For those of you who have converted to GT4 Calipers, looking for brake biasing information Options

[qatar11]

So I am going to switch over to the GT-Four Calipers, front and back and I have a question to anyone who has done this. What did you do about the brake bias? I have the ST205 valve... but it is plumbed for ABS so it is not immediately compatible with my current configuration.... Of course this thing sits behind the engine so the decision has to be made before I drop the engine in....

Let me know your thoughts.

[Tigawoods]

im not sure what the native bias will be without any bias control, but with just a brake proportioning valve, you will be able to take away from the rear and add to the front, which is what I think you may be looking for as a result. (you cannot take from the front and add to the rear)

A prop valve isnt going to shave off a ton of bias, its more for fine tuning the native bias.
I believe the native bias with the new brakes will be sufficient with a little tuning of a prop valve


I don't think you need a 2 master cylinder setup. But that setup WILL allow you to change the bias more drastically, as apposed to just a prop valve. Race cars use dual cylinders! (not saying you cant have a racecar haha)

what are you trying to achieve? (maybe someone else can haha) but for me it is hard to calculate what you will need to obtain a "perfect" bias until you actually drive the car with the setup. There is no OE specifications for the bias that your car needs. The gt-four bias is different that what you will need and the bias that those brakes give on a GT4 chassis wont be what you are getting.

Do the GT and GT4 brakes not have the same ratio front to back? (That's probably a really ignorant way to look at it, but it'd make sense to me)

Although I doubt they do, they could be somewhat similar. We need to do a test and produce some numbers!

This post has been edited by Tigawoods: May 14, 2013 - 12:57 PM

[qatar11]

what are you trying to achieve? (maybe someone else can haha) but for me it is hard to calculate what you will need to obtain a "perfect" bias until you actually drive the car with the setup. There is no OE specifications for the bias that your car needs. The gt-four bias is different that what you will need and the bias that those brakes give on a GT4 chassis wont be what you are getting.

I feel you think too much of me...

I am installing GT-FOUR calipers and rotors with grossly different performance metrics (not to mention the new car weight and balance) than the GT calipers and rotors... I would like something close to OE brake biasing so that I don't go ass before nose into a guard rail when I jam on the brake... It wouldn't be such a concern but the damn valve is not reachable when the engine is in.

I am not really trying to fine tune anything.. I am just trying to be proactive about the front / rear split of the brake circuits.... And really we (the royal we) don't know what the difference is.

[Tigawoods]

what are you trying to achieve? (maybe someone else can haha) but for me it is hard to calculate what you will need to obtain a "perfect" bias until you actually drive the car with the setup. There is no OE specifications for the bias that your car needs. The gt-four bias is different that what you will need and the bias that those brakes give on a GT4 chassis wont be what you are getting.

I feel you think too much of me...

I am installing GT-FOUR calipers and rotors with grossly different performance metrics (not to mention the new car weight and balance) than the GT calipers and rotors... I would like something close to OE brake biasing so that I don't go ass before nose into a guard rail when I jam on the brake... It wouldn't be such a concern but the damn valve is not reachable when the engine is in.

I am not really trying to fine tune anything.. I am just trying to be proactive about the front / rear split of the brake circuits.... And really we (the royal we) don't know what the difference is.

yeah I got ya. This is definitely a decision that needs to be made prior to installing the engine

Do you have the calipers in your possession? You can start gathering measurements and come up with a estimate for you bias http://www.tceperformanceproducts.com/bias-calculator/

This wont take into consideration the weight spread of your vehicle or the pad bite, which can also affect to some extent.


ah, so you are using the GT-Four rotors in front, at least youll have an even diameter on all fours. I have 300mm in the front and 315mm in the rear which will throw a bit of bias to the rear.

I think with just 1 Master Cylinder (st204 will do since the other is plumbed for ABS) with no bias modification. Your bias will be a little high in the front, so plumb in a Prop Valve to even it out to more of a 60/40 ratio


am I helping at all or am I just jumping around? hahaha