Yamaha YBR Front Brake Stuck

PsychoPigeon · 18 Oct 2020 at 16:17

Hi, just want to get a second opinion on what to do next after an issue with my front brake.

For the last couple of weeks I've heard a slight scraping sound coming from the front of the bike and it's started to become more noticeable. I've had no issues while riding, steering is great and brakes work as they always have done. I put the bike on the centre stand and got the front wheel off the ground and spun it and could hear the scraping while the wheel moved freely. I used the front brake then released and the wheel struggled to move freely after that, the piston in the caliper did not pull back all the way. Eventually it freed itself but I took off the caliper to rule out any other issues, the sound is definitely being generated by the caliper.

I wanted to clean the pads or see if anything was wrong with them, the bolt that has the 2 pins through it seems to have seized I cannot get this thing off. I thought ok I will clean what little I can see of the piston but it refuses to retract at all and has bitten down on the brake pads so I can't even get it back on the bike. Would anyone have any advice for that?!

Piston: https://i.ibb.co/zScL98Q/2222.jpg
Seized bolt holding the pads: https://i.ibb.co/P4gg4Qp/111.png

Should I look around for a new caliper, if so what would your procedure be for fitting it, should I take apart the new one and grease parts before fitting, drain brake fluid etc? What would your workflow be like?

tom_e · 18 Oct 2020 at 16:54

Buy a rebuild kit. Including a new piston it'll probably come to less than £20 and some red rubber grease.

Get some pliers/mole grips and rip the old piston out, doesn't matter if you gouge it.
Toothbrush, brake cleaner, brass wheel on a dremel and clean out the seal grooves.
Stick a good smear of grease in each groove and put the seals in, making sure they're the right way around (I can't remember if there's a difference in the ybr).
Little bit of grease around the bore and seals then push the piston in by hand making sure it's square.

Bolt it all back up to the bike with the pads in then bleed.

If you can't get that pin out after letting it soak in plusgas...Not wd40 it's pants and apply some heat then I'd just grab 2nd hand caliper. They're cheap as chips and again give it a rebuild when it arrives just to be sure.

I done this on my first bike having never touched brakes before and it really is that straight forward.

PsychoPigeon · 18 Oct 2020 at 17:49

Ok thank you that's pretty clear. Is there a way to get the piston to ease off and relieve pressure as I cannot get underneath it. Would bleeding while it in its current state work? Either way, I'll probably have to get a new caliper because of this seized bolt that prevents from getting anything loose

Fireskull · 19 Oct 2020 at 13:00

Afraid not, the piston isn't currently under any pressure until you pull the brake lever, judging by the pic you've pumped the brake lever a few times when it's off the disk so that's why it's now stuck out so far, the only way to get it back in is to push it, but the piston 'might' be ok and it might just be your pad slider pin is so corroded the pads can't move and that's whats causing your binding, but unlikely to only be that, usually when your slider pin is in a bad way your piston seals are also in the same state...
(In future put a piece of wood or something between the pads when you push the piston out otherwise you have a right pain pushing it back when both pads are pushed together)
If you get the slider pin out then you can try (Clean the exposed piston with some brake cleaner first) and push the piston back with a G-clamp or similar.
You could try and shove a screwdriver between the two pads if you really need to try and push the piston back but be aware you'll most likely damage and take chunks out of the pad material.

Fireskull · 19 Oct 2020 at 13:02

How is the slider pin secured? is it threaded or a circlip? if it's a circlip then remove it and wack it with a hammer, should get it moving, then pull it out the other end with some pliers, then once off give it a really good clean and get off any corrosion, alternatively buy a new one.

PsychoPigeon · 19 Oct 2020 at 21:35

It's not threaded just seized up, I will give it a go with a hammer (ordered some PlusGas for it.) Bit worried how I'm going to get the piston back in, seems like the only way is with a clamp. I ordered some chrome polish and grease will try and lube it up.

Diddums · 19 Oct 2020 at 21:40

PsychoPigeon said:
It's not threaded just seized up, I will give it a go with a hammer (ordered some PlusGas for it.) Bit worried how I'm going to get the piston back in, seems like the only way is with a clamp. I ordered some chrome polish and grease will try and lube it up.

Stop messing about and replace it, it's £20 for a reconditioned unit and removes that element of doubt when riding.

https://www.ebay.co.uk/itm/YBR125-Brake-Caliper-Front-Genuine-Yamaha-2007-2009-855/114459324080

Don't mess around with brakes, they're literally the difference between happy riding and splat.

PsychoPigeon · 20 Oct 2020 at 00:17

There's a lot new calipers available that come with break pads that fit the YBR 2016 model, but they're from China (the gold ones spammed all over Ebay and Amazon.) I wasn't sure if I should take my chances with one of them.

If I buy a second hand unit am I not going to run into this problem later on and still have to service the caliper? (or maybe you're just referring to me having to be rough with the current one?)

Diddums · 20 Oct 2020 at 06:15

PsychoPigeon said:
There's a lot new calipers available that come with break pads that fit the YBR 2016 model, but they're from China (the gold ones spammed all over Ebay and Amazon.) I wasn't sure if I should take my chances with one of them.

If I buy a second hand unit am I not going to run into this problem later on and still have to service the caliper? (or maybe you're just referring to me having to be rough with the current one?)

You may, you may not, I'd hazard a guess and say not for 5 years at least however. The one I linked is listed as a genuine Yamaha part so should be fine, I'd be avoiding Chinese stuff too.

If you're confident you can get it all back together and working smoothly then maybe do it, however from reading your posts it sounds properly seized and is likely to get damaged when you have to start forcing things.

Honestly for the sake of £20 I'd want that peace of mind tbh.

PsychoPigeon · 20 Oct 2020 at 12:24

I found one on Ebay that looks legit from VMP motorcycle parts, it's £50 with new brake pads and post included. I'll go with that and rebuild the old one as a side project and let you know if I need help fitting. I'll be draining the brake fluid for the first time too.

BUDFORCE · 21 Oct 2020 at 07:44

Does the bike have ABS?

If so don't let the brake fluid completely drain from the system, I've done if once on a Honda and managed to fix it eventually but it took a while. But generally it's not good to let the fluid drain out empty when you have ABS.

You won't need to drain the fluid right out of the system either, but worth changing the fluid after your done. (Note the difference between changing the fluid/letting it drain out empty).

I have rebuilt a set of calipers a few years ago, it's easy enough, but if you can just get a new one at a reasonable price, it does save some messing about.

PsychoPigeon · 21 Oct 2020 at 13:28

The YBR doesn't have ABS, it's a pretty basic learner bike. As far as I understand I'll only need to pump the brake fluid through the new caliper to push out all the air right, then top it up? I won't need to drain the entire reservoir (it had a fluid change recently during MOT.)

tom_e · 21 Oct 2020 at 13:31

PsychoPigeon said:
The YBR doesn't have ABS, it's a pretty basic learner bike. As far as I understand I'll only need to pump the brake fluid through the new caliper to push out all the air right, then top it up? I won't need to drain the entire reservoir (it had a fluid change recently during MOT.)

If you're removing the caliper, then you're best off just draining the res.
You could try clamping the brake hose but honestly a single caliper set up takes all of 5 minutes to bleed through so it's not worth messing about.

Scythe · 21 Oct 2020 at 13:37

PsychoPigeon said:
It's not threaded just seized up, I will give it a go with a hammer (ordered some PlusGas for it.) Bit worried how I'm going to get the piston back in, seems like the only way is with a clamp. I ordered some chrome polish and grease will try and lube it up.

don’t lube your brake piston with grease, you’ll contaminate your fluid! You need to order specific brake grease (red stuff) which is compatible with brake components and fluids.

Looking from the thread, it looks like you don’t understand the basics of hydraulic brakes. I strongly advise you take the bike to an experienced mechanic before you damage your brakes further. Next time, do your reading before you try to change pads or service brakes, they’re there for your (and everyone else’s) safety.

PsychoPigeon · 21 Oct 2020 at 18:00

Ok got it, I should only use the red rubber grease if it's coming into contact with the rubber seals. I have been reading but the problem is that people do different things, there's some using white grease to try and ease the piston back in saying that the seals block any contamination to the brake fluid so that's not an issue, others saying anything other than rubber grease erodes the seals faster. But it's good to learn, no one ever told me about the front brake eventually having to be serviced I know it's in the manual but I expected the MOT to pick it up if it showed signs of serious wear, I'm just glad it happened while the bike was stationary and didn't get stuck while riding.

wazza300 · 22 Oct 2020 at 14:56

Buy yourself a big g clamp to compress the piston back in,can do it with the pads still installed it won't hurt them

PsychoPigeon · 26 Oct 2020 at 15:12

New caliper and pads installed ok, drained the brake fluid reservoir 3 times (while topping it up before reaching the bottom) just to make sure there was no air left in the system and topped up the reservoir to the maximum since it's new pads.

I'm noticing the pads are dragging but from what I understand that's expected until they wear in? And the brake disc is lukewarm after a 30 minute ride not overly hot.

The brake itself feels like it has a little less resistance when pressing it than previously, could this be down to new caliper replacing a 5 year old one? But other than that the front brake works great.

Scythe · 26 Oct 2020 at 17:45

There should always be pad to disc contact but there shouldn’t be any drag. With the front wheel in the air, I would expect at least one full free rotation before it stops as a guide.

Pushing three reservoir’s worth of fluid does not guarantee a good bleed, but given it’s only a single brake line it shouldn’t be too far off. If the brake feels spongy, there will be air in the line. Is your lever getting close to the bar?

One trick to get final few bubbles out: Pull the lever quite hard, and cable tie the lever to the bar in that position overnight. Using a spanner or screw driver, tap up and down the brake line to encourage bubble to release into the fluid. Remove the cable tie the next day, your lever may feel a little more firm.