i have a 2006 street glide and cant keep the front brakes to stop leaking down if i pump them up they hold pressure but as soon as you roll the bike a little you have no pressure on the lever. we have replaced the master cylinder bled the brakes with a mighty vac. perlaced all brake lines on the front. the only thing not new are the calibers. cant find any leaking brake fluid.at my witts end with this thing please help.

 

Only two other items I can think of. First, would be the seals in the calipers. Fairly easy job overall. The second, the copper sealing washers at all of the banjo bolt joints. To me it sounds like air is somehow getting in. My first stop would be the calipers. Good luck.

Neil
RDMC

 

Sticking piston seals in the calipers and worn/dirty/sticking brake pads will also do this.

 

Without an EXTERNAL leak, the master cylinder is about the only option. Do your normal "pump up" procedure and then squeeze the lever gently. See if it bleeds down then. I have seen master cylinders that will hold firm pressure but they bypass around the plunger with gentle application. Yes, I saw that you have worked on the M/C.

There is one other possibility and it isn't a fluid leakage problem at all. If your rotor/rotors are bent they will push the caliper pistons farther back into the calipers as the wheel rotates and then need extra movement/fluid to get pushed out far enough to do the needed braking. If your master cylinder checks good and there is no leak, this is about the only other possibility. Has a new tire been installed lately and the rotor bent while mounting the tire?

 

btsom has pretty much narrowed it down. Did you notice/have any pulsation/surging when applying the brakes? Do you have a dial indicator? Check for run-out (like a warped record on a turntable ). If you have a micrometer you could also check for variation in parallelism ( thicker or thinner in one spot vs another ) If it's not out of spec you could try this. Unbolt the calipers leaving the lines in tact. Insert a spacer between the brake pads to eliminate the "gap" between the pads ( be sure that have spacers in both calipers ) then apply the brake. It will take a couple of pumps to energize the caliper pistons. Then let it sit for a bit ( seconds ). Now activate the brakes and see what you've got. It should be rock solid. If not, it's the master. It has an internal bleed. The original master could have and the replacement isn't functioning properly. Yes it's possible to get a bad master. Hope this helps.

 

Try cleaning your brake caliper pistons. Sticky pistons will give you the exact symptoms you're describing. If there's no actual fluid anywhere, it's the next check and the cost is time only - can be done in 30 minutes.

Lots of info on this elsewhere on the forums. Keep us posted.

 

btsom and Uncle Larry nailed it,you have a bent or warped rotor or both of them are bent.

 

Are you saying that the lever has no pressure, but if you pump the lever you can get pressure for a while, before it goes away? If so you still have air in the system. Try the Sticky in the Tech Brakes section, for a soft front brake.

 

We PM'd ... he has a bent rotor.

 

Thanks - hopefully all will be fine soon!