brakes have been giving me a problem forever.This car just does not stop!Changed all parts except front calipers.The other day I pushed down so hard the cover popped off the master cylinder.This is an '85 w/4 wheel disc. Help!

Are they power brakes? Are they ABS? Before you changed the master cylinder, did you 'bench bleed' it?

Did you change your three hoses? Sometimes they come apart from the inside, blocking flow and pressure.

Did you mix different brake fluids (DOT-3 with DOT-5)?

Are the back brakes stopping better than the fronts?

If your master cylinder cover is that loose, you have water in your fluid and it needs to be changed. DOT-3 sucks water out of air faster than Scotch mixes with water. There are too many unanswered questions to suggest any troubleshooting helps. Talk to me.

1onesy,
I take for granted that you replaced the master and other components trying to make this car stop right? Is your brake pedal hard or soft? How is your pedal height, high or low?
There are a number of issues that can cause increased stopping distances, so the more information you can supply, the better the chance of finding your issue.
Thanks,
Tim McCluskey