Rear drum to disc conversion question, Do I need to do anything with the master cylinder? Options

[GriffGirl]

Someone told me he thought I will need to do something with/replace my master cylinder when I convert my rear drum brakes to disc brakes; something about the proportioning valve.

Here's what he said:

In regard to your brake swap, I could be wrong, but I'm almost positive that you'll need a different proportioning valve...When you do it, though, you should see about swapping the proportioning valve and
master cylinder (if it's different on the GTs)... Drum brake wheel cylinders and disc brake calipers use different amounts of fluid (typically) and if you swap from the former to the latter, your rear discs brakes won't be doing as much work as they should.

This is all greek to me. Help? Is this something I should look further in to?

[hurley97]

I believe the only difference in the master cylinders is the amount of lines that come out of it. There still could be internal differences though.

Either way, the master cylinder and proportioning valves for the ST work just fine with GT brakes. I did not change either, which could possibly be why I really didn't feel a huge difference in braking power from the ST front/drums to the GT front/rear disc setup.

The complete GT setup does look much better though, especially with bigger wheels. With the ST fronts and GT rear discs I felt like the rotors appeared to be the same size between front and rear which looked very strange to me.

This post has been edited by hurley97: Jun 16, 2008 - 8:34 PM