# noisy front brake



## the_bing (31 Oct 2010)

managed to blag a deore xt front disc brake and wheel from a mates trashed diamond back. really pleased with it but under braking (much more noticable at speed) there's a brrrrrrrrrrr noise from the front brake; not really loud but def there. is this normal? 

i've been running hydraulic magura's for the past god-knows-how-many years; this my first disc brake on my 10 yr old specialized so i don't know if it's ok.

plus when wet, the front brake squeals too. is there any way to adjust this out or perhaps champher the leading edge of the pads?

cheers peeps.

get out and enjoy the autumn colours!


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## Cubist (31 Oct 2010)

the_bing said:


> managed to blag a deore xt front disc brake and wheel from a mates trashed diamond back. really pleased with it but under braking (much more noticable at speed) there's a brrrrrrrrrrr noise from the front brake; not really loud but def there. is this normal?
> 
> i've been running hydraulic magura's for the past god-knows-how-many years; this my first disc brake on my 10 yr old specialized so i don't know if it's ok.
> 
> ...



The Brrrrrrr noise is perfectly normal. It's the pads running over the ventilated surface of the rotor. It's a good thing. When it grates/shrieks/squeals, it means your pads are worn. 

All disc brakes are squealy in the wet. They sound even worse when they've got a bit of mud in them. Learn to live with it as again, it's sort of a sign that everything's OK.

How new are the pads? It may well be worth getting hold of a can of brake and clutch cleaner and giving the discs and pads a thorough cleansing. All sorts of accumulated shite can affect the way they work.


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## the_bing (8 Nov 2010)

excellent, thanks. that puts my mind at rest


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## 02GF74 (10 Nov 2010)

my magura martas squeel when wet.


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## I like Skol (16 Nov 2010)

Just been out in the rain on my F&R disc equiped new bike tonight and found the front brake squeals horribly when wet. It's only the front doing this (WHY?) and if I give it a few good pulls and releases it then shuts-up (dries off?).

Is there anything i can do about this? I know there shouldn't be any contamination of the front brakes as it is a new bike out of the box and hasn't been lubed yet and in my mind I would expect the rear brake to cop for more wet than the front with road spray thrown up from the front wheel. There must be a trick to eliminate this, could it be an alignment issue? The bike seems to be very well set up by the selling shop (JE James in Chesterfield) and needed minimal alteration by me just to tailor it to my personal requirements really (I always go through new bikes myself, it's a control freak thing!).

WHAT CAN I DO?


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## Cubist (16 Nov 2010)

Disc brakes squeal for all sorts of reasons, and are worse in the wet. A new pair of pads need to be bedded in in order to achieve maximum braking power. Once bedded they need to be re-centred or realigned, and you need to keep the rotors absolutely clean, without a hint of grease or oil. If all the above is sorted, and they still squeal, then ancient wisdom tells us to put a dab of grease or coppaslip on the BACK of the brakepads between them and the piston if you can't live with the noise. 

To bed pads in in quick time you need to get up to full speed and bring the bike to a halt several times, making sure that the brakes get hot enough to sizzle when splashed with water. Check by splashing them with clean water! This helps to put a glaze on the pad surface apparently.

Next, you need to realign the brake caliper so that the rotor runs through the centre of the gap between the pads. Most modern brake calipers are mounted with a self shimming style assembly, and you simply need to slack off the cap screws (allen bolts) holding the caliper to the frame, apply the brake and nip the bolts back up to finger tight whilst holding the brake on. Let go of the brake lever and spin the wheel to check that it doesn't rub, then. with the brake lever held on again, tighten the mounting bolts a quarter turn at a time, alternating between them until they are torqued up properly. Don't overtighten them! 

Buy yourself a can of brake and clutch cleaner. Use it sprayed onto a clean cloth to wipe the braking surface of your brake rotors, and spray it generously into the caliper. It loosens and swills out all sorts of crap, so use a clean rag to wipe out the excess.


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## I like Skol (16 Nov 2010)

Cubist said:


> ancient wisdom tells us to put a dab of grease or coppaslip on the BACK of the brakepads between them and the piston if you can't live with the noise.........
> 
> ......you need to realign the brake caliper so that the rotor runs through the centre of the gap between the pads. Most modern brake calipers are mounted with a self shimming style assembly, and you simply need to slack off the cap screws (allen bolts) holding the caliper to the frame, apply the brake and nip the bolts back up to finger tight whilst holding the brake on. Let go of the brake lever and spin the wheel to check that it doesn't rub, then. with the brake lever held on again, tighten the mounting bolts a quarter turn at a time, alternating between them until they are torqued up properly. Don't overtighten them!




Thanks for this. I did wonder about some copper grease, I have a large tin in the garage I use for doing brake jobs on my cars. I will try resetting the alignment now the brakes have a few miles on them and if that doesn't help then will have to whip out the pads and put a little copper grease between the piston faces and the pads. 

EDIT: I like how you highlighted to put the copperslip on the BACK of the pads, LOL


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## I like Skol (17 Nov 2010)

Well, just nipped out to garage to see about the caliper alignment on my front brakes and I hope we have it nailed now.

Before tinkering I noticed that a firm pull of the brakes resulted in slight movement/twisting of the rotor as the caliper clamped it. Once the mounting bolts were loosened and retorqued the rotor stayed put so fingers crossed that was the answer. I am planning to ride to work tonight and it is sure to rain at least a little so I should know soon enough.

Thanks for the advice.


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## I like Skol (20 Nov 2010)

I thought I would add an update to this in case anyone else reads it looking for hints.

I used my bike for a commute run to work (just under 11 miles each way) and the squeaky brakes were still there and got worse to the point the whole bike was vibrating when using the front brake (back brake still fine). I rechecked the caliper alignment and it still looks good and doesn't pull the rotor out of true but I did notice the headset had got some slack in it either because the newness is wearing off or the extreme rattle when braking has shaken it loose. Either way, I nipped it back up then took the caliper off and removed the pads. The pads were cleaned by rubbing the friction surface on a piece of fine emery paper on a flat surface then putting a small chamfer on the leading and trailing edges before reinstalling in the caliper with a smear of copper grease on the rear of the pad and carefully on the edges of the backing plate. I then reinstalled the caliper to the bike and a quick test ride up and down the street outside my house suggests the problem is sorted (I hope)

Tonight I plan to ride into work again, so that will be the real test but unless I post back here again to complain that the problem is still present we can all assume it is sorted.


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## I like Skol (20 Nov 2010)

NOOOOOoooooooo..............

The ride into work started well but by the time I was nearly halfway there the weather had changed from damp/misty to light rain and the brake squeal and judder had returned. To make matters worse, the rear seems to be starting too in sympathy with the front. I am really getting ticked off with this now as it is so bad I find myself trying not to use the front brake  

If I can't think of anything else to try I will have to get in touch with the shop that sold the bike and see what they suggest. This is my first foray into disc brakes and so far it isn't looking too promising. The brakes are Tektro Aigura Comp Hydraulic and I read somewhere they are a copy of an older Shimano design so shouldn't have any serious design faults?

Any more suggestions?


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## Ticktockmy (21 Nov 2010)

I think brake squeal on Disc brakes is quite normal for wet weather, my Hopes squeal like mad, but dont judder unless I ease the brake slightly to stop the squeal, then the front judder, mainly because the pads being spring loaded tend to oscillate on and off slightly thus creating a on/off effect which reflects through the front suspension. the answer is to ignore the squeal and continue to apply the brakes firmly rather than giving a shap strong pull


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## I like Skol (22 Nov 2010)

Ticktockmy said:


> I think brake squeal on Disc brakes is quite normal for wet weather, my Hopes squeal like mad, but dont judder unless I ease the brake slightly to stop the squeal, then the front judder, mainly because the pads being spring loaded tend to oscillate on and off slightly thus creating a on/off effect which reflects through the front suspension. the answer is to ignore the squeal and continue to apply the brakes firmly rather than giving a shap strong pull




Thanks TickTock

Despite my gloomy post after arriving at work, the ride home the following morning was entirely different. The weather was very dry and other than a brief squeak as I set off, the brakes were then silent all the way home. I even went out of my way to find some hills so I could get some heat into the brakes on the descents and by the time I got home the disc was begining to show some signs of polishing up. Maybe my problems were just down to the brakes needing to bed in properly? The bike has now covered about 70-80 miles so given a little more time (and some dry weather) hopefully the brakes will continue to improve.


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## Kestevan (29 Nov 2010)

If the pads on you Tektros are anything like the ones that came fitted to my Aurigas, then you'll probably find that they need replacing anytime soon.

The front pads on my new bike were trashed after less than 120miles, rears not far behind.

The std pads that came with the bike were crap, I've now fitted some decent sintered pads, and these have lasted much, much, much longer.


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## bungee (23 Mar 2011)

Guys, pretty new to disc brakes. Mine are whirring as well at high speeds but I think this has been answered. My issue in addition to this is the is an almighty squeaking noise, like when an old bus comes to a stop, when I am braking going downhill. Its that rough I can feel a strong vibration through my saddle. I have Shimano BR-M445 Hydraulic Disc Brakes and have only done about 150 miles on my bike. Does this sound like they just need re-centred or re-aligned as has been suggested ?


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## Cubist (24 Mar 2011)

bungee said:


> Guys, pretty new to disc brakes. Mine are whirring as well at high speeds but I think this has been answered. My issue in addition to this is the is an almighty squeaking noise, like when an old bus comes to a stop, when I am braking going downhill. Its that rough I can feel a strong vibration through my saddle. I have Shimano BR-M445 Hydraulic Disc Brakes and have only done about 150 miles on my bike. Does this sound like they just need re-centred or re-aligned as has been suggested ?


Yes,, but you could also do with making sure all the fitting bolts are torqued up properly, and that your rotor bolts are all snug. You'll need a torx key I expect. 
You also need to make sure the braking material hasn't come adrift from the backing on the pads.


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## bungee (24 Mar 2011)

Cubist said:


> Yes,, but you could also do with making sure all the fitting bolts are torqued up properly, and that your rotor bolts are all snug. You'll need a torx key I expect.
> You also need to make sure the braking material hasn't come adrift from the backing on the pads.



Thanks, don't quite understand the second bit, about the braking material coming adrift from the backing on the pads. What do you mean by that ? Excuse my ignorance.


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## Cubist (24 Mar 2011)

bungee said:


> Thanks, don't quite understand the second bit, about the braking material coming adrift from the backing on the pads. What do you mean by that ? Excuse my ignorance.


The brake pads have a block of friction material fixed to a metal backing plate, just like a car's brake pads. The material eventually wears off, but that isn't likely as you've only done 150 miles. Some pads fail, as the material simply comes adrift from the backing plate. That would then mean a metal on metal contact, and a possible reason for the squealing noises you describe. 

To check the pads, take your wheel off the bike and shine a torch at the pads. The should have a bare minimum of 1/2 mm of material left. If not, you'll need to change them. 

The vibrations you describe are possibly indicative of a loose rotor, loose caliper or a warped or bent rotor.


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## bungee (24 Mar 2011)

Thanks, makes sense now. Will have a look at everything tomorrow


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