Data Logging & Camera Mounting for Track Days

Lap times tell you how fast you are. Data tells you why. A driver reviewing video and telemetry after each session improves dramatically faster than one who doesn't. The good news: you can get meaningful data with nothing more than a phone and a $30 mount. The bad news: most people mount their phones wrong and the mount fails at the worst possible time.

I run TrackAddict on my S2000 with a RAM X-Grip suction mount. The single most useful thing it revealed early on was how much I was coasting — long stretches between braking and throttle where I was just rolling through corners doing nothing productive. Once I could see that in the data, I had something concrete to work on: tightening the brake zones and getting back to throttle sooner. That's the kind of thing you can't feel accurately when you're in the seat.

Why Data Logging Matters

Driving by feel is unreliable. You will consistently think you're braking later when you're not, think you're carrying more speed through a corner when you're not, and think a session felt better than the data shows. This isn't a skill issue — it's how human perception works under adrenaline. Data is objective.

The specific things data logging helps with:

• Lap time consistency — seeing how much your times vary run-to-run tells you how repeatable your driving is, which is often more useful than your fastest lap
• Braking points — GPS trace shows exactly where you braked on each lap. You can overlay two laps and see if you're braking earlier at turn 3 on your slower laps.
• Corner speed — minimum speed through each corner is a direct proxy for how well you're hitting the apex. Low minimum speed = early apex or too much braking.
• Coasting zones — most drivers coast far more than they realize. The throttle trace shows exactly how long you spent between braking and getting back on power. Eliminating unnecessary coasting is one of the highest-value improvements a developing driver can make.
• Throttle application — when you got back on throttle after apex tells you a lot about your confidence and car control
• Instructor debrief — video is the single best tool for working with a driving instructor. "You were late on the throttle at turn 7" lands very differently when you can both see it on video.

Data Logging Apps

TrackAddict

The top recommendation for most drivers. TrackAddict works on iOS and Android, has a free tier that covers the basics, and is simpler to set up than the competition. The video overlay is very well executed, and course timing is reliable on both full road courses and short autocross layouts. The paid upgrade ($20–$50 depending on tier) unlocks OBD-II integration, sector times, and detailed telemetry graphs.

What it does well: Track detection is automatic — the app knows the circuit and starts/stops timing correctly. The video overlay syncs your phone camera footage with GPS speed and g-force data, which is genuinely useful for post-session review. OBD-II integration (requires a Bluetooth OBD dongle) adds engine RPM, throttle position, and brake pressure to the telemetry stream.

Limitations: GPS accuracy on a phone is 3–5 meters, which is adequate for HPDE and coarse autocross analysis but not precise enough for professional-level data work. Phone GPS also has latency — data is slightly delayed relative to actual car position.

Harry's LapTimer

A solid alternative to TrackAddict with a deeper telemetry analysis suite. More complex to set up but offers more granular data views. Worth considering if you want to dig deeper into the numbers. Free tier available; paid upgrade comparable in price to TrackAddict.

RaceRender

Not a logger — a video editor. RaceRender takes your telemetry data from TrackAddict, Harry's LapTimer, or a dedicated logger and produces overlaid video with custom gauges, maps, and data displays. Use this when you want to produce clean session review video or share footage with an instructor or coach. Desktop software (Mac/Windows), free tier available.

Garmin Catalyst

A dedicated on-track coaching device, not just a data logger. The Catalyst analyzes your driving in real time and identifies your "optimal lap" — the best sector from your entire session combined into one theoretical best time. It then plays audio coaching cues during subsequent sessions: "brake 0.3 seconds later at turn 4." Genuinely useful for self-coaching without an instructor present.

Cost: ~$600. Significant investment. Worth it for drivers doing 8+ track days per year who are serious about improvement. Overkill for HPDE 1–2.

AiM Solo 2 / Solo 2 DL

The entry-level dedicated GPS data logger from AiM, widely used in club racing. The Solo 2 is GPS-only (~$400); the Solo 2 DL adds OBD-II/CAN bus integration for engine data (~$600). Both produce significantly more accurate GPS data than a phone — 10Hz update rate vs. the 1Hz typical of phones. If you're doing competitive time trials or want to do serious data analysis, this is where to start on dedicated hardware.

The tradeoff: No video. For video + data overlay you'd combine an AiM Solo with a separate camera and sync them in AiM's Race Studio software. More powerful, more setup work.

OBD-II Dongles

If you're running TrackAddict or Harry's LapTimer with OBD-II integration, you'll need a Bluetooth OBD-II dongle plugged into your car's OBD port (under the dash, driver's side). This gives the app access to engine data: RPM, throttle position, coolant temp, and on some cars, brake pressure.

Phone & Camera Mounting

This is where most people get it wrong. A phone or camera that breaks free at speed is a serious safety hazard — it can fly into your face, jam under a pedal, or hit a passenger. Mounting is not a "good enough" situation.

The two-component rule

Every in-car mount should have two independent retention systems. If the primary mount fails, the secondary catches the device. This is non-negotiable for anything at or above HPDE speeds.

• Primary mount — suction cup or roll bar clamp
• Secondary retention — a safety tether from the device to a fixed point in the car. If the mount pops, the device swings on the tether rather than flying across the cabin.

Suction Cup Mounts

The most common option. A good suction cup mount on clean glass holds very well under normal conditions. The failure modes are: dirty or oily windshield (suction doesn't seal), temperature extremes (summer heat can cause cups to release), and high-g impacts or bumps.

RAM Mounts is the industry standard. Their suction cup bases are significantly more reliable than generic alternatives. The RAM system uses interchangeable ball-and-socket arms so you can configure reach and angle precisely. Get the medium-arm version for most dashboard-to-phone setups.

Roll Bar / Cage Mounts

If your car has a roll bar or cage, this is the most secure mounting option for a camera. RAM and Joby both make tube clamps in various diameters. The mount is rigid, doesn't fail from suction issues, and positions the camera at a good angle for driver's-eye-view footage. Still use a tether — clamps can work loose over a full day of vibration.

Vent Mounts — Avoid Entirely

Vent mounts clip to HVAC vents and are fine for street use. At track they're not acceptable — the clip retention fails under g-loading, and a phone bouncing around the cabin at speed is a serious hazard. Don't use them at events, even with a tether. Use a suction cup or roll bar clamp instead.

Where to Aim the Camera

For HPDE and track days, the most useful camera positions are:

• Driver's eye view — camera on the dash or roll bar pointing forward. Shows your reference points, braking zones, and steering inputs. What most instructors want to see.
• Pedal cam — low angle pointing at the pedals. Reveals heel-toe technique, brake modulation, and throttle application timing. More useful for advanced drivers analyzing technique.
• Rear-facing — shows the instructor's face and reactions, and captures any car behavior behind you. Useful but secondary.

Heat and Battery

Phones overheat on track. Sitting in direct sun on a hot dashboard, running GPS + camera + screen simultaneously, a phone will throttle or shut down within 20–30 minutes on a summer day. Mitigations:

• Shade the phone from direct sun — a small piece of foam or positioning behind the rearview mirror helps
• Turn off screen brightness while recording — most apps run fine with the screen off
• Don't charge while recording if the car is hot — charging generates heat and can accelerate overheating
• Bring a backup phone or dedicated camera for long sessions

Getting Started — The Practical Setup

If you're going to your first few events and want to set up data logging without overcomplicating it:

1. Download TrackAddict (free tier to start)
2. Get a RAM suction cup mount — medium arm, sized for your phone
3. Rig a safety tether — paracord loop from the mount to the steering column works
4. Mount high on the windshield, aimed at the horizon
5. Let the app auto-detect the track and start recording
6. After each session, watch the video while the session is fresh. Note where you're lifting, where you're getting on throttle, where you feel rushed.
7. Compare your fast laps to your slow laps in the app's lap comparison view

That's it. You don't need an AiM Solo or a Garmin Catalyst to get meaningful improvement from data. Most drivers who invest in expensive dedicated loggers would improve faster if they spent that money on an instructor session instead — and used the phone data to prep for it.

Post-Session Review — How to Actually Use the Data

Having data is worthless if you don't review it. My process: as soon as I get back to the paddock after a session, I pull up TrackAddict while the car cools. I don't wait until the end of the day. The session is still fresh, the sensations are still in my body, and reviewing data immediately while I can still connect what I felt to what I see on screen is dramatically more useful than watching it that night at the hotel.

What I'm looking at, in order:

1. Corner entry speeds — am I carrying the same speed into each corner consistently, or are some entries erratic? Inconsistency here usually means I'm not confident in my braking point.
2. Minimum corner speed — the lowest speed through the corner. Low minimum speed means I'm either apexing too early, braking too deep, or both.
3. Corner exit speeds — where am I getting back to full throttle? Late throttle application on exit kills lap times more than almost anything else.
4. The line — video makes this visible. Am I actually hitting the apex I think I'm hitting? Am I tracking out to the edge on exit?

After the review, I write down one or two specific things to work on in the next session. Not a list of ten things — one or two. "Get back to throttle earlier at turn 4" is actionable. "Drive better" is not. The goal is to go into the next session with a specific focus, then check the data afterward to see if you actually made the change.