Brake binding

[Jazzscot]

Took the bike for her MOT today. I must be honest and say I didn't give her the once over like I usually do before an MOT as Iv been mega busy recently.

Anyway she failed on the front brakes appear to be slightly binding.

Took her home onto the ABBA type stand I made and jacked her up under the sump.

Tried spinning the wheel and right enough it isn't turning freely. So off with the left hand caliper and removed the pads and pumped the pistons out and gave them a bloody good clean with a toothbrush and some hot soapy water.

They now look as good as new and I managed to push them back in with my fingers no problem. Refitted the pads and pumped the pressure back up.

Wheel now spinning better. For good measure I gave the other caliper the same treatment and refitted.

When I spin the wheel by hand it gets to nearly two revolutions before coming to a stop.

How many revolutions should a wheel be able to do when spun by hand?

Your thoughts please as I want the bike to be spot on brake wise when I take her back for her retest.

Jazz

[tony.mon]

Sounds about right.
New seals would help; the small bellows bit at the edge is supposed to retract the piston back off of the disc slightly after the brake pressure drop again.
Mikstr fitted ceramic bearings to reduce friction, but I don't think he got a lot more revolutions than two, so I'd say all good for a retest.

[VTRDark]

How many revolutions should a wheel be able to do when spun by hand?

Wouldn't that depend on how fast you spin it.

Disc bobbins are a good one to check and free up as well mate. Sound like you have sorted the problem out freeing the pistons though, so good work, and re-test time.

(:-})

[sirch345]

Almost two full revolutions sounds good to me as well

Chris.

[bigtwinthing]

Don't be tempted to push the pistons back into the calliper to see if there free, pits and rust on the pistons will bugger up the seals etc.

Take them out and clean them, i was always told to polish them with "Brasso" and I've always done that since, i soak the seals first then install the pistons etc. I had a ZX9 once and had to do this yearly.

Most rock ups appear when people fit new pads and just push the pistons back in without cleaning them and then 3 months later the seals leak.

[sirch345]

Most rock ups appear when people fit new pads and just push the pistons back in without cleaning them and then 3 months later the seals leak.

The number of times I've seen so called car mechanic's do just that

Chris.

[Jazzscot]

Took her back in for a retest today and she now has a nice year long MOT

[bigtwinthing]

Most rock ups appear when people fit new pads and just push the pistons back in without cleaning them and then 3 months later the seals leak.

The number of times I've seen so called car mechanic's do just that

Chris.

me too, they push them in with big grips, don't take the lid off the master cylinder and shoot brake fluid all over the inside of the bonnet from the air hole.

[Watty]

Took her back in for a retest today and she now has a nice year long MOT

Good news Jazz

[sirch345]

Good one Jazz nothing quite like getting that out of the way for another year,

Most rock ups appear when people fit new pads and just push the pistons back in without cleaning them and then 3 months later the seals leak.

The number of times I've seen so called car mechanic's do just that

Chris.

me too, they push them in with big grips, don't take the lid off the master cylinder and shoot brake fluid all over the inside of the bonnet from the air hole.

Yes that too

Chris.

[Pistonguy]

I am having a similar issue, but i cannot get all pots to push in evenly with the MC cover off. Al pistons move freely but if i push one in another moves out and so on. Can get my new pads to fit on the right side without binding. Anything i can do without removing the caliper? Just changed the fluid and re bled and dont wanna do it again all over:-/


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[Pistonguy]

Ps i have already cleaned the caliper and pots as best i can while still attached to the bike.


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[MacV2]

Take 'em off & full refurb, worth doing despite the PITA of doing it, that way you can clean up the pistons & check or replace the seals.

You want it done full on ? Send them to Jonesy. The Master Braker ...

[tony.mon]

Use a flat price of wood across both pistons and a g clamp with a bit if rag tied round it.
Or an old brake pad.
Remember to remove enough brake fluid from the reservoir otherwise it can overflow as you push them all back.

[Pistonguy]

Today after work i pulled the caliper and totally disassembled. The seals were fine, not so dirty but one of the pistons had some gunk on it and was binding up. Cleaned it up real good and got it back on and took about an hour to pump up the brakes(no speed bleeder) and it is working ok. I can only get about a rotation and a half on the wheel freespin but its at least not binding anymore. My forkstand has little rubber feet that the fork legs sit on, and i also noticed when tightening the front axle if everything wasn't completely straight it wouldn't spin good, just something i didn't notice before. Will be a couple days till the rain lets off and i can ride but i think it should be good to go. Every time i am a little daunted by a project i grab the old honda shop manual and just take my time and seems to workout ok lol


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