Problems bleeding Shimano M6000 Brakes with worn pads.

Dave02

Dave02

Member
My brakes were getting very soft (lever goes to handlebar) so I bled the brakes.
With the yellow bleed block in place- the lever was nice and firm after the bleed.
Once the wheel was installed and the worn pads were installed, the lever was very soft- pumping the brakes didn’t help. I know that the brakes are supposed to self-adjust for the worn pads- but this wasn’t happening.
Both pistons extend while pulling the lever but retract the same amount when releasing. I cleaned and lubed the piston seals with mineral oil- the pistons seemed to move easier but otherwise no change. I also tried putting the funnel on the lever and pumping the lever to fill the reservoir to accommodate the worn pads. Didn’t help.
I was finally able to get it working by removing the pads and pumping, but am concerned that next time will still be a problem. Any suggestions, other than fire of course? The brakes are only 14 months old.

Sorry for the long post- I know there are many very skilled mechanics here that have been very helpful in the past- greatly appreciated.
 
the resevoir only holds so much fluid, when all the fluid is in the system because the pistons have been walked out there is no way to advance them any further and they get soft, or longer travel to engagement. I know my SRAM guides develop longer lever travel when the pads are shot. New pads is definitely where i would be going if i were you. then see if it keeps up with advancing the pistons as the pads wear out.
 
I didn't have replacement pads at the time and had a ride planned for the morning, and LBS wasn't open.
I will replace with new pads, but want to understand if there is a problem- they are supposed to compensate for worn pads.
I didn't realize at the time how worn they were- perhaps they were worn more than the reservoir could compensate for.
If replacing pads more frequently is the answer- I'm ok with that- but would like to know if they are working properly.
Perhaps I'm overthinking all of this- I'll replace with new, have to remove the bleed screw as the reservoir is now filled for the worn pads.
Thanks for the comments.
 
measure the pad thickness if your really worried, idk what shimano specs for min pad thickness, but for sram its 3mm including the backing plate, and the reservoir compensates for pretty much exatly that, the levers are starting to feel long/soft when you hit that point.

unfortunately i dont have an answer specific to shimano brakes, they should advance and then retract a little bit less every time you squeeze them, i would expect it to take many pumps to equalize for very worn pads.
 
shrpshtr325 said:
measure the pad thickness if your really worried, idk what shimano specs for min pad thickness, but for sram its 3mm including the backing plate, and the reservoir compensates for pretty much exatly that, the levers are starting to feel long/soft when you hit that point.

unfortunately i dont have an answer specific to shimano brakes, they should advance and then retract a little bit less every time you squeeze them, i would expect it to take many pumps to equalize for very worn pads.
Click to expand...

3mm (backing+friction material) is a good gauge regardless of brand.

Yes, @Dave02 , worn pads can cause the symptoms you are describing. Simply replace, and it should work fine. The response about fluid displacement farther upstream is correct.
 
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