The LG Optimus F3 is a dual core handset with a 4.0-inch display that runs Android 4.1.2 Jelly Bean out of the box. It came to four different carriers including MetroPCS, Virgin Mobile, Boost Mobile and the one we have here for you today, T-Mobile. There originally was a fifth, however, Sprint stock was discontinued.

The F3 is one of those smartphones that are a good buy at the right price, but it fails to stand out with the big guns of today. With only a 480 x 800 resolution at 233 ppi and a 5 megapixel camera, it is clear that the flagships from LG, Samsung, HTC and Apple all tower over this devices’ capabilities. I am not trying to put it down by saying this, but rather give off a fine example as to why rooting it becomes favorable. If something is not high-end I say go for it, keeping in mind that this method is made for the stock 4.1.2 JB firmware that it came with from the shop.

LG Optimus F3

 Checklist

Backup the personal and important data to the handsets MicroSD or MicroSDHC card if you have one. If you do not use the natural internal storage will suffice as long as you have enough free space. Backing up the apps is a little bit more tricky. To do this, there are ironically applications available from the Google Play Store that will help you out. Search for apps like Nandroid if you already have a custom recovery as ClockworkMod or TWRP recovery, Go Backup Pro, JS Backup, My Backup and the Ultimate Backup Tool.

This rooted method has been tested by us and also the develop extensively. However, that does not make us responsible for any damages that go wrong. You proceed and follow the guide on your own accord and not ours. With that being said, we do strive for excellence and do our best to bring you the correct information and nothing short of everything we know of the subject to see you through successfully.

Download the latest LG USB drivers so that the device does not have any issues connecting with a computer.
You will need an unlocked bootloader to use this tool. It does not and will not unlock it for you. No custom recovery such as CWM can be installed with a locked bootloader to this day.

Make sure USB Debugging Mode is enabled. Do this from Menu > Settings >Applications > Development enable the USB Debugging Mode.

When you plug the device into the computer with a USB cable it will automatically start charging the battery power, therefore, it is not necessary to ensure a certain level of power is preexisting.

Completing this guide will no set any “Warranty Void” flags. You can follow this and still be under warranty. Most other guides will tell you otherwise, however, they are so used to writing it every time that they do not even look. Nowadays, there are tools that have worked out how to get around this and Saferoot is one of them. Cool, right?

This guide that we are presenting you today is made with only the LG Optimus F3 in mind and should not be used or trialed on any other. Doing so may cause harm to the device.

How To Root The LG Optimus F3 Without tripping Knox

1. Download the Safe root package.

2. Locate the USB cable. Often people use it for the charger.

3. From inside the file you download in step one, run the install.bat file. It will open up CMD.

The bottom line will tell you to plug the handset in and press any key to continue so do that now by following the instructions below.

4. Plug one end of the USB cable into your LG Optimus handset and the other end into the computer making a connection.

5. An icon should come up in the taskbar letting you know it is picked up.

6. Wait for the software program to finish and then reboot the phone manually if not done automatically.

That is it. The Optimus F3 now has root.

Many people have asked about the Knox being tripped and the original developer has insisted that this method will not trip Knox so don not worry.

Via: XDA