Mountain Bike Reviews Forum banner
1 - 20 of 44 Posts

·
Registered
Joined
·
66 Posts
Discussion Starter · #1 ·
I thought I was fairly competent when it comes to mechanics. At least on cars and I didn't think these disc brakes would be so complicated.
The Hayes instructions stink to high hell and the illustrations are useless. I tried bleeding my own Hayes 9's and can't do squat. Anyone have better instructions or a pictoral? thanks.
 

·
Meh.
Joined
·
17,508 Posts
Use a HUGE syringe. Degas the fluid in the syringe. Push fluid through the caliper bleed nut. Force it out the bleed hole at the lever (pointed up). Have the fitting in place with something to catch the overflow. Keep going till no more bubbles come out, or before you run low on fluid in the syringe. You may need to tap the lines to get stubborn bubbles.
 

·
Registered
Joined
·
1,600 Posts
Also make sure you have the lever as high as possible, and the caliper as low as possible. In addition to flipping the brake like a few times to get air bubbles out, I also actuate the lever a few times also. A syringe will work better, but I haven't had any problems with the bottle. Try putting a small zip tie around the hose where you inserted onto the bleeder valve, that will get a pretty tight seal on there.
 

·
ride hard take risks
Joined
·
25,423 Posts
Be shure the master is pointed up & is the highest point, your bleeding up hill on these puppies. This pic is in the normal possition because i was to lazy to rotate for a pic. If you have a problem with hose expanding from the fluid go to the pet store & get air hose for a fish tank, works awsome & the fluid doesn't cause it to swell for a long time. :)
 

Attachments

·
Registered
Joined
·
66 Posts
Discussion Starter · #5 ·
I don't know which bolts to loosen etc. The instructions have no illustration as to where the bleeder screws are at and what not. I know the caliper from the MC but other than that I don't. I've never worked with disc brakes on a bike.
 

·
ride hard take risks
Joined
·
25,423 Posts
On the caliper there is a hex tube with a rubber cap, that is were the fluid goes in. Looking at the master on the right is the lever then a phillips screw then a plug, remove the plug & install a bleed addapter & hose going to a catch tank. The HFX-9 has the blader directly under the plug so you need to push it in very straight, it sux. :)
 

Attachments

·
Singletracker
Joined
·
410 Posts
With your bleed kit you should cut the hose in two aswell.

For the lever, you use the silver adapter that comes with the kit. Plug that one end into the hose tightly, then using a phillips head screwdriver, pry the rubber cap off that is between the two hex screws. This cap just prys off and on so dont worry.

Then insert the fitting into that hole, run the rest of the hose into an overflow bucket like shown above.

-----

At the Caliper, with the second bit of hose you have cut (this should be much smaller in length though) fit it to either the bleed bottle OR the syringe (which ever way you want to do it). The other end of the hose will just fit nicley over the 'plug' on the caliper, just make sure its seated.

Before openeing the bleed valve at the caliper, remove the air in the hose connected to etiher the bottle of syringe. The using a 6mm i think spanner end open the bleed valve 1/4 turn to 1/2 turn...now you can follow the instructions Hayes have given you and you should be right.
 

·
Registered
Joined
·
1 Posts
have done all this with copious amounts of brake fluid squirting all over an antique asian rug, I'd cycle off sharpish before my wife comes in and sees the mess but my brakes are still as spongy as santas sac the day after christmas.Does it help if the hose runs uphill all the way to top bleed hole?
 

·
Registered
Joined
·
1,939 Posts
kwest10 said:
I thought I was fairly competent when it comes to mechanics. At least on cars and I didn't think these disc brakes would be so complicated.
The Hayes instructions stink to high hell and the illustrations are useless. I tried bleeding my own Hayes 9's and can't do squat. Anyone have better instructions or a pictoral? thanks.
What I have found out is that you can not remove all the air from the system by pushing it in the caliper and letting it flow out the lever. You also have to pull a suction on the caliper to get entrapped air out. This is key. This is explained in the Hayes bleed instructions by squeezing the bottle for 5 seconds, and letting it return to its original shape to draw air out. You can do the same with a syringe. I found this out the hard way after much time was wasted. Another tip with the Hayes bleed kit that isn't covered in the instructions: slide the spring on the end of the bottle hose, put the hose on the bleeder fitting, and slip the spring over fitting. It keeps the hose on the fitting so it doesn't come off and make a mess.
 

·
Registered
Joined
·
1,939 Posts
2 problems I see: They say to remove the caliper from the bike but the illustrations show it clearly attached. Also, they do not pull a suction on the caliper to remove entrapped air, like the Hayes manual says. Perhaps if the caliper were properly oriented the air can be pushed out to the lever; don't know. The bit about the old pads and spacer is good, as you can easily pump out a piston by stroking the lever, with the bleed screw open and pressure applied to the syringe (happened to me).
 

·
The Quimby!
Joined
·
366 Posts
aznsap said:
this looks a lot easier to do than bleeding brakes on a car.

when are you supposed to bleed the brakes on a bike?
I was actually thinking the other way Aznsap. Bleeding car brakes is easy, just pour fluid into the reservoir, press the pedal, open the bleed screw on the caliper to let fluid through, retighten the bleed screw, release the pedal and repeat. All you need is brake fluid, a short length of clear plastic hose, an old plastic bottle and a ring spanner.

I am constantly amazed by the myriad of complex techniques and equipment needed to bleed bike brakes given that they are very similar to car brake systems in principle. The technique and equipment required to bleed Juicy's makes you think that you are performing open heart surgery with electron microscopes :D .
 

·
Nice no rass
Joined
·
682 Posts
Following JM's post, I just bled my 9's and replaced the pads for the 1st time. It couldn't be any more simple, thanks for the post. Haye's instructions in the bleed kit do kind of suck. I also bypassed the supplied bottle and went right to a syringe. It was too easy.
 

·
ride hard take risks
Joined
·
25,423 Posts
aznsap said:
this looks a lot easier to do than bleeding brakes on a car.

when are you supposed to bleed the brakes on a bike?
I find doing brakes on a moto so much easier than a bike, like JM says it's like performing heart surgery.

Realisticly you should be replacing the fluid once a year, i probibly do it every 2 years if im not feeling lazy. :)
 
1 - 20 of 44 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top