Getting my *** handed to me.. these damm brakes
The hydraulic system is a sealed system. Or should I say is supposed to be.
>If fluid is not getting out, then air cannot get in; unless the diaphragm under the cover is not sealing..
>If the liquid level in the M/C is not changing, then you are not losing fluid.
>If the liquid level is changing rapidly with no visible sign of leakage, it may be going into the booster.
> If the pedal is not staying hard, then, here are some possibilities;
1) the rear shoes are going out of adjustment; usually because the self-adjusters have failed or because you never back the car up, lol, which is what makes the automatic adjustment, lol.
2) the rear hose has gone soft
3) you have a mechanical problem
4) you are boiling the fluid; usually from dragging pads, two-foot driving, or just a big old boot hanging up on two pedals at once.
5) the M/C is defective. This one you can sometimes feel. pump the pedal hard and just hold it there. if the pedal starts sinking, badaboom!
> if your pedal, upon application, is getting closer to the floor over time then,
your rear brakes are going out of adjustment . BUT
> if your pedal is just hanging lower to the floor over time then; the compensating ports are not working, usually because the pushrod is too long. These ports are clever little devices. When you apply/lift-off the brakepedal, the fluid goes out and returns. But it only goes down the pipes a couple of inches. As the pads and shoes wear, the fluid has to go out a lil further, over time. Eventually, your pedal would be so far down, that no braking could occur. So the designers introduced tiny ports at the top of the system, to compensate for this. Therefore, about the first inch of pedal-travel, nothing is going on down by the slaves, until the pistons get past the ports.
study this illustration for a minute. Notice that the two pistons are not physically connected. Once bled they are hydraulically coupled. The frontmost chamber (on the left in this drawing) goes to the rear brakes. So when you step on the pedal, the pushrod moves the rear piston, which then moves the hydraulic coupler, which then drives the front piston. If the car has drums in the back, it will usually have a "Combination valve or a proportioning valve", which is just a spring-loaded hold-back valve. In either case; the piston-pair will move along until one of several things happen
1) if the hold back is holding, fluid will want to go out to the calipers, but pressure will not build yet, cuz the the entire coupler is just sliding
2) when the hold back lets go, the fluid will then go out to the rear shoes. During this time, the rearmost piston is just sliding on by the frontbrake port
and NOTHING is going on at the discs. When the front piston stops moving because the shoes have hit the drums, THEN the fluid goes out to the calipers. And BOTH systems are now proportionally controlled.
3) if the rear brake-system should fail, then the frontmost piston will slide to the front of the bore and park there, but the rear-piston/front-brake system will continue to function, allbeit with a lower pedal.
4) if the front-brake system/rear chamber should fail, fluid may get pumped out the front line, but the mechanical extension on the front of the rear piston will still activate the rear brakes via the frontmost piston, but the pedal will not return to the top. Since the reservoirs are isolated from eachother, the rear brake system will continue to function, even tho the other reservoir has gone dry.
5) when you release the pedal; the rear-brake return-springs drive the fluid back into the reservoir, at the same time as "seal-retraction at the calipers does. This returning fluid enters the chambers in the M/C, and simultaneously the pistons are returned to their designated parking spots by the piston return-springs, which then uncovers the Compensating ports which then normalizes the whole system, ready for the next application. Because the whole system is sealed, all these things happen simultaneously; but the rear return-springs are the driving force...... until hold back is once-again established at the P-Valve/C-Valve.
6) If the fluid-level is properly maintained in the reservoirs, then there is no place for air to get suctioned into the system. At the rear, the Dual-Braking System that uses a hold-back valve is under a constant minimum psi, never less than atmospheric, even if you pull the residual valve out. And at the front, there is no way that those piston seals would ever allow it. Inside the reservoirs, there is never a time when suctioning can happen, except during bench-bleeding; and even then, she really doesn't generate much suction.
7) so if you are losing fluid, it is going somewhere! and
8) if you are getting a change in pedal hardness, AFTER, it once was hard,( like the day after,lol) more than likely it will be traced to a mechanical problem, or boiled fluid, which itself could point to a mechanical problem like seized sliders.
9) in any case; C-clamping the slaves will prove your hydraulics in mere minutes, NOT HOURS of PITA fiddle-farting around.
The hydraulic system is a sealed system. Or should I say is supposed to be.
>If fluid is not getting out, then air cannot get in; unless the diaphragm under the cover is not sealing..
>If the liquid level in the M/C is not changing, then you are not losing fluid.
>If the liquid level is changing rapidly with no visible sign of leakage, it may be going into the booster.
> If the pedal is not staying hard, then, here are some possibilities;
1) the rear shoes are going out of adjustment; usually because the self-adjusters have failed or because you never back the car up, lol, which is what makes the automatic adjustment, lol.
2) the rear hose has gone soft
3) you have a mechanical problem
4) you are boiling the fluid; usually from dragging pads, two-foot driving, or just a big old boot hanging up on two pedals at once.
5) the M/C is defective. This one you can sometimes feel. pump the pedal hard and just hold it there. if the pedal starts sinking, badaboom!
> if your pedal, upon application, is getting closer to the floor over time then,
your rear brakes are going out of adjustment . BUT
> if your pedal is just hanging lower to the floor over time then; the compensating ports are not working, usually because the pushrod is too long. These ports are clever little devices. When you apply/lift-off the brakepedal, the fluid goes out and returns. But it only goes down the pipes a couple of inches. As the pads and shoes wear, the fluid has to go out a lil further, over time. Eventually, your pedal would be so far down, that no braking could occur. So the designers introduced tiny ports at the top of the system, to compensate for this. Therefore, about the first inch of pedal-travel, nothing is going on down by the slaves, until the pistons get past the ports.
study this illustration for a minute. Notice that the two pistons are not physically connected. Once bled they are hydraulically coupled. The frontmost chamber (on the left in this drawing) goes to the rear brakes. So when you step on the pedal, the pushrod moves the rear piston, which then moves the hydraulic coupler, which then drives the front piston. If the car has drums in the back, it will usually have a "Combination valve or a proportioning valve", which is just a spring-loaded hold-back valve. In either case; the piston-pair will move along until one of several things happen
1) if the hold back is holding, fluid will want to go out to the calipers, but pressure will not build yet, cuz the the entire coupler is just sliding
2) when the hold back lets go, the fluid will then go out to the rear shoes. During this time, the rearmost piston is just sliding on by the frontbrake port
and NOTHING is going on at the discs. When the front piston stops moving because the shoes have hit the drums, THEN the fluid goes out to the calipers. And BOTH systems are now proportionally controlled.
3) if the rear brake-system should fail, then the frontmost piston will slide to the front of the bore and park there, but the rear-piston/front-brake system will continue to function, allbeit with a lower pedal.
4) if the front-brake system/rear chamber should fail, fluid may get pumped out the front line, but the mechanical extension on the front of the rear piston will still activate the rear brakes via the frontmost piston, but the pedal will not return to the top. Since the reservoirs are isolated from eachother, the rear brake system will continue to function, even tho the other reservoir has gone dry.
5) when you release the pedal; the rear-brake return-springs drive the fluid back into the reservoir, at the same time as "seal-retraction at the calipers does. This returning fluid enters the chambers in the M/C, and simultaneously the pistons are returned to their designated parking spots by the piston return-springs, which then uncovers the Compensating ports which then normalizes the whole system, ready for the next application. Because the whole system is sealed, all these things happen simultaneously; but the rear return-springs are the driving force...... until hold back is once-again established at the P-Valve/C-Valve.
6) If the fluid-level is properly maintained in the reservoirs, then there is no place for air to get suctioned into the system. At the rear, the Dual-Braking System that uses a hold-back valve is under a constant minimum psi, never less than atmospheric, even if you pull the residual valve out. And at the front, there is no way that those piston seals would ever allow it. Inside the reservoirs, there is never a time when suctioning can happen, except during bench-bleeding; and even then, she really doesn't generate much suction.
7) so if you are losing fluid, it is going somewhere! and
8) if you are getting a change in pedal hardness, AFTER, it once was hard,( like the day after,lol) more than likely it will be traced to a mechanical problem, or boiled fluid, which itself could point to a mechanical problem like seized sliders.
9) in any case; C-clamping the slaves will prove your hydraulics in mere minutes, NOT HOURS of PITA fiddle-farting around.
