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Squeal like a pig!
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Author:  Inconceivable [ Thu Apr 26, 2018 11:35 am ]
Post subject:  Squeal like a pig!
Hey all, I have Shimano Deore brakes and generally they work well and silently. What I have noticed is that after a longish sustained downhill, or towards the end of the session, the front brake starts to squeal, LOUD. Otherwise, they don't make a sound.

They are the original rotors on a bike which is just shy of 3 years old (minus about a year for injury). I'm probably on my 2nd or 3rd set of pads. I have bled them myself once. They were properly (I think) bedded soon after I got the bike.

Any ideas as to why this is happening? Is there some heat-related issue going on?
Author:  Big Clyde [ Thu Apr 26, 2018 11:38 am ]
Post subject:  Re: Squeal like a pig!
Inconceivable wrote:
Hey all, I have Shimano Deore brakes and generally they work well and silently. What I have noticed is that after a longish sustained downhill, or towards the end of the session, the front brake starts to squeal, LOUD. Otherwise, they don't make a sound.

They are the original rotors on a bike which is just shy of 3 years old (minus about a year for injury). I'm probably on my 2nd or 3rd set of pads. I have bled them myself once. They were properly (I think) bedded soon after I got the bike.

Any ideas as to why this is happening? Is there some heat-related issue going on?


Stop following Orven and Shannon..........................


:cheers:
Author:  Kimba [ Thu Apr 26, 2018 12:22 pm ]
Post subject:  Re: Squeal like a pig!
^^^ That's funny. For the record, I have the same issue.
Author:  Dirtrider [ Thu Apr 26, 2018 1:00 pm ]
Post subject:  Re: Squeal like a pig!
I have Shimano brakes BUT have always run 203/180 rotors. The stock 180/160 didn't cut it and can't dissipate the heat like larger rotors could. (I guess I should just let off the brakes more :oops: )
I have found that the metallic pads are a bit noisier than organic also. Some of the newer pads have the thin metal backing that helps quiet the noise too.
Author:  Inconceivable [ Thu Apr 26, 2018 3:30 pm ]
Post subject:  Re: Squeal like a pig!
Big Clyde wrote:
Inconceivable wrote:
Hey all, I have Shimano Deore brakes and generally they work well and silently. What I have noticed is that after a longish sustained downhill, or towards the end of the session, the front brake starts to squeal, LOUD. Otherwise, they don't make a sound.

They are the original rotors on a bike which is just shy of 3 years old (minus about a year for injury). I'm probably on my 2nd or 3rd set of pads. I have bled them myself once. They were properly (I think) bedded soon after I got the bike.

Any ideas as to why this is happening? Is there some heat-related issue going on?


Stop following Orven and Shannon..........................


:cheers:


The last time I went riding with Shannon and Orven (and Kimba and Jimbro and Kimba's buddy) I decided to follow Shannon and Orven down Gabe's trail at [location redacted].

I think Shannon could tell that I was pretty nervous about it, so he tried to give me some confidence by saying (roughly):
"Don't worry, you're going to be fine. Even Harley did it, although he had to walk a bunch."
Author:  Inconceivable [ Thu Apr 26, 2018 3:32 pm ]
Post subject:  Re: Squeal like a pig!
Dirtrider wrote:
I have Shimano brakes BUT have always run 203/180 rotors. The stock 180/160 didn't cut it and can't dissipate the heat like larger rotors could. (I guess I should just let off the brakes more :oops: )
I have found that the metallic pads are a bit noisier than organic also. Some of the newer pads have the thin metal backing that helps quiet the noise too.


Yup, I'm running 180/160 right now and have been thinking about going with larger rotors for some time now. All you need to do is buy the rotors and a spacer to offset the calipers, right?
Author:  Dirtrider [ Thu Apr 26, 2018 3:44 pm ]
Post subject:  Re: Squeal like a pig!
Inconceivable wrote:
Dirtrider wrote:
I have Shimano brakes BUT have always run 203/180 rotors. The stock 180/160 didn't cut it and can't dissipate the heat like larger rotors could. (I guess I should just let off the brakes more :oops: )
I have found that the metallic pads are a bit noisier than organic also. Some of the newer pads have the thin metal backing that helps quiet the noise too.


Yup, I'm running 180/160 right now and have been thinking about going with larger rotors for some time now. All you need to do is buy the rotors and a spacer to offset the calipers, right?


Move the front 180 and adapter to the rear and buy a new 203 and adapter for the front.
Author:  OldDogDan [ Thu Apr 26, 2018 4:13 pm ]
Post subject:  Re: Squeal like a pig!
Make sure everything’s tight and clean, and the rotor is true. Pads, esp. if organic, might be glazed, which can be removed on clean sandpaper. Sometimes that helps to do to a rotor also. Take them off to do it, and put the fine sandpaper on something very flat.
Author:  Big Clyde [ Thu Apr 26, 2018 4:42 pm ]
Post subject:  Re: Squeal like a pig!
Inconceivable wrote:
Big Clyde wrote:
Inconceivable wrote:
Hey all, I have Shimano Deore brakes and generally they work well and silently. What I have noticed is that after a longish sustained downhill, or towards the end of the session, the front brake starts to squeal, LOUD. Otherwise, they don't make a sound.

They are the original rotors on a bike which is just shy of 3 years old (minus about a year for injury). I'm probably on my 2nd or 3rd set of pads. I have bled them myself once. They were properly (I think) bedded soon after I got the bike.

Any ideas as to why this is happening? Is there some heat-related issue going on?


Stop following Orven and Shannon..........................


:cheers:


The last time I went riding with Shannon and Orven (and Kimba and Jimbro and Kimba's buddy) I decided to follow Shannon and Orven down Gabe's trail at [location redacted].

I think Shannon could tell that I was pretty nervous about it, so he tried to give me some confidence by saying (roughly):
"Don't worry, you're going to be fine. Even Harley did it, although he had to walk a bunch."


HEY!


:cheers:
Author:  Dirtrider [ Thu Apr 26, 2018 6:12 pm ]
Post subject:  Re: Squeal like a pig!
OldDogDan wrote:
Make sure everything’s tight and clean, and the rotor is true. Pads, esp. if organic, might be glazed, which can be removed on clean sandpaper. Sometimes that helps to do to a rotor also. Take them off and put the fine sandpaper on something very flat.

Try to Keep your paws off everything and wipe it all off with alcohol when done to remove oils from your hands
( no, not beer :cheers: )
Author:  Big Clyde [ Thu Apr 26, 2018 7:04 pm ]
Post subject:  Re: Squeal like a pig!
Dirtrider wrote:
OldDogDan wrote:
Make sure everything’s tight and clean, and the rotor is true. Pads, esp. if organic, might be glazed, which can be removed on clean sandpaper. Sometimes that helps to do to a rotor also. Take them off and put the fine sandpaper on something very flat.

Try to Keep your paws off everything and wipe it all off with alcohol when done to remove oils from your hands
( no, not beer :cheers: )


Beer is not alcohol?


:cheers:
Author:  avidtest [ Thu Apr 26, 2018 8:44 pm ]
Post subject:  Re: Squeal like a pig!
Oh shit... Hit by the bus. :lol: :lol: Uh.. Love ya Harley!

Kimba, what the heck is going on with yours? We heard you a 1/2 mile away that last ride. :wink:

As for brakes, not much to offer, but here is my experience. 160/160 XT's on an 2011 29r were inadequate, squealed, and overheated till the rotors burned and felt like there was layer of grease on them.

XTR 180/180 on a 26r and then again on my current 27.5r were dang good. Icetech rotors and pads both times. Metallic pads too btw. Hard bite and never squealed. My only complaint eventually became lack of modulation. On or off essentially. 180/180 set up right with the right pads, (and the right brakes), should be sufficient, and not squeal on you.

it took me more than a few weeks, but now I'm loving my Hope upgrade. A brief parking lot style ride with RS Guides felt very similar, and a worth upgrade. I prefer mineral oil fluid though. It's my only disappointment, but not significant.

Anyway - that's not really what you asked. 180/180 set up right with the right pads, (and the right brakes), should be sufficient, and not squeal on you, but follow Mike and Dan's advice and go 203/180, if cleaning everything and deglazing your rotors does not solve the issue first.

Might have missed it, but do you use organic or metallic pads?
Author:  Big Clyde [ Thu Apr 26, 2018 10:43 pm ]
Post subject:  Re: Squeal like a pig!
203 and 180 Shimano XT.
180 front is not enough for me.
Organic pads always!
Like said before, a light sanding
on pads and beer (alcohol) on rotors.

And stay away from Orven and Shannon!

:cheers:
Author:  ozzer [ Thu Apr 26, 2018 11:24 pm ]
Post subject:  Re: Squeal like a pig!
LOL. Stay away from eBikes. Fuckers got more laps than us before we even got to the second climb.

Anyway. Dan and Harley are on point.
Heat which results in surface glazing is the primary culprit.
Start with a properly bled and firm feeling brakes. Air in the system is not good and you'd be forced to apply more pressure unnecessarily. More brakes = more heat build up.

To test if it's glazing, remove brake pads and rotors.
Skip the alcohol treatment as this is preferably used when you're in a hurry.
Wash your rotors under warm water with dish soap (dish soaps have surfactants that help break down grease). Rinse them good and air dry or paper towel.
I would advise wearing nitrile or plastic gloves when you're handling rotors.
Our skin is full of oil glands (palm your mirror and see the grimy print).

Once dry, get a coarse sand paper and rough up the rotor surface in circular sanding motion.
It's the same principle why auto rotors are "turned."
You just need to burr the glazed/smooth surface.
Do the same with the pad surface but don't overdo it as you may lose pad materials in the process.
Just skim the surface.

Reset the piston in each of the caliper, then reinstall the pads and rotor.
The noise should be instantly gone.If the squealing persist prior to heating up, your pads are contaminated. If they're organic, trash them. Hard to get contaminants off organic pads as they penetrate more over sintered or full metallic pads.

If the squealing comes back over time especially following a sustained descent, then you either need a higher volume brake system along with four piston calipers mated to slightly larger 180 front anfd rear rotor combo OR learn to brake "properly."

No brake system is immune to overheating if you drag your brakes excessively. That practice takes time. Start by practicing to "pulse" your braking rather than dragging. This would also help you get better control of your bike. Locked wheels don't roll and wheels that don't roll slide. Think ABS system in cars. It sends pulses to actuate brakes at intervals so they don't lock up.
Author:  Inconceivable [ Fri Apr 27, 2018 11:43 am ]
Post subject:  Re: Squeal like a pig!
Wow, great feedback all, and thank you.

Harley - if it soothes your wounded ego, I did remind Shannon that you are better than me shortly after he said that. :)

I currently have non-finned metallic pads. On my old bike I switched to organic b/c of the squeal but it hasn't been a problem on my new bike until very recently, and like I said, only at the end of the rides.

Ozzer - Do I need to "bed" the brakes again after I clean and sand them? Also, I am for sure a bad braker... you can call me Sir Drags-a-lot. I am trying to get better on that, and thank you for the tips on pulsing the brake. In the meantime, would going to larger rotors (e.g. 180 to 203) help dissipate the heat? I'm on a 27.5 bike and not exactly a big dude, as you know. I don't mind dropping a few bucks on the problem (i.e. new rotor + spacer) but upgrading my entire braking system wasn't in the plan.

thanks!
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