Ultegra R8050 hydraulics - long lever travel
Discussion
I have barely ridden my bike outside for a couple of years due to running more, but last year when I took it out the brake lever travel (both front and rear) was very long, to the point where the lever can touch the handlebars. I had the brake fluid changed and bled, the person who did it said the fluid actually looked OK and there are no leaks, and the fluid level was OK. The lever feel improved a TINY bit but I didn't ride since.
I have since ridden outside and, again, the lever travel is way too far and the stopping power is pretty poor. The pads are Shimano pads with plenty of life left in them, the calipers are centralised to the discs.
Any thoughts?!
I have since ridden outside and, again, the lever travel is way too far and the stopping power is pretty poor. The pads are Shimano pads with plenty of life left in them, the calipers are centralised to the discs.
Any thoughts?!
Take the pads out and look for any brake fluid residue on the back. Shimano had a period where the caliper seals would gradually start leaking. I’ve had to warranty 2 sets of GRX 800 calipers due to this, main symptoms is long lever travel and no stopping power.
Try zip tying the levers in the on position with a bleed block between the pistons and leaving overnight to check for any fluid passing by the seals.
Annoyingly this junks the pads as the fluid soaks through holes in the metal backing plates into the friction material.
Try zip tying the levers in the on position with a bleed block between the pistons and leaving overnight to check for any fluid passing by the seals.
Annoyingly this junks the pads as the fluid soaks through holes in the metal backing plates into the friction material.
I removed the pads and they're bone dry. I pulled the lever a couple of times to expose the pistons, cleaned them up, pushed them back in, put the pads back in and now it's even worse 
Considering it's now worse I'm inclined to think it's not the fluid/air lock, but I'm not sure. I'm far from a mechanic and beyond some basic tools I don't have anything to bleed them with etc.
Considering it's now worse I'm inclined to think it's not the fluid/air lock, but I'm not sure. I'm far from a mechanic and beyond some basic tools I don't have anything to bleed them with etc.
The levers can be squeezed almost to the handlebars even if the brakes are perfectly bleed. There is a lot more travel than motorbike brake levers.
However it takes quite a lot of effort and if you did it while moving you would be flipped over the bars.
Shimano do pretty good step by step guides for servicing all their components including bleeding the brakes.
I've replaced a couple of callipers and the it wasn't that hard to bleed the brakes and get the right lever feel.
If you push the pistons out you'll need to pump the brakes to restore the lever travel.
However it takes quite a lot of effort and if you did it while moving you would be flipped over the bars.
Shimano do pretty good step by step guides for servicing all their components including bleeding the brakes.
I've replaced a couple of callipers and the it wasn't that hard to bleed the brakes and get the right lever feel.
If you push the pistons out you'll need to pump the brakes to restore the lever travel.
This can be due to the caliper seals aging, or the pistons dirty or corroded.
The pistons are supposed to slide through the seals, but the seals grip them just enough to pull them back away from the disc. Apart from a little bit of suction from the master cylinder, and maybe the anti-squeal springs etc, that's all there is taking the pads away from the discs.
Also if one piston is sticky, the other will move more, the brake then works by bending the disc.
The pistons are supposed to slide through the seals, but the seals grip them just enough to pull them back away from the disc. Apart from a little bit of suction from the master cylinder, and maybe the anti-squeal springs etc, that's all there is taking the pads away from the discs.
Also if one piston is sticky, the other will move more, the brake then works by bending the disc.
SoliD said:
I had this with my grx, thought i'd got all the air out, no air bubbles or anything, but still spongy and long lever a day or two after a bleed, so forced through new fluid and the old stuff that came out was disgustingly dirty. fixed the lever travel straiight away.
When the fluid was changed it was still pretty good! Really odd. BOR said:
Sounds to me like the inner piston seal in the master cylinder is worn/torn/damaged so cannot build any pressure in the brake line.
Friend is looking at it next Wednesday. I'm not sure what's going on, but both pistons on both brakes do move equally and freely. I hope it's something simple like an air lock and not needing new seals etc. The bike is now 6 years old though. Gassing Station | Pedal Powered | Top of Page | What's New | My Stuff