Rear brake dragging - SMS!

ghetto_d

ghetto_d

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(SMS = Save My Sanity)
Looking for advice
This winter, I removed all brake components from my genII. Started out as just a disassembly/cleaning/replacing fluid, but I ended up replacing levers, rearsets, lines. Cleaned up rotors, calipers. After tons of bleeding, I couldn't get the rear brake to stop dragging, nor firm up. At this point, I have also rebuilt the rear caliper and master cylinder, in an effort to eliminate the rear brake drag. Fronts gave me no real hassle, and are done.
Currently, the rear is still dragging, causing a hot rotor within a ten minute stroll (with NO use of the brake). If I do use brake, brake pedal is too soft to do more than slightly slow the bike.
Sounds like air isn't allowing the piston to retract fully, right?
After using a mityvac to draw fluid through the ccomponents, I bled at master cylinder, and both points on caliper (line inlet & bleeder). Been resorting to pushing fluid out via pedal pressure, as I just had 2nd mityvac fail on me. Have tapped on components to move bubbles. Have put several reservoirs of fluid through system. And here we are...
WTF! ANY IDEAS??
 
After a rebuild of the caliper and still having it grabbing, I'd just ditch the caliper completely and jump on Ebay to get a used rear unit and be done with it. I'd say that somewhere in the piston bore the piston is getting hung up. A used unit won't be all that much money and you'll be back on the road quicker than trying to do another rebuild. Just my two cents bud.
 
Would it help to state that there's only 8k on her clock ; the piston looked new still. Absolutely no buildup. I properly lubed the components when rebuilding them. The only thing I haven't tried is taping the threads of bleeder.
 
Hey Getto once the caliber gets really hot the new seals are shot . I had a problem like this and i was sent the wrong seals with the right part number on the package . PIA
GOOD LUCK


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make sure the rear set is position properly and not engaging the rear brake. you can put a spring on the mc to keep the brake lever pushed fully open in case its not. its not fluid doing that to you but something else not done right. test the caliper with it off the bike. or, just buy a new one.

also, did you use new or old pads?
 
These are the same old pads, they have a lot of life left, but certainly aren't as thick as new pads.
The caliper really isn't getting hot, just the rotor. I think I'd be more worried about frying the wheel bearings before the caliper seals.
The rearsets brake pedal is allowing the MC to operate fully, I'm certain, but I suppose I could disconnect it to be sure.
 
How much is it dragging, you say the rotor gets hot, but not the caliper. There is often a slight drag of pad against rotor.

Was it definitely not doing it before?

If it is a slight drag, maybe you should just ride it more and see if over time any bubbles work out with use and it firms up the lever.

If it didn't drag before, Mike (Loosenut) has a good point.
 
It is dragging too much to ride; it gets rotor too hot to touch after just a few minutes. Once rotor heats up, pads constantly have a slight squeal. You can feel it just a bit when riding.
Someone else suggested the wheel spacers, but I don't think that's even possible. I haven't checked it out yet though. I just recall the two spacers being considerably different. At this point I'd might as well check...
 
Dustin said:
Could chain alignment/wheel alignment enough to cause the brake to drag?

Are you positive everything is straight and true?
Click to expand...

I'm confident that everything is in the right place and adjusted properly. However, tonight I'll pull the wheel off and double check the spacers.
 
I get a hot rotor on my gen1 as well even without using the brake at all. I can move the rear wheel with my hand ok when the bike isn't running. It will do about one revolution if I spin the tire with my hand. I've just sort of lived with this issue.
 
roggiedog said:
I get a hot rotor on my gen1 as well even without using the brake at all. I can move the rear wheel with my hand ok when the bike isn't running. It will do about one revolution if I spin the tire with my hand. I've just sort of lived with this issue.
Click to expand...

yeah, i get about 1 revolution when spinning the wheel by hand. seems acceptable, considering the chain drive and all, but then i go ride it, and...

so no problems with rotor warping, or frying the wheel bearings, etc??
 
FZ1inNH said:
Just reading through this and I'm with Dustin... the rear wheel may have the spacers on the wrong sides and/or is not aligned properly. Make sure the spacer with the flange is on the sprocket side and the one without is on the brake side.

Reference this exploded view: 2013 Yamaha FZ1 (FZS10D) Rear Wheel | Part Shark
Click to expand...

funny little fact: the earlier genII's had flanged spacers on both sides. dunno why the later ones employ a different spacer...
nonetheless, spacers are definitely on the correct sides.
 
at this point, i have torn the entire rear brake system off the bike (again). going to redo it all one last time before i completely throw the towel in. i am taking this opportunity to replace the banjo bolts, and possibly the bleeders. the crush washers are shot as well.
current banjos are the AL ones from spiegler; I knew i'd need to be real careful with these fasteners, but with all this work being done, they are already marred up. Considering the level of use, as well as the amount of torque required, i don't feel that AL is a good choice in material for this application. I believe i'll replace them with polished SS buttonhead bolts from Venhill.
As for the bleeders, has anyone any experience with either the Speed Bleeder valves, or the Stahlbus bleeder valves?
(respectively):
https://www-speedbleeder-zoovy-com....1oIatVP1dTmjJez/s=www.speedbleeder.zoovy.com/
Bleeding brakes - The stahlbus bleeder valve

As a side note, i was reading through the thread regarding SS lines, and which brand is best, yada yada... I have been prone to buy spiegler, but this set of lines is having some flaking of the anodizing happening (on the banjos). You also know at this point that i'm not a fan of the AL banjo bolts. i believe Core Moto powder coats their banjos, and supply SS bolts; i almost went with them...
 
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