Calipers, brake lines and proportioning valve, stop me if you've heard this one.

In the last post I talked about the master cylinder rebuild and the fact that the rebuild ultimately did not allow the brakes to bleed.  While trying to diagnose the issue, we made a few decisions (with the guidance of YouTube and the Corvette Forum) we decided we needed to check the calipers to see if they were seized.  As worked on removing the rear calipers, my brother in law worked on removing the proportioning valve to see if the piston was stuck in the unit.  As we moved through removing the calipers, we made the decision to replace the back caliper brake lines as we chewed up the bolts getting the old ones off.  As we went around the front of the car removing the caliper brake lines, we also decided to replace the rubber caliper brake lines up front and the steel left front brake line that runs to the proportioning valve.

Front Crossover brake line

While I was working on disconnecting the calipers, the proportioning valve became a challenge.  We removed the alternator to get more room and had everything disconnected with the exception of the cross over front brake line, we could not break it free from the valve.  At that point, we made the executive decision to cut that line and pull it out of the car and replace it with a new one.  Done.

What was of note, is that in the front end of the car, when we pulled the brake lines we were not greeted with any brake fluid in the lines, none, not a drop.  What we could not determine is if the proportioning valve was stuck and was diverting everything to the rear or if there was a different issue.  We tried blowing the valve out but did not get very far.  With everything pulled out, it was time to order parts to repair the braking system.  Ultimately, I ended up ordering the following:

• Front cross over brake line
• LR and RR steel caliper brake lines
• Proportioning valve
• Master cylinder lines to proportioning valve
• Master cylinder rebuild kit
• Master cylinder gasket
• LF and RF rubber brake lines
• 4 Rear caliper pistons
• 8 rear caliper seal kits
• 4 Front caliper pistons
• 8 front caliper seal kits

Rebuilding the rear calipers and brake lines was next on the list.  Details about that project will be posted soon.

Rear caliper 

Rear rotor

Proportioning valve