brake problems

Carterc · September 29, 2011, 02:08:49 PM

Hey guys,

my rear brake started lightly applying itself the last time i rode, i never used it but when i got off the bike to look at it, i touched the metal and it was hot as hell.
Is there an easy fix or spring to adjust? could there be air in the hose?

Thanks in advance!

Chris Carter

FJ111200 · September 29, 2011, 02:25:29 PM

Crimes kid.
96 posts and not one about the brakes. Oh sorry i've had a few.

The easiest fix would be to spray some brake cleaner at the caliper and hope it free's up the piston.
The next easiest fix would be to take off the caliper from the bracket and clean up with a toothbrush and brake cleaner.
If those 2 tricks fail, replace the caliper seals and you should be back to normal operating.

Never used the rear brake? Get real me old, you'll need it.

Shit, sarcasm. The lowest form of wit. At least it is wit.

Carterc · September 29, 2011, 02:34:03 PM

Thanks for the info, I'm assuming i can find the location of those items in the Clymers manual i have.
and for the record, I use my front and back brakes together, just not that ride due to fear of them locking up, if you have any more info, let me know! Thanks!

FJ111200 · September 29, 2011, 02:45:32 PM

Sometimes i'll just use the rear brake on it's own, just to slow down a little bit going into or halfway round a corner.
It stops the front diving at an inapropriate time and altering the geometry.
Remember it's not a racetrack just a normal road.
I don't always use both brakes together, usually if i do it's to scrub a lot of speed off quickly, especially if plod or cameras are about, or if some twat decides to pull out or change lanes, never mind about the sheep.

A quick dab on the levers does the trick, without having to stamp down or grab a big handfull.
Safe riding mate, and keep those eyes in the back of your head.

mz_rider · September 29, 2011, 03:31:35 PM

Quote from: Carterc on September 29, 2011, 02:08:49 PM
Hey guys,

my rear brake started lightly applying itself the last time i rode, i never used it but when i got off the bike to look at it, i touched the metal and it was hot as hell.
Is there an easy fix or spring to adjust? could there be air in the hose?

Thanks in advance!

Chris Carter

Chris,

As someone who has ridden an FJ through a Scottish winter I have plenty of experience of freeing seized pistons. The problem is that muck attaches onto the exposed piston and chews up the dust seal. If cleaning doesn't work you could strip and replaced both the dust & fluid seal. What I've done (and I expect a torrent of disapproval) is throw away the dust seal and use the fluid seal only. No further problems over many miles/years.

Stuart

flips · September 29, 2011, 03:48:46 PM

Hi Carterc

I would also suggest a good clean of the caliper and to check the condition of the pads.If their getting a bit thin or worn unevenly it might pay to replace them,How long has it been since the brake fluid has been changed?...if its been a while,I would add that to the to do list (do the whole bike-brake fluid degrades over time and use,absorbing moisture). Prevention is better (and cheaper!) than cure.I would also check the condition of the rotor,IE running true-not warped or under minimal thickness.Your manual should help with all this.
Hope this helps
Cheers and ride safe

Jeff P

Arnie · September 29, 2011, 07:46:27 PM

Carterc,

The only thing retracting your brake pads & pistons is the seals. If the piston is corroded or the seal cracked or torn it may not retract properly. You can try pressing the pads/pistons back into the caliper as far as possible after cleaning the exposed part of the piston. This may re-seat the seal so it retracts adequately.
Otherwise, you'll have to service the caliper properly replacing the seals and changing the fluid. Likely a good idea anyhow.

Cheers,
Arnie

Carterc · September 30, 2011, 10:36:05 AM

Arnie,
Are you saying i can just grab the brake pad and shove it back in? how far off the wheel should the pad rest?

andyb · September 30, 2011, 12:37:31 PM

Correct. The pad should just slightly touch normally (in normal use if your disc is warped it'll shove it back farther).

Sounds to me like you've got a bit of a stuck caliper though. A teardown, set of seals, and some quality TLC with it will get it working like new.

Carterc · September 30, 2011, 12:47:09 PM

ok great, is it easy to "teardown" i cant find my clymers anywhere

Sideburns · September 30, 2011, 05:56:00 PM

It's pretty easy if you have airpressure to pop out the pistons.

I would always try the old o-rings first. I've found that cleaning the calliper solves the problem, most of the time
I also found that OEM o-ring are a lot better than imitation ones.

This is roughly how I do it:

I use an old brakeline as an airhose with the nozzle of the airpistol stuck in the hose.
Scotchbrite and brakefluid are perfect for cleaning the pistons.

For the calliper itself I use Lamp oil (parafin oil) I've yet to find a better multipurpose cleaner than lamp oil.
Doesn't cost a dime, doesn't hurt paintwork, dissolves oil and baked-in old grease like the best.
Also works great on brakedust.

Hold one pistons in place with a good tie rip and pop out the other piston.
Note: Take it easy. you can damage the psiton if it pops out to fast/hard
Blow out all excess brakefluid.
remove both o-rings and put the piston back in the calliper
tie rip around that piston and pop out the other piston.
remove both O-rings.

with airpressure, the other (the one you put back) should come out. If if doesn't, you can fill the first hole with a cloth to direct more pressure to the piston still in place.

thoroughly blow out the empty calliper.
With brakecleaner clean the caliper.

clean/Grease and reinstall the o-rings.
don't pull on old o-rings. you'll make them longer and they'll be a b*tch to reinstall
Be gently
Use a purpose grease.

clean the pistons with brakefluid and scotchbrite. Grease and reinstall.

For bleeding I use a simple piece of hose that fit's over the bleeding nipple and a large sering
(total cost less than $2,-)

Takes me about 30 minutes and 2 beers from removal of the bike to re-installment on the bike.
Forgive my English. It might be "crooked at times" I'm Dutch. I bet your Dutch is worse

RichBaker · September 30, 2011, 10:21:39 PM

Quote from: Sideburns on September 30, 2011, 05:56:00 PM
It's pretty easy if you have airpressure to pop out the pistons.

I would always try the old o-rings first. I've found that cleaning the calliper solves the problem, most of the time
I also found that OEM o-ring are a lot better than imitation ones.

This is roughly how I do it:

I use an old brakeline as an airhose with the nozzle of the airpistol stuck in the hose.
Scotchbrite and brakefluid are perfect for cleaning the pistons.

For the calliper itself I use Lamp oil (parafin oil) I've yet to find a better multipurpose cleaner than lamp oil.
Doesn't cost a dime, doesn't hurt paintwork, dissolves oil and baked-in old grease like the best.
Also works great on brakedust. Hold one pistons in place with a good tie rip and pop out the other piston.
Note: Take it easy. you can damage the psiton if it pops out to fast/hard A piece of plywood over the piston you arent popping out, clamped to the workbench on either side of the caliper works well.
Blow out all excess brakefluid.
remove both o-rings and put the piston back in the calliper
tie rip around that piston and pop out the other piston.
remove both O-rings.

with airpressure, the other (the one you put back) should come out. If if doesn't, you can fill the first hole with a cloth to direct more pressure to the piston still in place.

thoroughly blow out the empty calliper.
With brakecleaner clean the caliper.

clean/Grease and reinstall the o-rings.
don't pull on old o-rings. you'll make them longer and they'll be a b*tch to reinstall
Be gently
Use a purpose grease.

clean the pistons with brakefluid and scotchbrite. Grease and reinstall.

For bleeding I use a simple piece of hose that fit's over the bleeding nipple and a large sering Syringe, took me a few seconds to figure out what you meant.
(total cost less than $2,-)

Takes me about 30 minutes and 2 beers from removal of the bike to re-installment on the bike.
Forgive my English. It might be "crooked at times" I'm Dutch. I bet your Dutch is worse

ribbert · October 01, 2011, 12:27:05 AM

Removing pistons with compressed air is very efficient but potentially dangerous. More often than not they fly out at high speed when they let go and if they don't take out an eye or shoot you in the nuts they will end up in the next suburb almost always with a flat spot from the impact. Put a heavily folded rag or towel over the piston you are removing before applying air pressure.
Noel

RichBaker · October 01, 2011, 05:50:21 AM

That's why I put a piece of plywood in there...... it stops the piston before it gets all the way out. Never had one get loose, in many years of doing it....especially with the pressure cranked down. Usually 35-40 PSI is plenty.

andyb · October 01, 2011, 08:38:39 AM

Never had luck with air myself. Usually it gets cocked in the bore and jammed, or just one piston comes out (on a multipiston caliper). I leave them hooked to the bike's brake system and use hydraulic pressure to push them out, nice and slow and controllable that way... and it's not like you weren't going to have to bleed it anyhow, just don't make a mess!

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