Brake Caliper Pins seized

nitro159 · Two Stroke Sniffer Joined: 21 Dec 2009 Karma :

Hey, right I hope anyone can help with this. While replacing the brake pads on my 2001 GPZ, I found out that during the process, the caliper pins have seized along with the mounting plate. Now I've tried differing levels of force and i only managed to move it in one direction so I'm a bit at a loss on this one, my dad also tried with no lucks, G clamp didn't really help as it pushes them in the wrong direction.

Now If I'm informed correctly they should move freely along the the pins to facilitate braking, right? So it's seized up, not sure if it's both pins or just one.

I really rather need the bike for wednesday morning (early) absolute latest for an interview (only form of transport) so any fixes are greatly appreciated. Tomorrow I'm going to try some WD-40 on the pins and some more pressure.

Thanks for reading and any advice you may give!

Wayne

Itchy · Super Spammer Joined: 07 Apr 2005 Karma :

Heating it up a bit maybe? Or some penetrating oil?

Heat worked on my NTV pins once first time I took the calipers apart.
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nitro159 · Two Stroke Sniffer Joined: 21 Dec 2009 Karma :

Annoyingly I don't have a heat source for that, and taking it off at the moment will be tricky, it's the dead of night! Sad

robocog · Traffic Copper Joined: 17 Apr 2009 Karma :

Be uber careful with the WD40
It WILL swell the rubber seals...not good

the bellows that are there to keep the grease in will also swell a little (not as drastic as the pistons rubbers taking on gigantic proportions!) , but if washed out thoroughly and left they will return to normal size
Only use rubber grease to lube them back up
(its always been red whenever I've used it)

It could be that the rubber bellows have already perished (hence why they are now sticking)
Don't think they were too expensive last I looked and well worth replacing if they are at all suspect of no longer being in tact

If the pistons rubbers start popping out/swelling up your going to have to strip the pistons down to ensure they will work properly again (they usually return back to normal size/proportions if washed in water or rinsed in brake fluid and left)

Much safer to first try a little brake fluid to try and moisten up/ persuade the pins out as its safe on the calipers rubbers

Watch out for paintwork though ...its pretty effective at stripping multiple layers of the stuff after a short exposure

Regards
Rob
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Dazbo666 · World Chat Champion Joined: 06 Jun 2004 Karma :

I had a similar problem which was a known issue with the pins on the Bandit.

Penetrating oil did it for me, then cleaned up the caliper, pins and retaining clips with an abrasive pad before re-installing.
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Ariel Badger · Super Spammer Joined: 02 Dec 2006 Karma :

Heat, penetrating oil and time, none of which you seem to have ( has your tribe really not discovered the secret of fire yet?) Do you have one working brake? If so just use that and take care for the interview
( If you die it is not my fault BTW).
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nitro159 · Two Stroke Sniffer Joined: 21 Dec 2009 Karma :

Pictures if it helps

I shall hold off with the WD 40 until later then thank you, and I assume by the bevels you are referring to the rubber I've pulled back slightly in the middle picture just below my thumb (see below)

The main problem is just getting them to move, I'm sure once they're free I can repair any damage I have but until then, I'm at someone elses house with a 50 mile trip home (presumably not tomorrow now) and I don't wish to do it without a rear brake!

I was thinking a whole new caliper at first but it seems to be a repeated problem amongst this caliper design among various bikes. I'll give my father a call in the morning regarding anything you guys and girls suggest, greatly appreciated!

https://i51.photobucket.com/albums/f379/nitro_159/02082010095.jpg
https://i51.photobucket.com/albums/f379/nitro_159/02082010094.jpg
https://i51.photobucket.com/albums/f379/nitro_159/02082010093.jpg

robocog · Traffic Copper Joined: 17 Apr 2009 Karma :

I just wonder....
I have just recently done mine on the GPZ500 (they look the same as mine)

You do know that the pins that run 'through' the plate are fixed and are not supposed to move?

The whole plate and pins are removed together as one piece

The /only/sliding bits on the caliper are the bits hidden by the rubber belows (the bit under your thumb in one picture)

Just checking incase your trying to move the plate completely from the pins...which would be bad

Mine were gummed up inside the rubber bellows and had caused just one side of the pads to wear down
If you pull the bellows back and pll them to one side and drip some brake fluid in there and "pump them" in and out ...eventually they will pop apart allowing the surfaces to be thoroughly cleaned and greased up

Only one side has a 'proper bush' running through the caliper , the other is part of the rubber bellows and runs throughout a drilling in the caliper and should be poking out the back
This side will come out completely...but only once the pin and plate arrangement had been removed fully
I did this to get it thoroughly clean and to remove the old "stuff" that was obviously not as rubber friendly as it could have been and had effectively "glued" the pin into the rubber tube bit and was not helping tha caliper center properly

Good luck

Regards
Rob
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Needs a bigger garage...

nitro159 · Two Stroke Sniffer Joined: 21 Dec 2009 Karma :

Hi Rob

I was aware of that (about halfway through), and the problem is precisely that, I never intended to split the caliper. The only reason I'm here at the moment is when awkwardly trying to put the calipers back on, after spending a few minutes lining up the bolt holes and bolting it on, I pushed the brake pedal and tada, the brake disc actually bent and was pulled outwards rather than the brakes "squeezing" the disc, they just caused it to bend.

Also the "inner" pad was just, hanging loosely and seemed to have no function whatsoever, not rubbing against the disc atall.

And ontop of that, if you tried to let the wheel run freely, it'd catch at about 3 or 4 points and it'd become difficult to move along until you overcame it and it was free again. It was strange and certainly didn't seem to be how it functioned beforehand.

To just clarify, the pins and plate do move around as one, meaning they DO move back and forth? Because mine do not. (I do apologise about confusing people here, I'm still learning things myself and try to refrain from having my dad show me how to do things)

Wayne

robocog · Traffic Copper Joined: 17 Apr 2009 Karma :

Yup plate is firmly attached to the two pins that run right through it

its the end inside the rubber boots that is free

https://mygpz.co.uk/_includes/galleries/gpz_fiche/images/29.jpg

Not the same bike, but parts look the same

Hope it helps a little, couldn't find a better diagram and too late to try and scan the Haynes (assuming it has a good exploded diagram anyway!)

Regards
Rob
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Needs a bigger garage...

nitro159 · Two Stroke Sniffer Joined: 21 Dec 2009 Karma :

Thank you, I have the Haynes, the diagram is annoyingly small but you can make it out somewhat.

I will try looking under the rubber bushels and doing as you said to them. Obviously I hope to not pull them to bits or anything but I'll take a look to see if it requires a full whip through but so far your advice seems to be the easiest and most effective route to take, start at the easier jobs and work your way up. I'll keep the crowbar handy just incase.

If I have any updates I'll post them up and probably be crying by the end of tomorrow.

Thank you for your help with this, and to others as I have procured a blowtorch to destroy the evidence with on friday if it comes to it.

Wayne

nitro159 · Two Stroke Sniffer Joined: 21 Dec 2009 Karma :

More good news this morning , I found out one side still "slides", it's the other side that's locked up, I found this out by sliding a chisel through at an angle and using the brake piston to power it, was hoping to break (Brake!) it free but I coincidentally put the chisel on the moving side so it shifted that side along the pin slightly, however, I tryed on the other side but... the chisel snapped, so I'm at a loss of what my next step is, I'll look for some ACF when I'm in town later, halfords should have it.

Also I hope using leverage between the sliding "frame carrier" and the piston won't break anything, if it doesn't I'll look for something stronger and attempt to use that to break it free, also I can't actually move the rubber bevel on the side that's pissing about, the clean side is no problem to move (it's in the picture, you can see the brass coloured metal).

Also if it helps... the free side is the one with the rubber bit on the other end of the pin, i.e. the outer side of it.

robocog · Traffic Copper Joined: 17 Apr 2009 Karma :

did you eventually get this sorted out?

Regards
Rob
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Needs a bigger garage...

ZRX61 · Victor Meldrew Joined: 05 Nov 2003 Karma :

So why exactly did you decide to overhaul your brakes 50 miles from home????