I have a set of Grex/Alcon brakes & rotors for the front which I decided to grab at a good price. The plan is to run them with the Wolfkatz rear BBk, however the money I had ready to order them is now going to be spent on an ECU and tune so they will have to wait.
 
I'm going to be very keen to push the car soon after the tune is finished and I have encounter fade issues with the stock 91 setup on the track. What I'm wondering is will it be possible to install the Grex brakes up front and adjust the brake bias and have a setup that will brake as well as the 91 setup but be more resistant to fade?
 
If not I'll just leave them stock setup alone but I'd rather have good reliable braking to go along with the increase in power. Any advice is appreciated as I've never worked on brakes beyond changing pads and bleeding the lines!

From what I heard ..... But would also like to hear what others that have the experience ...

I currently have wilwoods front and standard rear calipers with a rx8 rotor. I always lock up the front on heavy braking. If you can control the brake bias, I can't see why it wouldn't work. How are you going to control the brake bias?

Steve, u state u are getting fade on the track. What pads and fluid are u running?

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You could possibly setup the brakes to work with reasonable balance, but you will be far from getting the best performance from them.

It would take an adjustable bias adjuster, and a low coefficient eduro compound pad in the front, and a high coefficient compound in the rear of the car. Along with high quality fluid and ducting on the rear brakes, you'd get away with it.

But carmikey probably has the best thought process on this. What pads and brake fluid are you running? And what kind of fade? Boiling the fluid (pedal travel increases/ goes soft) or pad fade (pedal stays hard, but stopping distance increases)

Switch to a high quality fluid, with a high boiling point. Also once you have boiled brake fluid, you really need to rebleed or flush the fluid. High performance pads are also needed to allow for repeatable braking performance.

Also airflow to the brakes can improve perfomance as well. Whether it is a basic air guide bolted between the caliper mounting bolts or a proper ducted unit , keeping temps in check can go a long way to helping. I dont know if anyone actually makes them for mr2 calipers, but look for titanium anti rattle shims. They effectively act as a thermal barrier between the pad and the caliper piston, which can help prevent the brake fluid from boiling.

I do not recommend anyone run a BBK on the front and not the RX8 or similar conversions as the difference in bias is far too great and you do not get the benefit of what you have fitted to the front in the first place.
 
What MCT mentions about brake pad choice is the most cost effective way to bring the balance of your front and rear BBK's closer to what the car left the factory with. It will not be enough for a Grex front 4/6 piston kit and a factory rear however.
 

http://www.mr2oc.com/59-general-mk2-faq-newbie-center/292856-brake-faq-rotor-caliper-mc-sizes.html

A little info.... What I read into (love mr2 research), bias is factory set to release pressure on the rear when pressure exceeds the setting. A rear upgrade, such as a larger disc, does not change the piston or piston pressure managed by the bias. I can understand that not upgrading the rear (disc size to assist in heat dispersion or hot spots) would be a recipe for disaster if your pushing more "stress / demand" on the brakes.

Be interesting if anyone has had access to actual braking monitoring equipment that gives g and other data. Challenge is it is so dependant on brake pads used.

Pretty sure Eric had his on the brake dyno.

TonyMR2
http://www.mr2oc.com/59-g...-caliper-mc-sizes.html

A little info.... What I read into (love mr2 research), bias is factory set to release pressure on the rear when pressure exceeds the setting. A rear upgrade, such as a larger disc, does not change the piston or piston pressure managed by the bias. I can understand that not upgrading the rear (disc size to assist in heat dispersion or hot spots) would be a recipe for disaster if your pushing more "stress / demand" on the brakes.

Be interesting if anyone has had access to actual braking monitoring equipment that gives g and other data. Challenge is it is so dependant on brake pads used.

 
 
And tyres and suspension and....
 
So many variables. So back to back testing is where it is at.
 
Bias although a function of pressure applied is greatly affected by any friction exerted no? therefore pad material and disc size do play a part in this also.

Rotor size has a massive part vs pressure TonyMR2. A perfect practical example of how rotor size (thefore leverage) will have an impact for the same pressure.

Go somewhere in your house, and find a door. Have it partially open and stand in front of it. Without moving. Get your index finger and push the door open from a point in near the hinge. Hard wasn't it? Reset the door, and repeat from the middle of the door - a lot easier to do. Finally do it from the outer edge of the door - easier again.

Without altering pressure applied, we increased the effect of the applied pressure, by moving further from the fulcrum point. Same thing happens when the same caliper is placed on a larger diameter rotor.

In regards to your original question Steve A, what i meant to get at in my first post was, my opinion is you would be best of going for some quality pads and fluid, and hold off on the front upgrade until your have something to put on the rear with it.