So the brakes in your Z need some attention. Has it been a while since you changed your brake fluid (you have changed it haven't you)? If you have done the operation yourself and used the two person method did you get all of the old fluid out? It is a slow and labor intensive process that probably didn't get it all out. What follows may seem a little basic but there are many of us that need some encouragement before embarking on projects of this nature. So here goes...
I recently purchased a '78 289Z that was well cared for and actually had the fluid changed... 9 years ago! I was having some grinding sounds and pulling problems when braking so a good brake job was in order. Looking at the pads, the left side was worn to the backing and the right side had better than 50% material left. Both flex lines were cracked and ready to fail. The rear flex lines were in the same condition. It was time to rebuild the calipers, replace the flex lines, clean the master cylinder and replace the fluid.
I considered doing the operation the old college way but I'm:
First I removed the caps on the master cylinder reservoirs and suctioned out the old fluid. I added some new fluid and took a clean, stiff 1/4" flat artist type brush and scrubbed the inside of the reservoir. Again, I suctioned the dirty fluid out and repeated the operation. The reservoir was now clean. I replaced the fluid and moved to the right front brake area.
Another tool set that is a must are metric flare wrenches. Rounded brake line nuts are no fun. Break the flex line connections at the frame and strut mount points. Remove the clips holding the flex line in and remove the flex line. The fluid is probably running all over the place. Cap off the rigid line.
Remove the caliper and replace it with either a rebuilt unit or rebuild the caliper. I substituted the Toyota 4 piston calipers discussed elsewhere on the IZCC pages. Putting on the Toyota calipers is a little more involved so please see Craig Marcho's article on Toyota Calipers. (I also have rebuilt the original calipers so as to retain the original build date models if full restoration is deemed necessary.)
Take another piece of rigid brake tubing, purchased where you purchased the other components and comsummables and carefully bend it about so it will fit into a brake fluid can with the caliper sitting flat. Place the suction tube on the brake bleed screw and draw in some clean fluid. This really speeds up the bleeding process. Once the caliper is full close the bleeder screw and remove the rigid line. Cap off the opening with the cap that came with the caliper. Improvise if rebuilding the original units. Repeat for the other caliper.
Attach the Vacuum Bleeder to the rigid line currently capped off on the car. Here is where an assistant comes in handy. Draw off the old fluid that is between the clean reservoir and the end of the line. Refill the reservoir as required until the siphoned fluid is clean and clear. Attach the flex line and the rigid line for the caliper and let gravity fill the remaining line. Install the new caliper and pads, attach the rigid line to the caliper, tighten and re-install the retaining clips for the flex lines. Connect the vacuum bleeder to the bleed screw and complete the final bleed operation. Repeat for the left side.
The rears are similar and, if you don't need to replace the cylinders, should take less than 20 minutes per side. What you have accomplished is a complete clean-out of your brake system, put in fresh brake fluid and extended the life of the brake system immeasurably.
With the vacuum bleeding unit, flare nut wrenches and a quart of new fluid the operation is simple, efficient and quick. I was done with the job in less than two hours. Most of the time was spent checking on the master cylinder reservoir and keeping it full. The brakes in my Z work beautifully, stop straight and should give me no problems for quite some time. I will be changing the fluid much more regularly now that I've found it to be so easy. Now, when did I last change the fluid in my other.....