Yes I replaced it. And made sure the replacement was an exact match to the original.
And so what did it look like? Look you're car is thirty-five years old, help me out! Answer the questions please
New front rotors, pads, wheel bearings, and brake hoses all done together. The calipers were not seized as the returned freely.
Ok now we're getting somewhere.
When this car was new, it was well able to skid those skinny rollers at 20 mph. So the question is why can't yours? What is different about the parts you installed?
It is obvious to me that there is a problem in the front system.
Lets list what is new; booster,M/C,hoses, rotors,pads, and wheel bearings.
Let's list what is not new; calipers, caliper brackets, and hard lines.
Let's list what else we know; pedal is hard,caliper pistons were easy to return, and it has fresh brake fluid. And; the pads will not put a serious clamp on the rotors.
Ok so:
it could have a hydraulic problem, or it could have a mechanical /install problem.
If hydraulic, it could be;
H1)a bad M/C,
H2) or stuck caliper pistons
H3) or restricted lines.
H4) Or the energy from your foot is not getting to the M/C,
H5) or the most common, is a big old air bubble inside the M/C cuz it wasn't properly bench-bled.
H6) Or, it could be that the compensating port is not returning fluid properly and the front brakes are dragging and boiling the fluid
If mechanical,it could be;
M1) loose wheel bearings, knocking the pistons back into the bores,
M2) or pads installed wrong side to the rotor,
M3) or the calipers stuck on the slider pins or on the brackets and not getting out to the rotors,
M4) or the pads not contacting the rotors over their full faces,
M5) or only one pad per side braking.
M6) or those used caliper-pistons ain't coming to work.
So lets review;
you said yes to hard pedal. if true, this would tend to rule out;H1,H5,and H6. It would also rule out M1,M4,and M5. Boy that was easy,right? We're halfway done.
You said; the pistons went back into the bores easy. If the calipers are in fact clean and loose inside, then that would rule out H2
You said bled,bled, and more bled. If you did it right, That would tend to rule out H3 and H6, leaving only H4, as a hydraulic problem.
Now as to the remaining mechanical possibilities,namely M2,M3,and M6; M2 is unlikely, in that it is unlikely that you would have done it to both sides. And M6, is unlikely if you pushed them in with your thumbs.
That leaves just M3, and is a common beginners mistake. The pins need to be straight and smooth and lubed with rubber o-ring lube.The pins have to slide freely thru the caliper holes provided.Often the O-rings in there have to be removed and the grooves cleaned of all the years of accumulated rusty slag. As to the caliper ways. These accept the brake torque and transmit it into the knuckle and eventually into the frame. If the pads have dug deep grooves in them, then they will get stuck in there, and what little brake torque there is will keep them from climbing out. I have had to repair many,many,many slide ways, by hard brazing metal into the grooves and then filing it flat.
So now we are stuck with just M3 and H4,
H4 is an easy test, so let's do that first. Climb in and pump the brake pedal up and down (it doesn't have to be hard) about 10 times. Then push it down and hold it down with about 50 pounds of foot pressure,like you were preparing to climb up the stairs, but not enough to actually go.I use both legs, to make it easier cuz this is a long test.The pedal should be very hard with no sponginess. Then start up the engine. The brake pedal should immediately begin to fall as the engine comes to life. Wait about 5 seconds for it to stabilize.This proves the booster is multiplying your foot pressure, making it easier for you to achieve a lotta hydraulic pressure. The pedal should stop moving and remain at that pedal height forever. Or for as long as you continue with the same pedal pressure. If the pedal slowly sinks to the bottom and then gets hard again, the M/C is no good, it has an internal leak.. But if it remains at a fixed height,for a minute or so, then you can end the test .And so H4 is a pass, leaving just M3.
For M3 you will have to remove the calipers and pads again, and check the ways and pins as described above. And repair them as may be necessary. since the wheels are off, this is a good time to reset the wheel-bearing preload adjustment
And then it's roadtest time again.
Now please notice where I said "you said". I based my answer on what "you said". If you told me wrong or left something out, I mightof offered another solution.
It could also be that I missed something, and another mechanic will come along and mention it. I'm only human, and I make mistakes too.
You can go over the list yourself and go down some of those other roads, like back-tracking.
If you get M3 repaired and it still won't skid the tires at 20mph, then we're not finished! Then you will have to do a hydraulic pressure test. It is your last option.
I leave it for last, cuz you will need to plumb into the bleeder hole with a high pressure gauge of at least 1200psi.Mo-money,lol. It may be that the hard lines are clogged.
Personally I would do this test first, cuz I already have the tester,lol.
You did bench-bleed the M/C right?,lol.
done