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Old 10-21-07, 08:38 AM   #1
rankin116
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Hayes HFX 9 caliper rebuild and bleed issue

So long story short, I had to rebuild a caliper on my HFX-9's and replace a master cylinder cap on the rear only. And I bled both front and back because they were squeezed when off the bike. Now they both seem to be "looser" Before, the lever would only travel a short distance before engaging, now it seems like there is a lot of dead pull. I also put on all new pads. I searched and found this thread.

My question: is this just a poor bleed job, or could something else be causing a problem? The directions for the repairs I made were straight forward and easy, I'm 99% sure I followed them correctly, but I can't rule out completely that I did something wrong. The brakes work, but they don't feel like they used to, and that bothers me. Advice? Opinions?
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Old 10-21-07, 10:02 AM   #2
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Originally Posted by rankin116 View Post
...Before, the lever would only travel a short distance before engaging, now it seems like there is a lot of dead pull.

My question: is this just a poor bleed job, or could something else be causing a problem? Advice? Opinions?
You may have to separate the problem into either:

1) too much dead pull: the lever travel is regulated by operating the 2mm hex socket (Allen) screw at the lever pivot. Turn it clockwise and the lever engages with less travel. This is a matter of personal preference.

2) spongy lever feel: caused by air in the line, which will need more bleeding.

Once the pads engage the calipers (regardless of how much the lever travels), does the lever pull feel solid or does the lever feel mushy and continue to compress? This is an indication of #2.

It sounds like you have #1, which is the easier to fix.
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Old 10-21-07, 02:50 PM   #3
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You may have to separate the problem into either:

1) too much dead pull: the lever travel is regulated by operating the 2mm hex socket (Allen) screw at the lever pivot. Turn it clockwise and the lever engages with less travel. This is a matter of personal preference.

2) spongy lever feel: caused by air in the line, which will need more bleeding.

Once the pads engage the calipers (regardless of how much the lever travels), does the lever pull feel solid or does the lever feel mushy and continue to compress? This is an indication of #2.

It sounds like you have #1, which is the easier to fix.
Why would that change if I bled the lines correctly?

After reading your reply, I went and squeezed the handles, and I think the front may be bled ok, but the rear did feel a little spongey. I would squeeze, and when I felt resistance, if I really cranked down, the lever would continue to compress. And I wasn't going crazy, it was just a normal, hard squeeze I guess.

So I think I should re-bleed the line. It pisses me off though, I read the directions, and did exactly what they said. Maybe I'll follow those different ones in thread I linked to. Thanks.
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Old 10-21-07, 06:08 PM   #4
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Why would that change if I bled the lines correctly?


...I would squeeze, and when I felt resistance, if I really cranked down, the lever would continue to compress. And I wasn't going crazy, it was just a normal, hard squeeze I guess.

It pisses me off though, I read the directions, and did exactly what they said. Maybe I'll follow those different ones in thread I linked to. Thanks.

The lever travel (#1) is completely independent of the bleed process/quality (#2). And if you didn't operate that screw, then is should remain the same. I will note that on the earlier versions of the HFX 9's, that lever travel screws has a nasty habit of backing itself out. Bad enough that I carry a 2mm hex key in my Camelbak. However, now, I dab a bit of thread loctite onto the screw. It's a bit of a pain since it's hard to keep the loctite away from the lever pivot. Perhaps that screw on your system backed out during all the lever squeezing during the bleed process.

The old thread you linked in your original post was started by me years ago, and was a result of my frustration of taking many hours to successfully bleed the system. One thing I recalled was the instruction were a bit off. I believe it read to keep the bleed port on the reservoir level, but in actuality, I believe I rotated the lever and pointed it upwards, to ensure it was the highest point of the entire hydraulic system. Remember, you want air to escape the system, and that happens only if you let the air a path to escape - thus the bleed port should be the highest point.

If the levers continue to travel (feel soft) after the pads contact, it does sound like air in the lines, so a re-bleed is necessary.

After I successfully bled them years ago, I never touched them again, fearing a repeat of my previous experience. The good news is, I never had a reason to bleed.

One bit of good news is you can use automotive DOT 4 brake fluid, which is relative cheap and easily purchased and ubiquitous. There is no need to buy Hayes specific oil, although they do sell it. Other brands, like Shimano, require their specific fluid, which is expensive.
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Old 10-22-07, 06:42 AM   #5
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thanks for the help. I'll see what I can do using your old directions.
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Old 10-22-07, 08:25 AM   #6
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thanks for the help. I'll see what I can do using your old directions.
It seems the best luck is to use the syringe method to force fluid through the system, see recommendations on that old thread. If I ever have to bleed my brakes, I will try the syringe method.
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Old 09-10-08, 03:21 AM   #7
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Hi

I've got a similar problem. My son took the front brakes off his bike (Hayes 9) cause he had bent his rotor and wanted to ride anyway! We took the pads out 'cause they had nothing left. But the brakes were pulled while off the bike and I really had to work to get the pistons seperated. When I did get them apart I couldn't get them to both sit right back (which is what I needed to get the new brake pads in).

I let a little fluid out of the system and this let me get the pistons right back and install the new pads. I bled the system (using the syringe method) and that seemed to go fine. When I pull the brakes now nothing seems to happen - sure the pads move a tiny amount but nowhere near enough to actually engage the rotor (we're talking a fraction of a millimetre here). So what have I done wrong?

I've tried adjusting for dead pull, I've tried pumping the brakes, nothing seems to make any difference.

Any suggestions?
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