[Closed] tweaking shimano brakes

What do you have between the pistons while bleeding it? If you put in something slightly thinner, you can effectively "over-fill" the system, thereby achieving the result you're looking for.

I'd imagine if you bleed them with the free stroke adjusted to one extreme, then you'll get a different result when you adjust it afterwards?

Try propping up the front wheel about a foot, closing the levers with elastic bands or zip ties and leaving overnight. Tap the hoses occasionally to move any bubbles up.
In the morning release the levers slowly and then give them a very light tickling (er.. how else would I describe it?) and have a close listen at the lever for bubbling noises.
If they still pump up after this then you might need to re-bleed them from the bottom up.

Oh, and once you've done the tickling thing make sure that the pistons can retract fully. If not then remove the top cap and reset them.

druidh, rockthreegozy, those were a couple of things id considered, ill give them a bash.

bikewhisperer id not thought of that, ill give it a try.

Druid, you cant overfill an open system. The bite point is pretty much set by the lever.
Could try bleeding them with the bite point adjuster out?

Its the old sticky piston by my guess.

id be surprised, barand new brakes

druidh has it, I think everyone else is chatting shit.

I bleed mine with a block of kindlin or something between the pistons. Then, if the lever pulls too close to the bar when the wheel is in, I remove the wheel and pull the lever once (thus moving the pistons slightly further in), then add a bit more fluid to the reservoir. Repeat until the bite point is spot on

I thought shimanos were an open system? With an open system the amount of fluid ( so long as it is over the minimum) should have no effect on clearances or lever throw. If you are having to over fill the brake to get the correct lever throw either it is not an open system or you are masking a fault.

You're doing it again TJ. Stop analysing the "why's" and just accept that fact that practical experience is worth more than theoretical wrangling.

Stop talking rubbish TJ. An 'open' system is only open as far as the reservoir is big, if you catch my drift. If the reservoir is full then there's nowhere for excess fluid to go.

* of course this shouldn't happen under a normal bleed procedure (since the reservoir membrane should still allow some expansion even after being fitted to a 'full' reservoir, but it's still possible, especially doing a caliper first bleed if you add fluid with everything else closed.

i followed what the park website said in the end rather than the shimano one and it worked no probs. bikewhisperers thing worked temporarily but it turned out there was still a bit of air in the system, the park way of doing it seemed to get rid of the bubbles better.

cheers all.

I understand what you are suggesting doing Druidh.

Yes overfilling the system so the pads will not be able to completely return will bring the bite point out but as the pads wear the bite point will return to what it was before you overfilled. You also run the risk of having no room left for expansion of the fluid under heat and the brakes locking on.

I thought you never bled your brakes anyway.

TandemJeremy - Member
I understand what you are suggesting doing Druidh.

Yes [b]overfilling[/b] the system so the pads will not be able to completely return will bring the bite point out but as the pads wear the bite point will return to what it was before you overfilled. You also run the risk of having no room left for expansion of the fluid under heat and the brakes locking on.

I thought you never bled your brakes anyway.

No - but they do need to be set up initially.

Anyway - I thought you said above that it wasn't possible to overfill?