I've been having trouble bleeding the rear brakes on my 70. I've gone through about a bottle of brake fluid trying to bleed the rears, and after every single opening of the bleeder I get a small rush of air. So now it seems to me that there has to be air getting into the system somehow on the upstroke of the brake pedal. I have no leaks at all, the brake lines are all new along with a new (not reman.) master cylinder. The fronts bleed fine with no air at all. Everything worked perfect before the body off resto.

The brake cylinders in the rear are brand new as well, but could one of these be bad and causing air to get back in the system? The right rear is the one that is the worst. You can get the air out of the rear left one after a few pumps, but there is always air in the right rear.

Sounds like your right rear whl cyl is the culprit, check the fit of your line make sure it is fitting correctly and the flare is good. If you can, get someone to pump the brakes up while you check for leaks. The wheel cylinder itself may also be bad. I have gotten them with porous castings.

I've always bled the wheel cylinder farthest away from the master cylinder first,,,don't move to the next til you have no signs of air in the lines. Since they are brand new,you have alot of air to displace.

I might just try picking up a new wheel cylinder and hope thats the problem. I just took off the right rear drum and noticed a small ammount of brake fluid sitting on the drum surface. I guess theres a leak in there somewhere. Kinda makes me mad because all that stuff was brand new.

Bumping this to the top because I have the exact same problem, but I do not see any leaks at my wheel cylinder. Any ideas?

It takes a long time to get all the air out of a new brake system. Always make sure everything is tight, and make sure the master cyl was bench bled properly first. then go to the pass rear and start there. it will take about 6-8 times to get that clear. Be prepared to keep filling the master up, dont run it out at any time or you will be starting over.

The one thing i have done was connect a brake bleed cup to each rear cyl firs, then open the bleeder screws and let gravity take over for several hours.