Front disc brake issues

[hiddenyeti]

I have a 1974 Eldorado Civilian Police that I converted to dual disc, but here's the catch: I can bleed the brakes  to no air and the lever is solid but as soon as the bike moves, the brake lever goes right to the handlebar.  I have verified that the calipers are functioning correctly, taken apart and reassembled the front wheel, but nothing I do makes a difference.

The wheels were re-laced during the restoration and only have 500 miles on them at this point.  I checked the rotors and they seem true (both have the same 500 miles on them). It really feels like something is pushing the pucks back in the caliper and I'm left with the wheel not turning true. 

Before I send the wheel out to be checked, does this seem like the correct next step?  Am I missing anything?  Anyone had this happen to them?

Lastly, at some point I'll relate the fun I am having with the Yellow/Black SP I bought this spring.  For now I'll just say, some people should not be allowed to work on bikes and whoever did this bike wrong should be banned from owning tools and bikes in the future. Everything we touched led to new "fresh hells" as we came to call them.  It should finally be ready to ride again by the end of the month.  Wish me luck.

[hiddenyeti]

I'm using 2 F08's with a 15mm master cylinder and yes, I've felt a pulse when the brakes do (eventually) grab which lead me to suspect the wheel.    No wobble in the front end.  As best as I can test the rotors, they look and test true.

I guess I'll start looking for someone semi local who can true up laced wheels and hopefully verify the rotors at the same time.

[n3303j]

Get your hands on a dial indicator and indicate the disk face while spinning the wheel in the fork. Also get a micrometer and check that disk sides are parallel. Also if you have floating disks check that buttons allow the disk to float so it trues itself when braking and remains true when brakes are released.

[moto-uno]

  If the lever pulses at all , you have rotors that are not flat . As mentioned above , get a dial indicator and check
them . .005" and above is not good . And that's not that easy to see by just spinning the wheel .  Peter

[1down5up]

Save your pennies and dont send them back to the wheel guy -  its got nothing to do with how they are laced. Disks mount off the hubs which are (or should be) square to the forks by being compressed via the spacer/axel and the bearings.

You wither have warped disks or the disks ant sitting flat to the hubs

Prop the front of the bike up and spin the wheel, identify the high/low spot and then take the disk off, see if its warped or if its not sitting straight/shuart on the hub

If its pushing the pads back enough you go to the handle bar it will be visible by eye, but can also go down the dial indicator route as well if you want to know how much and exact high spot.

[Tom H]

If you don't have a dial indicator. A jack stand, block of wood, ect that is the height of the bottom/midpoint of rotor. Take a marking pen and hold it on the stand. Spin wheel and SLOWLY move the pen in to the rotor. If reasonably straight, a line will be all around, warped will have a section missing the marker.

Then follow previous directions to see if rotor is warped, or just not seated on the hub evenly.

Tom

[Sye]

If the discs are warped, then you will get pulsing but the leaver will still be firm. If the lever goes all of the way back to the bars there are only three possibilities.

1) Fluid is leaking past the caliper seals but this would be obvious and noticeable.
2) Fluid is returning to the master cylinder when under pressure, due to a faulty return valve or incorrect installation of the seals.
3) Air is still in the system somewhere.

[acogoff]

     My vote is a master cylinder internal leak that only happens when in one particular position.

[Stretch]

Vote #2 for rebuilding and cleaning the internals of the front master cylinder.

                                                                 -Stretch

[MattP]

I think a and b  but mostly the master cylinder.