Squealing Front Brake

[Zoglug]

Morning all, need a little help and advice trying to solve my front brake issue.

I have an On One 456 and have recently replaced the Avid Elixir 5 brakes with Shimano Deore (M775). Both installed with relatively little fuss, bled up pretty well (at least i think they have) and being used with Superstar sintered pads.

The back brake is perfect, grips well and stops me, the front however doesnt! As i pull the brake, the pad engages, but then just slips, it doesnt stop me and it howls like a banshee I spent yesterday bleeding the brakes yesterday but it did not solve the problem. I have also removed the pads and spent some time ensuring they were not contaminated during any of my diy.

When i removed the pads, i noticed that the rotor only appears to be being gripped by the bottom half of the pad so i think this may be where the issue is. Before i purchased the brakes, i did various google searches and they said the brakes should just drop on as a direct replacement no need to replace anything, however, i am now beginning to think this is not the case.

Has anybody got any experience of this? Do i need to replace rotors/mounts or am i missing something else here. If anybody could shed any light, i would be very grateful.

Many thanks

[Bearbonesnorm]

i noticed that the rotor only appears to be being gripped by the bottom half of the pad

It sounds like a mis-match of disc and adaptor ... either larger diameter disc required or 'smaller' adaptor. I bought some SH XT brakes a while ago that had obvously suffered the same, the bottom half of the pads were worn out but the top half as new ... when the brake was applied the top of the pads were touching before the bottom met the disc, resulting in a good lever but absolutely no braking.

Also it's fairly common for sintered pads to be a bit noisy.

[ScotRoutes]

Could do with more details and/or photos.
What size of rotor is fitted? What (if any) mounts/adapters are there between your forks and the new caliper?

It could be that your caliper isn't aligned correctly.
Or that you have some spacers between the mount and the caliper.
Or that you have a non-matching rotor and caliper mount.

[Zoglug]

Cheers guys, once ive cycled home from work later, I shall take some pics of the rotor, mount and pads at least ive some kind of an idea now what it may be and i dont just keep bleeding the brakes hoping for it to miraculously work!

[Dan_K]

My sintered superstar pads scream like a bitch too.

[chris n]

Did you leave the spherical Avid 'Tri-Align' washers on when fitting the Shimano calipers? These will push the caliper too far out so it only grips half the disc.
A dab of Coppaslip on the back of the pads can help to stop brakes squealing.

[johnnystorm]

I did something similar when fitting my first set of shimanos. I put wiggle washers in as suggested above, so it raised the caliper up.

It was:
Fork post mount/adapter/washers/caliper/bolt head

When fixed:
Fork PM/adapter/caliper/washers/bolt

Now so much better than Elixirs. Won't be going back.

[Zoglug]

It could well be the washers. At the moment, off the top of my head its

Fork / adapter / washers / caliper / washers / bolt (the washers are the dome washers to allow easy alignment of the caliper.

and this is how it was for the Avid's too, i literally changed the caliper. I shall try to remove one set of the washers and see how i go, if i have no joy i shall post up some pics too!

[pistonbroke]

Just be careful when re-installing the bolts when you've taken out the washers. The bolt may extend too far into the fork mount. A cracked mount due to doing this is very expensive as it's a casting which can't be mended.

[Zoglug]

Just be careful when re-installing the bolts when you've taken out the washers. The bolt may extend too far into the fork mount. A cracked mount due to doing this is very expensive as it's a casting which can't be mended.

I hadnt thought about that! Guess it'll be a trip to the LBS to pick up some alternative bolts tomorrow!

[Bearbonesnorm]

I hadnt thought about that! Guess it'll be a trip to the LBS to pick up some alternative bolts tomorrow!

Hacksaw?

[johnnystorm]

I hadnt thought about that! Guess it'll be a trip to the LBS to pick up some alternative bolts tomorrow!

Hacksaw?

Put all the washers directly under the bolt head?

[Chew]

Doesnt the caliper mount directly onto the mount?
(it does on my new shimanos)

Either you have the wrong mount or washers in there that you dont need.

If you need someone to look at it give me a shout as i believe you're not that far away

[Zoglug]

Morning all!

Many thanks for the suggestions/recommendations. Apologies i havent posted any pics, i took them on my iphone and like an idiot took the iphone to be repaired by Vodaphone before taking the pics off.

Anyways, started playing around a little last night, i have now mounted the caliper to the adapter and put all the washers under the bolt head (so simple, cant believe i didnt think to do that! ) which appeared to drop the caliper into the right place however, a quick blast around the block and the squeal was still there. Decided to change the pads this morning too before the commute to work and it appears to have solved the problem! no squealing and no more blind panic that im not going to stop!

Many thanks for the collective thoughts on this one! Saved me putting the Avid's back on!

[mountainbaker]

When I used to commute in the big smoke, my discs would get really squeaky from all the oils in the road spray. Best solution I found was to take the pads out and boil them in water for a few minutes. The oils would float to the surface, carfully drain the water so the oil doesn't contact the pads, and re-install.

[Zippy]

When I used to commute in the big smoke, my discs would get really squeaky from all the oils in the road spray. Best solution I found was to take the pads out and boil them in water for a few minutes. The oils would float to the surface, carfully drain the water so the oil doesn't contact the pads, and re-install.

That's one I haven't heard before, might give that a go. (when I get contaminated pads again, all ok at the moment!)

Meths/brake cleaner/isoprponal normally degreases discs well and I have used a file before on the pads if the pads are still ok but contaminated - which I guess only works if the contamination is baked in on the outer surface. If that doesn't work I'd normally put in a new set of pads (after cleaning the disc obvs!).

[Zoglug]

So i still have issues with the pads discs and i think it is something to do with the hosepipe contaminating them with some kind of oily residue. Im looking to replace the discs and just wanted to make sure these would fit well? http://www.on-one.co.uk/i/q/BSSHRT66/sh ... disc-rotor

I am assuming i only need 160mm front and rear but dont want to buy something it if itsnt going to be any good! Looking at buying from On One, so i can pick up a set of OG bars with free p&p

[Bearbonesnorm]

Those will work fine, 160mm F+R is okay as long as your not going mad.

What size are the discs at present? You'll need new adaptors if they're not already 160mm (which I suspect they're not).

[Zoglug]

Cheers Stu, ive got a feeling it is a 180mm up front and a 160mm at the rear (its a stock 456 from a few years ago so cant find the info online). May have a quick look around see if i can pick the same sizes up elsewhere to save me changing adapters as well. Its not the squealing which bothers me, but the distinct lack of braking power!

[Bearbonesnorm]

The discs from superstar are okay.

http://www.superstarcomponents.com/en/s ... sc-rotors/

[Zoglug]

Started dismantling my brakes to have a closer look at them/clean them up, so i thought id post some pics. Discs look like they are ruined as they now seem heavily marked:-

Front Disc:





Rear Disc:





As with the discs, the pads also show signs of uneven wear, the first set its because i had things set up wrong, since then though I have had the calipers aligned correctly, or at least i think i have!



I guess ill try to clean these up and stick them back on for my commute and order some new discs/pads and see how things go from there!

[Bearbonesnorm]

Those discs and pads (second set) actually look okay.

[Zoglug]

Those discs and pads (second set) actually look okay.

Cheers stu, im going to clean them up this morning, see if i can use something on the pads incase they have become contaminated and see how i go with them! Ill leave off buying more for now!