Removing rear wheel = brake pad rub + lever fail!

capoz77

Hi guys,

I wish my Heckler had a maxle on the rear! The front brake will never fall out of alignment no matter how many times I remove the wheel; the maxle ensures the wheel sits in exactly the same spot everytime.

My question, how on earth do I do this with the rear wheel? I've removed it tonight and instead of the usual rubbing due to slightly different alignment the brake lever has lost half its travel. I've tried numerous reseats of the wheel but no luck and the lever bites straight away.

Is my only fix now going to be readjusting the calipers?

:oops:


Capoz

stumpyjon

Sounds odd. I regularly take wheels off both of my bikes and rarely have to adjust the calipers. Best way to seat the wheel is with the bike on the gorund (number of times I've thought it was seated when replacing it with the bike in a worksatnd :roll: ).

Also give the QR axle and drop outs a good clean, is there any muck in there which is causing random alignment, or maybe you've crushed the QR springs so they are causing a problem.

supersonic

Have you knocked the lever with the wheel out? This will push the pads closer together.

I'd push the pistons/pads right back in then pump a few times to reset (with the wheel back in)

capoz77

Whenever i've tried to push pistons back in the past its never done much! Do the pistons have some kind of ratchet system which holds them back once pushed?

supersonic

Open brake systems auto adjust as the pads wear - when you let go of the brake lever the pistons can only move a set distance back (the seals act as the spring as they shear/flex). So as the pads wear, the pistons creep further out, but still retract the same set amount after they contact the rotor. Extra fluid is pumped from the reservoir. So if you have pushed them out a little further with the rotor missing, you could have what you are describing.

So when changing pads you must push the pistons all the way back in.

If they don't budge there may be too much fluid in the system ie have been bled with the pistons too far out.

Of course yo aren't changing pads or bleeding, just examples of how it works, but the principle is the same if you have pressed the lever with no rotor there.

capoz77

Thanks SS, i've deffo not pressed the lever but the gap between rotor and pads has always been so minimal it wouldn't take a lot for the wheel position to equate to the disc not being dead centre!

Its when changed pads on my old Hayes and Avids i've tried to reset pistons in the past and they will never go that last few mm as they were when new. This gives terrible brake pad rub and i've had to sand my new pads down a bit to get them to work :oops:

Will give the whole area a clean tomorrow and get wheel nice and secure then unmount caliper, push pistons back, then set caliper. Finger crossed

capoz77

Thanks SS, i've deffo not pressed the lever but the gap between rotor and pads has always been so minimal it wouldn't take a lot for the wheel position to equate to the disc not being dead centre!

Its when changed pads on my old Hayes and Avids i've tried to reset pistons in the past and they will never go that last few mm as they were when new. This gives terrible brake pad rub and i've had to sand my new pads down a bit to get them to work :oops:

Will give the whole area a clean tomorrow and get wheel nice and secure then unmount caliper, push pistons back, then set caliper. Finger crossed