Brakes dragging/sticking

**motorbyclist** · 2nd July 2008, 01:35

took front wheel to my NC30 into cycletreads for new bearings, got back home and wheel spins forever. attach & pump brakes and wheel is now hard to turn, whereas before it was fine.

lever felt rock solid, before it was a bit squishy.

pulled brakes off, found both brakes were dragging, pushed pistons back incase they were sticking, still have problem.

did 550km this weekend and they're still doing it.

i can feel them loading the chassis/suspension and loading the motor on the motorway, the discs are always quite warm, and pads must be getting mauled. this is less than ideal what with the weather lately and petrol prices

so, any ideas to remedy this before the weekend?

no i haven't bled the brakes for some time, planning to do that shortly. full seal kit/rebuild would be nice to do but i have a coro loop to attend on sunday!

cheers

(for those that don't know, these are standard NC30 twin 4pot each hydraulic calipers on some very heavily crossdrilled discs without much scoring. use same master cylinder joined to two seperate lines. pads have plenty of life)

EDIT: the boot around the "plunger" is and always has been broken

**cowboyz** · 2nd July 2008, 06:55

get some brake clean and pull everything to bits and clean it out. replace fluids. If you have brake issues it probably best to deal with it and skip corogp for the weekend. I dont think they are closing the road in the next few weeks.

**awayatc** · 2nd July 2008, 07:39

broken boot around plunger doesn't sound to good...it will allow grime buildup around plunger, and thus make it harder for plunger to retreat....
Good luck

**Katman** · 2nd July 2008, 08:25

Originally Posted by Katman

Rather pointless just cleaning up the pistons because that's not likely to be where the problem lies. Once the pistons are out the seals need to be removed from the calipers and the layer of shit that builds up on the back side of the seal and the grooves the seals locate in needs to be scraped clean. The problem is caused by the layer of shit forcing the seals into a tighter contact with the piston and therefore not allowing the piston to retract properly.

Here's your answer.

**more_fasterer** · 2nd July 2008, 13:12

Had the same problem a couple of months ago. Bought a master cylinder rebuild kit from Swindlespot for ~$100 & the problem went away. My plunger boot was broken too.

**vifferman** · 2nd July 2008, 13:45

Just a thought - are you sure the wheel spacers are properly installed, and that the front axle, calipers, etc are all installed straight?
It seems a bit odd that it was fine before, and now it's not; the only thing that's changed is new wheel bearings and the wheel's been off and back on again.

**mouldy** · 2nd July 2008, 13:50

Were the brakes releasing before you took the wheel out ? Sometimes when you do the front axle up on Hondas the left hand fork leg gets dragged in as you do up the bolt , check that the line on the left hand side of your axle lines up wirth the fork leg , if not loosen off all your pinch bolts and pump the font end up and down to centre your wheel properly as this can make your brakes drag .

**Katman** · 2nd July 2008, 13:51

Another thing to check is - remove the reservoir from the master cylinder body and you'll see two holes that the fluid passes through. The one closest to the brake hose is very small and can easily become blocked. This hole allows fluid to bleed back into the brake lines when the lever is released.

**imdying** · 2nd July 2008, 13:53

As always, a lot of things that basic maintenance covers are being touted as things to look at, and rightly so... so the real lesson is, do your basic maintenance dammit!!!!

**vifferman** · 2nd July 2008, 13:54

Originally Posted by mouldy

... loosen off all your pinch bolts and pump the font end up and down to centre your wheel properly ...

Er... just loosen one side at a time, or just some of them.

**motorbyclist** · 2nd July 2008, 14:57

Originally Posted by vifferman

Just a thought - are you sure the wheel spacers are properly installed, and that the front axle, calipers, etc are all installed straight?
It seems a bit odd that it was fine before, and now it's not; the only thing that's changed is new wheel bearings and the wheel's been off and back on again.

right, will look at that

Originally Posted by more_fasterer

Had the same problem a couple of months ago. Bought a master cylinder rebuild kit from Swindlespot for ~$100 & the problem went away. My plunger boot was broken too.

gah, weapon of last resort

Originally Posted by Katman

Here's your answer.

as above (yes i did search the forum first, and read that very post), but am looking for simple solution before i bury $100 in seals i don't need (yet) and may not receive before sunday

particularly as i don't have the $100 AND petrol money

Originally Posted by imdying

As always, a lot of things that basic maintenance covers are being touted as things to look at, and rightly so... so the real lesson is, do your basic maintenance dammit!!!!

guilty as charged, just left the brakes to their own devices and kept putting off that fluid change. just been flat out with uni/work/smc lately and this coro loop will (was to) be the first real ride on any of my bikes since february.....

cheers for the advice guys

**Max Preload** · 2nd July 2008, 15:03

Originally Posted by motorbyclist

did 550km this weekend and they're still doing it.

Ya don't say... I can't understand why they haven't fixed themselves, the lazy bastards!

Originally Posted by motorbyclist

i can feel them loading the chassis/suspension and loading the motor on the motorway, the discs are always quite warm, and pads must be getting mauled.

...full seal kit/rebuild would be nice to do but i have a coro loop to attend on sunday!

Good to see your priorities are in order! Dragging brakes, dragging schmakes!

Originally Posted by motorbyclist

EDIT: the boot around the "plunger" is and always has been broken

Do you think they came out of the factory like that?

The boot around the master cylinder piston is to stop dirt and water getting in to attack the back of the master cylinder piston seal - like the dust lip on an oil seal. If the master cylinder seal gets damaged from behind

it'll fail prematurely and possibly spectacularly.

I personally think KATMAN's spot on about the seal (I presume he's meaning the dust seals, not the piston seals, although I've seen both corroded grooves) and the grooves inside the caliper being clogged with shit too.

Also, what KATMAN states about the small hole in the reservoir is critical - if that's blocked, air can be drawn in, past the master cylinder piston seal, when the lever is released because the low pressure (vacuum) will not be broken.

**motorbyclist** · 2nd July 2008, 15:16

Originally Posted by Max Preload

Ya don't say... I can't understand why they haven't fixed themselves, the lazy bastards!

lol that's what i said too! (thought with a bit of riding in the hail they might magically free up - provided they aren't backing past a certain point due to corrosion/dirt as opposed to backing off at all due to valves, wearing out the pads a bit over several hundy kms may have fixed it

Originally Posted by Max Preload

Good to see your priorities are in order! Dragging brakes, dragging schmakes!

well i'm only commuting/cruising on them..... it's not like they don't work, quite the opposite infact.

if they weren't working i'd be riding my brother's FXR, i'm not a complete idiot

Originally Posted by Max Preload

Do you think they came out of the factory like that?

The boot around the master cylinder piston is to stop dirt and water getting in to attack the back of the master cylinder piston seal - like the dust lip on an oil seal. If the master cylinder seal gets damaged from behind

it'll fail prematurely and possibly spectacularly.

I personally think KATMAN's spot on about the seal (I presume he's meaning the dust seals, not the piston seals, although I've seen both corroded grooves) and the grooves inside the caliper being clogged with shit too.

Also, what KATMAN states about the small hole in the reservoir is critical - if that's blocked air, can be drawn in past the master cylinder piston seal when the lever is released because the low pressure (vacuum) will not be broken.

right, now i know what it actually does i can better appreciate why this matters that it's been split for atleast 18 months...

still going to try re-aligning the front axle. it just seems so random the way the problem has arisen, but by the same token you'd think even if the wheel was out the brakes would equalise around the discs anyway....

**imdying** · 2nd July 2008, 15:26

Originally Posted by motorbyclist

guilty as charged, just left the brakes to their own devices and kept putting off that fluid change. just been flat out with uni/work/smc lately and this coro loop will (was to) be the first real ride on any of my bikes since february.....

Don't worry nobody does it... first thing you should do when buying a second hand bike is rebuild the calipers. A good thing to do is attack the calipers (concentrating on the pistons) with a toothbrush and hot soapy water at every oil change (half that interval is better, but people have busy lives).

**motorbyclist** · 2nd July 2008, 15:44

Originally Posted by imdying

Don't worry nobody does it... first thing you should do when buying a second hand bike is rebuild the calipers. A good thing to do is attack the calipers (concentrating on the pistons) with a toothbrush and hot soapy water at every oil change (half that interval is better, but people have busy lives).

thanks, i'll keep that in mind

anyone got advice on doing this seal kit when i buy it? how would one go about removing all 8 pistons?