They will push all the way flush but when I release pressure they return to this position. I push one in flush, the other one comes back out. Push that one back, and the first one comes back out. What’s the deal?
Most obvious reason would be too much brake fluid.
Was it always like this, or have the brakes been bled recently?
Active_Ad_5322 on
over pressurized (ie too much fluid) in the brakes are a common reason for this. bleeding braked with the wrong bleed block can cause this.
set your bike upright, remove the lever bleed screw and push the pistons back, you will lose a little fluid, so have a rag wrapped around the lever body to soak up the fluid.
if no fluid comes out, then it is probably time for a bleed.
slowfun on
you might be fighting the fluid pressure, push some fluid out should help
SaltyScotsman on
I find pulling the lever a little while you have something against the piston to get things moving can help. It’s as if something has pulled a vacuum and that gets past it. Obviously be careful not to pull too much or the piston could come out.
SalvadorFolly on
Push the pistons back while the lever bleed port is open (set it up with a funnel of a syringe).
fattymcpoopants on
Everyone else is probably right that there’s too much fluid in the brakes. I have also seen the piston break internally and the broken pieces wedge behind the rest of the piston and stop it from being pushed back into its home. It will sound crunchy if this is the case, and only one side will resist being pushed back.
Azmtbkr on
If the brake lever was accidentally pulled, use a plastic tire lever to gently push the pistons back in place.
casualberry on
I had the same issue and i ended up buying a piston pusher. Seemed like a dumb thing to buy, but it worked like a charm. If you don’t wanna buy a tool, i think the key is equal pressure on both pistons at the same time, or your basically just pushing fluid back and forth. Another tool is to jam a tire lever in there and lever it around. Try that to see if you can at least get movement.
Memeseek69 on
Open the bleed port at the lever while pushing the pistons back. If there’s nowhere for the fluid to go, the pistons can’t move
Substantial-Fun-48 on
Too much pressure in the lines. Undo the top bleed port and open up the pistons while the port is open
willm1123 on
Thank you everyone for your input, I tried the best I can to apply even pressure and get them back but they didn’t quite go. Tomorrow ill go to a bike shop and either 1) get the proper tool and then try to push them back while letting fluid out or 2) accept defeat and let the shop do it, depending on the price of each option. Will update.
--Timshel on
Just need to open the system and, possibly need to bleed it.
Work on the bike right way up when doing this – a stand is the best option.
Level off the lever and install a bleed funnel or syringe. Now push the pistons back – any excess fluid can exit into the funnel/syringe.
By doing all the lever pulling and piston pushing upside down, you may have introduced some air into the lines. At a minimum you should do a lever bleed, and possibly do a full system bleed.
12 Comments
Most obvious reason would be too much brake fluid.
Was it always like this, or have the brakes been bled recently?
over pressurized (ie too much fluid) in the brakes are a common reason for this. bleeding braked with the wrong bleed block can cause this.
set your bike upright, remove the lever bleed screw and push the pistons back, you will lose a little fluid, so have a rag wrapped around the lever body to soak up the fluid.
if no fluid comes out, then it is probably time for a bleed.
you might be fighting the fluid pressure, push some fluid out should help
I find pulling the lever a little while you have something against the piston to get things moving can help. It’s as if something has pulled a vacuum and that gets past it. Obviously be careful not to pull too much or the piston could come out.
Push the pistons back while the lever bleed port is open (set it up with a funnel of a syringe).
Everyone else is probably right that there’s too much fluid in the brakes. I have also seen the piston break internally and the broken pieces wedge behind the rest of the piston and stop it from being pushed back into its home. It will sound crunchy if this is the case, and only one side will resist being pushed back.
If the brake lever was accidentally pulled, use a plastic tire lever to gently push the pistons back in place.
I had the same issue and i ended up buying a piston pusher. Seemed like a dumb thing to buy, but it worked like a charm. If you don’t wanna buy a tool, i think the key is equal pressure on both pistons at the same time, or your basically just pushing fluid back and forth. Another tool is to jam a tire lever in there and lever it around. Try that to see if you can at least get movement.
Open the bleed port at the lever while pushing the pistons back. If there’s nowhere for the fluid to go, the pistons can’t move
Too much pressure in the lines. Undo the top bleed port and open up the pistons while the port is open
Thank you everyone for your input, I tried the best I can to apply even pressure and get them back but they didn’t quite go. Tomorrow ill go to a bike shop and either 1) get the proper tool and then try to push them back while letting fluid out or 2) accept defeat and let the shop do it, depending on the price of each option. Will update.
Just need to open the system and, possibly need to bleed it.
Work on the bike right way up when doing this – a stand is the best option.
Level off the lever and install a bleed funnel or syringe. Now push the pistons back – any excess fluid can exit into the funnel/syringe.
By doing all the lever pulling and piston pushing upside down, you may have introduced some air into the lines. At a minimum you should do a lever bleed, and possibly do a full system bleed.