I recently replaced the front brake pads and have ridden it several times without hearing any noise. Yesterday I pulled the wheel to check the bearings, pulled the rotor off to tighten a few spokes (not enough to change the truing) and reinstalled everything. Took it for a test run and heard this.

https://www.youtube.com/shorts/c5vffgXhcg8

You can hear it more clearly as I apply the brakes but it starts without any brake application.
I pulled the wheel off today (but did not pull the pads), repositioned the rubber spacer behind the rotor, cleaned the rotor with the appropriate brake cleaner and retorqued all bolts. Still have the noise.

Any thoughts about the cause and possible correction? Screams like a banshee (or so it seems) when just riding.

 

Hmmm, sounds like the tea kettle mod. Any noticeable scoring on the rotor? I'd lift the front end and spin the wheel, see if you can pin point the source. Something (a pebble?) stuck in the dust groove of the pad maybe.
Randy

 

Tea kettle mod The next rage in the KLX world.

It's really hot in the garage this week. Figure I'll get out there early tomorrow and pull the pads to check for irregularities.

Rotor has been fine for the three years since I put it on.

 

Definitely diagnose what is rubbing and fix before riding it. It is clearly something that you touch/moved, so go through that list thoroughly.

 

Agree. The only thing I didn't pull is the pads. That will be this morning.

Don't need heat building up on the rotor. That could go bad quickly.

 

Quick update--pulled the brake pads at the expense of rounding off one of the Allen head bolts. Now waiting on new one.

Pulled the brake pads and could not see any obvious reason for the noise. Sanded them down with 80 grit and cleaned them with brake parts cleaner.

Bolts should be here tomorrow, so I'll update once I've got them back in.

 

I have a 2019 that is doing the same thing, I replaced the rotor, drained and replaced the brake fluid, changed pads as well. Still doing it, irritating as hell. I'm on the verge of replacing the caliper, but may go with a different brake line, probably a galfer braided. I have heard of instances where the brake lines might have an interenal flap that could act as a oneway valve????. Just occurred to me to get the bike up on a lift, spin the wheel apply brakes and see if they release.

 

I replaced the sintered pads with organic pads and double checked torque values. The problem has been resolved on my bike.

 

Here is a possibility - dirty pistons hanging up in the caliper.

It is possible you had some crud on the OD of the pistons with the old pads, then putting in what may be thicker new pads with the possibly dirty pistons will cause the pistons to stick. This would hold the pads out against the rotor. The easiest fix is to try to clean the pistons without popping them out.

• pull the caliper off the rotor,
• pull the pads out
• use a small c-clamp to hold one piston in while exposing the other piston
• very gently apply the brakes to push the pistons out a fair amount - one at a time - but not all the way out,
• clean the outer diameter surface of the piston. I use chrome polish to do so. Do not use any coarse abrasive. If using wet/dry sand paper use 1500 or 2000 grit ultra-fine, but chrome polish is likely best choice in my opinion.

 

At least as often as you pull the wheel or calipers off, clean the pistons. My method is slightly different.

Quick note: With regard to maintenance of the braking system. Think about it like this, you have the fluid system, which you'll be flushing to remove debris and air, and you have the mechanics of the system.

The mechanics are things like the pivot at the lever, which should be clean and lightly lubed to work freely. The piston in the master should move easily and smoothly.

The pads should have enough pad on them and should be clean of debris and fluids. I clean mine with the brass brush to make them look like new before reinstalling. The calipers themselves are primarily a metal hollow to hold fluid as the brake caliper pistons and pads move in and out. The pistons should be clean as should the O-rings. An easy way to do this is to but a "pad replacement" where the pads go. That can be old pads or a piece of wood that won't damage anything.

Cycle the brakes so that the pistons move in around the "pad replacement." Note that you don't want air in the system from the top (don't overflow as you'll be pushing all of that fluid back up at the end). Be sure that the pistons don't pop out, or you'll be bleeding a dry system and cleaning up a mess. With the pistons pushed out, you'll see all of the crud on the pistons and the O-ring.

Use something rubber friendly to clean all of that with a toothbrush. I use Simple Green, at the suggestion of a world renowned expert, but like anything, you'll find people on their soap boxes about how bad that is. Use what you're comfy with. Rinse with water or brake clean.

Once done with that step, the pistons should move freely with one finger. That is how you know you've got it right. Note that pushing them in can overflow the reservoir. From there, reinstall pads/pins/locks and flush the system. The test. Id you've never done it, you'll likely discover a night-day difference.