Jump to content
Sign in to follow this  
ddog

Rear brake not working

Recommended Posts

ddog
I took my wheels off and swapped my tires this evening, as well as replaced the rear brake pads. I went to test ride after putting everything back together and I get no lever at the rear brake. If I remove the forward mounting bolt on the caliper the lever feel is fine. As soon as I tighten down the forward bolt I lose all lever and braking ability. The caliper appears to pitch over instead of slide along the mounting bolts. I tried loosening the axle nut, removing the wheel and reinstalling, swapping back to the old pads, and nothing seems to work. What the heck could be wrong? I'm hoping I'm making some obvious stupid mistake, but I had someone else look over things with me and although we're both mechanically inclined and familiar with the task at hand we are stumped.

Share this post


Link to post
Share on other sites
Guest Ralph
Can't really think of anything that you could get wrong
there is a slot on the bracket that lines up with a lug
on the swinging arm is that engaged it is very hard to
see maybe a few pic may help someone spot something,
you don't want to be riding it like that as beside the
risk of having no brakes damage may be caused,
is it abs?

Share this post


Link to post
Share on other sites
Guest Ralph
You must have the bracket right or the slot and lug would not line up
does the disc look to be in the right place one pad each side, if the
disc is to one side you may have the spacers in wrong in the wheel,
I've just done mine but cant think of any thing apart from the spacers
and that lug that would be easy to get wrong.
 

Share this post


Link to post
Share on other sites
ddog
We have floating calipers; did you lube the sliding pin and not over tighten it? Have to ask; not even sure it's possible, but could the wheel have been put on backwards?  Just grasping for straws .... show us a video. 
http://www.yamahapartshouse.com/oemparts/a/yam/53a99b08f8700220a4415848/rear-brake-caliper
 
Without the forward mounting bolt in place; normal function:
 
Forward mounting bolt installed without tightening; caliper pitching:

Share this post


Link to post
Share on other sites
jerryv
Something is definitely skewed or misaligned .. I'll see if I can video or at least take a close up of mine in the next hours or so.
  • Like 1

Share this post


Link to post
Share on other sites
ddog
I also noticed that I have to put a fair amount of downward pressure on the caliper to line up the forward mount. The pads push against the spring plate, but the plate is seated all the way and looks normal as far as I can tell.

Share this post


Link to post
Share on other sites
jerryv
jerryv
It does appear yours is not pulling straight .. how would something have gotten bent?

Share this post


Link to post
Share on other sites
ddog
It does appear yours is not pulling straight .. how would something have gotten bent?
 
I was able to figure it out! @fzak007 is a saint and allowed me to borrow his fz07 so I could swap parts around until I found the culprit. It turns out that the rear caliper mounting bolt bushing is loose and that is what is allowing the pitching. After riding the other bike I realized that his rear brakes are much better than my brakes have ever been, even when I picked up the bike from the dealership. I believe this is a factory defect I've had on my bike since day one because my brakes have always felt spongy to me. I just assumed the FZ O7 had a garbage rear master cylinder. I believe that the pitching causes the pads to not fully depress leaving some open space within the caliper. Subsequently, the caliper traps some air and is unable to be fully bled. With the bolt in place I was completely unable to bleed my rear system out of the spongy feel, but in half the time I reinstalled and bled the brakes on the other bike. I'll call the dealership on Tuesday to see what can be done.

Share this post


Link to post
Share on other sites
pattonme
which bushing would that be?
 
It may not apply to your case, but a common mistake is to not fully spread the pads and then try to put the bolts in and tighten the caliper. It was a common mistake in the SV650/Ninja650 community. Always fully spread the pads. torque mounting bolts to spec. THEN and only then press on master cylinder to get pads back into contact with rotor.
 

bannerfans_1095431.jpg

Share this post


Link to post
Share on other sites
ddog
which bushing would that be? 
It may not apply to your case, but a common mistake is to not fully spread the pads and then try to put the bolts in and tighten the caliper. It was a common mistake in the SV650/Ninja650 community. Always fully spread the pads. torque mounting bolts to spec. THEN and only then press on master cylinder to get pads back into contact with rotor.

 
I'm referring to the bushing the allen bolt on the rear of the caliper goes through. I'm not sure if bushing is the proper nomenclature. Item 6&7 in this diagram:
http://www.yamahapartshouse.com/oemparts/a/yam/53a99b08f8700220a4415848/rear-brake-caliper
I don't know if I was spreading the pads to the full extent of their reach, but with the caliper from the other bike I had no trouble getting it to compress properly. The twisting was consistent with my caliper. To test the bushing I threaded only the Allen bolt in on both calipers and attempted to wiggle the caliper around. The working caliper displayed little to no movement and the improperly functioning caliper twisted easily.

Share this post


Link to post
Share on other sites
jerryv
Glad you got that sorted .. it could have been dangerous if it was the front.
  • Like 1

Share this post


Link to post
Share on other sites
rick
That bushing/sleeve is part of the slide mechanism that allows the caliper to align as the pads wear. I would think there should be far less space between the pads and disk on either side w/o depressing the pedal. Maybe if the sleeve is missing it might cause this, but hard to imagine you got a bad one.
 
Maybe it's just an optical illusion, but to my eye, it looks like that support bracket ([HASH]10 in that diagram) is also moving toward the disk rotor in that second vid. As soon as the wheel axle is torqued properly, that bracket shouldn't move sideways at all.
 
The left and right axle spacers have different part numbers - are you absolutely certain they weren't swapped - even if you didn't do it when you pulled the wheel, it could have been done wrong at the factory.

Share this post


Link to post
Share on other sites
ddog
That bushing/sleeve is part of the slide mechanism that allows the caliper to align as the pads wear. I would think there should be far less space between the pads and disk on either side w/o depressing the pedal. Maybe if the sleeve is missing it might cause this, but hard to imagine you got a bad one.  
Maybe it's just an optical illusion, but to my eye, it looks like that support bracket ([HASH]10 in that diagram) is also moving toward the disk rotor in that second vid. As soon as the wheel axle is torqued properly, that bracket shouldn't move sideways at all.
 
The left and right axle spacers have different part numbers - are you absolutely certain they weren't swapped - even if you didn't do it when you pulled the wheel, it could have been done wrong at the factory.
 
I thought that was the case too, but upon further inspection I realized that the caliper is pulling the rotor not the other way around. I held a tape measure against the wheel perpendicular to the rotor and when I depressed the brake pedal the caliper actually pulled the rotor towards the outside. Looking at the boot with the caliper off of the mounting bracket it is entirely intact and the bushing tube inside it is present. However, the tube wiggles freely within the boot. I'm assuming the bushing that interacts between the slide bushing and the housing is in some way damaged. I'm planning on removing the caliper entirely and taking it into the dealer to have them inspect it. I will take a video of the movement of the mounting bolt within the boot when I get a chance so you guys can see how much it's moving. It is definitely related to the pitching of the caliper, if not wholly responsible.

Share this post


Link to post
Share on other sites
rick
HJmm, ok I can see that now.
 
The caliper actually slides on the forward pin [HASH]9, not the one in back you are looking at. That rear bolt and sleeve keeps the caliper from rotating forward.
 
hAve you removed that forward slide pin. It should be nicely lubed with a caliper grease like this stuff http://www.bing.com/images/search?q=brake+caliper+grease%2c&view=detailv2&&id=B468206A4771C8621634080237C5A174D179069C&selectedIndex=10&ccid=kY330ea0&simid=608040076033459489&thid=OIP.M918df7d1e6b4d3551766cd2459735baao0&ajaxhist=0
 
If that's binding the caliper can't slide

Share this post


Link to post
Share on other sites
ddog
HJmm, ok I can see that now.  
The caliper actually slides on the forward pin [HASH]9, not the one in back you are looking at. That rear bolt and sleeve keeps the caliper from rotating forward.
 
hAve you removed that forward slide pin. It should be nicely lubed with a caliper grease like this stuff http://www.bing.com/images/search?q=brake+caliper+grease%2c&view=detailv2&&id=B468206A4771C8621634080237C5A174D179069C&selectedIndex=10&ccid=kY330ea0&simid=608040076033459489&thid=OIP.M918df7d1e6b4d3551766cd2459735baao0&ajaxhist=0
 
If that's binding the caliper can't slide
 
The forward slide pin is thoroughly greased, yes.

Share this post


Link to post
Share on other sites
Guest ChicagoAJ
That bushing/sleeve is part of the slide mechanism that allows the caliper to align as the pads wear. I would think there should be far less space between the pads and disk on either side w/o depressing the pedal. Maybe if the sleeve is missing it might cause this, but hard to imagine you got a bad one.  
Maybe it's just an optical illusion, but to my eye, it looks like that support bracket ([HASH]10 in that diagram) is also moving toward the disk rotor in that second vid. As soon as the wheel axle is torqued properly, that bracket shouldn't move sideways at all.
 
The left and right axle spacers have different part numbers - are you absolutely certain they weren't swapped - even if you didn't do it when you pulled the wheel, it could have been done wrong at the factory.
Can't swap the spacers, one is much larger than the other.  
 
@ddog - when I swapped my rear wheel this rear brake setup gave me some problems getting everything lined up. Are you sure the brake pads are resting on their mounts INSIDE the brake caliper? You have to look from the side of the bike with the chain to see if they're in right or not. Mine jumped out a few times when trying to get the caliper to sit right. After making sure they stayed in the slots everything went together fairly easily. 

Share this post


Link to post
Share on other sites
ddog
That bushing/sleeve is part of the slide mechanism that allows the caliper to align as the pads wear. I would think there should be far less space between the pads and disk on either side w/o depressing the pedal. Maybe if the sleeve is missing it might cause this, but hard to imagine you got a bad one.  
Maybe it's just an optical illusion, but to my eye, it looks like that support bracket ([HASH]10 in that diagram) is also moving toward the disk rotor in that second vid. As soon as the wheel axle is torqued properly, that bracket shouldn't move sideways at all.
 
The left and right axle spacers have different part numbers - are you absolutely certain they weren't swapped - even if you didn't do it when you pulled the wheel, it could have been done wrong at the factory.
Can't swap the spacers, one is much larger than the other.  
 
@ddog - when I swapped my rear wheel this rear brake setup gave me some problems getting everything lined up. Are you sure the brake pads are resting on their mounts INSIDE the brake caliper? You have to look from the side of the bike with the chain to see if they're in right or not. Mine jumped out a few times when trying to get the caliper to sit right. After making sure they stayed in the slots everything went together fairly easily. 
 
Yes, I made certain to align the pads within the wells in the caliper. I am especially certain I'm doing things right because with the functioning caliper I changed nothing in my install process and it functioned normally both times I installed it on both bikes, all else the same.

Share this post


Link to post
Share on other sites
Guest Ralph
That looks to be a awful lot of lash almost as if something is missing.
And the front bolt looks to be a long way from lined up which is a bit strange
you would think with all that movement the bolt would line up easily.

Share this post


Link to post
Share on other sites
rick
Had a look at mine last night. Even with the pads touching the rotor at rest, there's a bit of rotational play about that rear mount that has the sleeve. When I push down on the pedal, I'm sure there's some movement, but it's so slight, it's pretty much impossible to see.
 
Even if that bushing/sleeve of yours was worn/machined badly, the pads should square everything up and pretty much stay that way. That your pads will not square to the rotor says they are either in wrong or or that bracket is badly bent. The front slide pin should dictate the attitude of the caliper to the rotor, not that back sleeve and bolt.
 
With so much space between your rotor and pads and the pads not sitting square to the rotor. I was gonna ask the same question about seating those front hooks of the pads properly. I too have had problems getting new pads in the right place on other bikes with a caliper set-up like this. And the result looked the same - the pads were at an angle, there was a ton of space and everything looked and felt wrong.
 
The only other thing I can ask - did you have trouble pushing the piston back into the caliper to put the new pads in? and have you ever changed the adjustment of the stop screw for the pedal to make the start position of the pedal lower?
 
BTW, i use the back brake so infrequently, I almost never wear out rear pads. I hammered the front brakes hard this past weekend, but never once touched the back pedal except to keep the bike rolling after it was stopped somewhere to deal with gloves etc..

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Restore formatting

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Sign in to follow this  


×

Important Information

By using this site, you agree to our Terms of Use.