Issues with rear brake (possibly bleeding)

[i28]

Installed stainless steel lines and new brake pads on my bike.
The installation for the front went well but when I changed out the rear lines and bled the system, I lost all pressure. Bled the rear many times and still no improvement.
I installed the OEM brake lines back on the rear to see if the issue was with the line. Bled the brakes and got a constant flow of fluid coming out without any air bubbles but still had the same issue.
Is there a chance air could still be trapped in the system somehow even when I'm getting a constant flow of brake fluid out without any air bubbles?
 
My next option is a vacuum bleeder. (If you think this will solve my problem, any recommendations on one?)
 

[DewMan]

If you've bleed it properly and you still  "lost all pressure" the fluid has to either be leaking out somewhere or leaking back past your pushrod back into the reservoir. Or your steel braided lines aren't doing their job at all and they're flexing excessively (though not likely).
 
Can you be more specific with that? When you have the bleeder valve open I'm assuming you're getting fluid when you push the pedal? With the bleeder closed are you getting spongey pressure or no pressure as when the bleeder is open?
And you're having the same issue now with the both the OEM and steel lines?
 
 

[i28]

I originally checked the braided line to make sure it isn't flexing excessively.
I checked and didn't see any fluid leaking anywhere and the reservoir stays at the same level throughout.
I do have brake fluid coming out with the valve open and I did not experience any spongy pressure (but it definitely feels light).
I have the same issue with OEM and steel lines.
 

[DewMan]

If you pushed the pistons all the way back in... as you normally would on a pad replacement.... have they pushed out all the way to the rotor yet? the light pressure could just be due to the piston still "taking up slack" so to speak.

[i28]

The pistons were pushed back after the replacement and after bleeding the brakes, they were sitting where they should be.
My buddy who was helping me has an R1 with an almost identical caliper and lines and he couldn't catch the issue either. I'm wondering if it's not being bleed properly even though I get brake fluid out without any air bubbles. That's why I want to give vacuum bleeding it a shot to guarantee all the air is out.

[DewMan]

I've not had to do any brake work on my FZ-07 yet, so I have no more insight to give you... not sure it would be a rogue trapped air bubble with swapping out the lines as you've done.
 
Are you getting pressure against the rotors but just not enough? Is the pedal bottoming out even after bleeding?
 

[i28]

Are you getting pressure against the rotors but just not enough? Is the pedal bottoming out even after bleeding?

I believe there is pressure but just not enough and yes, the pedal bottoms out even after bleeding. 

[mossrider]

With the rear brake line it can tricky to get all the air out of the line because it runs horizontally and even uphill for a spell. I've attached a pic to illustrate. Using a good vacuum bleeder will help get the darned thing bled, I know. It is possible to keep getting some fluid through the line without getting the air out causing heaps of frustration. Another trick is to take the rear caliper off the disc and let it dangle, essentially taking the rise out of the line, (with a piece of scrap between the pads) Then bleed it. 

 
facebook com upload photos
hope this helps.

[i28]

Using a good vacuum bleeder will help get the darned thing bled, I know. It is possible to keep getting some fluid through the line without getting the air out causing heaps of frustration. Another trick is to take the rear caliper off the disc and let it dangle, essentially taking the rise out of the line, (with a piece of scrap between the pads) Then bleed it.

I actually tried bleeding it with the caliper danging and that didn't work either. Good to see know that I'm not the only one who has experienced this and that a vacuum bleeding will probably solve my issue.
So finicky sometimes but I still love my FZ.
 

[rick]

You have the right thought, just not the right execution. Air likes to go uphill. Remove the caliper - put a piece of 1/4 hardboard or something between the pads so they don't pop out - and RAISE the caliper well above the master cylinder. You may even have to tilt the caliper to get the bleeder valve up as high as possible.
 
I have to do this procedure with my Aprilia - there's no other way.

[rick]

One other thing you can try - and you can do this with the caliper low.
 
try pushing the piston back in to push the fluid uphill. 1st do this with the bleed valve on the caliper open(hose attached of course). If that doesn't get an air bubble out and you still have no pressure, leave the bleeder closed and push the fluid uphill and back into the reservoir. Keep an eye on the reservoir so it's not overfilled by this

[avanti]

Any time I've had similar issues on cars, a vacuum or pressure bleeder immediately solved the problem. All the best.

[i28]

Still haven't had the time to try bleeding the brakes again since I've been so busy with work. Hopefully I'll have the time within the next week. I'll report back as soon as I do.

[i28]

Tried vacuum bleeding a few times and even pushed the piston back and tried again and no results. Still no pressure on the rear brake lever.
 
What else may cause this?
Can it be an issue with the rear master cylinder or bleeder screw?
I haven't noticed any fluid leaking anywhere.

[stickshift]

Reading all of the above, it seems likely that there's air in your master cylinder, it can get trapped there depending on your line setup.
 
Bleed as normal, cracking open the line from your master cylinder when you have pressure on your system. Use a rag wrapped closely around your master cylinder/hose to prevent any fluid getting on your bike. Watch for bubbles/spurts coming from you m/c when you bleed.
 
After this bleed as normal, i.e caliper bleed nipple.

[rick]

Tried vacuum bleeding a few times and even pushed the piston back and tried again and no results. Still no pressure on the rear brake lever. 
What else may cause this?
Can it be an issue with the rear master cylinder or bleeder screw?
I haven't noticed any fluid leaking anywhere.

Vac bleeders are nice, but this caliper's bleed nipple is not as high as the banjo.mAn air bubble can stuck there and just stay as fluid is pulled by your vac bleeder.   
I'm still gonna recommend you pull the caliper and raise it up higher than the master cyl and also tilt the caliper so the bleed nipple is at 12 o'clock. 

[snowdriftless]

Tried vacuum bleeding a few times and even pushed the piston back and tried again and no results. Still no pressure on the rear brake lever. 
What else may cause this?
Can it be an issue with the rear master cylinder or bleeder screw?
I haven't noticed any fluid leaking anywhere.

Ok so story time. I had a similar issue and here is what caused it: 
I had this same issue with my brakes when I tried to save money (Spoiler: it didn't work) by removing the wheels myself. The front brakes were fine but the rear brake was spongy, and would not stop the bike when I pushed the brake pedal to the stop. My problem was that I cross-threaded the front bolt on the rear caliper. This prevented the rear caliper from sliding correctly. One thing I would check is install the brake and look at the brake as you press on the brake pedal. You shouldn't see any movement. My brake with the cross-threaded pin was deflecting slightly because the caliper couldn't slide back and forth the more I pressed down the more the caliper and mount deflected. Also look to see if your brake pads are flush with the disk. If only one end is of the pad is touching the disk and the other end has a gap between the rotor and pad this is likely the problem.
 
Let me know if that helps.

[i28]

Vac bleeders are nice, but this caliper's bleed nipple is not as high as the banjo.mAn air bubble can stuck there and just stay as fluid is pulled by your vac bleeder.   
I'm still gonna recommend you pull the caliper and raise it up higher than the master cyl and also tilt the caliper so the bleed nipple is at 12 o'clock. 

Thanks again. Will definitely try this sometime this week.  
 
 

Ok so story time. I had a similar issue and here is what caused it: 
I had this same issue with my brakes when I tried to save money (Spoiler: it didn't work) by removing the wheels myself. The front brakes were fine but the rear brake was spongy, and would not stop the bike when I pushed the brake pedal to the stop. My problem was that I cross-threaded the front bolt on the rear caliper. This prevented the rear caliper from sliding correctly. One thing I would check is install the brake and look at the brake as you press on the brake pedal. You shouldn't see any movement. My brake with the cross-threaded pin was deflecting slightly because the caliper couldn't slide back and forth the more I pressed down the more the caliper and mount deflected. Also look to see if your brake pads are flush with the disk. If only one end is of the pad is touching the disk and the other end has a gap between the rotor and pad this is likely the problem.
 
Let me know if that helps.

Will definitely double check this. I've always wondered about how much movement the rear caliper should have.  

[rick]

page down to post 20 http://www.apriliaforum.com/forums/showthread.php?292294-Rear-Brake-Question/page2&highlight=bleed+back+brake
 
it'll look a bit odd cause of the single sided swinger, but ordinarily, the caliper will sit somewhere around 11 o'clock on the disk rotor.
 
Ours (the fz) will have a similar orientation between where the bleeder is vs. the banjo connection. . this guy used that square to both hold the caliper in that tipped position and keep the pads from being pushed out.
 
Look how high the master cyl is in relation to where the caliper normally sits. That sure doesn't help.

[avanti]

As Sherlock Holmes said, "Once you eliminate the impossible, whatever remains, no matter how improbable, must be the truth."
 
I've not reread all this for a while so excuse me if I'm redundant. If you are not getting fluid out the caliper bleeder when you open it and squeeze the handle, you know the problem is at the master-cylinder, if you have eliminated air OR obstruction in the line... If you are getting pressurized fluid out the bleeder at this time, instead, then you know the problem must be at the caliper. All you have is the M/C, line, and caliper. Eliminate each and go to the next. All the best.

[i28]

I don't have the time yet to do what @rick suggested but a quick question since @snowdriftless brought it up.
I initially thought the bolt on the front of the caliper may have almost been crossthreaded when I was putting it back on but I stopped early, double checked and it looked normal. I'm wondering if I've got the same issue you had.
I had installed new brake pads correctly, I thought I had even double checked, but after one ride they had fallen out of place. Wondering if it's because of the misalignment because of the bolt. Here's a video of the movement of the caliper:
 

 
 
Is there too much movement in the caliper or is this normal? thoughts?
 

[ddog]

Tried vacuum bleeding a few times and even pushed the piston back and tried again and no results. Still no pressure on the rear brake lever. 
What else may cause this?
Can it be an issue with the rear master cylinder or bleeder screw?
I haven't noticed any fluid leaking anywhere.

Ok so story time. I had a similar issue and here is what caused it: 
I had this same issue with my brakes when I tried to save money (Spoiler: it didn't work) by removing the wheels myself. The front brakes were fine but the rear brake was spongy, and would not stop the bike when I pushed the brake pedal to the stop. My problem was that I cross-threaded the front bolt on the rear caliper. This prevented the rear caliper from sliding correctly. One thing I would check is install the brake and look at the brake as you press on the brake pedal. You shouldn't see any movement. My brake with the cross-threaded pin was deflecting slightly because the caliper couldn't slide back and forth the more I pressed down the more the caliper and mount deflected. Also look to see if your brake pads are flush with the disk. If only one end is of the pad is touching the disk and the other end has a gap between the rotor and pad this is likely the problem.
 
Let me know if that helps.

I feel less bad now that I know the same thing happened to someone else. I wound up replacing the rear caliper with one from eBay, because after swapping every other component with those on @fzak007 's FZ-07 it was the only constant in the twisting. I'm guessing I misaligned the caliper mounting bracket with its slot in the swingarm and attempted to tighten the rear axle nut. That's the only way I could see bending it I have no clue how else I could've done it. 

[ddog]

I don't have the time yet to do what @rick suggested but a quick question since @snowdriftless brought it up. I initially thought the bolt on the front of the caliper may have almost been crossthreaded when I was putting it back on but I stopped early, double checked and it looked normal.
Is there too much movement in the caliper or is this normal? thoughts?

 
Let's keep it simple for now and I'll add more details afterwards

If you look down the plane of the rotor into the caliper and it appears to be rocking and not sliding, something is bent/misaligned. It appears in the video that it might be rocking, but it's a little hard to be sure without looking at it directly. 

[i28]

I feel less bad now that I know the same thing happened to someone else. I wound up replacing the rear caliper with one from eBay, because after swapping every other component with those on @fzak007 's FZ-07 it was the only constant in the twisting. I'm guessing I misaligned the caliper mounting bracket with its slot in the swingarm and attempted to tighten the rear axle nut. That's the only way I could see bending it I have no clue how else I could've done it. 

I believe it's the front bolt and it seems easy to cross thread IMO.  I'm a little surprised I'm not the only one who has had an issue with the rear caliper on this bike. 

If you look down the plane of the rotor into the caliper and it appears to be rocking and not sliding, something is bent/misaligned. It appears in the video that it might be rocking, but it's a little hard to be sure without looking at it directly.

I don't think there's supposed to be this much movement that's why I got a video to ask for opinions. I edited my old post to mention how the brake pads had fallen out of alignment once.
 

[ddog]

@i2837856393 I'll take a look and compare tomorrow morning and get back to you.