danb

Well.... the latest thing i tried was removing and disassembleing the brake booster. I got it out of another '73 (same year as mine) with good working brakes. When I opened it up there was no reaction disc to be found???? Is this normal? I proceeded to adjust out the pushrod by unthreading the "nut" that inserts into the MC. I adjusted it out approx the the same amount as the thickness of the reaction disc would be. After everything is hooked back up I drove the car and the brakes did the exact same thing as before I messed with the booster....the rears lock up with very little pressure applied to the pedal. SO FRUSTRATING!! Im not giving up though.......any ideas or suggestions? I have tried sooooooooooooooo many things and checked every part of the system i can think of.

Right on Rich! Glad to hear ya got it goin! One less Z parked in disassembly. Ya, I'll get it going one of these days. I just have to keep trying diffent things. I havent been able to drive my car for allmost 10yrs now because of these damn brakes. Worst part is my rebuilt motor is just waiting to get broke in, I'm thinking on OR hwy 101!

Ya, its been a long process getting to this point. I've tried everything that friends and fellow Z enthusiests have recommended, but still no luck! I dismanteled the proportioning valve, cleaned it, reassembled it, and it seems to allow brake fluid to bleed through for the rear brakes perfectly...... as long as I dont bleed the front brakes. Once the fronts are bleed, no fluid moves to the rear brakes. It acts as if the piston inside the proportioning valve is stuck...but only after I bleed the front brakes. To weird! Good luck with your car! I assume you have the stock early 240 setup (without the front/ rear prop. valve) ?

Thanks for the response! Where Im at right now is the car is sitting on jackstands with all 4 wheels off. I replaced both rear wheel cylinders about 2 years ago. The rear drums will slide on and off as they should during a routine brake job. I asssume your refering to the piston at each rear brake cylinder right? I havent checked them since I installed the new cylinder. Since the car has been sitting for quite some time, could those have gone bad in a couple years time? Also, I can get the rear brakes to bleed ONLY if I do them before the fronts (the way they are suppose to be done). Once I have bleed the fronts, thats when I can no longer get any fluid to the rear.

Hi Guys and Gals, Quick History: I have a white 73 that Ive owned for about 13 years. I bought the car right after high school (1996) rebuilt the motor, had the car stolen in Sept '97 right before I entered the US Coast Guard, retrieved the car in July '98, rebuilt the engine (again), and now the only mechanical gremlin I can't figure out is the brakes. The brakes have been a constant frustration for me for the past 10 years!!!!! (OK, there was some down time in there, but still ) I have the brake setup that is used on the 260z and I think on the 280z??? This has the valve with the brake light incorperated in it (directly after the Master cylinder), and the porportioning valve after that located on the fire wall. The m/c has the front brake reservoir nearest the firewall. I have replaced every brake component except the 2 valves after the m/c, and the rigid brake lines, only because I haven't been able the find replacements for the valves. So, I bench bled the m/c in the car. Hooked everything up and started bleeding at the wheels starting with driver side rear first (longest run) and finishing with driver side front (shortest run). As I bleed the rear, everything bleeds through fine. Then I go to bleed the front and everything bleeds fine as well, and I have a very firm pedal. Problem is, when I go back the try to bleed the rear again (just double checking it) nothing bleeds out. I even remove the bleeder screws completely and the pedal is rock hard and wont depress at all. I assume the porportioning valve is bad????? Also, when I drive the car down the street the rear brakes lock up after the pedal travels about half way down. There is no way to ease the brakes on. Its all or nothin on the rear. I dont think the front calipers even engage. Please!!!! Any help would be awsome!!! Thanks in advance!