Trouble bleeding brakes.

[MorganH91]

Hi all, need to ask for some help here as I'm pretty stuck. I've got a 2000 curvy & needed to change the pads - obviously the retaining pins were stuck in so all three calipers ended up coming off. Tried to reinstall them with the new pads but haven't been able to bleed them properly. If i just outline what i've tried, could someone tell me if i'm doing it wrong, or if something needs replacing?

- i've got one of those vizibleeds (clear tube with a no-return valve on the end), refilled the front reservior and used it on the right caliper bleed nipple to suck the fluid through.

- Bled the left caliper, seemed ok. kept the reservior topped up. bled the right as best i could, didn't seem to be any bubbles coming out of it but can't maintain pressure in the system. if i pump the lever a few times in quick succession i can build it up to normal level, but once i release it & try again i can squeeze it almost back to the bar again

- the pads seem to bind fine on the left disc but don't seem to align properly with the right one; consequently squeezing the lever visibly bends the disc inwards, and it pushes the pistons back when released

- the bike's on a pretty steep hill, so i'd have thought any air would've worked its way up to the reservior

basically i've kept trying, been through rather a lot of dot 4 but the lever just stays spongy. Anyone have any ideas what it could be? Seals gone? I just don't know what to do next, can't even give up and take it to a garage for obvious reasons. Any help greatly appreciated!

[andrewsmith]

Morgan put a shout into the Guilford Massive if your stuck http://forums.sv650.org/forumdisplay.php?f=118

Is it standards hoses or braided lines?
I would get the bike on the level and retry bleeding. Bleed the lowest point on the side stand (which is the left caliper) then bleed the right. Seals are shot when the brakes drag when moving and that is noticeable

[Fallout]

If the disc is bending when you squeeze the lever then something isn't right. It sounds like what you're saying is one pad is coming out and pushing the disc across while the other one is stuck in place. If that's the case it sounds like you'll need to overhaul that calliper and stop those pistons sticking.

It's possible with the right pressure in the brake lines that pad would start to move, but either way a rebuild would be worth doing because its not moving freely. Once you've done it once its easy so it's a good thing to learn.

Also most people will tell you those bleed kits are unnecessary and often don't work. I have to admit though, I used a mityvac when I overhauled my callipers and it made the flushing process really straight forward.

[markc123]

Stuck slider pins? SV is only 2 pot so the slide pins would be my guess based on the bending disc symptom... Sound like they need a strip and rebuild.

[MorganH91]

Sorry, should've been clearer when i mentioned the disc bending. The caliper is stock so only has two pistons, both on the outside face of the disc & both moving freely. If you imagine the right-side caliper's mounted & you're looking down along it, the wheel-side (fixed) pad is only in contact with the disc at it's inner portion, and there's a gap of a couple of mm between the outer edge of the disc & the pad. The fork-side (moving) pad is the opposite, so the disc's surfaces aren't parallel to the pads. Squeezing the brake basically drags the outer edge of the disc backwards in relation to the inner radius of the contact area, which is visible around the whole disc.

Mark - I thought it could be the sliders, but i was able to adjust the mounting bracket along them with some grips. It's like the bracket just isn't at the right angle in relation to the rest of the caliper, as when it's on the forks the pads aren't parallel to the disc.


And I was thinking of getting a vacuum unit yeah - will always be useful & brake fluid tastes foul!

[Biker Biggles]

Is something bent?Like the mounts on the fork leg,or something wrong with the way it is bolted up?

[andrewsmith]

Is something bent?Like the mounts on the fork leg,or something wrong with the way it is bolted up?

I'm thinking the same.
Morgan could you get a couple of pictures put up so we can see

[MorganH91]

I'll try to get some photos up when I get home yeah, thanks guys. I agree it seems like something's bent, I don't think it could be the forks though as they were fine before and the bike literally hasn't moved since I took the calipers off

[Murley.]

I went to put a freshly rebuilt set of calipers on my SV the other weekend and had the same thing happening. Thought it was a bad bleed but turned out that the mounting bracket that the caliper slides on was bent. Changed it out and all was golden. Just pull the caliper off and have a look to see if the bracket is straight.

[MorganH91]

Here's the photos:

http://i1297.photobucket.com/albums/ag22/morganh91/2013-03-25173722_zps5b628ae3.jpg

http://i1297.photobucket.com/albums/ag22/morganh91/2013-03-25173918_zps8054ba0f.jpg

http://i1297.photobucket.com/albums/ag22/morganh91/2013-03-25173858_zps4def3544.jpg


I'm thinking the bracket must be bent to cause the misalignment, I just don't get why i can build up pressure in the system by pumping the lever but it dissipates when released