bleeding brakes -help!
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Road Warrior
Joined: Mar 2012
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From: USA
bleeding brakes -help!
I bled the brakes on a 2005 fatboy that uses DOT 5 fluid. Problem I'm getting is spongy brakes. It seems like i have to pull the lever in half way before I get any braking.
I have even reverse bled using a syringe and clear tubing, and have gotten all air out (as best I can tell) and the problem persists.
Now I'm not sure if this is just how DOT 5 feels compared to DOT 4? I've read that DOT 5 feels more "compressible"?
Another thing is if the fluid is topped off and I hold in the lever and bleed some fluid out of the valve, then close the valve and release the lever, all breaking pressure is lost. I have to pump a few times to rebuild the pressure up. Does that mean air is getting into the system?
I'm trying to rule out whether it could need a master cylinder rebuild, so any help anyone can give is appreciated.
I have even reverse bled using a syringe and clear tubing, and have gotten all air out (as best I can tell) and the problem persists.
Now I'm not sure if this is just how DOT 5 feels compared to DOT 4? I've read that DOT 5 feels more "compressible"?
Another thing is if the fluid is topped off and I hold in the lever and bleed some fluid out of the valve, then close the valve and release the lever, all breaking pressure is lost. I have to pump a few times to rebuild the pressure up. Does that mean air is getting into the system?
I'm trying to rule out whether it could need a master cylinder rebuild, so any help anyone can give is appreciated.
Last edited by izzyryder; Jul 11, 2012 at 12:50 PM.
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Road Warrior
Joined: Mar 2012
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From: USA
They haven't been bled since 2004..also the bike is a 2005... I've edited my above post. But it was done strictly for maintenance purposes. It's my father is law's bike, so having not been familiar with the feel of the brakes before hand is making me wonder if there is even an issue.
Grand HDF Member
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From: On the Front Range, CO
Another thing is if the fluid is topped off and I hold in the lever and bleed some fluid out of the valve, then close the valve and release the lever, all breaking pressure is lost. I have to pump a few times to rebuild the pressure up. Does that mean air is getting into the system?
Need some more details, like why you did it.
Does the spongy feeling return immediately? Is it during a ride?
If you aren't bleeding the brakes with a second person to help, you could be doing an inadequate job as you just don't have enough hands!
If the spongy feel comes back during a ride, you could have a warped rotor, which would push the pistons back into the caliper, requiring a few pumps to push the pads back to the router.
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Road Warrior
Joined: Mar 2012
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From: USA
I did have a person helping. It was done just as a preventative maintenance issue (old fluid).
The brake lever doesn't become any more or less spongy after pressure builds up..it just stays that way. Even after riding, it doesn't get better or worse, just stays the same. It brakes fine, it's just that i have to pull in the lever halfway before it starts to grab. On my Harley (2010 -DOT 4) it grabs almost right away.
So is that just how a pre 2006 softail brake feels like? Could the DOT 5 have become aerated?
I am doubtful that it is the master cylinder as i cannot pull the lever to the grip, even if i hold it using pressure.
The brake lever doesn't become any more or less spongy after pressure builds up..it just stays that way. Even after riding, it doesn't get better or worse, just stays the same. It brakes fine, it's just that i have to pull in the lever halfway before it starts to grab. On my Harley (2010 -DOT 4) it grabs almost right away.
So is that just how a pre 2006 softail brake feels like? Could the DOT 5 have become aerated?
I am doubtful that it is the master cylinder as i cannot pull the lever to the grip, even if i hold it using pressure.
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Road Warrior
Joined: Mar 2012
Posts: 1,514
Likes: 88
From: USA
If i take off the caliper and look at the pads, it looks as if they are crooked (for example, the top end of the pad is closer to the caliper than the bottom half) If that makes sense..
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The brake should feel the same, from your bike to his. I have an 06 with dot 5 and it starts to grab instantly. There is not any real difference in the feeling of the brakes from dot 4 or dot 5.
When I replaced my brake line, the brake felt exactly the way you are describing your issue.
I was really careful to back fill my system, so I would not introduce any air into the caliper. I still did, I don't think it was any more than a small bubble, that was somewhere in the caliper. I had to pull the caliper off compress the pistons, pump them back, bleed, and do it about 3-4 times before I got the air out of the system. I used a full bottle of brake fuild.
I am not going to take a screw driver to my front brake, but I bet you can just pry the pads back and work the brake and bleed them.
Make sure you are bleeding them correctly. If you open and close the bleeder, without fluid still spraying out, you could be sucking air back in.
Honestly, the next time I have to replace or rebuild a master cylinder, I am going to buy a brake vacuum system. They are 20 bucks about anywhere from sears to harbor freight.
When I replaced my brake line, the brake felt exactly the way you are describing your issue.
I was really careful to back fill my system, so I would not introduce any air into the caliper. I still did, I don't think it was any more than a small bubble, that was somewhere in the caliper. I had to pull the caliper off compress the pistons, pump them back, bleed, and do it about 3-4 times before I got the air out of the system. I used a full bottle of brake fuild.
I am not going to take a screw driver to my front brake, but I bet you can just pry the pads back and work the brake and bleed them.
Make sure you are bleeding them correctly. If you open and close the bleeder, without fluid still spraying out, you could be sucking air back in.
Honestly, the next time I have to replace or rebuild a master cylinder, I am going to buy a brake vacuum system. They are 20 bucks about anywhere from sears to harbor freight.
Last edited by tlb; Jul 11, 2012 at 02:10 PM.
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Grand HDF Member
Joined: Jun 2009
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From: On the Front Range, CO
Could you elaborate more please? Do you mean bleed the system, push them back, then refill? Or do you mean something different?
If i take off the caliper and look at the pads, it looks as if they are crooked (for example, the top end of the pad is closer to the caliper than the bottom half) If that makes sense..
If i take off the caliper and look at the pads, it looks as if they are crooked (for example, the top end of the pad is closer to the caliper than the bottom half) If that makes sense..
Basically, remove the caliper from the fork, and remove the pads.
Remove the master cylinder cover.
Compress the pistons in the caliper all the way back into the caliper.
Button everything back up, and re-bleed the brakes.
