Caliper Knocking

ConTRo13R

ConTRo13R

ConTRo13R

Soldato
Joined
3 Mar 2008
Posts
3,147
Location
Canterbury, Kent
Whats going on here :(

Its not the wheel bearing as iv had both calipers off and the wheel spins freely, no notches, right hand side caliper attached, spin wheel, its fine, add left hand caliper into the mix and this happens. Most annoying whilst riding around town.

I have replaced all seals and bleed the lines though i think one of the pistons is still sticking.. when i apply the brakes i have full braking power and no noises of judder. just when i release the brakes then this constant knocking noise seemingly every wheel rotation.

Video link:
http://youtu.be/pnQ6d6ru090
 
Yeah warped disk or something? turn the wheel really slowly, do you get more resistance trying to turn the wheel when it reaches the knocking bit?
 
do you have any little spring plates/shims etc in them?
any missing
had something similar and it was one missing spring plate, letting the pads rattle around when the brakes weren't being used
 
Fireskull said:
Yeah warped disk or something? turn the wheel really slowly, do you get more resistance trying to turn the wheel when it reaches the knocking bit?
Click to expand...

A lot of resistance just before and slightly during the knock, If i bought a new disc would i need to replace the other side too? or just the pads.. this is depressing as i need a new rear tyre and chain, and have my MOT next month
 
wazza300 said:
warped disc or loose disc buttons
Click to expand...

By loose disc buttom do you mean the blots holding the disc to the wheel/carrier

ShakenNstirred said:
do you have any little spring plates/shims etc in them?
any missing
had something similar and it was one missing spring plate, letting the pads rattle around when the brakes weren't being used
Click to expand...

both my plates that hold the pads are in place, the calipers don't have any shims on them and never did.
 
Yh the buttons hold the outer disc to the inner rotor

They are floating so should move ever so slightly but not rattle
 
Watching the video a couple of things come to mind:

Are the pads rocking backwards and forwards in the caliper, so that if they bind slightly on the disc they are moving then knocking on the caliper/pad pin?

Also have you checked the condition of the sliding pins and rubber bushes where the caliper slides on it's mount?

If none of the above help how about swapping pads left to right, that isolates if it's a pad issue or disc/caliper. If it stays with the lhs then swap the discs around, or even try turning the wheel round if the spindle/collars let you do it.

My experience of sticking pistons is that you'll get a spongy feeling like there is air in the system. You can check further by popping the caliper off and seeing if you can slowly push the pistons back into the caliper. Usually helps to clean up around the pistons/seals first so you don't push a dirty piston back into the caliper. And if needed take the top off the reservoir to check there's free space for the fluid level to rise while you do this.

If pistons are sticking next step is applying some more force to push them back in. Helps to use piece of wood or similar to protect the pistons or put an old brake pad in there and you can lean on that as much as you like.

Repeating process of pushing pistons in and pumping them out again to free it off as much as possible. Handy usually to set up something across the caliper body so that you don't pump the pistons right out of the caliper - a long allen key, spanner etc with bit of tape wrapped round it or big wide flat tyre lever is ideal.
 
tl45 said:
Watching the video a couple of things come to mind:

Are the pads rocking backwards and forwards in the caliper, so that if they bind slightly on the disc they are moving then knocking on the caliper/pad pin?

Also have you checked the condition of the sliding pins and rubber bushes where the caliper slides on it's mount?
Click to expand...

The knocking is clearly coming from either the caliper moving on the sliders or the pads moving within the caliper, but IMO this is the symptom, not the cause.

The brakes are binding at one point only, which can only be caused by a problem with the disc. Spinning the wheel with the caliper removed and supporting a marker pen against the fork leg and moving it slowly towards the spinning disc will show any significant run-out, which may be caused by either a warped disc or occasionally corroded and seized bobbins.

It's also possible for discs to wear unevenly, resulting in thin/thick points and the difference only has to be tiny to cause braking problems.
 
What is the bike again? and are new discs expensive?

If you can do without the bike for a while you can send your discs off to Maidstone motoliners in Kent and they will straighten your disks, and whilst they are doing that you can dismantle the calipers and give the pistons a good clean and maybe new seals if needed, usually its just one of the pistons not sliding as well as it should be and this causes a warp.

Of course you could just get a new disk, but theres no guarantee without checking over the calipers that it wont do it again, and I speak from experience here :p
 
I would say that the noise is coming from the caliper moving on the pins once a certain point of the disk runs through the pads. Iv found one point on the disc that once having passed through the pads the caliper pushes out and then knocks back in. Is this definitely a symptom of a warped disc?

Iv already replaced the seals and cleaned the pistons in the caliper, although one piston is definitely more reluctant to move than the other so may need to do a better cleaning job when i next get a day off

New OEM discs are 125 form David Silvers, bike is a CBR 600 F3 from 1997, i use it everyday as its my only mode of transport.
 
Yeah if one pistons is difficult to push back then yes definitely need to sort that one out, did you replace the seals on that piston? it may be that the piston is pitted? might be worth looking into a new one.
Pistons when you have greased them up and fitted new seals should be easy to push back just by hand.

Yes if the disc has resistance at a certain point then definitely warped, a disc should spin freely all the way around, the knocking will just be the pads knocking against the caliper, pads should wobble slightly up and down and when its getting to the warped bit its just knocking the pad against the caliper.
 
Last edited:
replaced all seals on all pistons on all calipers. I had this problem about 3-4 weeks ago which is why i replaced and rebuilt the calipers, the knocking went away and is now back with a vengeance! So looks like a new piston and a new disc for xmas
 
any crap or corrosion around any of the buttons? might need cleaning off?

does seem like warped disc,i also enquired about disc rebuild on my zx10 and it worked out cheaper to buy second hand used pair so I did that,£45 for the pair

if you can pick just one up though id do that and just replace the one disc,whatever you can get cheaper pair or single

pads should rub ever so slightly on the disc at all times not knock so it has to be warped at some point
 
I see you are in Kent I would seriously consider asking Maidstone motoliners to have a look at your disk, might be worth calling and they might be able to do a ride in ride out service if you are desperate?

Piston I would check ebay and also call a local dealer, there must be official online Honda parts but not that I know of, maybe someone else here knows more about Hondas :p
 
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