Some Brake Questions

[Draketh]

Alright, so I set about replacing the seals in my forks today, haven't gotten there yet. I got my caliper off and the pads are good shape, plenty of pad left. But, the thing is, the pads have squeezed themselves all the way together. How am I going to get the caliper back on the rotor? Took a look inside the main cylinder, doesn't seem to be alot of fluid in there and the site glass has been less than half full.

[Draketh]

Hmm. Seems I removed the whole caliper instead of just the one side. Maybe this where I went wrong.

[Dave8338]

If everything is working correctly, you should be able to slip a small screw driver in between the pads and lightly pry them apart, moving the screw driver several times, to ensure that you don't bind up the caliper piston. At that point...you should be able to squeeze the piston back in by hand.

[Piston720]

Iwould normally remove the whole caliper as well.
I also loosen the reservoir cap when I pry the pads apart.

[lucabond]

Cover your tank with a rag, as you move in the piston it will force the fluid back up into the MC and it could spurt out. You could also take out the brake pads and use a c-clamp to move the piston back. Get it in the center of the piston and slowly turn the screw in. Good luck

[tkent02]

If everything is working correctly, you should be able to slip a small screw driver in between the pads and lightly pry them apart, moving the screw driver several times, to ensure that you don't bind up the caliper piston. At that point...you should be able to squeeze the piston back in by hand.

If there is space for a slot head screwdriver, try putting two in side by side, and pulling the handles apart, it's just easier.
If there's not enough space, stick in a tiny one and twist it to spread them apart a little.
Make sure the cap is on the reservoir, the fluid will get forced back into it, you don't want it to spray out.
The reservoir is supposed to be low at this point, as a lot of the fluid has run down into the calipers to move the pads together.
Once you get the pads pushed apart you can put a piece of steel or something between to keep the pads from coming together again.
Or just don't squeeze the lever when the calipers are off the disc.

[Draketh]

Ideally how full should my reservoir in the sight glass be?

edit: I noticed when I had the center stand on, and the front wheel was off the ground the pads were making light contact with the rotor even when the handle wasn't squeezed causing the front wheel to not spin freely too easily. Now that the caliper is off the wheel spins freely much easier. What could the cause of this be and what can I do to prevent it from happening when the caliper goes back on?

[rudy]

Ideally how full should my reservoir in the sight glass be?

edit: I noticed when I had the center stand on, and the front wheel was off the ground the pads were making light contact with the rotor even when the handle wasn't squeezed causing the front wheel to not spin freely too easily. Now that the caliper is off the wheel spins freely much easier. What could the cause of this be and what can I do to prevent it from happening when the caliper goes back on?

It's normal for it to drag a little, it's just the nature of a disc system. Plus, if you have a little bit of a warp in your rotor it will catch a little in one spot more than the rest. Don't worry about it unless it makes it really hard to turn. If your disc is super hot after a ride, look into doing a rebuild on the calipers and master.

[Suzuki_Don]

If I was you I would look into why the pads have squeezed themselves together. And as you have not said that you have squeezed the MC lever then there could be a problem with the caliper. Also you seem to think that the pads rub a bit excessively on the rotor. Again something might be amiss in the caliper.

Check out the caliper while it is off. You might need new seals or it might just be gummed up in there. Also check the bleed hole in the MC is clear. It blocks up sometimes and does not let the fluid retun to the reservior in the master cylinder.

[Draketh]

If I was you I would look into why the pads have squeezed themselves together. And as you have not said that you have squeezed the MC lever then there could be a problem with the caliper. Also you seem to think that the pads rub a bit excessively on the rotor. Again something might be amiss in the caliper.

Check out the caliper while it is off. You might need new seals or it might just be gummed up in there. Also check the bleed hole in the MC is clear. It blocks up sometimes and does not let the fluid retun to the reservior in the master cylinder.

I squeezed the lever while the caliper was off like a retard.

[Suzuki_Don]

I squeezed the lever while the caliper was off like a retard.

OK. Forget everything I said then.

[psyguy]

I squeezed the lever while the caliper was off like a retard.

lucky the pads are still thick
were they at their end the piston could have come out and that would have been a mess for sure

as don said, look at rebuilding your brakes, there shouldn't be really any brake drag when the brake lever is released

you can try (with the pads removed) pulling the lever SLIGHTLY and see if the piston goes back in as you release the lever

[Draketh]

Shouldn't the pads separate when the lever is released? I'm just kind of confused as to this whole brake thing since I've never worked on them. If the pad's don't separate when you release the lever how does the bike stop braking?

[argonsagas]

I squeezed the lever while the caliper was off like a retard.

With this you may have a problem. Once extended fully, the brake piston may object to being returned inside the caliper. Quite often there are ridges built up on the piston and they cause problems when a return is attempted. When you jam the pads together you are actually extending the pistons beyond their normal maximum travel, and the ridges come into play. Additionally, it can be misaligned, and will not easily return because of that.

At this point you MUST loosen the cover on the master cylinder and very carefully try to work the pads apart.

Place a wide piece of heavy plastic under the handlebar to catch any drops of brake fluid that escape the cloth that you wrap around the bar and the cover while the cover is loose.

If the piston fails to return you will have to remove the pads, and then get to work on rebuilding the cylinder. I have not done this on my bike, but the most common way to do it is to replace the piston assembly, which comes with the necessary parts, but it may be possible to obtain the cups needed as separate components. If so, you can attempt a light sanding to remove the ridge/burr on the piston, and polish the entire part before using it again.

Back to the lid.

You MUST have the lid loosened before trying to return the piston because there is a chance that it will happen suddenly. You have to move a lot of fluid and there will be a great resistance in the master cylinder to having all that fluid very suddenly rammed backwards against the valves. Having the lid loosened reduces the pressure anyway and is of benefit to you, but if it happens quickly then the fluid will spurt out of the MC, thus you need the cloth to absorb it, and the plastic to catch any stray drips.

It is best to remove the cloth after moving the piston back into place to avoid accidental contact with paint.

[Draketh]

With this you may have a problem. Once extended fully, the brake piston may object to being returned inside the caliper. Quite often there are ridges built up on the piston and they cause problems when a return is attempted. When you jam the pads together you are actually extending the pistons beyond their normal maximum travel, and the ridges come into play. Additionally, it can be misaligned, and will not easily return because of that.

At this point you MUST loosen the cover on the master cylinder and very carefully try to work the pads apart.

Place a wide piece of heavy plastic under the handlebar to catch any drops of brake fluid that escape the cloth that you wrap around the bar and the cover while the cover is loose.

If the piston fails to return you will have to remove the pads, and then get to work on rebuilding the cylinder. I have not done this on my bike, but the most common way to do it is to replace the piston assembly, which comes with the necessary parts, but it may be possible to obtain the cups needed as separate components. If so, you can attempt a light sanding to remove the ridge/burr on the piston, and polish the entire part before using it again.

Back to the lid.

You MUST have the lid loosened before trying to return the piston because there is a chance that it will happen suddenly. You have to move a lot of fluid and there will be a great resistance in the master cylinder to having all that fluid very suddenly rammed backwards against the valves. Having the lid loosened reduces the pressure anyway and is of benefit to you, but if it happens quickly then the fluid will spurt out of the MC, thus you need the cloth to absorb it, and the plastic to catch any stray drips.

It is best to remove the cloth after moving the piston back into place to avoid accidental contact with paint.

This was an awesome post, thank you so much. People like you are the reason I love this site and have the confidence to work on my own bike.