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Loud, squealing brakes on brand new C400GT

emjoa

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Mar 3, 2025
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Vancouver Island, British Columbia, Canada
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Hello, new member here, first post. 👋 (I have tried searching the forum for this but came up empty handed so I'm hoping someone can answer this or point me at a thread that does.)

I've recently purchased a brand new 2023 C400GT that the dealership had on deep discount as it's been on their sales floor for a couple of years. Although it's a couple of years old it only had 30 km on it from a test drive or two so I'm considering it to be in "brand new" condition. The first thing I've noticed is that the brakes (pretty sure it's the front, not the back) squeal quite loudly at times, especially when braking at very low speeds in city traffic. It sounds just like what I've heard when indicators on a car's breaks begin to squeal, letting you know you need to change pads soon, but these are brand new pads and discs, so I'm wondering if this is a problem, or just what these bikes sound like. So far there's only 450KM on the odometer, and I've really only ridden in dry weather so far.

Is it possible that this is just condensation moisture forming on the disc while I ride, which then gets evaporated after a couple of brake applications, then re-forms enough if I ride long enough without braking so that the sound happens again? As mentioned, I haven't ridden in the rain yet, but ambient temperature around here has been around 8-11Celcius (46-52F) and it is a humid environment so I'm wondering if that might be all it is. I haven't seen moisture condensing on my windscreen/body panels at any point while riding it so far, but perhaps the metal discs are getting cold enough from windchill while riding to form condensation on them, while the plastic fairings/windscreen do not?

Or is this just part of the break-in period for new brakes of this type? I've only owned one other brand new motorbike of any kind (Honda PCX150 scooter) that had a disc on the front and a drum on the back and I don't recall this happening when it was new (or after putting on a new disc and pads a couple of years ago). Is it possible that this is a normal break-in sound for the brakes on this bike and it will go away once the pads and rotors have married properly to each other? Is it possible that this is normal for most new brakes until they are run in, and that I just got lucky with my Honda's brakes? Any ideas or suggestions would be appreciated.
 
Welcome and congratulations on your new bike!
Your issue is definitely not moisture/condensation on the discs. It should also not be caused by the 'newness'.
I would be more inclined to think the prolonged sitting has resulted in the pistons inside the brake calipers to be slightly 'seized' and they don't go in and out as smoothly as they should. That could free up with use.
Alternatively, maybe the grease that is supposed to be applied to the sides and back of the pads, to prevent squealing, has dried out while it was sitting on the showroom floor.
I would go back to the dealer and have them have a look.
 
Welcome and congratulations on your new bike!
Your issue is definitely not moisture/condensation on the discs. It should also not be caused by the 'newness'.
I would be more inclined to think the prolonged sitting has resulted in the pistons inside the brake calipers to be slightly 'seized' and they don't go in and out as smoothly as they should. That could free up with use.
Alternatively, maybe the grease that is supposed to be applied to the sides and back of the pads, to prevent squealing, has dried out while it was sitting on the showroom floor.
I would go back to the dealer and have them have a look.
Thanks for your reply and welcome! Yes, that's exactly what I'm trying to determine, if I should take this back under warranty and ask if it can be fixed, but I wasn't sure if it's just my inexperience with brand new bikes and if it would just "fix itself" after some run-in time. Based on this response I now have an idea what to ask the dealer about. I did notice a small amount of dirt under the fender and on the rims from it having been ridden in the rain at some point before I got it so I wonder if that has helped exacerbate the kinds of things you suggest here as well. I'm quickly approaching the end of the engine run-in period and my firs service, so I'll ask them about the brake squeal at that point. It's not constant (thankfully) but only seems to happen when braking slowly at low speeds, or just before coming to a full stop when braking gently in city traffic.

Other than this I am absolutely loving this bike!
 
I've had that issue as well. In my case, I have blamed it on improper breaking in or bedding the pads. I can use brake cleaner and the squealing goes away for a while but it always comes back. I'm pretty sure I could fix this if it really bothered me enough by lightly sanding the pads or putting the special grease on the back of the pads.
 
I've had that issue as well. In my case, I have blamed it on improper breaking in or bedding the pads. I can use brake cleaner and the squealing goes away for a while but it always comes back. I'm pretty sure I could fix this if it really bothered me enough by lightly sanding the pads or putting the special grease on the back of the pads.
Thanks Hornblower, this is also good info to have. I remember hearing about that lubricant for the backs of the pads so I'll get me some of that and give that a try first. Cheers.
 
I had the same problem around 500kms and had it looked by bmw and they cleaned all the brake dust and it was gone for good, it does make some squeak cold mornings but goes away.
 
I had the same problem around 500kms and had it looked by bmw and they cleaned all the brake dust and it was gone for good, it does make some squeak cold mornings but goes away.
Thanks STiago, I'm thinking it's something like this or what others suggested above so I'm gonna ask about this at my first service which is coming up soon. Cheers.
 
Thanks STiago, I'm thinking it's something like this or what others suggested above so I'm gonna ask about this at my first service which is coming up soon. Cheers.
Yes I told BMW to look at it during the break-in service and thats when they cleaned and it was good after that.
 
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