[ZR1dogan]

You didn't say if it was just front or both.

I have had this issue on a motorcycle and later on my Z (front brakes). I learned the root cause and solution on a Honda Interceptor forum (another group of super helpful guys). The problem I had was a plugged hydraulic weep hole in the Master Cylinder. When plugged it won't allow the brake fluid to expand (and return back into the MC reservoir) as the calipers get warm (and hot) while driving. As you noticed it will only get worse until you either bleed the calipers or let the car sit long enough to cool the calipers and fluid.

You can get a new MC or try what I have done. Note that I am speeking from 3+ year old memory and mine is a '94 (I think the MCs are the same), so this is the concept but the exact details may be a little off.

Take off the MC cap and lower the fluid in the MC as low as it takes to be able to see to the bottom. Near the back is where the weep hole is. Obtain a long thin needle (I tried sharpening something long - it doesn't work - not thin enough). Hold the needle in a set of needle nosed pliers (I taped the pliers shut on the needle, so that the needle wouldn't fall out of the jaws if I accidentally let off compression on the handles). From the top, with the needle in the pliers, feel for where the weep hole is (where the needle feels like it can be pushed in). Push it in and see if it works. It did for me.

Good Luck - Let us know if this does it.

Robin
'94 Dark Red - Almost Stock
'94 Adm Blue - Not Stock