SSBC disc brakes won't stop

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AJ/FormS said:
This sounds like a mechanical issue. As in bent pads or those pesky anti-squeal shims between the pads and pistons, or some kindof flex in the system,including but not limited to,the rubber flex-hoses, or pads not running flat to the rotors,or even the bracketry.
Click to expand...

I had three Wilwood M/Cs available to me when I put the system together. Started off with a 7/8" and worked up to the 1 1/8" which gave the best pedal, and highest operating pressure. I get 1300lbs to the calipers, no booster.
 
ab7fh said:
When I went to 4 wheel discs I had to go with a 1 1/8" bore M/C to supply enough volume to the calipers. Prior to that the pedal was low, wouldn't stop well, and felt like I was running out of pedal before full pressure would get to the brakes.
Click to expand...
The above may very well be the problem.... the existing MC does not push out enough fluid to activate disc calipers at BOTH ends. It runs out of stroke before enough fluid can be pushed out. The fact that the front work fine with the rear line pinched would be another indicator of that.

Here is another thread just updated to indicate this was the solution on a 4 disc setup:
Wilwood/Strange 4 Piston Calipers soft feeling pedal

One thing that is important is to make sure the the pedal and rod and MC setup is such that the MC pistons are coming as far back out in the bore when released as possible to give maximum stroke.
 
nm9stheham said:
The above may very well be the problem.... the existing MC does not push out enough fluid to activate disc calipers at BOTH ends. It runs out of stroke before enough fluid can be pushed out. The fact that the front work fine with the rear line pinched would be another indicator of that.

Here is another thread just updated to indicate this was the solution on a 4 disc setup:
Wilwood/Strange 4 Piston Calipers soft feeling pedal

One thing that is important is to make sure the the pedal and rod and MC setup is such that the MC pistons are coming as far back out in the bore when released as possible to give maximum stroke.
Click to expand...
Another thing I just noticed when I tried the front brakes again with the backs isolated. The front don't lock up even jamming on them. Mmaybe the MC isn't putting out enough pressure??? IDK?
 
No! Lemme think, I mighta told you wrong.Nope, I reread what I wrote and emboldened the tricky part
The first thing you need to remember is that the front most chamber in the M/C operates the rear brakes, and the rear-most chamber operates the front brakes. You do have it plumbed that way,correct?
OK then, I got it.
You have a mechanical lock-up. This is caused by how the M/C is internally built, and the fact that the rear is clamped solid.Here's what I see. The rear system has air in it.During the course of your work, the rear has built up air-pressure. The compressed air has moved the associated piston inside the M/C to a position up next to the other piston. This locks the two pistons together mechanically,and the piston for the front brakes can no longer move, and hence no front brakes. The solution is to loosen the clamp at the back,being sure to have at least one bleeder back there open. This will allow the pressure to escape. Next pump up the front brakes, and then while holding the pedal down, have a helper tighten the clamp, just enough to slow down the fluid travel at the back, but NOT ENOUGH TO TOTALLY PREVENT FLUID TRAVEL. If you refer back to my earlier post, I think you will find that this is what I wrote.
So now, we have pushed the piston for the rear brakes all the way forward, away from the firewall.Now this is not the correct working position for that front piston (which operates the rear brakes), but it will self center upon release of the pedal.And so now the front brakes will again work.If not, then the clamp is too tight,again.Try it.
 
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71Demon said:
Another thing I just noticed when I tried the front brakes again with the backs isolated. The front don't lock up even jamming on them. Mmaybe the MC isn't putting out enough pressure??? IDK?
Click to expand...

I beat my head with this too. Everyone said... "small bore for manual disc brakes". Well it may work for some, but it doesn't work for everyone... All depends on the components. The larger bore solved my problem in the same way it solved the problem of the person in the post linked above.
 
Those speed bleeders, can you close them and run them or do you take them out after its bled? Seems like taking them out after its bled is inviting air back in. Disk brakes require more fluid, just look at a Disk/Drum M/C. I bet a larger bore will help. I would be interested in the rear disk choice from drum. Fade resistance? Much easier to work on but thats about the only positive I see in running them in the rear.
 
71Demon said:
Another thing I just noticed when I tried the front brakes again with the backs isolated. The front don't lock up even jamming on them. Mmaybe the MC isn't putting out enough pressure??? IDK?
Click to expand...
Obviously... or the front pads are contaminated. Did you:
- Wash off the front rotors and pads completely and thoroughly with Brakeleen before assembling, and keep all grease and oil off of them?
- Is you pedal rod the original and is the brake pedal coming all the way back when released?
- Did you have the added prop valve fully screwed in?
- Are the bleeders pointing up on all 4 calipers?
If all the above is OK, then you may have air in the MC.
- When you changed the rear brakes, did the fluid all drain out of the front chamber in the MC?

When you bleed the rears, it is going take a LOT of brake fluid to get all the air out. It would not shock me for you to have used a quart or more in the whole bleeding process.
 
Thanks. I'm going to try your suggestions today. Thinking air in the MC. Or contaminated surfaces. The fluid did not drain from the mc when doing the rear brake change. Did not clean the new rear surfaces with cleaner. Could be contaminated and affecting the grab. The front brakes have been on the car for a while and should not need cleaning but the rotors had rust film on them from sitting for about a year. Driving it took the rust off. All bleeders are pointing up. Had the added prop valve closed completely.
 
AJ/FormS said:
No! Lemme think, I mighta told you wrong.Nope, I reread what I wrote and emboldened the tricky part
The first thing you need to remember is that the front most chamber in the M/C operates the rear brakes, and the rear-most chamber operates the front brakes. You do have it plumbed that way,correct?
OK then, I got it.
You have a mechanical lock-up. This is caused by how the M/C is internally built, and the fact that the rear is clamped solid.Here's what I see. The rear system has air in it.During the course of your work, the rear has built up air-pressure. The compressed air has moved the associated piston inside the M/C to a position up next to the other piston. This locks the two pistons together mechanically,and the piston for the front brakes can no longer move, and hence no front brakes. The solution is to loosen the clamp at the back,being sure to have at least one bleeder back there open. This will allow the pressure to escape. Next pump up the front brakes, and then while holding the pedal down, have a helper tighten the clamp, just enough to slow down the fluid travel at the back, but NOT ENOUGH TO TOTALLY PREVENT FLUID TRAVEL. If you refer back to my earlier post, I think you will find that this is what I wrote.
So now, we have pushed the piston for the rear brakes all the way forward, away from the firewall.Now this is not the correct working position for that front piston (which operates the rear brakes), but it will self center upon release of the pedal.And so now the front brakes will again work.If not, then the clamp is too tight,again.Try it.
Click to expand...


After loosening the clamp and the pressure is released on the rears do I re-tighten the bleeder before pumping up the fronts? Im guessing so or it would not pump up, right?
 
pishta said:
Those speed bleeders, can you close them and run them or do you take them out after its bled? Seems like taking them out after its bled is inviting air back in. Disk brakes require more fluid, just look at a Disk/Drum M/C. I bet a larger bore will help. I would be interested in the rear disk choice from drum. Fade resistance? Much easier to work on but thats about the only positive I see in running them in the rear.
Click to expand...
You leave the speed bleeders in. They work exactly like regular bleeder screws, the only difference is that they have a one-way valve inside them so they can't suck air or old fluid back in while bleeding.
 
Rust can embed int he pads and make them less effective. I'd take the pads out and sand them on a flat surface with a drywall mesh sanding strip on the flat surface. The sand off the rotors lightly too. Then clean and flush them. The iron oxide is an abrasive and will score the rotors.
 
AJ/FormS said:
No! Lemme think, I mighta told you wrong.Nope, I reread what I wrote and emboldened the tricky part
The first thing you need to remember is that the front most chamber in the M/C operates the rear brakes, and the rear-most chamber operates the front brakes. You do have it plumbed that way,correct?
OK then, I got it.
You have a mechanical lock-up. This is caused by how the M/C is internally built, and the fact that the rear is clamped solid.Here's what I see. The rear system has air in it.During the course of your work, the rear has built up air-pressure. The compressed air has moved the associated piston inside the M/C to a position up next to the other piston. This locks the two pistons together mechanically,and the piston for the front brakes can no longer move, and hence no front brakes. The solution is to loosen the clamp at the back,being sure to have at least one bleeder back there open. This will allow the pressure to escape. Next pump up the front brakes, and then while holding the pedal down, have a helper tighten the clamp, just enough to slow down the fluid travel at the back, but NOT ENOUGH TO TOTALLY PREVENT FLUID TRAVEL. If you refer back to my earlier post, I think you will find that this is what I wrote.
So now, we have pushed the piston for the rear brakes all the way forward, away from the firewall.Now this is not the correct working position for that front piston (which operates the rear brakes), but it will self center upon release of the pedal.And so now the front brakes will again work.If not, then the clamp is too tight,again.Try it.
Click to expand...


Tried this but no change in the fronts. There was some pressure in the rear lines when I opened it up. Still just slowly stops. Thinking not enough pressure to the calipers. IDK for sure though.
 
ab7fh said:
When I went to 4 wheel discs I had to go with a 1 1/8" bore M/C to supply enough volume to the calipers. Prior to that the pedal was low, wouldn't stop well, and felt like I was running out of pedal before full pressure would get to the brakes.
Click to expand...
Leaning toward the Wilwood 1 1/8 MC since it worked for you. Says its for power assisted and 1" for manual but I'll go with tried and true. Are your brakes SSBC or Wilwood? Guy at SSBC said the old Disc Drum MC won't work on 4 disc setups, so that may well be my problem. He says Disc Drum MC's work more on volume not pressure. SSBC's MC's for Mopar are 1-1/32 but 1 1/8 would just push more fluid. My setup is not power assist either. Wilwood MC's look so much better and less bulky.
 
71Demon said:
Are your brakes SSBC or Wilwood?
Click to expand...

Neither, it's a custom setup on my '60 Dart. The front calipers are '99 Dodge Ram, and the rear are from an '04 Cobra.
 
71Demon said:
Tried this but no change in the fronts. There was some pressure in the rear lines when I opened it up. Still just slowly stops. Thinking not enough pressure to the calipers. IDK for sure though.
Click to expand...

Well then we better check that the compensating port is open.
Let me start by saying, if you were able to bleed the front brakes, and you have not changed anything to do with the M/C, or it's pushrod or the brake pedal, since then; then I think your C-port is just fine.You can skip over everything, and go down straight to HERE
But if you have messed with any of those, then here we go.
Have a helper in the car. You pop the cap off the M/C.Make sure the P-valve is open,and the clamp is loose on the back flexhose, and at least one bleeder loose, if the rear has not yet been bled.If you don't have Dot5silicon fluid, and you DO have paint you wanna keep, then you need to drape everything within about a two foot radius, with something that will prevent direct contact of the brake fluid to th paint, cuz the next step is unpredictable.With drum brakes, I also protect the underside of the hood.
While you eyeball the fluid in the reservoir, and shine a little Maglite down into the fluid, have your helper very gently press down on the pedal and stroke it about 1/4 of the way to the floor or about 1 to 1.5 inches;and hold it there. You should have observed a slight roiling of the fluid.This is a good thing.
-Now the tricky part. Have your helper very slowly let the pedal up. You should see a little fountain above the liquid line.If the helper lets up too fast, the fountain can become a gusher, so SLOW is the operative.Repeat several times as may be necessary, increasing the stroke a little bit each time, until you are sure you have seen it.Then end the test by securing the cap.
---Now the interpretation:
NO roiling at all, and NO fountain; the C-port is not working.
Roiling but NO fountain at all.Your flexlines ain't flexing and your pistons ain't moving.
Roiling and a TINY fountain; probably the pistons ain't moving and the flexhoses are flexing normally;but could be the reverse if you have teflon-lined hoses.
Roiling and SMALL fountain; this is normal.
Roiling and a gusher; there is compressed air forcing the fluid back.
-If the pedal cannot be depressed with the rear bleeder open, and with fluid or air dripping there, then the front is either mechanically or hydraulically locked.
-To find out which, you will have to crack a front bleeder. If fluid spurts out, you probably have a hydraulic problem, but not for sure. If no fluid spurts out, you will have to check the other side. If no fluid spurts out this side either, then you will have to crack the fitting at the M/C. A spurt here means at least one of the flex hoses is plugged, or the distribution block is, if you still have one.After the spurts, you should again have pedal travel, until it all locks up again.
But if there are no spurts anywhere,then the piston inside the M/C is locked up. If it is stuck at the end of it's travel,and not returning to it's parked position,the pedal will be very low. But if it is stuck at the top of it's stroke, the pedal will be normal.If it is stuck partway, the pedal will be a little low, and If you have a booster,you will be able to lift it back up with a toe, and then it will fall down again.Try not to lift it more than a few millimeters.With no booster, the pushrod is mechanically anchored at both ends,so you won't be able to lift the pedal very far.
Ok so now we have to figure out why it's locked. To do that, you will have to install the bench bleeder hoses in both outlets, looping the hoses back into the reservoirs, and into the fluid. Then get your helper to again slowly push the pedal to the floor, while you observe the fluid action.Then very slowly return the pedal to the top.If the pedal now moves back and forth, then the pistons were not mechanically stuck.Stroke it several times until no more air comes out of the hoses.While doing that, shine your Maglite down directly into the compensating port. If the port is large enough you may see the piston moving back and forth in the hole. Well what you might see the edge of it. It is aluminum and will flash at you as it goes by.It may also still roil the fluid, but you will have no fountain.No matter cuz if the fluid goes round and round,and round, then the port is working. But if the fluid just goes back and forth in the hoses, then the port is not working.The way to see that is to pinch the little hoses when the pedal hits the floor. Then when the pedal returns the pistons will collapse the hoses trying to draw the fluid back.
HEREAssuming by now you are confident that the M/C is working properly, leave the bench bleeder on for the rear system(which is the port nearest the rad), and re-connect the front system(which is the port nearest the firewall).You can bleed the fitting right at the port, and get most or even all of the air out. But the the next step will send any air back into the reservoir. Or if you jumped to HERE, just leave the rear system open, with fluid able to be collected in a little jar. Follow that firewall-side line to make sure it goes to BOTH of the front brakes.
So now give the pedal a few stabs.The pedal should get hard,about half way down.The open rear system should not affect anything except the pedal will travel a little further and will not return to the top.That is normal.
Now, the big question is does the outgoing fluid get to the calipers, and do the calipers respond by putting a bite on the rotors.And when you release the pedal, does the caliper release.So check it.
 
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AJ/FormS said:
Well then we better check that the compensating port is open.
Let me start by saying, if you were able to bleed the front brakes, and you have not changed anything to do with the M/C, or it's pushrod or the brake pedal, since then; then I think your C-port is just fine.You can skip over everything, and go down straight to HERE
But if you have messed with any of those, then here we go.
Have a helper in the car. You pop the cap off the M/C.Make sure the P-valve is open,and the clamp is loose on the back flexhose, and at least one bleeder loose, if the rear has not yet been bled.If you don't have Dot5silicon fluid, and you DO have paint you wanna keep, then you need to drape everything within about a two foot radius, with something that will prevent direct contact of the brake fluid to th paint, cuz the next step is unpredictable.With drum brakes, I also protect the underside of the hood.
While you eyeball the fluid in the reservoir, and shine a little Maglite down into the fluid, have your helper very gently press down on the pedal and stroke it about 1/4 of the way to the floor or about 1 to 1.5 inches;and hold it there. You should have observed a slight roiling of the fluid.This is a good thing.
-Now the tricky part. Have your helper very slowly let the pedal up. You should see a little fountain above the liquid line.If the helper lets up too fast, the fountain can become a gusher, so SLOW is the operative.Repeat several times as may be necessary, increasing the stroke a little bit each time, until you are sure you have seen it.Then end the test by securing the cap.
---Now the interpretation:
NO roiling at all, and NO fountain; the C-port is not working.
Roiling but NO fountain at all.Your flexlines ain't flexing and your pistons ain't moving.
Roiling and a TINY fountain; probably the pistons ain't moving and the flexhoses are flexing normally;but could be the reverse if you have teflon-lined hoses.
Roiling and SMALL fountain; this is normal.
Roiling and a gusher; there is compressed air forcing the fluid back.
-If the pedal cannot be depressed with the rear bleeder open, and with fluid or air dripping there, then the front is either mechanically or hydraulically locked.
-To find out which, you will have to crack a front bleeder. If fluid spurts out, you probably have a hydraulic problem, but not for sure. If no fluid spurts out, you will have to check the other side. If no fluid spurts out this side either, then you will have to crack the fitting at the M/C. A spurt here means at least one of the flex hoses is plugged, or the distribution block is, if you still have one.After the spurts, you should again have pedal travel, until it all locks up again.
But if there are no spurts anywhere,then the piston inside the M/C is locked up. If it is stuck at the end of it's travel,and not returning to it's parked position,the pedal will be very low. But if it is stuck at the top of it's stroke, the pedal will be normal.If it is stuck partway, the pedal will be a little low, and If you have a booster,you will be able to lift it back up with a toe, and then it will fall down again.Try not to lift it more than a few millimeters.With no booster, the pushrod is mechanically anchored at both ends,so you won't be able to lift the pedal very far.
Ok so now we have to figure out why it's locked. To do that, you will have to install the bench bleeder hoses in both outlets, looping the hoses back into the reservoirs, and into the fluid. Then get your helper to again slowly push the pedal to the floor, while you observe the fluid action.Then very slowly return the pedal to the top.If the pedal now moves back and forth, then the pistons were not mechanically stuck.Stroke it several times until no more air comes out of the hoses.While doing that, shine your Maglite down directly into the compensating port. If the port is large enough you may see the piston moving back and forth in the hole. Well what you might see the edge of it. It is aluminum and will flash at you as it goes by.It may also still roil the fluid, but you will have no fountain.No matter cuz if the fluid goes round and round,and round, then the port is working. But if the fluid just goes back and forth in the hoses, then the port is not working.The way to see that is to pinch the little hoses when the pedal hits the floor. Then when the pedal returns the pistons will collapse the hoses trying to draw the fluid back.
HEREAssuming by now you are confident that the M/C is working properly, leave the bench bleeder on for the rear system(which is the port nearest the rad), and re-connect the front system(which is the port nearest the firewall).You can bleed the fitting right at the port, and get most or even all of the air out. But the the next step will send any air back into the reservoir. Or if you jumped to HERE, just leave the rear system open, with fluid able to be collected in a little jar. Follow the that firewall-side line to make sure it goes to BOTH of the front brakes.
So now give the pedal a few stabs.The pedal should get hard,about half way down.The open rear system should not affect anything except the pedal will travel a little further and will not return to the top.That is normal.
Now, the big question is does the outgoing fluid get to the calipers, and do the calipers respond by putting a bite on the rotors.And when you release the pedal, does the caliper release.So check it.
Click to expand...

Ok thanks. One other question I had. Is the stock distribution block on drum/drum cars a proportioning valve too or just a distro block? If its a prop valve too that could be affecting things too I was thinking. If its a prop valve I probably need to gut it or bypass it.
 
It's a distribution block/safety sw to turn on the dash lite..
If it has a little pin sticking out the bottom with a black thing on it, itmay be a P-valve. If you see that pin, take a pic.
 
AJ/FormS said:
It's a distribution block/safety sw to turn on the dash lite..
If it has a little pin sticking out the bottom with a black thing on it, itmay be a P-valve. If you see that pin, take a pic.
Click to expand...
No pin at the bottom. Thanks.
 
Pulling my hair out on this brake system. SSBC disc brakes front and back. 4 piston kelsey hays type ssbc on front and single piston calipers on the rears. Replaced the 1" Master with a 7/8" wilwood master to increase pressure to the calipers, but didn't seem to change a thing. Brake light coming on now when I jam on the brakes. Why would this happen?
 
One more thing I did was change the plumbing. front brakes are now on the front port of the mc(farthest from the firewall and back brakes on the the port nearest the firewall. This is as directed by Wilwood Tech help. Correct??
 
If you have a big reservoir, and a little one. the big one gets the front brakes.
I prefer the front brakes to be operated by the closest reservoir to the firewall.
But I've seen it both ways.
If you have two same size reservoirs, it shouldn't make difference.
 
AJ/FormS said:
If you have a big reservoir, and a little one. the big one gets the front brakes.
I prefer the front brakes to be operated by the closest reservoir to the firewall.
But I've seen it both ways.
If you have two same size reservoirs, it shouldn't make difference.
Click to expand...
Big reservoir is on the front of the mc and Farthest and front brakes are plumbed to it. so I guess thats good.
 
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