Topic: Front wheel/brake squeal - but not when braking

[bmcdonou]

Hi - so my front wheel squeals, but stops when I apply the brake. Most of the threads are about the opposite problem, so I am a bit lost.

I assumed it was that the pad/piston was not returning and thus always rubbing just a bit on the caliper. I've rebuilt the brakes, piston, pads, fluid etc. applied the anti-noise stuff on the back of the pad.

I don't think it's the pad vibrating bc it will do it even when I am just pushing the bike around the garage. Assume it's not the wheels bearing or anything other than the brakes given it stops when brake is applied.

Any other thoughts to try? Ways to test? Driving me crazy.

CB500F, btw.

[Oddjob]

Push the pad back into the caliper, use the adjusting screw to set the back pad away from the disc so that there is no way for the pads to touch the disc. Does it still do it?  If so then most likely wheel bearings.

[rotortiller]

Put it on center stand lift the front end and spin the wheel to see if there is any amount of drag. If it has drag fix it by cleaning the seal groove after making sure there is no fluid return issue. Check for bearing play etc as someone mentioned with check setscrew.

[HondaMan]

The cause of this squeaking is a lightly dragging disc pad: it can be either of the two pads. The little adjuster on the brake arm should be set so there is 0.002"-0.006" clearance for the inner (stationary) pad: the larger clearance makes for more brake lever travel, so make sure yours will still stop without running out of brake lever travel!

The square-section O-ring is supposed to deform rhombically (there's a word you haven't heard since geometry class?) when the brake is applied, and then when the lever is released this O-ring becomes square again, retracting the moving pad. This amounts to about 0.004" of movement, total.

So, it ain't much...

When you installed these pads (if you did it), did you also replace the square-section O-ring in the caliper? It is old now and (like me) is less flexible than it once was. It also doesn't grip the moving caliper so well: its friction surface is less sticky than it was when young.

If you happened to apply any form of lube to the square O-ring where it grips the piston, it will have to be replaced: I have never seen them made clean enough, once lubed with something, to make them work right again.

[Oddjob]

Surely it has to be lubed with something Mark or it would not allow the piston to be slid past it when you first fit the piston, I've always put some brake fluid on the surface to allow the piston to slide over the surface. I seem to recall Honda mentioning silicon grease at some time in the past.

[HondaMan]

Surely it has to be lubed with something Mark or it would not allow the piston to be slid past it when you first fit the piston, I've always put some brake fluid on the surface to allow the piston to slide over the surface. I seem to recall Honda mentioning silicon grease at some time in the past.

The brake fluid is a lubricant (but not very viscous) along the moving piston, behind the seal. I've also used silicone or "brake grease" on the sides of the piston (on the disc side of the seal), but over time it always seemed to get onto the disc surface and make the puck slippery, so I abandoned that approach - although, it did make it quiet!

I remember the Honda grease mention, but I can't remember what kind of grease they recommended? At one time we successfully used the parts-washer solvent (Safety-Kleen company) by applying it to the sides of the puck where the puck & seal (that's not quite what my mechanics called it...) had to slide together. This didn't seem to adversely affect things, but I also left there within 3 years so I don't know if there were long-term issues with the solvent. It is (or was then) an oil-based solvent with detergents added, and would make suds if water was added and stirred in. After assembly we washed out the solvent with alcohol (I think it was isopropyl, the water-absorbing kind?) on the disc side of the caliper so the seal would anchor in place again, as it is the force that retracts the piston when the brake lever is released - so, it must grip the same piston that you just slid past it!

These kinds of brake calipers are all a bit of an oxymoron, requiring the same seal to grip the piston with high adhesion so as to retract the brake pad, yet let you slip the piston past it if you want to assemble the #$@! thing. 

[RAFster122s]

It will squeal if not square to the rotor too, that can be checked with feeler gauges around the pad to find if it is of different clearances...

[HondaMan]

It will squeal if not square to the rotor too, that can be checked with feeler gauges around the pad to find if it is of different clearances...

You've brought up a great point, Raf! While it shows up most often when the 2nd disc gets installed, the pad's faces may not be parallel to the pads, depending on who made them. The OEM versions had a slight domed shape to them while many aftermarket versions are flat. Those edges always squeak until broken in/down, so I have filed the edges into a bevel when using the aftermarket flat-style pads.

[BenelliSEI]

I’ve also found that when everything is new and replaced you might want to wait a few weeks and see if it all settles in, squares off and stops squealing…..

[MauiK3]

My second disc assembly was not square and squealed rolling around the garage. After some fiddling and re-spacing it went away.
Learning curve

[bmcdonou]

Thanks all for the thoughts. Some more context and an update:

Context - I did the work when I first got the bike years ago. They were very stuck back then and the work done helped tremendously. I just did the pads, fluid, and seal. Piston looked fine, and I think I had issues getting the one I purchased in (perhaps this was a mistake). I pretty sure I would have used brake fluid to lube the seal, and then the pink noise grease on the back of the pad. I did not replace the lines or the master as I thought at the time this fixed the issue. Which it did in the since was drivable and there wasn't an always-on front brake. The squealing started soon after, but only after the brakes were warm, and intermittently so. Sadly, I didn't ride as much for a season and half, but am back at it now. I live in Chicago, is my daily, and thus a lot of braking. The noise now is constant and more noticeable (and embarrassing when riding on a busy street). For those in the USA, I used the Common Motor Collective rebuild kit.

Update - I took the caliper off and spun the wheel. No friction or noise. So I think we are good there. I put the brakes back on, pumped the handle once, and the wheel definitely has friction. The adjustment screw was set loose enough for no tension. So it seems while the brakes return enough to drive without noticing the resistance, it is not enough to give a gap. I noticed the the pad were more warn slightly more on the front. Not sure what would cause this or how I could adjust....but seem akin to the last comment about the pad not being parallel to the backing plate.

Thoughts on next steps: How best to troubleshoot the pad return? Is this just a factor of rebuilding the entire system, master included? Or do I just need to focus on the caliber, seal and piston? I did but new stainless lines that I never got around to installing, so could do those as well. I am prepping to do the front suspension here soon, so I guess that would be the time as I will be into it anyway.

[bryanj]

Tiny hole in master cylinder blocke
Hoses deteriorated
Caliper sesl groove still has crud in it
Caliper pivot pin siezing

[Oddjob]

Odd thing to say but is the upper caliper mount under the mudguard brace or above it?

[bmcdonou]

Odd thing to say but is the upper caliper mount under the mudguard brace or above it?

Not sure what you mean exactly. The caliper brace is below the mud guard, but shares a mounting point on the fork tube with the mudguard. See images.

[Oddjob]

There’s your problem, the brace goes on after the caliper mount, the way you have it means the caliper and thus the pad is not in line with the disc. Did a job once where the owner was complaining about poor brake performance, took the pads out and they were chamfered to death, then spotted the brace underneath the mount. The brace should be bent outwards as standard to allow it to fit on the outside.

Just fix that and new pads and you should be a lot better off

[bmcdonou]

There’s your problem, the brace goes on after the caliper mount, they way you have it means the caliper and thus the pad is not in line with the disc. Did a job once where the owner was complaining about poor brake performance, took the pads out and they were chamfered to death, then spotted the brace underneath the mount. The brace should be bent outwards as standard to allow it to fit on the outside.

Just fix that and new pads and you should be a lot better off

Wow. I would have never caught that. Im glad that I can blame the previous owner as I have never touched those. However, while I would like to think I would have followed the manual when reassembling after doing the suspension, I probably would have just taken a bunch of pics and reassembled as it was.

so switching the mounting order and that should create better alignment and who know, solve my problem.

I guess while I have you - what should the piston performance feel like in my hand. Should I feel the pad move forward when I squeeze the handle, and then retract when releasing? or will I not really be able to feel/manipulate with my hand?

[RAFster122s]

Dare say you cannot detect that retract movement as it is a tiny amount

[Oddjob]

I’d imagine the pads are so chamfered now that they are next to useless, hence why I said get a new set. Bed them in properly and make sure you set the fixed pad correctly by the adjusting screw and not only should that fix the squeaking problem but the front brake should work and feel 100% better than before.

As RAF says, you probably won’t be able to feel the pad movement, especially off the bike as the pad will move more than the normal seal movement and just pop further out.

[scottly]

How worn are the pads? Please post a pic.
Also, I quit using the adjuster screw and spring years ago; they are more trouble than they are worth, IMHO.

[HondaMan]

Dare say you cannot detect that retract movement as it is a tiny amount

Yep, it's only about 0.002" on the 750 (up to the K6 version) and a little less (just barely over 0.001") on the 500/550 caliper. I haven't measured one on the F2/3 or K7/8, they are a little different.

When the winters got too long in IL, I had to do SOMETHING constructive, so I measured it.

[bryanj]

If you put your hand on the complete mounted caliper with pads you will feel the movement as you squeeze and release, or should do

[Deltarider]

[...]
Also, I quit using the adjuster screw and spring years ago; they are more trouble than they are worth, IMHO.

I'd like to know more about this. How do you adjust then? Is the adjuster screw to be used just once after one has worked on the brake and should the in action deformed square O-ring in the caliper take it from there or is it OK to readjust every now and then thereafter? That brake always gives me headaches when I try to understand it.
@Hondaman I see your point NOT to lube that square-section O-ring. Makes sense.

[scottly]

You simply leave the screw and spring on the bench, and let the caliper float on the rotor, just like most calipers.

[Oddjob]

To me that just encourages both pad and disc wear, everytime the bike leans the pads will touch the disc as there is nothing stopping them. Whilst the adjusting screw isn't a perfect design it's there for a reason.

[bmcdonou]

I wasn't sure if I should respond here or start a new thread, but figure what I found could be a potential cause to my issue.

As I was taking apart my forks to rebuild this, something I was planning to do, I noticed a crack on one of the brake forks mounts. Not sure if this is a common issue or just something I'm unlucky with. Perhaps caused by a loose bolt and thus too much leverage and pressure on the mount? Or perhaps from the incorrect mounting order with the fender. Idk.  The bolt itself looks bent which I didn't realize until seeing the pic.

I have two questions:

1) could this have created vibrations that led to my noise issues?
2) how best to fix? JB weld, actual weld, or should I just replace.