Shudder with front brake on XJ11 - And Disk replacement?

[KA1J]

When I got the bike, the right front grip was hard to pull. I rebuilt the MC, the calipers and replaced the lines with SS. It's still difficult to squeeze and there's a kind of shudder when the brake is applied which sort of reminds me of ABS which o'course these bikes don't have. Using the rear brake with proportioning control to the other front rotor, it works smooth and very effectively. While the bike decidedly brakes with just the handlebar brake, it takes much more effort to get it to stop this way and the shudder is more noticeable at slower speeds than faster.

I thought it might be a warped rotor but the shudder is at a quicker tempo than wheel rotation so if there's a warp causing this, it would have to be appearing like ripples on the disk. I don't see any wear marks to cause me to think that's the problem.

Ideas of where I should look to resolve?

If it is the rotor, is there a newer, better rotor to use that is a drop in replacement than the originals?

Thanks

[crazy steve]

EBC sells replacement rotors for these, but at $130 each I'm not sure you want to go there... They don't look the same either, so you'd need two...

Do check the rotor for runout, as any problems here may not be obvious. Also make sure it's firmly seated on the wheel if it's been off. You don't say what kind of pads you have, but sometimes you'll get a mismatch between the pads and the rotor material. If the pads are new, it can take some time to 'bed' them sometimes.

[KA1J]

Hi Steve, No... not at that price... Do you know if there's better rotors from a stock bike that will fit?

Runout? what does that describe? Final safe wear (thickness) of the rotor?

As to new; All the brake components except the rotors are new as of this year. The front rotors seem to have been have been replaced because I see that yellow junk yard yellow printing still on the parts that don't get friction.

[crazy steve]

There's no 'better' OEM Yamaha rotors available if that's what you mean. You've got the choice of slotted/non-slotted XS rotors off the various models that shared this part, that's all.

As far as 'runout', that's checking for warpage; the FSM calls it 'deflection'. You can't always see this, you really need to set up some sort of check with a pointer or preferably a dial indicator. Maximum allowed is only .006", so it doesn't take much to cause problems. If you can see any with a rough check, the rotor needs to be replaced.

Minimum thickness is .260" (new is about .270"), but wear doesn't seem to be an issue.