Spider Brakes

I am in the process of restoring a 79 Spider, I am working on the brakes, I have installed all new front and back rotors pads and calipers, I also installed a new master cylinder. I am now in the process of bleeding them out, the petal is getting a little stiffer but still spongie, the front ones bled like I normally have seen, but i couldn't get any fluid out of the rear bleeders. I thought maybe the weight distribution mechanism was bad, so i bypassed it, that didn't help, I then thought the T on top of the rear axle was clogged so i opened it up and was able to get a steady stream out there, so i removed the new rear caliper and was able to get fluid out of the line but was able to hold my finger over the hose while the petal was pushed and it didn't push it off, can someone help me in knowing why i cant get these rear brakes to bled?

very important:
1. wheels off the ground, supported under the AXLE by jack stands.

and...
2. do the pistons move at ALL when someone pumps the brake pedal?

The hint about supporting the rear axle is very, very important. The rear brake system in these cars have an old anti-lock rear brake regulator that reduces and finally cuts off brake fluid to the rear calipers as the rear of the body rises in relation to the axle - as in a hard braking situation. If you are trying to bleed the rears with the axle hanging down, you won't get anywhere.

My shop manual also warned about this wasn't aware of why but now i am thanks for the info. I do have it on the stands as both of you recommended but I am not sure about the cylinder if its moving or not, I plan on putting it back together tonight and I will check that out. let me know if you have any other ideas.

diagnostics by braille isn't easy, you've given very little to go on that we haven't already addressed. sorry to sound harsh, but you need to get much more detailed before we can address your issue.

if your pistons do not move in or out, and you have properly addressed the brake compensator leveling isue, then the piston is frozen in place. or, another problem is keeping hydraulic pressure from reaching the piston.

you cannot, repeat cannot adjust the rear brake pistons with a C-clamp. if you have attempted to do so...or if the previous owner has attempted to do so, it is quite probable that the pistons have become inoperative in the process.

rear brake pistons MUST be screwed in or out for adjustment. that is what that big slot across the top of the piston is for.

I was lead to believe by the Chiltons manual part# 7042 page 192 under the ADJUSTMENTS section there is no adjustments on disc brakes. It reads, " disc brakes are self-adjusting, and need no adjustments."
What I did from the local Fiat shop where I picked up my calipers is that the slot in the piston must be up. The tech did not elaborate on why other than if not you will not be able to bleed the brakes fully. I also see mention of this on page 205 of the same Chiltons manual. It reads from section 9, Screw in the piston until it is properly seated and the mark cut in the piston is opposite the bleed connection.
I too am having problems with my brake system. I have replaced the master cylinder, all rubber hoses and the calipers/pads at each wheel. I can bleed the system and have a stiff pedal but when I start the car, the pedal will drop almost to the floor. Somehow the power booster seems to be the culprit but I have never experienced this type of failure with a booster. When a booster has failed on me in the past the pedal will become very stiff as you have lost the power assist, but this seems to be opposite..??

Hi Not sure if I'm doing this right. I have a 80 spider and have done the brakes as well,had the same problems.1 as mentioned make sure the wheels are suspended by the axles, won't work otherwise. 2 the "T" fitting was sucking in air( the top of the axle was damp from brake fluid),perhaps I had a gibbled flare but I wrapped the flex hose male end with plumbers tape.. no more air issues. 3 I found out the mark/thin cut on the rear brake piston has to be in line with the bleed screw(top), there evidently is a passage in the piston that allows fluid to pass and if it is not lined up...impossible to bleed brakes.
I also bought a vacume guage/bleeder tool,sure made the job easy with one person. good luck
Narfire