letting out a 'little' brake fluid hayes hfx 9's pads tight

mulley

just fitted new pads to my hfx 9's and now the back wheel wont turn, i tried seperating the pads with a screw driver but no good, i think i will need to let a bit of fluid out, any ideas on the best way to do it without needing to bleed them after?

dave_hill

What sort of pads? Are they OE, Goodridge?

Restting the calipers can be a real pain with 9s. I find that the best way is to take the caliper off the bike (leave it attached to the hose) and use a thin flat screwdriver to push the pistons back with the new pads in place (take care not to damage the pad material and make sure that the screwdriver blade is clean).

Then place a piece of thin plastic, steel or even layers of cardboard between the pads that is thicker than the disc.

Now leave it overnight - this will allow the pressure in the system to equalize as what you're effectively doing is forcing fluid back up into the master cylinder. Take your plastic/steel/card out and refit the caliper before pumping the lever to bring the pads back in contact.

You may find that some cheap pads are way too thick (Fibrax in particular) so if you've got these you're going to struggle anyway.

If you do decide to bleed a bit of fluid out (it can help, but not much), fit a length of windscreen-washer hose (4mm from halfords, about £2.50 for 2 metres) to the bleed nipple on the caliper. Crack the bleed nipple open a 1/4 turn then quickly close it again - some fluid should come out into the hose. Remove the hose and use a rag to catch the excess fluid. Don't get it on skin or paintwork as it is corrosive - latex or vinyl gloves are a good idea.

Try the padded caliper method first though, you may have more success.

mulley

ta, i brought metalic super star componets pads as they seem to get good reviews and are cheap.... i'll try the idea you suggested, thanks

supersonic

I wouldn't be to keen on letting fluid out of the system. The reservoir would have to be filled to the brim for this to need doing which would have been noticable in normal use as the brakes heated up. What can happen if the fluid is too little that when the pads wear and the sytem auto adjusts, there may not be enough fluid available, so you will lose control of the brakes.

You need to take off the pads, push the pistons back in as far as possible, refit pads, and allow them to bed in.

nicklouse

have the brakes been bled at any time? with worn pads in?

SiLanc

This can be a nightmare with the Hayes HFX-9's. I would try the "leave overnight" method described above first and foremost. At the end of the day you just need to get those calipers back but it has taken me 90 minutes before now to full reset them. If you do anything with the brake fluid wear some goggles...I was refilling my tubeless last year and got sealant in my eyes...I won't go into details but for about two minutes I was absolutely sh***ing myself.

Good luck.

mulley

great coments, went back to them today, i put the old pads in and was going to try the wedge back and leave over night but when i forced the pistons back it made a noise and the piston went back enough for the pads to fit like normal. i must have been trying to be a little to careful. happy days.