Soft Front Brake Pull

[RibEye]

RibEye,

In my experience with a similar situation that you describe, I bled and re-bled, left the cap off over night with the lever tied, etc. I tried most tricks. I finally removed calipers from fork one at a time. I removed the pads and cleaned the pistons as you describe. I pulled the brake lever carefully using a block of wood so as to not allow the pistons to pop out. I cleaned them and removed master cylinder cover and pushed them back in. I found a huge air bubble behind the the top piston on the right hand caliper. When i forced piston back in, I could hear the bubble travel up to the MC. It helped a tremendously. My brake pull is still very good.
If you look at the bleed point on the caliper and the location of the top piston it would make sense that you could pump 10 gallons of brake fluid and never get rid of that bubble. trapped behind the piston and it is higher than the bleed point and out of the fluid flow.
Also.
This months American Iron Magazine's Hog Helpline article has a write-in question with a similar issue as ours with an 04 RK. The author states that many 03's and some 04's had a different master cylinder on them that causes the condition you describe. The fix is to replace MC with the newer style #45013-96D. I have not tried this but sounds logical. He states the bleed holes in the MC are different.

Hope that helps and let me/us know how it goes,

Bodeen

I had new Lyndal Z+ brake pads put on all three calipers. In the process, I had them clean all the pistons. Braking is like new, with little lever play. Could be because the new pads are full thickness. We'll see if they auto-adjust as the pads wear...

Enjoy,
Rich P

 

[Bodeen]

Rich,

Report back your experience over time. I would be interested to see if your front goes back to the same old thing. If so, I would try replacing the MC.

Thanks,

Bodeen

 

[Brutal FXDX]

One trick that i use is reverse bleed or back bleed. Remove the calipers from the disc and pump the lever until the pads are touching each other. If you have dual disc start with the farthest caliper and spread the pads back out with a scraper. Sometimes perform twice for best results. Makes the lever feel solid again.

Also i read on here that you should only use dot 4 with the brembos on touring models. im using touring brembos and master cyl on my fxdx with dot 5 in them. I rebuilt the master cyl but the calipers were purchased new so i didnt see a need to rebuild to use dot 5. ive always liked dot 5 better. JD

 

[judgeman6970]

another very helpful thread....just finished installing new tubes, tires, rear brake pads & front fork oil on my '01 RKC, but now my front brake lever seems to have "excessive" travel. I think I'll pick up some new front pads, brake cleaner & fluid, and dig in to this "caliper/piston cleaning & fluid change/bleed" project next

 

[judgeman6970]

another very helpful thread....just finished installing new tubes, tires, rear brake pads & front fork oil on my '01 RKC, but now my front brake lever seems to have "excessive" travel. I think I'll pick up some new front pads, brake cleaner & fluid, and dig in to this "caliper/piston cleaning & fluid change/bleed" project next

front brake job completed, and no more "excess lever travel"....I think its finally time to ride the bike again & put the tools away for "awhile"

 

[Mad Greek]

My fellow Riders
I paid enough money to fix the soft front brake on my FXDC 2005.
28 euros for each bottle of brake fluid DOT 5 from HD dealer,(I bought 2) and some euros for the technician to flash and clean the front brake system but nothing the soft brake was existed. I follow the direction of the Chopper and the "TRICK" works! The brake is normal now!
CHOPPER thank you for your advise.

 

[glider]

Good tip and it works too. It's posted in the self help area as well.

Harley Davidson Community

 

[brownfoxx1]

use a5' piece clear tubeing and bleed the fluid back into the resivor. then just slowly keep bleeding till all the air is gone. just a suggestion.

 

[RibEye]

I had new Lyndal Z+ brake pads put on all three calipers. In the process, I had them clean all the pistons. Braking is like new, with little lever play. Could be because the new pads are full thickness. We'll see if they auto-adjust as the pads wear...

Enjoy,
Rich P

Rich,

Report back your experience over time. I would be interested to see if your front goes back to the same old thing. If so, I would try replacing the MC.

Thanks,

Bodeen

Follow-up: Here I am, 13 months later, and the problem has not returned. The Lyndal Z+ pads do not generate the dust that the OEM pads did. They are quiet, and work great. I think that since the pads don't dust like the OEM, that the dust does not accumulate and bake on to the pistons, causing them to stick to the rubber seals, which then pull the pads back in too far to allow the brakes to auto-adjust as they ought.

Just my own mental image of the problem...

Enjoy,
Rich P

 

[RibEye]

I had new Lyndal Z+ brake pads put on all three calipers. In the process, I had them clean all the pistons. Braking is like new, with little lever play. Could be because the new pads are full thickness. We'll see if they auto-adjust as the pads wear...

Enjoy,
Rich P

Rich,

Report back your experience over time. I would be interested to see if your front goes back to the same old thing. If so, I would try replacing the MC.

Thanks,

Bodeen

Follow-up: Here I am, 13 months later, and the problem has not returned. The Lyndal Z+ pads do not generate the dust that the OEM pads did. They are quiet, and work great. I think that since the pads don't dust like the OEM, that the dust does not accumulate and bake on to the pistons, causing them to stick to the rubber seals, which then pull the pads back in too far to allow the brakes to auto-adjust as they ought.

Just my own mental image of the problem...

Enjoy,
Rich P

Just checking back in, 22 months later.

The Lyndalls are still strong, quiet, and relatively dust free. The brake lever and response are still well within normal. The brakes are still auto-adjusting correctly.

My understanding is: The pistons had baked on dust and grime. These lines of baked on muck had slipped inside the rubber piston seals. The brakes could be pumped up and will work well while pumped up. After sitting for a bit, the rubber seals drag the pistons back in too far, acting like retraction springs, having been hooked on the baked on muck lines.

I won't be going back to OEM pads. Keep your pistons clean.

Enjoy,
Rich P