Re: Crisis takes to chattering, brakes that is.. .. ..
2014-01-04 Inspection:
First off, best of plans did not come into play - i.e. change one thing at a time and determine the primary root cause. So, this is more of a restore the baseline.
I measured the SAG and found the R6 forks had settled from 31mm to 36mm. The spring free length did drop a mm from 252mm to 251mm (recorded in previous thread below).
I didn't measure the oil depth in the fork before dumping but they weren't leaking so I just dumped them and refilled them with Yamaha 7.5 wt. A NEW change from 10Wt to 7.5 wt.at a depth set to 106mm. Note: Old oil looked pretty clean, not grey, no metallic bits. A 2 year interval it is!
FROM: 2012-02
http://www.600riders.com/forum/fz6-general-discussion/36842-somethin-black.html#post461560
OIL FILL SPEC: 490mL should have come out. I got 470mL. Without the spring and spacers and washers in the way and with the tube collapsed it should measure from the top 106 mm (4.17 in).
FILL Height to level: a 1 pint bottle or 473mL
Note: the coil spring winding is supposed to be wound tighter at the top. Nada - equal throughout the entire coil. This is begging the question if these are/are not OEM R6 springs.
As found:
Coil Dia= 4.72mm 0.186"
Coil spacing = 9.26mm .366" between coils
Free length = 252mm spec: >244 <249 (9.81" - 9.62")
Coil count: 7coils/10cm or 17 coils not counting ground ends.
Forks were assembled, SAG returned to 31mm. New oil will likely require damping rate adjustments.
BRAKES:
Right side pad thickness all over 3mm
Left side pad inner >3mm, outer slight taper 2.5 to 3.0mm.
Caliper Pistons:
RS caliper all pistons freely move by thumb pressure.
LS caliper one piston firm but not stuck. By holding other the 3 in place by HAND, break pressure applied, piston moves for cleaning. Repeated 3 times, all pistons move with finger pressure. Although I have new pads, I did not install them.
Wheel hub, rotor visual inspection:
No obvious run out from wheel or tire. Rotor surface. Anyone familiar with hot spots, hard spots on surfaces? Its not obvious but the rotors appear to have tell-tale signs of being too hot. The only time I could see the imperfection was after wiping them with brake cleaner. It appears as circles between the drill holes. If these were meant to be resurfaced, often times the process reveals the hard spots when cutting or being ground away. I did not measure run out on rotors as I was freezing at 35F for the last few hours and put it back together. A more thorough inspection is required.
ROTORS: My Actual Rotor:
Lighting in the area the bike is sucks and I couldn't get anything to show up last night. Here is pic of the Rotor from 2013-06 when the S20 front tire went on.
View attachment 51648
Borrowed from a search for reference. Mine now have a dark blue hue closer to this.
View attachment 51650
But not as bad or pronounced as this showing the hot spots.
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My take away is I might be asking a bit much of the brakes as some entry speeds require more brakes than she has to offer. Another thought is the Thicker (NEWER) pads have more mass and may have made a better heat sink extracting some of the heat from the rotors. As they thin, the temperatures climb quicker and the rotor gets hotter. SO, perhaps a different pad is in order or those new pads should be installed.
Finished the evening by bleeding the brakes:
Emptied fluid reservoir with 50cc syringe. Added new Dot 4. Bled brakes manually, tapping calipers with hardwood to displace any residual air. Tap only upwards and NOT from the sides.
I'm undecided about any ONE item as the cause. I don't believe the rotor condition is directly related to the suspension bouncing like rubber ball. So, that's where it stands right now.
I'll make an adapter for this so I can secure it at the caliper bolts. Runout and deviation of the rotors hard spots may be detectable.
View attachment 51654
