Hydraulic Disc Brakes Problem
 

Hello all!
I was changing a tire and I made the mistake of pressing the brake without the wheel on, with the result that the pads closed and I couldn't put the wheel between the discs, I followed a guide from YT "Oops! Fix (most) hydraulic disc brakes" that helped me, the problem is now that it doesn't work they whey was before ..I press it and the brake lever it goes all the way back to the handlebars in my hand and the bike just like you're crawling, also when i was trying to fix it, I unscrewed the cap that has liquid with the result that it spilled a little, is this a problem? or did it get air inside, any idea would be appreciated.

I can tell you what you did wrong and how you would fix it, but you seem to be a novice. So instead, I’ll just suggest that you take the bike to a shop and let them deal with it. I think the repair will be a bit beyond your skill level.

I'm too-recently acquainted with riding bikes with discs to have anything first hand to share. Your plight reinforces my desire to proceed with due caution when the time comes for my brakes to need attention.

I did find this fairly new web article describing what happens when a brake lever is inadvertently applied without a disc being between the pads. There may be something in it that helps you get beyond what you're facing.

Other forum members with greater personal experience ought to be replying soon. I'm looking to learn from what they tell us as much as I'm hoping they help you solve your issue.

Yes, All done were No-no's...
Don't mess with it .
Take it to your Local Good Bike Shop, and let them set it right - they have the knowledge and the right tools to get it done quickly...
or
Break out your backup bike, and then learn more lessons as you work on making it right.
mistakes are one of the best instructors...

Ride On
Yuri

You can probably just top off the missing brake fluid.

Usually after re-setting the pistons and closing the bleed port, you have to pump the brakes a bit for them to return to the initial position. If they don't, it indicates air (and possibly a leak).

At this point, you are probably best served to take it to a bike shop.

I've replaced rotors and pads on auto disc brakes myself for decades. Mechanically the differences between bicycle and auto hydraulic discs have to be minimal save aspects of size and scale. On the autos, often a 'special tool' was necessary as the caliper pistons required rotating while moving them back into the caliper bores during re-padding operation. I've not yet read that this is an aspect confronting bicycle techs when dealing with hydraulics so that's one minor difference.

Is it simply a matter of opening the bleed port before repositioning a caliper's pistons when performing what would have avoided the OP's mishap?

Are the various designs of bicycle hydraulic discs so different that basic maintenance is unique to each?

Put in simple terms, the procedure for replacing pads ought to be what needs to be understood by an owner confronted by what the OP's asking about, right?


True that while also being a fine way to lighten your wallet if you go in head first. You'll learn much by DIY, ask me how I know.

Remove wheel, push pistons outward as far as possible, remove old pads, insert new pads, reinstall wheel, then give a couple quick squeezes on the brake lever. DO NOT squeeze brake lever while wheel is removed, DO NOT open the bleed port.

The whole thing should take ten minutes, unless they are the fiddly Shimano brake pads that are sometimes tricky to reinsert (well, for me anyway) properly.

The problem is some people suggest opening the bleed port. If you over-filled to begin with, pushing the pistons (inward?) can pop that little bladder thingie. (Ask me how I know?)

Yep, it looks like I messed up a bit down there with the brakes.. at that stage I will choose a shop that is familiar with the subject and has the tools for this job. Thanks to everyone who replied!:)

So the idea is that pushing the old pads back pushes the fluid back upstream into the reservoir in the brake lever housing, there's no need to open the bleed port to relieve fluid back pressure? Simple enough.

Any particular 'special tool' needed to push pads back into calipers? I'd opt for a largish flat-bladed screw driver myself unless someone had told me beforehand something else is safer as well as more practical.

https://cimg9.ibsrv.net/gimg/bikefor...244d7ec0b5.jpg
https://cimg0.ibsrv.net/gimg/bikefor...bfa5793b10.jpg

Just FYI - I found some hobby grade plywood, 6mm thick - about the same thickness of the rotors on my bike. I cut out a section shaped like a brake pad. If I have to remove a wheel, I just slip the wood between the pads, so if I accidentally press the brake lever (easy enough to do when changing a flat in the rain out on the road. Trust me) it's no harm, no foul. Just remove the wood and slide the rotor back in.
The wooden block is small enough to carry in my under-saddle bag, along with my spare tube and tire levers.

You can just use an old rotor, or a plastic tire lever...Just be sure that the tool is clean of all oils (even from your fingers) if you ever use it on new pads.

Though those makeshift tools will work, I did buy the one below...Just 'cause I like tools.

As do I.

Wife keeps needling me about "When are you gonna start getting rid of all this c*rp!"

https://cimg3.ibsrv.net/gimg/bikefor...46095a7d88.png
$.98

The OP needs one of these spacer thingies so it never happens again. Remove wheel and insert spacer thingy in caliper.
https://cimg1.ibsrv.net/gimg/bikefor...de120ed00.jpeg

jamming something in between the pad & rotor could tweak the disc. Pull the wheel off.

I believe I said, “Remove wheel and insert spacer”. But you are absolutely correct about jammin’ mon.

It’s referred to as a bleed block and used to keep the pistons in place when the pads are removed for performing a brake bleed.

sometimes I take a while to post a reply & other comments happens in-between.

these tools are definitely preferred, but a wide standard screw driver will work, used carefully, not to damage the pads or the pistons

Enlighten me please as to why it's necessary to remove the brake pads when doing a fluid bleed?

My experience with auto disc brakes has always been that bleeding the system (of possible air entrapment or for a replacement of aged or contaminated fluid) is done with pads in place.

Any potential for pads to be contaminated by leaked fluid is supposed to be circumvented by placing a hose over the end of the bleeder ports to redirect escaping fluid into a proper reservoir.

Is this not possible with popular bicycle hydraulic brake systems?

(Being new to hydraulic disc brakes on bicycles I fully expect to have to get up to speed with proper maintenance sooner or later. I'm not at all the type to leave what ought to be routine maintenance to my LBS staffers. There's only one LBS in town, any others are a fair drive distant, no co-op closer than a two hour, one-way drive.)

It is advisable (as opposed to necessary) to avoid contamination with brake fluid.

Autos, and their brakes, differ somewhat from bicycles and their brakes.

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I suspect in the case of auto brakes, you aren't using aquarium air hose jammed onto a little barb.

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I've done it, but I've also sprayed mineral oil all over myself, so there is that.

Analogy with car brakes will only get you so far. But it isn't really that hard, either. It can be a bit fiddly.

Just take it into the shop, but best practice would be putting a spacer between the pads anytime you are taking off a wheel to prevent this, but if this does happen I personally would just try and spread the pistons manually with a dedicated tool or even a tire lever and then spray down the pistons with some alcohol and wipe clean. In the case of opening the bleed port, you possibly did get some air in there. Again you could try and a minor bleed on that lever but frankly if this is your first hydraulic bike just take it into the shop especially if you can't reset the pistons

Hydraulic pistons are rarely 100% sealed. One in theory you could have pushed the pistons out far enough were DOT/Mineral oil was released but also the seals on the pistons can be defective or can deteriorate to where some fluid is weeping through. Also you have the fact you simply could spill fluid by an accident and it lands or makes its way to the calipers. So no you don't have to take out the pads to bleed, but it's just best practice and possibly could prevent you having to get out a torch or buy new pads.