spongy brakes

[scott]

Hi Guys.....i need some help. I'm having problems with my brake calipers. I have replaced all the seals and dust boots on my six pot tokico calipers and bled them and bled them, however there is still a spongy feel to the levers. The brakes work but feel very inefficient. I replaced the brake lines for braided ones last year and the bleeding process was easy. So if i have only taken the calipers off and stripped and rebiult and not the lines, why am i having such a problem? Do the seals in this type of caliper go in one way only?...they look like they can go in either way. There are no fluid leaks at all as far as i can see, so i think i have'nt damaged the pistons....they did get a quick wipe with very fine wet and dry paper for a few seconds to remove the shite....this would'nt have compromised the piston would it? I am asking for help because i've noticed a few zeds with these calipers fitted and someone may be able to shed some light on the situation. The calipers are fitted on my zx7r but they are also fitted on zrx1200 i think. The brakes worked really well before i stripped them. I had to strip them becuse they were binding.....i found the dust boots were being pulled out partially by all the road shite forming on the pistons and hence not doing well for an MOT. any ideas?

[fletch]

scott,
might be a silly question but were the all of the pistons pushed completely
back before you started to bleed them,when i replaced my calipers i
did'nt do this because i thought the fluid would push out any air,
well 1hour later and lots of wasted fluid i done what my mate said,and
pushed them back,it must have took 5 minutes to get them sorted all because i was too stubburn to listen in the first place.
It's worth a try before you take them apart again.
good luck.

[scott]

I'm pretty sure they were pushed fully home.....because i fitted new pads as well and that normally means you will have to push them fully home to get them back on the disc. I think i'll double check tonight. Thanks for the info....greatly appreciated.

Scott

[Dark Skies]

Try removing the calipers off the fork legs, putting a disc sized piece of wood in between the pads, lifting them as high as you can raise them and then bleeding them - you might just have a stubborn air pocket.

[chrisNI]

One thing I found before - with Billet six pots - was that the easiest way to bleed them is with the calipers off the bike and raised upas high as you can so that the air is being pushed out upwards. Unbolt then and have them bite horizontally, bleed nipple upwards, on a bit of wood or metal about the thickness of a disk. This can make it esaier to get the air out, and once the get solid bolt them back on.

When I started typing this Dark Skies hadn't posted - like he said.

[Pigford]

I also had probs with a pair (now only use 1 ) of Tokico's

Turned out one of the calipers was NOT square on the fork leg, so was at a slight angle to the disc. This caused the disc to act like a large 'spring washer'. The throw of the pistons was not enough to completely take up the flex of the disc, and clamp it hard enough to act as a proper brake
I eventually worked it out (after many nights of bleeding the brakes - off the bike as Dark Skies & Chrisu say), when I noticed the disc moving slightly

I also rebuilt my Tokico 6-pot with no probs

[chrisu]

mark - you need to borrow my reading glasses - wasn't me.........

[Pigford]

Sorry Chrisu & ChrisNI

[Rich]

Tapping them with a screw driver handle helps to get the air bubbles out as well.

[scott]

Thanks guys.....i'll try checking the disc for movement and if it's ok i'll try bleeding them horizontally. I'll need a few beers first to enable me to be horizontal

Cheers

Scott

[02GF74]

about the seals - so far on the calipers I have rebuilt, and that is not that mamy, the seals are no more than square section o-rings so fit either way.

[Pigford]

02GF74, they appear square until you take a real close butchers....
then you can notice a slight angle on the inner face on ones I've used