Here is a video to show you how to change the spring in your proportioning valve or prop valve for short. This will increase the braking pressure sent to your rear brakes so there is less of a bias towards your front brakes.
Here is the 19lb spring: http://amzn.to/2qEgUu0
Here is the 22lb spring: http://amzn.to/2rdzYfC
Check out every product that I review or I recommend in my videos here on amazon: https://www.amazon.com/shop/jrobling
These can also be found on other websites but you need to have a business account.