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Rear caliper won’t release.


Dotetcher

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Its stupid hot.  But when I wrote that it was 11:30 at night and I was in my underwear.  Not going out into the  mosquito infested regions of my 0.2 acre estate with a flashlight to look at a brake line.  I could be accosted by a bear, a stink kitty, or a whistle pig.  Much too dangerous.

 

And today its raining.  But if Skip asks, I'll go out.

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  • 9 months later...

Ok. It's a year later and still have the same issue. Replaced the pcv and the secondary (front) master cylinder. Still have same problem. Pressure is not being released from the secondary master cylinder to the rear caliper. Is there anything before the secondary master cylinder that would cause it to not release pressure to the rear caliper. Anybody wanna buy a '97 with 123000 miles on it? :)

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Have you cleaned and inspected the bar mounted cylinder?

Did you check the relief passage to see if is clogged?

Edited by XXBirdSlapper
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I believe there is a proportioning valve under the seat that should be considered.

I'll say it again.  You'll save your self a lot of headache by just de-linking.

Then it will be a real motorcycle braking system. 😉

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On 5/30/2019 at 11:00 PM, superhawk996 said:

The feedback from the linked system bugs me, even if it's not actually doing anything bad, it's a little distracting.

It's really distracting when the rear locks up and stays that way.

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A thought just hit me on the dragging rear brake; make sure you're not over-filling the reservoir.  Probably not the problem in this case, but worth mentioning just in case.

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Possibilities: secondary master pushrod length is wrong or the linkage is binding so that it can't release the pressure.  We pretty much know the problem isn't in the caliper since releasing the pressure at the caliper bleeder cures it.  Pumping the secondary and loosening the banjo/bleeder at different points should narrow down exactly which component is causing the bind.  I've heard of hoses on cars getting fucked up internally to where they'll cause a drag.  Throwing that out there because 'nobody' would expect it to be possible, but apparently it does happen.

 

De-linking isn't crazy money, depending on what you think is expensive, but I don't know the price.

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On 6/9/2019 at 7:38 AM, superhawk996 said:

Possibilities: secondary master pushrod length is wrong or the linkage is binding so that it can't release the pressure.  We pretty much know the problem isn't in the caliper since releasing the pressure at the caliper bleeder cures it.  Pumping the secondary and loosening the banjo/bleeder at different points should narrow down exactly which component is causing the bind.  I've heard of hoses on cars getting fucked up internally to where they'll cause a drag.  Throwing that out there because 'nobody' would expect it to be possible, but apparently it does happen.

 

De-linking isn't crazy money, depending on what you think is expensive, but I don't know the price.

If you're not afraid to pop the pistons out of the calipers and re-install, you can do it super cheap.  Biggest expense is a different master cylinder (Ebay).  One from a CBR600F4 looks identical to the Bird's, but is 5/8" diameter instead of 1/2".  The size of the master is usually molded into the casting under the reservoir, so you could use almost anything with that diameter piston.  You could even go with a radial M/C.

Currently, my Bird is de-linked, and using all stock hoses and a Hayabusa M/C.  All you need is some very short 10mm bolts (and likely some new copper washers) to plug the extra caliper holes.  It's likely that you'll only be able to find longer bolts, and then have to cut them down.  I'm lucky enough to have a metric thread file to "de-burr" the ends after hack-sawing the extra length.  I recommend getting some s.s. braided lines for the front to firm-up the feel.

There is a thread on here by Red J in the "Important and useful threads" section, detailing the caliper mods.  You can also PM me, if you have any questions.

Better yet, find a member close to you that has done it, and see if they will help you.

Edited by jon haney
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19 minutes ago, superhawk996 said:

My '01 is de-linked, has the stock 1/2" master, and works just fine so it's not a requirement to change it.

True, but the lever travel was way too much for my tastes.  I even tried a 14mm M/C off a Superhawk, and still wanted more firmness.  Ha, I think I just "chummed the waters" for some ubiquitous .Org humor.

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10 minutes ago, jon haney said:

True, but the lever travel was way too much for my tastes.  I even tried a 14mm M/C off a Superhawk, and still wanted more firmness.  Ha, I think I just "chummed the waters" for some ubiquitous .Org humor.

I've never felt that there was too much travel, but each has their own pickiness level.  It's not awesome like my 999s was, but not bad feeling at all.

 

I got curious so I compared it to my stock '97 and there's a bit less travel and more firmness once the pressure starts rising, guessing because it has braided hoses.  It was already de-linked when I got it.  It's possible that whoever did it didn't drill the calipers so not having those extra pistons to actuate is reducing travel compared to one that is.

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34 minutes ago, SwampNut said:

 

Hmmm.  

I know you're a fan of the LBS, if that detracts from desire no prob.  We're still gonna come out and shoot your gun(s) so you ain't getting out of that.  And I'll probably bring a couple.

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