Rear brake issue

[BigDukeSix]

I am having an issue with my rear brakes. When I press the brake pedal, it feels like nothing happens. If I stand on it, I get a little bit of engagement but not much at all. However, if I pump the brakes 2 to 3 times, it works as it should.

My brakes were working just fine until I removed my rear wheel and put it back on after changing the tire. It looks like I put everything back where it belongs – I can’t visually see what the issue is, but I can’t ignore the timing of this issue presenting itself right after I took the wheel off and put it back on again.

I already tried adjusting the brake at the lever – didn’t help anything.
Any thoughts here? It might be something easy – I am new to wrenching on bikes. Any guidance you can provide would be greatly appreciated.

[JerryHawk250]

Have you tried bleeding the brake system?

[BigDukeSix]

Originally Posted by JerryHawk250

Have you tried bleeding the brake system?

No. I hadn't thought to do it as the bike only has 400 miles on it - was working fine and I noticed no leaks or anything like that. Not sure what would have happened to need a bleed at this point, but I suppose it's worth a try.

[calvarez]

That's the first step when hydraulic brakes won't engage. Is there any chance you got grease/oil on the pads? And...I've actually seen this done, so don't think I'm being an a-hole, but...are you sure you have the pads the right way? I've seen someone put the metal side towards the rotor, and yeah, it had little braking power. Aside from that, most brakes have an "inside" and "outside" pad. I haven't done the rear on this bike yet, so don't know if it does, but very likely. Check that they are in the right place.

[BigDukeSix]

Originally Posted by calvarez

That's the first step when hydraulic brakes won't engage. Is there any chance you got grease/oil on the pads? And...I've actually seen this done, so don't think I'm being an a-hole, but...are you sure you have the pads the right way? I've seen someone put the metal side towards the rotor, and yeah, it had little braking power. Aside from that, most brakes have an "inside" and "outside" pad. I haven't done the rear on this bike yet, so don't know if it does, but very likely. Check that they are in the right place.

• I'm thinking it's not grease or oil on the pads since pumping the brakes temporarily corrects the problem.
• I assume the pads are on correctly as per your suggestion because I never took them off and they used to function well. This part of the equation didn't change. When I took the rear wheel off, the caliper kind of dropped (it seems to need the wheel to hold it in place). But when I put the wheel back on, I put the caliper right back where it was. I am pretty sure I got this part right.
• I will try bleeding the system here in a few minutes - gotta finish up some work first. Will report back what happens.

[calvarez]

Pumping the brakes and then having them work is a common symptom of air. It all sounds pretty strange, so we're going to shoot out some stuff that might not make sense, because the whole problem makes no sense. When it's figured out, we'll slap our foreheads and wonder why we didn't all think of that first.

Humor me and look in there and make sure you actually see both pads and that they look to be in the correct place.

[NzBrakelathes]

Sounds like caliper or pads missalignd or not fitting together and twisting
Photos plz

[rjmorel]

If all you did was take rear tire assembly off and did nothing to the brakes then there may not be anything wrong with the brake. Try pumping the brake pedal a bunch of times as far as it will go with your hand with every thing assembled back together.
Sometimes the brake pads get forced open the maximum travel away from the rotor when trying to put them back on the rotor. The brake fluid is forced up into the reservoir and it takes several pumps to get the pads moved out to where they are touching the rotor. Once they are forced out against the rotor they should work and not need the pumping. Unless somehow air got in the system. Which doesn't sound like in your case happened. rj

[BigDukeSix]

I wound up working pretty late tonight and didn't get a chance to look at the bike. Will check it out tomorrow afternoon and look at the things you guys mentioned.

[fjmartin]

Just make darn sure that the front portion of the brake bracket which has a chunk of square metal is slid into the rail on the swingarm. If not slid in there then things can move and twist. I've seen a guy with a bike who had done this and things went very badly for his bike....destroyed rotor and pads!

[pete]

if they work after pumping them a few time = Air in the system...

the only other possabiliy that would need pumping is pads returning to far
but i can't think of any reason that would / could happen...

so back to air in the system...

Bleed them..... If by chance that dose not work... master cylinder maybe..

I may only have 400 miles on it... But remember..
it's a chinese bike put togeather on a assembly line in china by chinese..




.

[BigDukeSix]

Well I made things worse.
When I tried taking the top off of the master cylinder to bleed the brakes, I discovered that the screws holding it on are made out of the softest metal on earth – or maybe cheese. I’m not sure. I got one off then stripped the other – have never seen a screw this soft before. So I ran down to the store and bought some drill bit that is supposed to bite into a stripped screw and pull it out but that wound up just boring a nice dish shaped indentation into the screw and now the top of it is nice and smooth and shiny . Interestingly, both of my next door neighbors are named Bob. One of them used to be some sort of mechanic so when he gets home I’m going to have to see if he can fix what I have apparently broken.
This is why I have two bikes…

[calvarez]

Yeah, some of the screws on this thing are soft. I guess that does prevent the aluminum hard bits from being the sacrificial part.

[rjmorel]

Any update BDsix on brake? rj

[sqwert]

Rotor bent during tire change?