Brake caliper Question ( probly a blonde Question )

[huffanpuff]

just fitted new brake pads but decided to clean the calipers up a bit, however as my mechanical knowledge is rather limited can any one tell me if the pistons in the calipers should all come out Simultaneously? there only seems to be one and a half coming out on either side i've cleaned and pumped out and squeezed back in but to no avail,how can i cure this?

[Dickie]

They will tend to come out unevenly. Get a bit of wood to stop the pistons being pushed out completely. You should be able to apply a bit of pressure against the ones that are coming out more readily than the others to get them all reasonably even. You don't need them out too far, enough to clean just past where the dust seal's been sitting.

HTH

[huffanpuff]

if they dont come out even wont that distributed the pad pressure uneven? or is that normal?

[Dickie]

It's normal,every caliper I've cleaned has done the same. Take a look at your old pads if they aren't already in the bin. The movement in the pistons is so slight that within the small movement at the lever to apply your brakes, every piston will have moved the distance it requires to squeeze the pad against the disc. Remember, the pistons don't move right back into the calipers when you let the brakes off, they just move back enough to allow the pads to move away from the disc, hence the need for a fluid reservoir to take up the slack as the pads wear.

Hope that makes sense.

[chewbacca]

Hi Huffanpuff.Are they 6 pot Tokico Calipers.All pots should come out at the same time,notorious for sticking ,require a stripdown at least once a year,especially if run through winter months.Messy business removing pots.Dust seals will be swollen and full of crud which prevents them coming out properly.If you can be bothered you can take them back to new condition the pots should push in with your fingers.Probably wont require new piston seals, may require new dust seals,but not cheap,bought in sets about £30 per caliper(that includes the piston seals).Other option is to pick up a good second hand set.Fitted to plenty different models.Make sure spacing between fixing holes are same dimensions as ones you have if going down this route.Hope this helps.

[Dickie]

Agree with what Chewie said, but unless the chrome on the pistons is pitted or scored, or there's evidence of fluid leaking from the caliper then I wouldn't be doing anything with the seals.

Another thing worth mentioning, ffs don't put coppaslip near any of the seals. If there's one thing that will make them swell that's it. Proper 'brake paste' (A 5.5g sachet of Wurth Brake Paste should be about £1 from a dealer) on the back of the pads is fine if you're getting squealing under braking, otherwise just leave them be, maybe a little (and a really mean a little) silicone grease (not silicone sealant) on the seals and pistons if you want to help things move smoothly.

http://www.oilsandsprays.com/wurth-brak ... -144-p.asp

[al]

Clean the body of the pistons with brake fluid & cotton buds. Do them one at a time and don't let the piston come out to far. Be sure not to let the fluid spill an any pint work and do not use the fluid for anything else once you have opened it (I keep a small bottle specially for cleaning caliper pistons).

Big Kneed Al (master of the emergency stop & "stand up" comedian).

[Dickie]

I prefer



"It does what it says on the tin"

[al]

"It does what it says on the tin"

What is this used for then??

[Dickie]

No idea, that's office stuff for office people.

[huffanpuff]

CHEWIE: it is tokico calipers and the pistons dont all come out at once

DICKIE: thats the same cleaner i use, so are you saying DONT use copper grease on back of pads? almost did.. i did contemplate stripping them down, but with me being a bit of a numpty i'd prob foook it up..makes sense what you have both said but ultimately should the pistons come out evenly on both side of the caliper? i mean rather than the middle one on one side and the top one on the other if you see what i mean... prob should invest in a haynes manual too eh?

[Dickie]

Haynes manual's always good, I wouldn't take it as gospel but at least you can size up a job and decide whether you'll tackle a job before it's too late.

I wouldn't put copper grease anywhere around my brakes, I'm sure others will swear by it but I've always found other greases and pastes are better suited. Neither of my bikes have copper grease anywhere on them and the brakes work fine on both.

As for the pistons coming out evenly, in an ideal world I suppose there's no reason they shouldn't. I've never seen it happen though. My mille isn't subjected to any of the crap that they put on the roads and they're cleaned regularly, pistons still don't come out evenly though. They're pad-per-piston, so any uneven pressure or wear on the pads would be very obvious and there isn't any.

[chewbacca]

Aye huffanpuff as Dickie says all should come out ,at least to meet the pads.Probably will after a stripdown.Good calipers used on many models gsxr's, zx7r's etc.In reality doesn't take long for a pot or two to stick.The thing is after a stripdown you realise how your brakes should work,and then after a while you then realise how poor your brakes have become.A symptom of all year round biking.With the 6 pots it's almost impossible to get them all coming out evenly.Best bet is maybe placing a piece of wood between the pots and pushing them out using the brake lever,(make sure its thick enough to prevent the pots coming out totally)so that they're coming out slightly further than they normally would,you'll see the marks on the pots, and you should manage to get all six out with a bit of perseverance.Carefull with the dust seals(that's the swollen bits of rubber around the pots)they're supposed to be sitting in grooves just below the surface of the caliper,go too quick and you'll pull them out with the pots and the only way to get them back in is to remove the pots totally.Clean them up push them back in,which in reality you can do with your fingers when they're working right,and see how they feel.Think only long term soloution is a stripdown if you want the brakes to be anything like they should be.But you'll probably be able to get them to a point where you would consider the brakes to be decent just with a bit of cleaning .Hope this helps.
Cheers
j.

[huffanpuff]

cheers for the advice guys, after spending around 6hrs cleaning them up with pistons in and out in and out, i used the piece of wood trick and got all done except one, seems the rubber is swollen so i've left it for now and stuck them back together ( no copper grease applied ) i'll see how that goes in the road test.

[Dickie]

Sounds like you do need a new dust seal then. See how you get on. Make sure they aren't binding, that's the most important thing.