Brake Lever Travel

[imdying]

how far though? Always thought the discs played a part.

The minor (generally less than 2 thou) acceptable runout on discs is responsible for pushing the pads just off of the discs surface, but not responsible for the pistons retracting at all.

[sAsLEX]

pushing the pads just off of the discs surface, but not responsible for the pistons retracting at all.

Umm if the pads are being pushed back does that not imply the pistons also are moving back since the two are attached? As I am sure the discs moving at a faster rate than the rubber rings

[imdying]

Umm if the pads are being pushed back does that not imply the pistons also are moving back since the two are attached? As I am sure the discs moving at a faster rate than the rubber rings

No, the pads can only move back because the pistons have retracted. The runout on the discs that pushes the pads off of them is miniscule, especially when compared to the amount of retraction the caliper seals do.

[XP@]

how many times have you bled them?
is there a huge air bubble in the calipers?
Did you remove them & all the fluid? if so did the old fluid chrystalize(sp?) in the inside the brakes?
Is the rotor flat?

Being a mechanical spoon I made all of the above errors and at various points had similar effects to what you described.

[The Stranger:Me]

how many times have you bled them?
is there a huge air bubble in the calipers?
Did you remove them & all the fluid? if so did the old fluid chrystalize(sp?) in the inside the brakes?
Is the rotor flat?

Well I hope I have bled them corectly and left no air bubbles. I don't think one can ever be 100% certain though.
I had removed all the fluid previously and popped the pistons out and cleaned these up and got all the gunk out from in the cylinders, though there were no crystals.

Last tiem I reasembled them they were the same but yeah just giving them another bash as I had to rework the brakes due to shall we say, an unfortunate incident.

Rotor flat? well not buckled, though there is some ridging and wear, though nothing abnormal. They are a little below the wear limit, but not badly so.

[FROSTY:Me]

CAN a couple of points. 1)use rubberlube on the pistons when putting it all back together. 2 I strongly susspect your pistons need to be pumped out another 1/2 mm. Try this trick. Pull one caliper off then give ONE pump on the brakes.The caliper should still fit back over the disk but will be reluctant
bolt it back up and repeat the exersize with the other side.
I bet your brakes will improve heaps

[Scouse]

Because mine don't actually seperate from the disk they come on early and softly, getting extremely strong near the end of the travel. They're so strong the forks bottom out (standard springs soon to be changed) and the front end then starts bouncing like a pogo stick.

Shane dont change yer fork springs change yer bike

[The Stranger:Me]

Thank you, will give that a try.

[The Stranger:Me]

CAN a couple of points. 1)use rubberlube on the pistons when putting it all back together. 2 I strongly susspect your pistons need to be pumped out another 1/2 mm. Try this trick. Pull one caliper off then give ONE pump on the brakes.The caliper should still fit back over the disk but will be reluctant
bolt it back up and repeat the exersize with the other side.
I bet your brakes will improve heaps

Hmm no real change.
When I pulled the pumped the lever the pistons travelled out ok, but when I released they travelled back the same amount. Tried it with both calipers, same result.

Oh well.

[FROSTY:Me]

cam--dude um -it works like this -the caliper seals are big (ish) square section O rings -they act as return springs for your pads.
The way they do that is they distort inwards as you apply the brakes -as soon as you release the pressure they twist back into shape pulling the pistons with them.
What you need to do is get the pistons to move a little bit beyond the return point of the o ring. Then the pads wil be a tiny bit closer to the disks and I bet ya brakes will be tonnes better

[Mental Trousers]

Shane dont change yer fork springs change yer bike

Quiet or I'll learn ya.

[Scouse]

Quiet or I'll learn ya.

Oh ok just as long as you don't sin bin me oh mighty Moderator

[Mental Trousers]

Oh ok just as long as you don't sin bin me oh mighty Moderator

Smart arse

[erik]

I think I've got the opposite problem, the pistons aren't pulling back far enough from the discs on my bike. Anyway...

I wonder if there might be an air bubble at the top of the lines, near the master cylinder?
Try pushing the pistons back into the calipers so that some of the fluid flows back up into the master cylinder reservoir. I did this on my bike today and it has made the brakes feel a lot less mushy (they were feeling mushy after the bin at taupo, DEATH suggested some air might've got into the top of the lines since the fluid level in the master cylinder was low).

[WINJA]

The distance the pads a re retracting kinda points to the discs being out of true

MAYBE , BUT CHECK THE AXLE FIRST CAUSE IF THE AXLES BENT THE DISCS SIT ONTHE PISS , HAD THIS WITH THE 9 I DID PADS AND MASTER CYLINDER STILL NO JOY , THEN I CHECKED THE AXLE FOUND IT BENT REPLACED IT AND JOY , A BENT AXLE CAN BE HARD TO SPOT CAUSE ITS POSIBLE THAT JUST THE THREADED PORTION IS BENT ,
GOT A EASY WAY TO CHECK IF YA WANNA KNOW