master cyl sizes

[RallySnake]

Jess,

I've been working on this for the last few months. I removed my MasterPower remote brake booster and went with manual brakes to get more consistant feel and to get that ugly lump out of my engine compartment.

Ron Butler recommends a balance bar pushing a 3/4 inch cylinder for the front brakes and a 5/8 inch cylinder for the rear brakes. This is based on a mix of Dodge Dart calipers on Chevy rotors on the front and Jaguar XJ6 brakes on the rear. I believe that the different sized cylinders are based on using smaller front tires. I have 275/60/15 tires all around and with this set up the rear brakes tend to lock up first. I actually spun the car while testing because of this.

So, I changed the front MS to a Tilton 7/10 inch inch unit and that helped some. But, if I hit the brakes hard while cold, the rears lock up first. The next thing I tried, was replacing the front pads with Porterfield Autocross units to give them more grip. This was better, but only when they get hot. Then, I changed the rear pads to a less agressive compund. I removed the Ferodo's and put in Axxius Quiet Stop. This helped a little more. Now, if the brakes are hot the ballance is very good, with a little front bias. If you stab them cold, however the rears lock first. I am not happy.

The balance bar adjustment does not seem to make much difference. I have tried adjusting to the rear but that only made the situation a little worse. So, it's set to full front bias. My next options are: 1. Buy a proportioning valve to reduce the pressure to the rear brakes. 2. Buy smaller front tires. 3. Buy Porterfield pads for the rear so they take longer to heat up. 4. Replace the front MS with a 5/8 inch unit.

I hope this helps you and I am open to suggestions,
Paul