front brake problem

[mad brian]

I recenty fitted new pads to a 2004 Varadero xl 1000 (non abs) and they worked fine for a few 100 miles. Now they are tending to have a pulsing feal to them as if the disc was worped, but its not. I've had the callipers off a few times, all moving parts are clean (now) and have copper slip on them but it soon comes back. The only problem I've found is the middle piston, when I push it back it won't push out, but when I remove the caliper after a bit it is out (same on both sides). Any comments please

[Steve T]

Cant help regards the pulsing - it does sound like a warped disc though, but if it was fine before you changed the pads, who knows (not me)

However, the front caliper middle piston - they are operated by the rear brake on your machine (CBS = Combined Braking System), hence when you try and pump them out with the front brake they dont move.

Hope someone pops in with a helpful hint on the pulsing side of things.

Steve T

[jamie92j]

did you wear the pads in after fitting? they could be 'glazed' not sure if this would make them pulse though

[Peltsi]

Maybe the new front pads dragged? If the pads dragged to disk and heated and the you stopped the bike for some time? There could be glasing in the disk. Does the pulsing feel more like chance in grip in brake or does the brake lever actually pulse?

I bet you could clean it up with a proper brake cleaning solvent. Both of them. And while your at it do some sanding/gringing for the pads.

[africajim]

If the slides were jammed the pistons would push one side of the disc and warp it giving a pulsing feeling?
I'd strip the calipers again, make sure the pistons are all clean and free, then clean and grease the slides with copperslip and replace, should be fine.

[mad brian]

Thanks for the ideas to date. I've eliminated warped disc so I'll be trying a good clean of everything and redressing the pads, lets see how it goes

[paulc]

Could it be the back brake warped or damaged in some way as the front and back hydrolics are linked ?

[Freerangestormer]

After all you have checked and checking the discs for true, if the problem persists it is more likely to be either air in the system or one of the balance valves sticking.

The CBS is tricky to bleed sucessfully, if you don't feel up to it I would take it in to get the fluid changed and bled.

[pbc0]

Maybe the new front pads dragged? If the pads dragged to disk and heated and the you stopped the bike for some time? There could be glasing in the disk. Does the pulsing feel more like chance in grip in brake or does the brake lever actually pulse?

I bet you could clean it up with a proper brake cleaning solvent. Both of them. And while your at it do some sanding/gringing for the pads.

Mines the same and its definately a glased area on the disk.
Ain't that bad and you don't feel it on the lever.
re-dress the disks but you'll have to cut past the glasing to get rid of it, otherwise you'll just make it worse.

My cure is to save up for a new pair of disks.