Squealing brakes

Dellortoman

Dellortoman

Hero member
Location
Tasmania, Australia
I have a disk brake that squeaks like a bastard. As it happens, it's the rear disk on my Kawasaki that's been driving me nuts lately, but I've also had squealing to a lesser extent with my Jota rear brake. So it's a problem that could afflict any bike.

It only happens at low speed under relatively light braking. If I stomp hard on the pedal it doesn't do it. Nor does it happen at higher speed, around 60kph or above. It makes a godawful noise when slowing down or stopping at traffic lights. I've seen pedestrians cover their ears.

I've tried replacing the pads, to no effect. I've also tried a self-adhesive product that sticks to the back of the pads that's supposed to damp out vibration. Yeah, right. A complete waste of money.

Another thing I tried was de-glazing the disk with fine emery cloth, which was also a failure.

The bloody thing still makes a horrible racket.

Does anyone have any tips on how to fix it?
 
Ive arrised the edges of pads before Cam, so that they do not have a sharp leading or trailing edge.
works for me.
just on a grinding wheel or linisher or even with a blunt spoon.... :)
 
Cast iron disc,cam? Chamfer the edges of the pad as TC says, wurth do a red paint anti squeal that I use on every new set of pads I install. Jap bikes usually come with stainless steel shims, which I paint both sides of.
 
My Toyota used to squeal something shocking and i sprayed some special anti-squeal stuff on the discs, which worked a treat. Came from a std auto parts joint like Burson, Autobarn or Supacheap. Only used it once and chucked the can when i cleared the garage because it had ben sitting for years unused.
 
T.C said:
Ive arrised the edges of pads before Cam, so that they do not have a sharp leading or trailing edge.
works for me.
just on a grinding wheel or linisher or even with a blunt spoon.... :)
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I've always believed, because someone smarter than me told me, it was due to vibration.

My daughters Volvo brakes squeal like a old mole, but a few uses of the brakes, and it doesn't do it until cold, again.
She asked me why it squealed so much, I told her it was a safety system employed by Volvo, so pedestrians could hear her approaching. :)
 
New stainless discs on my Guzzi squeal bad, blue pads Brembo 08. Never used to squeal on the old cast iron discs. I'm waiting till they bed in before I pull it apart, haven't ridden it for a month, too many other toys. Will chamfer the edges if they don't quieten down.


Or wd40😜
 
Is there meant to be a steel shim behind one or both pads? A smear of grease on the shims and the pad backing has worked for me in the past.
Not sure about rubber shims… maybe they’re only for more modern ones…
 
martymoose said:
Can of anti squeal was probably wd40 Q😜
Click to expand...
From memory it was like lightweight paint, Marty!

I had a friend who was working on his Lemoans and was bemoaning how the cast discs rusted and asked if i knew of a cure - I jokingly said to put oil on them and to my horror i came out later and there he was oiling the bloody things until I yelled 'NO!! It was a joke!'

Had plenty of bicycles in the shop where owners had decided the easiest route to quiet brakes was lubrication ... you could save the discs but the pads were always cactus.
 
the reason that hydraulic calipers have square section seals in them, is this, when the brakes are applied the seal bends just a tiny bit to allow the pads to contact the disc, when the brakes are released it straightens and moves the pistons/pads away from the disc just a few thou to gain clearance, there are no springs to bring this clearance, just the relaese of the hydraulic pressure and a bit of vacuum it creates, plus the give in the seals, all adds up to it doing the job, what your squealing says to me is that the seals may be getting hard or the pistons beginning to seize.

I have no idea why a smear of copper grease on the backs of the pads sometimes works, but it does

CLEM
 
The squealing is a resonant vibration, putting the smear of the special grease behind the pad, ideally on the stainless shim (that usually comes with new pads for a car along with the grease), stops the resonance from getting out into the chassis and amplifying. The first time I saw a production race in the early ´70s I thought some of the bikes were tooting at each other while braking. Kawasaki introduced those weird oddly drilled discs back then to prevent the squealing, so that the disc couldn't resonate.
 
I just took the pads out out of my Kawasaki rear brake. Pain in the arse job because the brake is on the sidecar side which restricts access. Also, the rear wheel has a 15" car rim on it and there's barely room inside the rim to get the pads out.

The pads had about 3mm of friction material still on them which looked a bit thin to me, so I dug around in my Kawasaki spares and found a new set of pads. They actually weren't much thicker. They only have about 4mm to begin with. So I bevelled the leading and trailing edges of the old pads and put them back in. I haven't taken it for a test ride yet so the jury is still out on whether it'll fix the squealing problem.

Incidentally, the "anti squeak" adhesive foil shit that I stuck on the back of the pads a couple of years ago had pretty much disintegrated. The adhesive had come un-stuck (not heat resistant?) and a couple of scraps of remaining foil fell out when I took the pads out.
 
Hi Cam. If the damping doesn't work, ensure the caliper are mounted true (square on) to the disc. A very small angle can occasionally cause a squeal.
 
Hi Cam, when I had my GPX 600 all year round commute bike the brakes could be a pain in winter. Twin piston setup. A big one and a wee one. The problem I had was the wiper seal being held out with crap behind it causing it to stop the piston retracting properly. Cleaning out that wee groove and lubing it white white grease cut the maintenance down to a more normal level. Took a while to get to the white grease trick as I'd try copper slip high point types etc to no avail. The pinching of the pistons was causing the pads to sit off square etc etc.
 
I noticed that one of the pads had worn at a slight angle when I had them out. I was wondering if that might have been the scrunched up adhesive foil making the piston contact uneven.

The caliper could probably do with a bit of maintenance. But it's a bugger to get off. It's all cast in one piece with its carrier so the axle and wheel have to come out. The disk also has to come off the wheel because there's not enough clearance between it and the rim to get the caliper off. Stupid bit of design, made worse by the sidecar wheel modifications. I don't wanna dismantle the bike right now because I'm relying on it for transport while my car is off the road (buggered clutch). The sidecar is handy for carting stuff around, like groceries, car parts, etc. The car is booked in next week to get a new clutch (not a job I wanna tackle myself) so maybe after that the poor old Kawasaki will get a bit of overdue TLC.
 
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