Hayes bleed trouble

[radam]

I took the collective's advice to try to bleed my own brakes and once I assembled a bleed kit and started to give it a go I thought.. hey, they were right, this is not that hard.

The results I'm getting are sucky though.
Hayes Stroker Ryde brakes. DIY bleed kit with syringes, air tubing and DOT 3 fluid.
I know DOT 4 is probably preferred but when I was at the store last all they had was DOT 3. The bleed kit fits tight on the caliper bleed nipple and fits fairly tight into the master cylinder bleed port. I am collecting the fluid in a regular old soda bottle. I'm using the bleed procedure recommended by Hayes, but I'll summarize here in case my understanding of it is incorrect.

1. Bike in stand, lever higher than caliper.
2. Box end wrench over caliper bleed screen, syring+tubing filled with DOT fluid securely connected to bleed nipple. Fluid degassed prior to connection.
3. Remove master cylinder bleed screen and connect tubing to bleed port to allow fluid/air to drain.
4. Loose caliper bleed screen, push DOT fluid through system using syringe until a stream of clean, air-free fluid is exiting the bleed port.
5. Flick the brake lever a few time to help de-gas the system. Rotate lever on bars to accomplish the same. Tap caliper, brake line and lever/MC to release any trapped air bubbles.
6. Push fluid through once more to confirm all the air is out.
7. Disconnect tubing from bleed port and replace the MC bleed screw.
8. Close caliper bleed screw and disconnect tubing+syringe.
9. Clean up and test.

When I test my work, the pistons move, but they don't move nearly far enough to provide any true braking force. It's almost like I didn't get enough fluid moved into the system... but I can't figure out how to put any more in.

Thoughts? Did I mis-understand the bleed procedure? Do I just need to send a lot more fluid through? I've repeated the bleed process 3 times now with no luck.

[Whiteroom_Guardian]

Maybe Hayes are different (I have only bled avids) but, don't you have to pressurize the system somehow between your steps 6 and 7?

Either way I am curious because I have a set of used Strokers and a bleed kit in the mail.

[Telemahn]

Your problem could be with incompatibility between fluids, purging a few times could help. I had some older Hayes that required pretty frequent bleeding. Here is my method from memory:

1. Bike in stand, lever higher than caliper.
2. Rotate lever so lever bleed port is straight up.
3. Box end wrench over caliper bleed port, syring+tubing filled with DOT fluid securely connected to bleed nipple. Fluid degassed prior to connection.
4. Connect tubing to lever bleed port to allow fluid/air to drain.
5. Loosen caliper bleed port, apply positive pressure to push fluid through system using syringe.
6. Loosen lever bleed port to allow purge of old fluid, push new fluid until a stream of clean, air-free fluid is exiting the bleed port.
7. Tap caliper, brake line and lever/MC to release any trapped air bubbles.
Don't Flick the brake lever a few time to help de-gas the system. Rotate lever on bars to accomplish the same.
8. Push fluid through once more to confirm all the air is out.
9. Close lever bleed port while keeping positive pressure on the syringe
10. Close caliper bleed port
11. Disconnect tubing from both bleed ports and replace the MC bleed screw.
12. Clean up and test.

[drsmonkey]

Sounds like you are doing everything correctly to me.

Maybe the problem is you are expecting more piston movement than they are designed to have. When you are testing things after the bleed are you re-installing the pads and wheel, pumping the brake until you get resistance, then testing? The pistons actually move very very little under use, and the pistons will push out until they meet resistance from the disk, then only retract a tiny bit when the lever is released, < a mm each maybe.

Another thing it could be is that if your pads and/or disk are really worn out, and you are pushing the pistons all the way back in before bleeding, there may not be a sufficient volume of fluid to move the pistons out far enough to make contact. I would think both the pads and disk have to be VERY worn out to get this result though.

2 solutions are possible in this case...the first and best is replace the pads, and measure the disk to make sure it meets the minimum thickness, and if not replace it too. The second is a trick to increase the fluid volume, and it's not a great idea, so I'll skip it.

Hope that helps.

[radam]

I've been putting everything back in to test. The pistons move a bit but it seems like the starting point is too far retracted into the caliper and adding fluid to the system isn't pushing the pistons out any further. The pads are new and the disc is minimally worn. Things moved fine before the bleed attempt. Guess I'll give things another go with some extra attention to pressurizing the system at the end of the bleed (and minus the lever flicking)

[forty]

strokers are a bladder system, takes a while to get them pumped back up to pressure, i did this procedure after a bleed to get back the tight feel i like

press pots all the way in
put pads in, wheel on
place a super thin feeler gauge between disc and pad on both sides
(i used a flexible plastic old ski pass bent around the disc)
squeeze and pump like hell
remove feelers
one strong squeeze and release
another strong squeeze and release
done

this would reset the pots just away from the disc enough to not rub, then when you engage the lever it only moves them a short distance to engage the disc
i had to do this every dozen rides or so as the pots would creep out and rub eventually as they got dirty
worked great on my stroker carbons anyway, good luck

[stuckathuntermtn]

I'm pretty sure there is a big difference between DOT numbers.
(on a related note, how the fuck to they measure brake fluid in yurp?)

[jqualls]

From what I understand there should not be a big difference between DOT3 and DOT4 aside from boiling temps. There should not be a problem mixing the two other then you might notice a bigger drop off when the brakes get hot. Just dont mix with DOT5 which is silicone based and not compatible with DOT3/4. I had Hayes nine brakes a few years ago and used DOT3 fluid without any problems.

[tripice351]

From what I understand there should not be a big difference between DOT3 and DOT4 aside from boiling temps. There should not be a problem mixing the two other then you might notice a bigger drop off when the brakes get hot. Just dont mix with DOT5.1 which is silicone based and not compatible with DOT3/4. I had Hayes nine brakes a few years ago and used DOT3 fluid without any problems.

Small correction - DOT 3, 4, 5.1 are all polyethylene glycol based and can be mixed. DOT 5 is silicone based and cannot be mixed with 3, 4, or 5.1

Sent from my SPH-M580 using TGR Forums

[jqualls]

Thanks for the correction I made the edit.

[radam]

Skipping the lever nonsense and making sure to pressurize at the end yielded a better result, but with a bit of sponginess in the lever feel, so there must be some air in there I didn't quite knock out. I'll give it one more go soon

[zombinate]

while the strokers are a little different, I found this thread more than handy when I was bleeding my nine's:

bleeding the hayes way