Alternative rear disc conversion?

[Neinris]

Originally Posted by 06YarisRS

Sub'd. This is something I've thought would be a great upgrade. Would there be any issues with fluid metering and balancing of brake forces front to rear? The Yaris brakes must be designed to distribute a specific force per axle. The caliper pistons are surely much larger in surface area than the tiny wheel cylinder pistons. I'm no fluid dynamics engineer, but I do wonder about this. Do the rear disk and rear drum cars use the same master cylinder?

Adam, at another thread it's mentioned that if you have ABS you're fine without having to install a proportioning valve. If you don't have ABS, it's is highly recommended that you install one. It's not really that hard to install one, I was trying to argue if having braided lines on the front, and regular lines on the rear would suffice, but that's not advisable neither.
Obviously if or WHEN I do this, I'll be installing the bigger rotors in front. The stock front rotors are 255mm in diameter, the SE rear rotors are 259mm, and the SE front rotors are 275mm. Most of you already knew that.