Quarter Midget Gear Ratio Calculator
Getting the gear ratio right can be the difference between a car that runs up front and one that's a step off all night. VAST has partnered with my-qm.com to offer a free, purpose-built quarter midget gear ratio calculator — designed for the pits, not the classroom. Works on your phone, no app download required.
Everything you need at the track, right on your phone.
The my-qm.com calculator is built for race day. Enter your current setup, hit Calculate, and immediately see every gear combination ranked by how close it gets you to your target — with the best match highlighted in green.
- Results table ranked by closest ratio match, with delta from target shown for every combination
- Full gear reference chart updates live when you switch gearboxes
- Log in to see only combinations you can build with gears you actually own
- Save setups with an optional label — track name, date, notes — and reload them anytime
- Works in any phone browser, no download required
my-qm.com — results table with best match highlighted (left) and the calculator with gear reference chart (right)Supports all three common quarter midget gearboxes. Select your engine type and the internal ratio is handled automatically.
A complete gear chart for the selected gearbox — same style used by engine builders — with your best match highlighted directly on the grid.
Create a free account to save which gears you own. Results filter to only show combinations you can actually run with what's in your trailer.
Runs in your phone's browser. Add it to your home screen for instant pit-lane access that opens just like a native app.
How to Use the Gear Ratio Calculator
No account needed for a quick calculation. Open the calculator at my-qm.com, fill in your current setup, and hit Calculate. You'll see the closest available gear combinations ranked by how tight they get you to your target RPM, plus the full ratio reference chart with the best match highlighted on the grid.
Choose Honda, Briggs, or Deco. The internal gearbox ratio is applied automatically — you don't need to know the number.
What RPM is your car currently turning? Pull this from your tachometer or data logger during a practice session.
What RPM do you want to hit? This is typically your engine's optimal power band for the class you're running.
Choose your engine sprocket (28–38T) and axle gear (24–34T) from the dropdowns. These are your current gears, not your target.
Results show every combination ranked by closeness to your target RPM, with the best match highlighted in green at the top.
The full gear chart below the results highlights your best match on the grid so you can see the full ratio landscape at a glance.
Save Your Gear Inventory — Log In for Smarter Results
The calculator is free to use without an account, but creating a free account at my-qm.com unlocks a feature that makes it genuinely more useful at the track: saving the gears you actually have in your trailer.
Rather than showing every theoretical combination, the calculator filters results to only show gear combinations you can actually run — right now, with the gears on your shelf. If the closest combination to your target ratio requires a 31-tooth axle gear you don't own, the calculator skips it and shows you the next-best option using what you have. No more hunting through combinations you can't build.
Saved setups also serve as a quick reference across race weekends. If you ran a particular combination at a track last season and want to revisit it, your previous calculations are stored in your account and can be reloaded in one tap.
Creating an account is free. Visit my-qm.com, register with your email and a password, and you're in. No subscription required.
Supported Gearboxes and Gear Ranges
| Gearbox | Internal Ratio | Common Classes |
|---|---|---|
| Honda | 6.14 : 1 | Jr Honda, Sr Honda, Heavy Honda, Junior 160, Light 160, Heavy 160 |
| Briggs & Stratton | 6.07 : 1 | Junior Animal, Senior Animal, Unrestricted Animal, Light World Formula, Heavy World Formula, Mod World Formula |
| Deco | 5.73 : 1 | Select local and regional classes — check with your club |
The calculator covers engine sprockets from 28 to 38 teeth and axle gears from 24 to 34 teeth — the range used by the overwhelming majority of competitive NASCAR Youth Series setups. The full reference chart extends to 42 teeth on the engine side and 36 teeth on the axle side.
Understanding Gear Ratios in Quarter Midget Racing
Gear selection in quarter midget racing isn't just about picking a sprocket. Unlike a go-kart, a quarter midget engine has an internal gearbox that multiplies the ratio before the chain even gets involved. That internal gearbox ratio is why a one- or two-tooth change on the axle gear has a noticeably bigger effect than it might look like on paper.
A higher final ratio means the engine turns more times per revolution of the rear axle — more pull off the corner, better acceleration, but a lower top speed on long straightaways. A lower final ratio means the car can carry more speed down the straight but may feel flat coming off turns. Getting it dialed in for a specific track requires knowing your engine's optimal RPM range, the track length, and how the car is handling — the calculator handles the math so you can focus on the car.
Tips for Getting the Most Out of the Calculator
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Get your RPM numbers from actual track time. A tachometer or data logger gives you real current RPM. The calculator is only as accurate as the numbers you put in — estimates won't get you where you want to be.
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Use the reference chart alongside the results. The grid shows the full landscape of available ratios — not just the single best match. You can see how close neighboring combinations are before deciding which way to go.
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Set up your gear inventory before race day. Log in and enter your inventory at home. At the track, the calculator filters to show only combinations you can actually build with what's in your trailer.
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Make one change at a time. Gear ratio is one variable among many. When chasing a setup, change the gear first and evaluate before combining it with a spring change, hub swap, or weight adjustment.
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Use saved combinations as a setup log. Label each saved result with the track name and date. Over a full season you'll build a useful reference — especially helpful when you return to a track you haven't visited in a year.
Add the Calculator to Your Phone Home Screen
my-qm.com is a mobile-friendly web app — nothing to download from the App Store or Google Play. Add it to your phone's home screen so it opens instantly in full-screen mode, just like a native app. Here's how on both iPhone and Android.
Once it's on your home screen the calculator opens in full-screen mode with no browser address bar — exactly like a native app, with nothing to install or update. Your login stays active between sessions, so your saved gear inventory is always ready when you open it.
Frequently Asked Questions
Yes. The calculator at my-qm.com is completely free to use without an account. Creating a free account to save your gear inventory and previous calculations is also free — no subscription or payment required.
No. The calculator runs in your phone's web browser. You can add it to your home screen using the instructions above so it opens like a native app, but there is nothing to install from the App Store or Google Play.
Honda (6.14:1), Briggs & Stratton (6.07:1), and Deco (5.73:1) — the three gearbox types used in competitive quarter midget racing. Select your gearbox before calculating and the internal ratio is applied automatically.
When you create a free account, you can enter which engine sprockets and axle gears you physically own. When you run a calculation, results are filtered to show only the combinations you can build with the gears in your trailer — no results that require parts you don't have.
Yes. Select the Briggs gearbox option (6.07:1) for Animal and World Formula classes. The internal gearbox ratio is the same across both Briggs engine families used in these classes.
Yes. The calculator works on any device with a web browser. The experience is optimized for phone use at the track, but the full desktop version at my-qm.com includes the same calculator and complete reference chart.
VAST stocks quarter midget axle gears in multiple tooth counts, machined for standard quarter midget axle hubs using #40 pitch chain. View VAST Quarter Midget Axle Gears, or browse the full Gears, Hubs & Chain collection. Questions? Call 248-414-1835, Monday–Friday 9AM–4PM Eastern.
Gear ratio calculator provided by my-qm.com · Questions? 248-414-1835 or racing@vastrp.com · Mon–Fri, 9AM–4PM ET