Brake pistons won't go back - not seized!

wheeliecrazy

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I am trying to refit my front calipers after a tyre change on my 51 plate 1150gs, with ABS, and the pistons won't go back into the caliper far enough to get it over the disc. The pads are very well worn too. As I push one side, the other pops out, as if its got pressure behind it. I have done this job many times on various bike including the GS and never had a problem. The pistons are free, its just as if there is pressure behind them. Could the ABS system be causing my issue? They weren't sticking or anything prior to me taking them off to get the wheel off.

After an hour of struggling, I've had a huff and come in for a :beer: !!

Any suggestions would be appreciated:thumb
 
slacken the bleed valve when you push the pistons back
 
will I not get air in the system then?

Can you bleed these ABS models in the normal old school way - as normal non abs bikes?

cheers
emrys
 
read my post again, I'll not repeat it
 
top up the brake reservoir and bleed as per the traditional method

if you are bending the brake hoses while you're trying to push back the pistons you could be crimping the line and prevent fluid returning
 
It will

wheeliecrazy said:
I am trying to refit my front calipers after a tyre change on my 51 plate 1150gs, with ABS, and the pistons won't go back into the caliper far enough to get it over the disc. The pads are very well worn too. As I push one side, the other pops out, as if its got pressure behind it. I have done this job many times on various bike including the GS and never had a problem. The pistons are free, its just as if there is pressure behind them. Could the ABS system be causing my issue? They weren't sticking or anything prior to me taking them off to get the wheel off.

After an hour of struggling, I've had a huff and come in for a :beer: !!

Any suggestions would be appreciated:thumb
Click to expand...

If you trying to push the pistons back without the pads in place the very nature of a hydraulic system will cause one piston to move when you push another back. Leave the pads in place and insert a blunt wide object between the pads so there is equal pressure on all pistons. An old chisel or ball joint splitter is ideal.
 
Changed my fluid recently. Read a good tip to get any air out of the calliper is to push the pistons back. I've got a winding tool but the gap between the pads isn't big enough. I would go with Timolgras advice and let a bit of fluid out.I did this first before I ran the fluid through. Gets all the naff fluid out and a bit of air. As long as you go slowly and close the nipple as soon as the pistons are home I can't see you letting any air back in. If you are concerned then a quick bleed Will sort. I have an 1150 abs non servo.
 
2nd that , you will have room to push the pads if they are badly worn , but wrap cloth around just in case you push to hard .
 
hops said:
If you trying to push the pistons back without the pads in place the very nature of a hydraulic system will cause one piston to move when you push another back. Leave the pads in place and insert a blunt wide object between the pads so there is equal pressure on all pistons. An old chisel or ball joint splitter is ideal.
Click to expand...

What he said.

Push the pistons back with the pads in place. Not only will that help to solve your problem, but it will stop any damage to the pistons.
Tools exist for the job, but I tend to put a big screwdriver or tyre lever in between the pads and twist.
 
cookie said:
What he said.

Push the pistons back with the pads in place. Not only will that help to solve your problem, but it will stop any damage to the pistons.
Tools exist for the job, but I tend to put a big screwdriver or tyre lever in between the pads and twist.
Click to expand...

I'll also add - only push back one caliper at a time. Fit the caliper back in place, squeeze the brake lever a few times to reseat the pads then do the other caliper.
Pushing back both calipers pistons at the same time will use up any free fluid space. :D
 
Nippy Normans supply Touratech, Wunderlich, Desert Fox and many other makes of accessories.
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