Hydraulic discs problem
Discussion
I've got a set of Shimano hydraulic disc brakes and recently replaced the pads on them as they are knackered. After few rides with them to bed them in the fronts now feel fine but the back is very weak and needs a lot of pull on the lever to start braking.
With the old pads I could lock the back wheel up with one finger, now I can't do it at all. I have bled the system front and rear too (and I'm pretty sure there can't possibly be any more air in there) but it isn't helping.
Any suggestions as to how to improve braking at the rear would be gratefully received.
With the old pads I could lock the back wheel up with one finger, now I can't do it at all. I have bled the system front and rear too (and I'm pretty sure there can't possibly be any more air in there) but it isn't helping.
Any suggestions as to how to improve braking at the rear would be gratefully received.
TheDetailDoctor said:
Nevin said:
TheDetailDoctor said:
In the event of any disc issues, (especially on my Shimano XT ones), I always start with a bleed of the system. 95% of the time it sorts it.
Yup, but done that 3 times and its not helping unfortunately.Edited by Nevin on Tuesday 1st June 14:23
TheDetailDoctor said:
Yep, push the fluid from the bleed nipple to the reservior, sometimes they can be a PITA to get clear. Also, try tapping the lines/calipers/levers when bleeding as it can help free the trapped air also.
Cheers, will give that a go. Just need to find somewhere to get a syringe now.Nevin said:
TheDetailDoctor said:
Yep, push the fluid from the bleed nipple to the reservior, sometimes they can be a PITA to get clear. Also, try tapping the lines/calipers/levers when bleeding as it can help free the trapped air also.
Cheers, will give that a go. Just need to find somewhere to get a syringe now.TheDetailDoctor said:
Nevin said:
TheDetailDoctor said:
Yep, push the fluid from the bleed nipple to the reservior, sometimes they can be a PITA to get clear. Also, try tapping the lines/calipers/levers when bleeding as it can help free the trapped air also.
Cheers, will give that a go. Just need to find somewhere to get a syringe now.Hmmm, we if the bite point is good / lever doesn't come to the bar it could be: caliper needs a centre, or pads are contaminated - happens or they're just not bedded in yet.
Experienced riders use little rear brake, could be they're just still 'green' try a few big stops using the rear only.
Experienced riders use little rear brake, could be they're just still 'green' try a few big stops using the rear only.
I'd be tempted to swap the pads front and rear, just to confirm that it's the hydraulics not the pads that are at fault.
TBH it sounds like contaminated pads to me, but presumably you know your onions if you're happy to rebleed your brakes and you know the classic symptoms (ie. squealing!).
How's the lever feel, is it spongey or as it should be?
Word of warning: when you swap the pads over clean the rotor thoroughly to prevent any cross contamination if present!
TBH it sounds like contaminated pads to me, but presumably you know your onions if you're happy to rebleed your brakes and you know the classic symptoms (ie. squealing!).
How's the lever feel, is it spongey or as it should be?
Word of warning: when you swap the pads over clean the rotor thoroughly to prevent any cross contamination if present!
P-Jay said:
Hmmm, we if the bite point is good / lever doesn't come to the bar it could be: caliper needs a centre, or pads are contaminated - happens or they're just not bedded in yet.
Experienced riders use little rear brake, could be they're just still 'green' try a few big stops using the rear only.
May have to look at it all again. Caliper was sticking but I thought I had sorted that so will take it apart.Experienced riders use little rear brake, could be they're just still 'green' try a few big stops using the rear only.
Experienced riders weighing as much as I do need as much braking power as they can get, both front and rear.
Pads could be contaminated but shouldn't be. I'll pull it apart in the shop again tomorrow.
Brake lever is very spongy thougfh.
Parrot of Doom said:
If the lever action is progressive (ie slowly gets harder and harder to pull) then you've still got air in there.
If, however, the lever is nice and solid the moment the pads hit the discs, then your problem is elsewhere.
It doesn't really get hard to pull at all, which I suspect may mean there is still air in there.If, however, the lever is nice and solid the moment the pads hit the discs, then your problem is elsewhere.
Nevin said:
Parrot of Doom said:
If the lever action is progressive (ie slowly gets harder and harder to pull) then you've still got air in there.
If, however, the lever is nice and solid the moment the pads hit the discs, then your problem is elsewhere.
It doesn't really get hard to pull at all......If, however, the lever is nice and solid the moment the pads hit the discs, then your problem is elsewhere.
TheDetailDoctor said:
Nevin said:
Parrot of Doom said:
If the lever action is progressive (ie slowly gets harder and harder to pull) then you've still got air in there.
If, however, the lever is nice and solid the moment the pads hit the discs, then your problem is elsewhere.
It doesn't really get hard to pull at all......If, however, the lever is nice and solid the moment the pads hit the discs, then your problem is elsewhere.
Sometimes a brake caliper or brake resevoir will have a bad casting which makes bleeding the brake nigh on impossible.
I have a set of XTR's which I simply can never ever get bled the way I like them, yet a set of XT levers I got done in 3 seconds flat.
Therefore it's worth taking a close look at the casting underneath the top hats, and/or ensuring that you have all of the correct seals, washers and o-rings in the assembly.
Short of that, look at your cables, and ensure no kinks or undue tight bends.
After that, try sacrificing a small child.
Or do it drunk, as you tend to go 'ahhh feck it. that'll do'.
I have a set of XTR's which I simply can never ever get bled the way I like them, yet a set of XT levers I got done in 3 seconds flat.
Therefore it's worth taking a close look at the casting underneath the top hats, and/or ensuring that you have all of the correct seals, washers and o-rings in the assembly.
Short of that, look at your cables, and ensure no kinks or undue tight bends.
After that, try sacrificing a small child.
Or do it drunk, as you tend to go 'ahhh feck it. that'll do'.
neil_bolton said:
Sometimes a brake caliper or brake resevoir will have a bad casting which makes bleeding the brake nigh on impossible.
I have a set of XTR's which I simply can never ever get bled the way I like them, yet a set of XT levers I got done in 3 seconds flat.
Therefore it's worth taking a close look at the casting underneath the top hats, and/or ensuring that you have all of the correct seals, washers and o-rings in the assembly.
Short of that, look at your cables, and ensure no kinks or undue tight bends.
After that, try sacrificing a small child.
Or do it drunk, as you tend to go 'ahhh feck it. that'll do'.
I have bled it previously though and its been fine so that seems less likely, but who knows. Tis a black art and no mistake.I have a set of XTR's which I simply can never ever get bled the way I like them, yet a set of XT levers I got done in 3 seconds flat.
Therefore it's worth taking a close look at the casting underneath the top hats, and/or ensuring that you have all of the correct seals, washers and o-rings in the assembly.
Short of that, look at your cables, and ensure no kinks or undue tight bends.
After that, try sacrificing a small child.
Or do it drunk, as you tend to go 'ahhh feck it. that'll do'.
Nevin said:
neil_bolton said:
Sometimes a brake caliper or brake resevoir will have a bad casting which makes bleeding the brake nigh on impossible.
I have a set of XTR's which I simply can never ever get bled the way I like them, yet a set of XT levers I got done in 3 seconds flat.
Therefore it's worth taking a close look at the casting underneath the top hats, and/or ensuring that you have all of the correct seals, washers and o-rings in the assembly.
Short of that, look at your cables, and ensure no kinks or undue tight bends.
After that, try sacrificing a small child.
Or do it drunk, as you tend to go 'ahhh feck it. that'll do'.
I have bled it previously though and its been fine so that seems less likely, but who knows. Tis a black art and no mistake.I have a set of XTR's which I simply can never ever get bled the way I like them, yet a set of XT levers I got done in 3 seconds flat.
Therefore it's worth taking a close look at the casting underneath the top hats, and/or ensuring that you have all of the correct seals, washers and o-rings in the assembly.
Short of that, look at your cables, and ensure no kinks or undue tight bends.
After that, try sacrificing a small child.
Or do it drunk, as you tend to go 'ahhh feck it. that'll do'.
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