jonno12345 Posted July 8, 2018 Share Posted July 8, 2018 My rear brake seems to have a fair bit of travel in it before it actually does anything in the way of stopping (but even a tiny press I can see the pistons are moving). I've flushed the fluid, no air bubbles when I manually bleed (loads of small ones when I use a vacuum, but wasn't sure if there's a small leak around the tube/threads maybe causing that?) - no change in performance after a bleed. I can't see any other real adjustment other than the bolt for pedal height, thought I'd try that but to make a decent difference I had to adjust it as far as it would go, really awkward position and definitely not a solution..! Pads still have plenty of meat on them. Wondering if there's air in the abs system. Anyone know a method to check this, or anything I may have missed? Side question, do front and rear brakes use separate abs pumps? Front had a load of air in it before and after bleeding feels perfect. Thanks! Link to comment Share on other sites More sharing options...
jonno12345 Posted July 10, 2018 Author Share Posted July 10, 2018 Bled it again, using a vac tool I get loads of small bubbles from inside the bleed nipple, but if I use the manual method of pressure on the lever, open the nipple, hold the lever down, close, I get only fluid and no air at all. Guessing the vac is pulling air from the bleed nipple threads? Brake lever, even after flushing the entire thing again, still has a lot of travel before it makes any attempt to brake (probably 1-2cm from the end point of the lever before I feel any resistance on the wheel). Doesn't appear to be any warping in the disc. Piston naturally rests slightly off the pads themselves, not making contact with them. Anything I've missed..? Link to comment Share on other sites More sharing options...
jonno12345 Posted July 14, 2018 Author Share Posted July 14, 2018 Resolved this - for anyone who may have the issue further down, there was a slight but noticable (I'd be surprised if it was even 1mm) gap between the piston touching the brakepad. I removed the two bolts (one allen, one hex) from the caliper, pushed the pads to one side and then used the brake lever to extend the piston a little. At this point, I knocked off most of the crud gathered around where it normally sits, then tried to fit the pads around the caliper again, naturally where I'd extended a little more it wasn't quite fitting. I wiggled the pads a little around the disc until the piston moved in *just* enough to allow the pads to seat, then fitted the hex bolt (the fitting closest to the front of the bike) finger tight. This allowed me to pivot the caliper down onto the second bolt, without any wiggling side to side (which would cause the piston to retract again ever so slightly). I then torqued up both bolts again. This now has left my piston always in contact with the back of the brake pad, so the pedal usage is now instant. I think the key to this was getting it just tight enough and then using the rotating along the bolt method, rather than my previous 'put it in place and bolt them both up good' which meant that the piston was as fully out as it could be when reseated. Whether it'll stay like this I don't know, but certainly for now I'm a lot happier and my brake works as intended! Link to comment Share on other sites More sharing options...
BBB Posted July 14, 2018 Share Posted July 14, 2018 Glad it worked for you. I’m not sure I understand why it should do this, as the piston should always be in contact with the pads. It would imply that either the piston is not free moving or the pads are sticking on the caliper pin. Hope it stays fixed! Red 2015 Tracer, UK spec (well, it was until I started messing with it...) Link to comment Share on other sites More sharing options...
jonno12345 Posted July 14, 2018 Author Share Posted July 14, 2018 Glad it worked for you. I’m not sure I understand why it should do this, as the piston should always be in contact with the pads. It would imply that either the piston is not free moving or the pads are sticking on the caliper pin. Hope it stays fixed! Yeah I'm unsure too, it just kept seeming to retract too far... Bikes only done 7.6k miles so wouldn't expect the caliper to have issues, but it's certainly something I've not come across before. Next time I take it to a garage I'll have them look at it properly..! I also suspect I'll get more issues as the pads wear... Link to comment Share on other sites More sharing options...
nhchris Posted July 15, 2018 Share Posted July 15, 2018 My rear brake also has lots of lever travel and take A LOT of pressure to do any actual braking. A friend's 09 is the same way. We just figured the rear brake sucked. I'm going to sintered EBC pads when the origs wear out. Not sure why piston would back off pads upon release of the foot lever. Strange... cb 1968 Triumph Bonneville 650 1971 Norton Commando Roadster 2002 Harley 1200 Sportster 2003 Honda ST 1300 2016 FJ 09 Link to comment Share on other sites More sharing options...
Supporting Member betoney Posted July 15, 2018 Supporting Member Share Posted July 15, 2018 My rear brake also has lots of lever travel and take A LOT of pressure to do any actual braking. A friend's 09 is the same way. We just figured the rear brake sucked. I'm going to sintered EBC pads when the origs wear out. Not sure why piston would back off pads upon release of the foot lever. Strange... cb That doesn't sound normal at all, you should not have to press hard to get brake pressure. My rear brake (oem pads) has very good stopping power w/o excess pressure. My buddy has an FJ as well (both 2015's) and his brakes also have normal pedal feel. Pull the caliper from the carrier and inspect the pins, extent the piston a bit and clean all of the crud until it is shiny. Try bleeding to see if fluid moves correctly. ***2015 Candy Red FJ-09*** Link to comment Share on other sites More sharing options...
jonno12345 Posted July 15, 2018 Author Share Posted July 15, 2018 My rear brake also has lots of lever travel and take A LOT of pressure to do any actual braking. A friend's 09 is the same way. We just figured the rear brake sucked. I'm going to sintered EBC pads when the origs wear out. Not sure why piston would back off pads upon release of the foot lever. Strange... cb Yeah that sounds more like air in the lines than mine. Mine worked fine, but I had more travel in the pedal to get to the point it started braking. But yes, I don't know either. I've actually just found another thread about the FZ-09 where someone had the same issue and resolution.. maybe it's a caliper flaw?? https://www.somefz09forum/forum/34-yamaha-fz-09-common-problems-issues/37865-rear-brake-no-power-pressure-3.html#/topics/37865 (link won't work because apparently we can't link to it) Note in their images the size of that gap? Mine was a lot smaller, but yes, every press it would return to it. Here's their video, again, my gap wasn't quite this large, but was the same issue. Link to comment Share on other sites More sharing options...
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