Beginner question on making sure brakes are safe after bleeding?
 

Hey guys, so I'm in the slow process of gravity bleeding my brakes before I replace the rear calipers with some OEM replacements from Autozone. I've read up on the forums on how to do gravity bleeding and it seems easy enough, but how do you check that the brakes are safe after they're replaced?

Like if I have the car running and pump the brake pedal and it feels nice and stiff, I assume that means it's safe to drive? No other steps in checking?

One problem I have is that my E-brake is non-functional and the adjustments don't seem to help it to work so I can't rely on that backup until I have the budget to pull all that apart and replace some parts. Car is a low mileage '75 with surprisingly good condition stock components minus the broken e-brake.

Why bleed before you change. Gravity takes a while and you will have to do again after changing calipers. Gravity bleeding worked well for me and when you have a firm brake pedal with no sinking when you hold it the brakes are good. Of course when you go to first drive test in drivewayy and at 20 mph to make sure

Fluid sat quite a long time with the PO and was really dark, was mildly concerned there was gunk in the lines that I didn't want to get in the new calipers. Just did the first bit of bleeding, lines seem nice and don't have extremely dark fluid so that seemed to have just been local to the MC reservoir, luckily. Will take your advice, thank you.

I guess you know for best results gravity bleeding is to start at the right rear caliper then left rear, right front, left front. Some will swear that you can't get a good pedal gravity bleeding a C3 but I've done it twice on my car (and I've bleed a lot of other cars brakes and clutches in the past) and have never had any problems. And I'm even running DOT 5 brake fluid and my pedal is very stiff (non-power brakes). Since there are 4 pistons and two sides of the caliper with fluid channels to the other side some small air bubbles can get trapped in the calipers. Lightly tapping on the calipers while your helper is pressing the pedal with the bleeder open helps unseat those bubbles.
Just take you time.

EDIT - I forgot my opinion on your original question. :crazy2:
If you have a decently stiff pedal just start your car and move slowly at first. Jab the brakes real hard when barely moving. If it stop immediately then just increase your speed but keep it under 20. Once you get to about 20 panic stop by jamming the brake pedal. You should again stop almost immediately. If it takes a while to stop completely from 20 then you probably still have some air in the lines. If all is well at 20 then I have more confidence that the brakes are OK. I then increase my speed to 30-35 and do another panic stop. At this point all 4 corners should lock up and you shouldn't pull to one side or the other. Just make sure you have 4 rubber marks on the road. That will tell you that all 4 calipers are working. If that is good then your brakes are good.