[Tenaus]

Had new powerstop pads, rotors and powder coated calipers installed on my 2004 ssr.

Prior to install brakes were hard as a rock. After, they were spongy, no air in lines, so replaced the power booster and the control module, still spongy. GM tech help said to replace booster, then module.

If i clamp both front rubber parts of brake lines pedal is hard as a rock. Unclamp either one and it is spongy again.

GM tech help can't figure it out, what do you guys think?

Any help would be greatly appreciated.

 

[SWT RYD]

Sounds like you have air in system. Did you use a power bleeder or did you do a press on the brake pedal with foot procedure you might have to go with a power bleeder sounds like you got air in it. Also I don't know whether the ssr have them I'm almost certain they do maybe your proportioning valve took a crap.

 

[Autoprof]

Check to make sure bleed valve is at the top of the caliper when installed.
I have seen calipers mounted on wrong side of car (not as easily screwed up on dual piston calipers but still possible) Air would then be trapped at top of caliper. :banghead

Customer brought a car in he had been working on to save himself some money - same scenario. Replaced calipers because of age - spongy pedal- replaced hoses, then master cylinder, then booster, then brought it to me. Calipers reversed, bleed valves were at not at the top - reversed calipers to opposite sides and all was good. I wonder what his total savings actually were? :whistling:

 

[moscooter]

:|

I agree it sounds like there is air in the lines. (I can't understand what you mean by this comment)....."If i clamp both front rubber parts of brake lines pedal is hard as a rock. Unclamp either one and it is spongy again.":frown2:

Anyway, hopefully you're not trying to use DOT 5 in the system. Not really compatible with an ABS system and famous for micro bubbles that are a bitch to get out.

Other than a power bleed, you could try this trick.............Pull off the calipers and remove the pads. Take a flat steel bar that will span the pistons and then using a LARGE C Clamp, compress those pistons back into their bore as far as they will go. Repeat with each wheel.
Then re install the pads/calipers and bleed as usual. Air should now be gone and system should function normally.:wink2:

 

[Tenaus]

The front calipers rubber line was clamped off to rule out any problems with the rear calipers.

 

[Autoprof]

:|

I agree it sounds like there is air in the lines. (I can't understand what you mean by this comment)....."If i clamp both front rubber parts of brake lines pedal is hard as a rock. Un-clamp either one and it is spongy again.":frown2:

Anyway, hopefully you're not trying to use DOT 5 in the system. Not really compatible with an ABS system and famous for micro bubbles that are a bitch to get out.

Other than a power bleed, you could try this trick.............Pull off the calipers and remove the pads. Take a flat steel bar that will span the pistons and then using a LARGE C Clamp, compress those pistons back into their bore as far as they will go. Repeat with each wheel.
Then re install the pads/calipers and bleed as usual. Air should now be gone and system should function normally.:wink2:

Clamping off (pinching the front hoses) and then getting a solid pedal confirms the problem is beyond where the clamps are located -- the calipers or remaining part of the hose.
BY the way NOT a recommended practice - this could damage the inner lining of the hose. May not be a problem now but could pop up in the future as a dragging caliper.

FYI I think you forgot a step in your C clamp method - pushing the piston back in with a C clamp will only help remove any trapped air if the bleed valve were opened and pointing to the top.

Also I don't know whether the ssr have them I'm almost certain they do maybe your proportioning valve took a crap.

No proportioning valve on most cars with ABS. Pressure balance control is achieved through Dynamic Rear Proportioning (DRP) , which is a function of the ABS modulator

 

[poppa]

The front calipers rubber line was clamped off to rule out any problems with the rear calipers.

As already stated clamping a brake hose is not something I would ever recommend it could damage the hose and cause catastrophic failure. I also agree with the others that there must be air in the system when bleeding brakes start with the caliper furthest from the master cylinder and work to the master cylinder.

 

[moscooter]

:smile2:
"FYI I think you forgot a step in your C clamp method - pushing the piston back in with a C clamp will only help remove any trapped air if the bleed valve were opened and pointing to the top."

I don't recall that we needed to be concerned about the bleed valve being opened and pointing to the top for this procedure. This process was a (last resort) recommended by a factory Harley tech rep back in the early 2001 or so models. At that time, Harley had moved to the DOT 5 fluid which many times caused front brake problems. The solution described, was able to force those bubbles from behind the calipers on up into the line where they would then migrate to the top (master cylinder). It solved the problem for many a Harley owner back during the time of using DOT 5 silicone fluid. Once Harley started using ABS braking systems, they found that DOT 5 and ABS do not "play well" together...........thus they went back to using DOT 3.

It seemed to me that this procedure might resolve the posters trapped air situation.:|

 

[Autoprof]

:smile2:

I don't recall that we needed to be concerned about the bleed valve being opened and pointing to the top for this procedure. This process was a (last resort) recommended by a factory Harley tech rep back in the early 2001 or so models. At that time, Harley had moved to the DOT 5 fluid which many times caused front brake problems. The solution described, was able to force those bubbles from behind the calipers on up into the line where they would then migrate to the top (master cylinder). It solved the problem for many a Harley owner back during the time of using DOT 5 silicone fluid. Once Harley started using ABS braking systems, they found that DOT 5 and ABS do not "play well" together...........thus they went back to using DOT 3.

It seemed to me that this procedure might resolve the posters trapped air situation.:|

OK so now I understand how it would work going straight uphill to the master cylinder on a motorcycle. Kind of a reverse gravity bleed method. I can see that working on a motorcycle and its a good thought.
Unfortunately with an automobile, the brake line may have a few places along the way to the master cylinder that would require the air pocket to travel downhill - which it won't do. This is even more apparent on cars that have ABS.
I believe this method would also require that you remove the lid from the master cylinder to allow the air bubble to "migrate" out. And unlike DOT 5 Brake fluid, DOT 3 or DOT 4 Brake fluid is hygroscopic and will absorb moisture, thus making it more prone to corrosion and worse yet boiling.

He might also have an air pocket stuck in the lower piston or that is stuck between either piston and the seal. I have read that taping on the caliper with a mallet or unbolting it and holding it with the pistons horizontal and still keeping the bleed valve at the highest point of the caliper while gravity bleeding can help dislodge that stubborn air pocket. DO NOT attempt to pedal bleed with caliper unbolted without something for the pistons to squeeze or they will be blown out of the caliper.

Personally I have never had one that with an air pocket that difficult to get out.

 

[Tenaus]

I appreciate all the input. I left the SSR at home today so will check it tonight and give an update tomorrow. Thanks again.

 

[yellow bear]

I don't remember the details, but, there was a procedure for "burning in" new brake pads. Different from the old brake shoes.

 

[TXNSSR]

I don't remember the details, but, there was a procedure for "burning in" new brake pads. Different from the old brake shoes.

Correct. The Powerstop pads have a very specific break-in procedure. I’ve got them and they are firm, but I also replaced the front flex lines with ss braided lines which helped too.

- Robert
:silver:

 

[Tenaus]

Well i checked the calipers last night when i got home and they are installed correctly, with the bleeders on top.

I pumped the brakes and you can hear the air come out, i assume the brake booster, but they still will go to the floor. At half way the brakes do hold but then if you keep pushing they will go to the floor.

I have no idea what to do now because the GM dealership allready threw 2 new parts at it, that GM techs support told them to do, that didn't fix it and they have no more ideas.

 

[Autoprof]

Was there any difference when original calipers were put back on.
Seems to me problem was isolated to both fronts beyond clamps. Air trapped, bad calipers, or hoses flexing.
Try re-installing old calipers.

 

[SWT RYD]

Well i checked the calipers last night when i got home and they are installed correctly, with the bleeders on top.

I pumped the brakes and you can hear the air come out, i assume the brake booster, but they still will go to the floor. At half way the brakes do hold but then if you keep pushing they will go to the floor.

I have no idea what to do now because the GM dealership allready threw 2 new parts at it, that GM techs support told them to do, that didn't fix it and they have no more ideas.

if the pedal is going to the floor, sounds like you have a master cylinder that's going bad or went bad.

 

[SWT RYD]

I don't remember the details, but, there was a procedure for "burning in" new brake pads. Different from the old brake shoes.

Correct. The Powerstop pads have a very specific break-in procedure. I’ve got them and they are firm, but I also replaced the front flex lines with ss braided lines which helped too.

- Robert

Robert, where did you get your braided Flex lines I tried all over the place and couldn't find any that will fit directly. Did you have to modify them at all. Appreciate any information you can throw at me, thanks

 

[Tenaus]

I had suggested reinstalling the old calipers but i was told they were garbage.

Does the fact that i can hear air hissing near my feet inside the car when i press the brakes mean anything?

 

[Autoprof]

The fact you hear some air noise at the pedal is normal -- I can't hear it to tell it yours is excessive or normal
Here is a description of operation from the manual.

Vacuum Brake Booster: Uses source vacuum to decrease effort required by driver when applying brake system input force. When brake system input force is applied, air at atmospheric pressure is admitted to the rear of both vacuum diaphragms, providing a decrease in brake pedal effort required. When input force is removed, vacuum replaces atmospheric pressure within the booster.

I have posted some pictures from a textbook that illustrates the booster in action
1. Brakes not applied
2. Brakes applied - note that atmospheric air has entered the booster and it is equipped with a silencer to quite that noise down somewhat -- listen in your other car if it has a vacuum booster you will hear some noise, some cars are sometimes louder than others.

I agree with SWT RD that if pedal feels good and freeplay is normal but it slowly sinks to the floor with constant pedal pressure and there are no external leaks this is typically an internal master cylinder leak. You didn't mention this earlier

Was this also a symptom before? And did the pedal still drop to the floor when the lines were blocked off?

If the pedal felt perfectly fine with the lines blocked then the problem HAS to be beyond the clamps -- I am really surprised that because the brakes became spongy only after replacing the calipers that they didn't tell you that you purchased faulty calipers (although I don't know what could be faulty).

I personally still think if pedal was fine when clamped there is a stubborn air pocket. Did they try bleeding the brakes after the car had been driven - maybe the movement of the car and the application of brakes a few more times allowed the pocket to become "untrapped" and can now be bleed. You could also try part of what Moscooter said only open bleed valve.
Open bleed valve push pistons back in close bleed valve -- reapply brake to push pistons out again and then repeat. After doing both sides trying to get the air pocket "untrapped" re-bleed brakes.

Unfortunately you are just a little too far away for me to make a service call.

 

[Tenaus]

Thank you very much. I will try squeezing the caliper pistons a few times and see what happens.

 

[nj6969]

Thank you very much. I will try squeezing the caliper pistons a few times and see what happens.

Just remember Autoprof's previous post #9, last sentence---Don't step on the pedal unless the caliper is positioned on the Rotor or you will blow the Cylinders out. I agree with others. If the pedal creeps down while your foot is applying pressure, the Master Cylinder has an internal leak.

Nick