Thanks!

The pistons will move at different rates based on the friction. They are all the same size.
As one piston/pad makes rotor contact the resistance increases, then next makes contact etc. Passages are good in the calipers.

Something changes during the tightening and loosening of the calipers.

was thinking line restriction as the pad and pistons slightly retract when tightening on the inboard side. Then the fluid is not returning to the master. Took the cap off to eliminate the compensating port. Thinking lower line..........

 

For me, at least, anything "upstream from the caliper should affect both sides of a properly functioning caliper equally. In your case, the inner side pistons are not extending to match the outers, this suggests an internal caliper problem to me. If there were a return problem with the hose, the caliper would clamp, but not release. The second and subsequent lever pulls would be solid, not spongy. The spongy lever also eliminates the equalization port as being a problem.

I have never split the caliper assembly, but I can't help but suspect something between the halves is not correct, something not drilled or cast correctly, or perhaps some sealing material plugging or restricting a passage. Also, I don't know if the banjo bolt passes fluid into the caliper through holes in the side of the bolt or if the bolt is hollow for its full length and fluid exits from the bottom, much like the bleeder screw. If the fluid exits from holes in the side of the bolt, one of the holes could be plugged or aligned against a spot which blocks fluid flow.

The need to modify the banjo fitting is still a concern. Perhaps fluid flow is not as "relieved" as you believe. Are you using the banjo bolts from your previous calipers or did the new ones come with their own bolts?

 

I am still suspicious of the need to drill out the lower lines. I am betting this may be the issue. My 2 pennys FWIW......
I did the exact same swap on my 06. All parts bolted up without any issues. Replaced everything including the master to the rotors. All were from a 2011 Street Glide.

 

I gotta give it to the OP. By this time I would have thrown that sh*t in the trash and put the stock brakes back on.

 

I've been following this thread but haven't had any real ideas to contribute so I've been sitting on the sidelines. I doubt that the issue is with the line or banjo fitting that you modified and I'm more inclined to agree with btsom and direct the fault at the caliper.

Anyways, I did think of something here so I'll throw it out for your consideration. Before I do let me make this comment... A slight misalignment from left to right shouldn't have any effect as the pistons should compensate for that.

Now here's what I'm thinking. And this is simply speculation but worth a try at this point. There may be some misalignment at the mounting points themselves. If so, when you tighten the caliper you are possibly distorting it somehow and potentially binding the pistons on one side. To check this out here's what I would do... Tighten the caliper to the forks using only one of the screws. Then look at the other mounting point and see if you have a significant gap. Repeat by loosening and then tightening the other bolt. I'm thinking that when you torque the caliper in place you might be flexing the housing such that you're creating a bind on one or more of the pistons.

Longshot but worth a look at this point. And if this is in fact the problem a simple shim at one or the other of the mounting points could be the fix.

 

Well at this point I have ruled out the complete hydraulic system. It is working as designed. The problem appears to misalignment of the calipers/ pads to the rotors. During all of this I have attempted shimming the calipers and manipulated the wheel spacing etc. With no results.

But came back to the fact that everything works fine when loosened off. Visually everything seems aligned and centred. Any lateral alignment will and can be compensated for by the pistons movement,under one condition. The caliper and rotor HAVE to be on the same vertical plane.

The reason for the rotor flex is a bit complicated. The pads/pistons at 11 and 5 o'clock are off the rotor by .010. The remaining area of the pad is in contact with the rotor. The force in the system is equal to the pressure x area(piston). Piston movement is based on diameter and opposing resistance to movement.

Applying the brake causes the following: the pistons/pads at 1 and 7 o'clock touching the rotor, encounter the resistance of the rotor. The rotor then flexes due to the .010 clearance between the opposite pad. The pistons at 11 and 5 don't move because their opposing resistance is higher than the others. ( they would have to bend the pad backing plate which would require greater force than what is required to flex the rotor)

In fact the moving pistons are applying a counter force to the 11 and 5 pistons through the tilted pad. If you watch real close you can see those pistons retract.

Sliding .010 feeler gauges between the pads and rotor at 11 and 5 solves the problem. Hard lever no rotor flex!

Now the fix. Close inspection of the pads (new Lyndal Z)reveals the following: with the friction surfaces together and pinching them at end shows a gap between them. On the backing plate side they appear slightly bowed in the centre. I need to look into this further. Also I'm going to try and shim the calipers again.

After that its time to toss the calipers as they maybe distorted at the mounting area.

I'll post back my findings later.

Thanks

 

I had a similar problem on a Honda VTX. I tried everything you have mentioned but still the brakes weren't firm. I shimmed the caliper as best I could and just rode the bike. Eventually the brakes improved as the pad material wore down. I hope this helps.

Al

 

One more thing just occurred to me. The anti rattle spring is solid all the way across on one end but has separate tabs on the other end. Have you checked to see if the tabs on the inner side have gotten wedged down where they don't belong and are impeding pad movement? IIRC, the tabs should press against the backing plate and not fall down onto the pad material or get wedged between the caliper and the backing plate. Did the calipers come with the springs or are you trying to use the old springs on the new calipers. Just another random thought. Have you tried installing the whole shebang minus the anti rattle springs to see what happens? Does the pin slide in easily or does it bind and require considerable force to get back in position? On mine, if I press on the pads against the anti rattle spring, the pin slides right in with no binding.

 

guys, wondering if someone could help me out with some numbers. I need the following:

1. The width of the mounting ears on the Brembo caliper.
2. Rotor width.
3. Caliper Centering on an 07 or earlier bike. Are your rotors centered between the caliper bosses or off to one side.

much appreciated!

I found 2 Quad seals that seem different than the others and now waiting for a seal kit.