I have 12 speed shimano di2 hydraulic levers, R8170. The free stroke adjust screw works fine on the left lever. Turning the screw on the right lever doesn’t do anything. I tried loosening the screw and bleeding the brake but that didn’t fix it. Is there a way to fix it without disassembling the entire lever? The brakes work fine, it’s just annoying that when I adjust the reach to be the same left and right the right lever gets much closer to the bar.
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Does the lever need to be bled with the free stroke adjustment in a particular position - i.e. fully open or fully closed? I seem to recall this is a thing and could be having an effect on what the adjustment is capable of achieving as a consequence, but I’m running off a vague memory so I may be wrong…
Could you clarify the doesn’t do anything? The free stroke adjustment on Shimano brakes is usually misunderstood. The factory default (screw turned in all the way, clockwise) results in the shortest lever throw before pad engagement. If you unthread the screw from this point you will both increase the lever reach and increase the lever throw.
I’m assuming you have adjusted the reach separately of the free stroke adjustment. It’s not uncommon for the reach adjust on the right lever on these to wander in over time.
If you’re trying to match the throw of both brakes, I would ensure one isn’t overfilled. These brakes are quite easy to get good bleeds on but I see them overfilled quite often which makes one brake have a much shorter throw.
Lastly there was a batch of these calipers that had out of spec piston seals which didn’t allow the pistons to retract correctly once pulled. These often feel extremely stiff with very short throw which is abnormal. I wonder if your front brake has this issue.
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It’s strange, after I finished bleeding the brakes the left lever was working as expected. Loosening the free stroke adjustment screw made the lever move away from the bar. Turning the free stroke adjust screw on the right lever didn’t make the lever move. After a ride I checked the right lever again and now the turning the screw does move the lever. Not sure if something happened on the ride or if I just messed up earlier.
Do you have more info about the faulty seal batch? I’ve been dealing with such calipers from time to time and I’m feeling like a zealot. No one ever agrees with me that there are some calipers, which just doesen’t seem to work as they should. When I confront my local Shimano warranty/dealer center, they once warrantied one set of calipers with no explanation and keep telling me there’s just no such issue and every 12sp caliper is perfect.