Mot costs, hire a trailer then remove the worry of blowing it up on track and having to fork out for a recovery vehicle (not covered by standard breakdown insurance) and £100 per TD.

My plan is to get the next track day out of the way find out how much the insurance costs will be and then decide from there. Obviously a trailer will need to be stored and I’m not sure whether I have the space. My usual road car is already equipped for trailer towing so that is not an additional cost for me.

I’ve also been thinking about taking it further afield e.g Anglesey / Spa next year and that would definitely require the reassurance of being able to recover the vehicle in the event of a mishap.

Cost this month

In this new series we’ll be tracking costs each month so that readers can get a good idea of the true lifestyle costs. This month the bill has been.

Replacement Equipment £166

As we’ve discussed above, this month saw the replacement of the Intercom unit and the two head sets so that driver and passenger can communicate more clearly :without the need to yell at each other over the engine and cabin noise.

Thruxton Track Day Booking £209

For a single driver and garage booking. The additional driver is £40.