Front brake rubbing/always on

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Evening all.

My GS500's front brake seems to have decided it wants to stay on. When wheeling the bike you can hear it rub and squeak, and when riding you can feel the difference, I think, it may mostly be psychological though.

When it comes to using the front brake, there is nothing much except full emergency stopping power (presumably because the rest of the braking power is already applied)

Is there a simply fix to this, a way to release the brake and perhaps reposition it a bit.

As always, any and all help appreciated as I need this bike every day, as it's my only form of transport.
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Current bike: ZX6R J1
Previous bikes: CLR 125 | GS500 | ZX6R G2 | SV650

[.....]

It sounds like the brakes need a bit of an overhaul. The first thing I'd try is pumping the brake pistons out a bit and trying to give them a bit of a clean up using some brake fluid with a tooth brush.

If that doesn't work I'd go for the full strip down, clean and new seals.

[Ariel Badger]

If it is rubbing it will create heat. Heat will boil fluids.
Ask Pete what happens if you boil brake fluid.
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Bikers make great organ donors, get 115 on your licence today.

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[Dan79]

One other test you might want to try, take the bike for ride for a couple or so miles, only need to ride at sensible speeds up to 30 or 40 should be okay, using bare minimal front brake, stop and feel (VERY CAUTIOUSLY) the front discs, with gloves hands initially. If they're still cool or close to ambient temperature to touch, the brakes aren't the problem; if they are hot, you've diagnosed likely brake seizure. If discs are hot, you should cease use of the bike until problem is rectified, not only for reasons of safety, also if you carry on riding a bike with brakes dragging, discs will be at risk of warping due to the heat.

Obviously don't try this test at high speed or over any distance, because if the brakes are seizing, the discs will get very hot indeed; not to mention danger of fluid overheating alluded to by Ariel Badger.
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Previous bikes - 1984 Honda VF500 (FII) Interceptor and 1990 Yamaha RXS100
Current bikes - 1984 Honda VF500 (V30) Magna

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Cheers for that Dan. I did check the brakes for warping earlier, but it was too dark to really tell.

I'm hoping it's not that serious, but I'll be sure to check all of this as soon as I can.

However, if none of what you have said turns up, and it isn't the brakes that are the problem - what is??
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Current bike: ZX6R J1
Previous bikes: CLR 125 | GS500 | ZX6R G2 | SV650

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I gave it a couple of runs today. Stopped and checked the disc temperature. It's warm, maybe a little hot, but by no means very hot or too hot. If that makes sense.
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Current bike: ZX6R J1
Previous bikes: CLR 125 | GS500 | ZX6R G2 | SV650

[Kickstart]

Hi

Brakes will rub very slightly anyway.

However the GS500 has a twin piston sliding caliper. The pistons can stick but also the pins the caliper slides on can stick.

Plus point is that twin piston sliding calipers are generally a doddle to strip down.

Take the caliper off an then take alloy caliper body off the steel carrier it slides on. This might take some force. Clean up the pins and lube with a suitable grease (I normally use red rubber greases - there are rubber boots around the pins which you want to avoid getting normal grease on).

With the main body of the caliper, pump the pistons out gradually. Try and do this so both come out at the same time. As they come out brake fluid will pee out (one trick is to put the caliper in a clear plastic bag while you do this, so you can see the pistons and slow one coming out while also catching most of the fluid). Clean the pistons up carefully and look pitting or scores on them. They might need replaceing. In the main caliper body you will find 2 seals in each hole. Take these out carefully and inspect the grooves they live in. Often there is corrosion in these grooves which pushes the seals hard onto the pistons making them stick. Then carefully reassemble. If you are at all concerned about the condition of the seals then replace them with new ones, and soak the seals in brake fluid before using them. Lube the pistons with brake fluid as well and push them into place, making very sure you push them in straight. Make sure that the pads are free to slide slightly in the caliper as you reassemble them. Once the caliper is back together put it in place and bleed the brakes.

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

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Thanks for that Keith.

If I get the chance I'll be doing all of this on Saturday morning.

The thing is the brake seems to work fine at the stronger end, and a little with normal braking. The discs are slightly warm after use, meaning there is some rubbing, but surely that's normal? Or would it nor be enough to warm the disc?

I'm in two minds as to whether a lot of this is psychological, but I'll definitely look to give it an overhaul anyway.
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Current bike: ZX6R J1
Previous bikes: CLR 125 | GS500 | ZX6R G2 | SV650

[Noxious89123]

Sounds to me like they are starting to get a bit "sticky" but haven't yet seized badly.

When my brakes were rubbing (due to a mechanic refitting old pads the "wrong way round") the brakes were very sharp to use, and were hot enough to make my leather gloves smoke when I poked the disc... Had only ridden a couple of miles too.
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'06 Honda CBR125RW-6 ~ '00 Honda CBR600F-Y ~ '07 Honda CBR600RR-7 ~ Bikeless
'53 Ford Ka 1.3 ~ '03 Vauxhall Astra SRi 1.8 ~ '52 Vauxhall Astra SRi 2.2 ~ '53 Vauxhall Astra GSi

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Well my disc is barely warm enough to feel it through the gloves. It's only when I take them off that I can feel they have warmed a little. Where as the back one is very hot.
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Current bike: ZX6R J1
Previous bikes: CLR 125 | GS500 | ZX6R G2 | SV650

[Fizzer Thou]

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Don't worry I'm not due to use the bike tomorrow anyway. So Saturday morning I'll be going at it.

I'll be sure to report back with how badly it's gone and the fact I barely know which end of a screwdriver to use
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Current bike: ZX6R J1
Previous bikes: CLR 125 | GS500 | ZX6R G2 | SV650

[Kickstart]

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Thanks again Keith, looks like I have a busy saturday morning ahead of me!
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Current bike: ZX6R J1
Previous bikes: CLR 125 | GS500 | ZX6R G2 | SV650

[chris-red]

It it was stuck on there would be more heat in the disc. Could it be knackers wheel bearings your hear? Sounds like the brakes need an overhall anyway.
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Well, you know what they say. If you want to save the world, you have to push a few old ladies down the stairs.
Skudd:- Perhaps she just thinks you are a window licker and is being nice just in case she becomes another Jill Dando.
WANTED:- Fujinon (Fuji) M42 (Screw on) lenses, let me know if you have anything.

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I thought so. I cant really hear anything, but thought i could feel something. Oh and using the brake it doesnt feel quite right. The brake does need an overhaul, so I'll be looking to do that soon anyway, just nice to know its not a major issue.

Cheers all.
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Current bike: ZX6R J1
Previous bikes: CLR 125 | GS500 | ZX6R G2 | SV650