Ysterpikkewyn Posted February 11, 2021 Share Hi there. I need some advice please. I have Shimano XTR brakes which I have bled (flushed front and rear and added new mineral oil) but it still feels spongy. I have new pads at the rear and measured both the rotors at 1.65mm. Left the bike upright for about a day with the screws open on the levers to let any air bubbles out. Topped up with fluid. Also tried inserting the fluid from the bottom and the top, but neither seems to work. Not sure what to do anymore. Can anyone perhaps assist please? TIA Link to comment Share on other sites More sharing options...
100Tours Posted February 11, 2021 Share A gravity bleed with a bleed cup or open syringe on the top on any of the newer model Shimano brakes has always given me great results, and it is really easy. The best I can think of is that your pads may now be off centre in the caliper and you need to ride it to bed them down. 1.65mm is somewhat worn on the discs, but Shimano says you're ok until 1.5. Is the sponginess in the caliper or the lever however. If your lever is slow to return (I wouldn't call this spongy, but it is a bit subjective) then you may have some lever work to do. Cappi and Ysterpikkewyn 2 Link to comment Share on other sites More sharing options...
dasilvarsa Posted February 11, 2021 Share When you first got the Bike Were you Happy with the brakes ? My Shimano Brakes (not XTR) on 2 Bikes also feel Spongy but the Back Wheel Locks when I press hard and they release properly so I just ride it like that. I went to LBS Last Week and Felt the Brakes on Various Bikes and they also Felt Spongy. (The Lever Does not Come to An Abrupt Lock like Car Brake Pedal Does) Link to comment Share on other sites More sharing options...
ChunkyMonkey Posted February 11, 2021 Share Check if both pads hit the rotor at the same time when brakingwhen they’re off centre, they can also feel a bit spongy after the first pad touched...they( Shimano brakes) should hit hard. if this still doesn’t work ensure lever is level...(horizontal) and use piston spicer in caliper.try connecting two syringes, and do bottom up bleed to force air out in the hose.once in top syringe, cycle a few time to ensure all air is forced to top.ensure not to force any air back down( keep the top syringe upright) once done, close bottom feednut. Then gently unscrew top syringe.( some oil might spill)screw seal nut back in...squeeze lever... and feel happiness!!!!pour yourself a tall beer.... dasilvarsa and Ysterpikkewyn 2 Link to comment Share on other sites More sharing options...
BaGearA Posted February 11, 2021 Share I might be wrong here but shouldn't the very newest gen Shimano brakes only be bled from the top? I. E. Gravity bleed ChrisF 1 Link to comment Share on other sites More sharing options...
TCTG Posted February 11, 2021 Share When you first got the Bike Were you Happy with the brakes ? My Shimano Brakes (not XTR) on 2 Bikes also feel Spongy but the Back Wheel Locks when I press hard and they release properly so I just ride it like that. I went to LBS Last Week and Felt the Brakes on Various Bikes and they also Felt Spongy. (The Lever Does not Come to An Abrupt Lock like Car Brake Pedal Does)Shimano brakes always feel spongy but they perform when needed as mentioned. Link to comment Share on other sites More sharing options...
Ysterpikkewyn Posted February 11, 2021 Share Yes, I was happy to about 3 weeks ago when I started noticing I have to "pull" harder just to stop. I normally used my index finger and now I have to use at least 2 fingers to just have some brakes. When you first got the Bike Were you Happy with the brakes ? My Shimano Brakes (not XTR) on 2 Bikes also feel Spongy but the Back Wheel Locks when I press hard and they release properly so I just ride it like that. I went to LBS Last Week and Felt the Brakes on Various Bikes and they also Felt Spongy. (The Lever Does not Come to An Abrupt Lock like Car Brake Pedal Does) Link to comment Share on other sites More sharing options...
pedal menace Posted February 11, 2021 Share *MINI THREAD HIJACK* I have several bikes that run Shimano brakes - Is there a way to bleed them without buying a Shimano bleeding kit? They seem to be very hard to come by. I have reached the point that I simply ride my bikes and pump the brakes when needed until they are "hard". It works but not ideal. Just too much of a schlep to book bike into a bike shop just for a bleed every single time. Do-it-yourself YouTube Video/Website perhaps? *MINI THREAD HIJACK OFF* Link to comment Share on other sites More sharing options...
GhostSixFour Posted February 11, 2021 Share It might be that you've blown some seals by trying to bleed form the bottom. ChrisF 1 Link to comment Share on other sites More sharing options...
Jehosefat Posted February 11, 2021 Share Yes, I was happy to about 3 weeks ago when I started noticing I have to "pull" harder just to stop. I normally used my index finger and now I have to use at least 2 fingers to just have some brakes. That sounds more like you have some contamination on the discs or pads or both. If the brakes desperately need a bleed the lever generally reaches the bar before you get any proper braking force. If the lever travel is the same but the brakes are not slowing you down it's more likely that you need to degrease/decontaminate the pads and discs. You can use isopropyl alcohol or a dedicated brake cleaner. If that doesn't work give the discs and brakes a light sand with a coarse sandpaper (like 400 grit or lower). dasilvarsa and ChrisF 2 Link to comment Share on other sites More sharing options...
Jehosefat Posted February 11, 2021 Share *MINI THREAD HIJACK* I have several bikes that run Shimano brakes - Is there a way to bleed them without buying a Shimano bleeding kit? They seem to be very hard to come by. I have reached the point that I simply ride my bikes and pump the brakes when needed until they are "hard". It works but not ideal. Just too much of a schlep to book bike into a bike shop just for a bleed every single time. Do-it-yourself YouTube Video/Website perhaps? *MINI THREAD HIJACK OFF* Use a syringe. Take out the plunger and stick it in the bleed port at the lever and screw it in. Then fill with oil and pump the brake lever (make sure you have a bleed block in or keep the wheel on the bike) until the bubbles stop. Use a second syringe with some clear hose in the end to suck almost all of the oil out of the first syringe before removing it otherwise it will get quite messy. dasilvarsa and 100Tours 2 Link to comment Share on other sites More sharing options...
Jehosefat Posted February 11, 2021 Share I might be wrong here but shouldn't the very newest gen Shimano brakes only be bled from the top? I. E. Gravity bleedNope, not according to the official Shimano dealer guide: https://si.shimano.com/pdfs/dm/DM-MADBR01-02-ENG.pdf If you can fill the system with oil by pumping it up from the caliper I can't see how bleeding it that way would be a problem. Edited February 11, 2021 by Jehosefat ChunkyMonkey 1 Link to comment Share on other sites More sharing options...
David Marshall Posted February 11, 2021 Share Push the pistons fully into the caliper with a flat tool between the pads. Make sure that the lever travel is adjusted to maximum. Take the pads out and fit the bleed block. If you now operate the lever and it is hard then you don't have a bleed issue. Start looking at discs and pads. Cappi 1 Link to comment Share on other sites More sharing options...
MarcW Posted February 11, 2021 Share I'm having a similar problem with my M9100's especially the rear brake. Going to try the gravity bleed method this evening. I am also going to switch over to metallic pads. Currently have Resin pads and it feels like they overheat quite fast. Link to comment Share on other sites More sharing options...
erikt123 Posted February 11, 2021 Share A word of warning:-Just be very, very careful with XTR pistons when pushing them back as they are ceramic and are easily damaged dasilvarsa and ChunkyMonkey 2 Link to comment Share on other sites More sharing options...
arendoog Posted February 11, 2021 Share Similar problem i had .Turned out that the brake hose had a crack and i was inflating the hose when pulling the lever .Replaced the hose and problem solved .You have to check the whole length of the hose for a bubble when braking hard Link to comment Share on other sites More sharing options...
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