Weird braking noise[sound clip]

[Andre]

After a long or particularly hard drive, I get this weird grinding noise under braking. It only does this under light – medium brake pedal pressure at all speeds below 30mph. Above that I can’t hear it. It sounds like its coming from the front left (passenger side for RHD vehicles)

So far I have replaced discs, pads, swapped the front springs/shocks with another used pair, replaced wheel bearing on the left, flushed and bled the brake fluid.

I did the work myself but then took it to an inspection place but couldn’t recreate the sound there, so I recorded it and thought I’d share it here too.

I’ve had the wheels off so many times now to do a visual inspection and can’t see anything wrong!
Any ideas?

Topic

[Rob]

sounds like your rotors might be bad not round….. do you feel the brakes palsate when braking?
jack the car up and take each tire and shake it right/left, Up/down, and spin it…. and see wich makes it make noise… also try shaking your sway bar abd sway bar links

[Andre]

I just replaced the discs there is no pulsating. No movement in the wheel or ARB, the end links are new.

[Frank Heiser]

The only thing I can suggest is to not necessarily trust your hearing as to where the sound is coming from. Have you checked out your rear brakes yourself? (I find most shops can’t find their own butts)

I had a sound that I swore up and down was from the front passenger side and it turned out to be both my rear wheel bearings were groaning.

[James P Grosso]

I can’t hear it very well on my computer, but is the exhaust loose or cracked? The deceleration could be causing shifting of the enhaust and suspension?

[Mike]

First, isolate it to a single wheel by rolling the windows down and listening for when the sound is loudest as you apply the brakes while passing parked cars.
If it’s loudest when you first begin to pass, it’s the fronts; loudest when nearly past it, it’s the rear.
Loudest on the driver’s side or passenger’s side isolates it further.
Once you have it down to a single wheel it will be much easier to figure out the exact cause.
If the pads or shoes are riveted, rivets are sometimes installed at uneven depths and just 1 rivet can be making contact with a rotor or drum.
Don’t rely on looking at just an outer pad or lust at the thickness of the pads (which is what some lousy shops may do , as Nodak81 alluded to).
A problem with the way the caliper is sliding or if the brake clips are worn can result in 1 pad wearing down much faster than the other or the pad not making even contact, so the top looks great while the bottom is grinding into the rotor.
If the problem is not with rivets or uneven wear—look at the friction surface itself; a cracked pad can make grinding noises.

[Andre]

Thanks for the replies.

@Bonnieman I will try to isolate it further next time I have a buddy with me. I’m fairly certain its coming from the front left.

I’m ruling out the pads because the noise happened since I bought the car. I’ve changed the pads twice since then thinking it could be because aftermarket pads (a brand I was unfamiliar with) were fitted. First I replaced just pads, then when the noise persisted, I replaced the discs (rotors) as well.
The original pads had even wear on them, I also lubed the slide pins and cleaned the calipers with a wire brush. I didn’t replace the shims but cleaned under them and put a light coat of copper grease where the shim touches the caliper and where the pad touches the shim.

@451Mopar good ear, the exhaust is blowing slightly, I have new full exhaust replacement sitting in my garage but I’m prioritising my time with the braking noise as the exhaust is structurally secure for now. The noise is definitely rotational, the number of grinds decreases as I slow down. Its quite rhythmic in that sense.

@Nodak81 The first thing I did to try to eliminate the noise was service the brakes, including removing the front/rear discs (rotors) and clean everything and adjust the handbrake shoes. (It has a handbrake drum/shoe inside the rear discs.)

Thanks for the replies once again, I’m tempted to get replacement calipers from the junkyard and rebuild them and fit those but as you can see I also need to address the exhaust (which started leaking a week after owning the car lol).

[Mike]

I don’t see how replacing the calipers would help if the pads are wearing evenly.
Are the shims on tight–sometimes the tabs need to be bent to tighten them up?
Is all the brake hardware present, such as the anti-rattle clips that hold the pads in place on the caliper brackets?
No spacers or bushings missing on the caliper sliding pins?
Look for anything rubbing inside the wheel well or for shiny rub spots on the backing plate itself.

[Andre]

@Bonnieman
Neither do I, just running out of ideas… the shims are in good condition but I never replaced them (they are about half the cost of the pads). Maybe I should do that first. When I put the caliper back on I always spin the wheel and make sure nothing is making contact. There are spring clips on the rear calipers, all present and look good but not brand new. The fronts don’t have them.

No signs of anything making contact with the wheels.

[Andre]

Thanks for the help guys, if anyone was wondering…

I took the slide pins off and found them to have no grease!! I used some silicone lube last time I did the pads but I think the product I used wasn’t thick enough, it was really more of a liquid grease in a tube rather than a grease or paste. I put CV Lithium moly grease for now, (I figure CVs get hot and the CV boot is rubber so its similar enough) and went for a hard drive, the sound is gone!!! I have also ordered a specific ceramic brake grease which should be better suited for this use.

[Mike]

Glad you found the problem.
I had assumed you had lubed the slide pins every time you changed the pads, which hopefully will become your standard practice..
Just so you’re aware, using grease on the caliper pins is a bad idea.
CV boots are typically neoprene, which is a synthetic material, not actually rubber or they’re plastic.
Grease swells any rubber bushings inside the caliper bracket and then makes the calipers stick and/or softens the dust boots protecting the caliper pins and also causes them to stick as the pins rust and accumulate dirt. See the ETCG page on this here https://www.ericthecarguy.com/faq/solving-brake-problems?start=3#DiscBrakeService..
SilGlyde is the lubricant that many pros use, as it is a heat resistant, silicone-based lubricant that is compatible with rubber parts.
Brake cleaner will dissolve the grease .

[Andre]

Yeah it has been standard practice… just using the wrong grease. I’ve bought some brake lubricant that says its suitable for slide pins, its a ceramic lube and a respected OEM brand (in Europe anyway) so I’ll see how it goes. I will clean them out with brake clean. If the rubber goes bad its fine I’ll replace that too. But till then, the CV grease is doing a good enough job of lubricating it.

[Paul]

For what it’s worth, I used Permatex Ceramic Extreme (24125, purple can) on one set of slide pins, as the product label said it worked with caliper pins. I had a strong, intermittent wheel vibration at high way speeds within 9 months. The cause was traced to sticking of the caliper pins where the purple product was used . I don’t know why the product lost its lubricating properties – if there was an incompatibility with the old residual lubricant, if the purple product dried out, etc . I cleaned it all out and replaced it with silicone paste, and the problem was solved. I now know why ETCG only recommends silicone paste.

+1 for verifying that product you purchased is silicone-based (it may be called PDMS or polydimethylsiloxane in datasheet).

[Andre]

I got the stuff. Its branded as Mintex / Textar / Pagid Ceratec and claims to be metal-free.

Instructions:
Clean slide bushes, holder and all caliper to pad contact points and lubricate.

It looks like regular grease to me but I’ll find out once I get it out of the tube. As said, I’m prepared to replace anything that is damaged in the process.

I’m not convinced on silicone paste, I know ETCG has had success with it but I can’t get brand he uses at reasonable time/cost. I can get Millers Oils Silicone grease but it says its for lubricating plastic and polythene water pipes and O ring assembly etc. There is nothing to suggest it is suitable for use with brake systems.

[Andre]

So… time to revive this thread.

The noise came back soon after I posted on here that it was fixed.

I ended up replacing the caliper, once again, it was fine for a week – then the noise came back.

So far I’ve replaced every brake component in the front left apart from the brake hose.

I’ve swapped and changed various combinations of pad, disc, hardware, etc. to no avail.

I’m tempted to condemn the the hub/bearing/spindle assembly and find a used one of those to swap in.

Unless anyone has a better idea?

[Mike]

I don’t see how something besides the caliper would cause a noise to go away when the caliper is replaced.
I am not sold on the Ceratec actually being suitable for the sliding portion of sliding caliper pins.
Read the description of Cera Tec in this ad
https://brakedepot.co.uk/Mintex-Ceratec-Anti-Squeal-Grease-with-EBC-Brake-Pad-Anti-Squeal-Shims.html

The description on Pagid’s webpage calls it Anti Squeal.
There also appears to be a totally different product included with their “Caliper Slider Kits”
I tried to use the Can we help button but am apparently blocked due to being outside the UK.
Perhaps you can ask them this exact question:
Can Cera Tec be applied to lubricate the portion of the caliper pin that the sliding caliper of my 2003 Toyota Yaris actually slides along?
I would be most interested in their reply.

Here in the US, we also have anti-squeal compounds and they are never applied to the portion of the caliper pin that the caliper actually slides along.
Anti squeal is applied to the backs of brake pads to prevent squealing when the brakes are applied–just as the ad above describes its use..
We also have anti seize which can be used on backing plates, the shims and backs of pads and on the threads of bolts—but not on the sliding portion of sliding caliper pins.
Neither anti squeal nor anti seize is ever used on the sliding portion of caliper pins because they either gum up or swell the o rings and dust boots.
There are many calipers which simply bolt on (they’re called Fixed Calipers) and for those, yes an anti-seize compound is fine for those.

Only high temp silicone lubricant (like Silglyde) is used for the portion of the caliper pin that the caliper actually slides along.
High temp Silglyde is not suitable for use on axle bearings.

From the Pagid website at http://pagid.com/products/
Cera Tec – The metal-free anti-squeal lubricant for braking systems – is highly resistant (up to 1000°C) and is available in a 75ml tube and a 5ml sachet.. Cera Tec is non-conductive, contains no solid constituents, is anti-lock approved and facilitates brake assembly. It reduces brake squealing, protects against scratching and corrosion and is free of copper and acids. Cera Tec also perfectly lubricates disc and drum brakes, compressors, central lubricating systems, axle bearings, chains, seat tracks, sunroof guides and battery contacts.

[Author]

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