Hoping someone can help with a squealing brake issue I’ve been having. I have a Trek Checkpoint+ eGravel bike with SRAM Force E1 brakes. The rotors are 160mm SRAM Paceline X (which SRAM’s website says are for road use). The bike also has a Rockshox Rudy XPLR fork.
When I first got the bike I performed a proper brake bed-in and they were silent and worked really well. After a few rides the front brake started to squeal under light braking pressure. Basic cleaning with isopropyl alcohol didn’t fix it, so I thought maybe I had somehow contaminated it. So, I lightly sanded the rotor and pads, cleaned some more, and did the bed-in procedure again. That didn’t help, so I loosened the caliper bolts, held the brake lever down, and tightened them. That, along with some more bed-in procedure helped, but not completely. However, after a few rides they became silent again and I figured the root cause was some contaminant or dirt that was eventually abraded away.
Yesterday I went for a ride that was mostly paved and the front brake was silent. After a short stint down a dirt trail (dusty and dry Los Angeles conditions), however, the squealing came back. I then had a long steep descent on pavement and it was really disconcerting having this squealing front brake under light to moderate pressure. I’m now assuming that the original squealing was from riding on dirt.
All along, this has only been an issue with the front brake. The rear has always been silent. This has made me wonder if the fork needs to have the tabs faced, but the fact that it has been silent at times makes me think that’s not the issue.
I’m also wondering if I should switch to a different rotor like SRAM Centerline (which the website says is compatible with both road and mountain brakes), or if that would be a complete waste of time.
Any ideas on what the root cause is, how to resolve it etc would be much appreciated!
Just picking on the point that there wasn’t any mention about any remedial action having been done on the pads themselves. On a number of bikes that have come through with squealing disc brakes, the usual culprits are the rotors and the pads. On the rotors, you’d see some form of glazing and/or discolouration in the form of rainbow-ish streaks. For reference, clean rotors look like chromed vinyl records. When dealing with squealing brakes, both the rotor and the pads need to be looked at.
Rotors
For mild cases, cleaning both sides of the rotors should suffice. In more egregious cases, I’d usually sand down the friction surface with a foam backed disc with 240 grit sandpaper or finer.
Pads
I’d usually scrub one pad against another using undiluted dishwashing detergent under running tap water, until the resulting slurry is clear, through repeated cycles of fresh detergent. For badly contaminated pads, you’re just better off replacing them, but if/when you do, also match them with clean(ed) rotors to avoid having the contamination migrate from pad to rotor and vice versa.
In my experience dry dirt, like the sort you get off gravel paths, rarely ever contribute to squealing, unlike curb-side dirt and debris that can sometimes get flung up. These could be coated with whatever petroleum contaminants that have come off of vehicular exhausts, etc., depending of course, on where you’re riding.
Thanks for the detailed reply. I did sand down the pads lightly (mentioned briefly in my post), but next time I’ll try your dish detergent approach. The strange thing is that the brake eventually was silent, and then got noisy again as soon as I rode on dirt for a short time.
I have the same front only issue but mine is Red E1 on my Tarmac. And it doesn’t need dirt to squeal. I’ve cleaned and replaced the Paceline X 160mm rotor. And cleaned and replaced multiple pairs of pads. Refaced the forks mounts too.
Still squeals like a banshee under moderate braking. Whereas under very light or heaving braking it’s quiet. Very frustrating.
If anyone knows of a cure I’d be keen to hear about it.
Apologies for missing that point from your earlier post. But I do wonder, in your instance, whether the brakes going from silent to squealing was more a function of time elapsed, rather than dirt contaminating the braking surface. It might be a good idea to check (and confirm) that there aren’t any leaks, etc where the brake fluid could find its way from, and onto your rotors/pads. I’d certainly do that before installing any new rotors/pads, etc to avoid fouling the new parts.
For the record, I work mostly with Shimano systems and mineral oil, not DOT.
That said, I’ve had the odd bike come in now and then with recurring squealing issues that no amount of cleaning could solve. New rotors and pads end up the same. The most common issue is a tiny link somewhere (common symptom is the oily ring of death on the backing plate of the pads, where the pistons push against, so check for this). I’ve also uncovered trigger factors that include haphazard home wrenching where a little drip of lube/grease finds it way onto the rotor, gets spread around during braking, migrates to the pad, and then gets exchanged back and forth. The rotor should also always be shiny, if not close to being so, and not discoloured.
So not exactly a solution, but maybe something to check on, re: the front brakes.
Thanks again - I’ll remove the pads and see if I can tell if there are any leaks. I also get what you say about the silent to squeaking timing - I jumped to that conclusion just because it happened once, which clearly isn’t much evidence now that you point it out
I would try some non-SRAM pads if you get the chance (maybe Sinter, Galfer, or MTX). I have found SRAM MTB and road pads to be prone to various noises. The classic ‘turkey gobble’ which I can induce by bedding them in too quickly (overheating the pads/rotor). Also the noise you mention under moderate braking but silence under light or heavy braking. Swapping from resin pads to metallic makes noise more likely, but it’s not the only culprit.
Shimano brakes tend to be quiet unless the calipers are leaking, too common with the previous ceramic piston calipers.
Good cleanliness recommendations here, and I would also add that sometimes resonance is a problem. I think your rotor should be centerlock, which can sometimes move/warp differently from a 6-bolt design and especially under light brake load small misalignments can cause flex that induces vibration leading to squeals. The rear of the bike is pretty stout but forks, especially suspension forks, have a lot more flex to them and can enhance the resonance.
One thing you could also try as a last resort if other pad compounds don’t help is applying a little bit of CRC Disc Brake Quiet to the back of the pads.
Is the appearance of the noise accompanied by a degradation in braking performance? I once had to have an internally-routed handlebar on my Venge replaced by a bike shop in Singapore because it was damaged in a Scicon Aerocomfort 3.0 bag during my journey there. I suspect the mechanic who replaced the bar contaminated the front brake and not only was the brake extremely noisy, the braking performance was noticeably degraded. Scrubbing the rotor and rubbing the pads against each other using dishwashing detergent under running water did not help one bit. Eventually replacing the pads fixed the issue, both the noise and the brake performance degradation.
As mentioned above, SRAM pads are the most fickle in their bedding in procedure, and are the most prone to making noise. I would try a different brand of pad.
It’s me again, being a busybody. If it were me, and the budget allows for it, I’d definitely swap both rotors and pads, so that both can be eliminated as possible causes.
The above obviously assumes that there’s no leaks to be found anywhere in the system.
I’ve got EXACTLY the same problem. I’ve tried replacing the rotor, and three types of pad (both Sram compounds and Galfer). The noise is still there. Sram Red ASX, latest generation of 160mm rotor
I too don’t think dirt is the issue, my best guess is heat.
Start the ride, no noise
Do some hard braking, then the noise is there under “medium to light pressure” For 5 minutes or so, then it’s gone again.
If I do a descent with hard braking, the noise comes back
Continue to repeat the process all day for any hilly ride…
It’s also NEVER the 140mm rotor on the rear.
This has been driving me mad. I’ve recorded the sound and will post this as a question on “ask a mechanic”
Just curious if it’s a higher-pitched “squeal/squeak” or a lower tone “hum”? The former is usually indicative of contamination on either (or both) the pads and rotors. Some symptoms include rotor discolouration (could be a rainbow-ish tinge exactly where the pads contact the rotors).
The latter could be due to misaligned calipers (with respect to the rotors), causing the rotors to very slightly flex as it rotates through the calipers, before flexing back to its normal position when exiting the calipers. This constant flexing is what causes the hum, similar to the hum you’d get from waving jacksaw blades.
Did you happen to check for leaks when replacing the rotors and pads? Ring of death on the backing plate, stains on the inside of the calipers, near the pistons. etc
I removed the pads yesterday and there was no indication of leaks on the back of the pads. I’ve attached photos of the pads and rotor prior to cleaning them with isopropyl alcohol - would love some confirmation if they look ok or if there’s an obvious issue. After cleaning and reinstalling, the noise was still there. I didn’t try sanding pads or rotor this time, as I decided to order new Galfer pads, a new 180mm Centerline disc (decided to size up in case that helps with heat) and adapter.
I got similar noise on my 12-speed Shimano Dura-Ace brakes occasionally and they go away after I clean the rotor and pads with Silca’s drivetrain/brake cleaner (I just spray onto the rotor and into the brake caliper and wait about 5 minutes before hosing it off). On my gravel bike with the Force calipers, I only get that sound immediately after washing my bike, when the pads are still wet.
@LAStu, can’t really tell the conditions of the pads on account of poor eyesight, and the colour of the backing plate.
The rotors however, look a little contaminated. Looking at them, from the 9 o’clock position to the 12 o’clock position, you can see how there are gray-ish streaks along the circumference of the rotor. I’ve attached images of mine, for reference. You’ll see how they’re cleaner with near zero streaks around the rotor, where the pads contact the surface. Some streaks are fine, but yours look problematic.
If you’ve swapped out the pads and rotors, I’d take the added step of running a clean, dry finger around the back of the pads, calipers, etc just to be doubly sure that there aren’t any leaks of note.
Also sounds like you’ve down what most would so good on ya for working through it.
Couple “additional” thoughts.
Have you read @Dave_Rome’s how to bed brakes and other maintenance tips from threaded? Perhaps you’re cleaning too much and need some more time for pad material to build up? TRP suggests a dragging bed-in procedure which I’ve found to be helpful at distributing material and heating up rotors/pads
Did you buy bike this brand new?
If purchased a Trek retailer/direct owned store (DOTS) you might be able to get some replacement parts under warranty.
I had initially been thinking about compounds of pad as the culprit…but also liked what one friend said about vibrations in the front fork.
For quality pads I’ve really liked Sinter.
The variable speed thing is interesting too maybe get em really hot? See what happens?
This chat box is really cool Escape Team! Very powerful lil tool. Excited to be part of the community.
