# UnderDrive — UnderDrive calculations

> Transmission gear ratio and RPM drop calculator for three-speed setups. (iPhone/iPad app by Dave Clark.)

- Source: https://appshunter.io/ios/app/underdrive/id6803322640 (this page in markdown: same URL + `.md`)
- Developer: [Dave Clark](https://appshunter.io/developer/6803322642)
- Category: Utilities, Education
- Price: $9.99
- Rating: 5.00/5 from 1 App Store ratings
- Age rating: 4+
- Requires: iOS 18.6 · 2 MB
- Languages: American English
- Released: 2026-09-09
- Data updated: 2026-10-01
- Monetization: paid
- User reviews in markdown: https://appshunter.io/ios/app/underdrive/id6803322640/reviews.md

## What is UnderDrive?

App for calculating speeds, final drive and RPM drop when shifting gears. App is setup for a three speed transmission. An input to define torque converter loss. A manual clutch is closer to 100 percent efficient, however a converter could be anywhere from 80 to 98 percent efficient. All input boxes have a typical value entered for reference. Different transmission setups can be named, dated and saved for later retrieval. This app makes quick work of comparing different ratios and underdrive gears.

## Key features

- Calculate speeds, final drive, and RPM drop
- Supports three-speed transmissions
- Torque converter loss input
- Save and name custom transmission setups
- Compare different gear ratios


## Frequently asked questions about UnderDrive

### What is the price of UnderDrive?

UnderDrive is a paid application priced at $9.99. This one-time purchase grants you access to all its features for calculating transmission parameters.

### Does UnderDrive have ads?

No, UnderDrive does not contain advertisements. As a paid app, it offers an ad-free experience for users.

### What devices does UnderDrive support?

UnderDrive is available for both iPhone and iPad devices. It is designed to run on Apple's mobile operating system.

### How often is UnderDrive updated?

The latest version of UnderDrive is 1.1, which was last updated on September 17, 2026. Updates typically address bug fixes and feature enhancements.

### What is the age rating for UnderDrive?

UnderDrive has an age rating of 4+, making it suitable for a wide range of users. This rating indicates minimal content concerns.

### Can I save my transmission calculations in UnderDrive?

Yes, UnderDrive allows you to name, date, and save different transmission setups. This feature is useful for retrieving and comparing various configurations later.

### What kind of transmissions does UnderDrive support?

UnderDrive is specifically set up for calculating parameters related to three-speed transmissions. It also includes an input for torque converter loss.

## Version history (last 2 releases)

### 1.1 — 2026-09-17

Fixed a Dark Mode display issue where input values were not visible.

### 1.0 — 2026-09-09

No release notes.

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*Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-10-01.*