Just something to check which had me fooled for a while once. Besides air in the system excessive brake lever travel could also be due to the pistons retracting more than normal so that they have too far to travel next time the lever is pulled.
By getting up very close and carefully watching what was happening to the pads and disc as I applied/released the brake lever I was able to see that the disc itself was bending on brake application and then bending back on release, pushing the pistons back more than would be normal. We are talking about a small movement that was barely visible perhaps 5 - 10 thou but it was enough to cause excessive travel at the handle bar lever. In my case the underlying cause was that in spite of noting how they came out I'd managed to put the old pads back in the wrong way around. I assumed that the reason this caused the problem was the pads had worn slightly tapered rather than being exactly parallel. Swapped the pads around and the excess lever travel went away.
Your pads may be new but in principle worth a close up look at the calipers in action.
what master cylinder piston size for 40mm ATEs?
Re: what master cylinder piston size for 40mm ATEs?
barry
Cheshire
England
Cheshire
England
Re: what master cylinder piston size for 40mm ATEs?
This is probably really old news but,
Due to struggling on all the old bikes I try to bleed brakes on, mine and my friend's, I've taken to including a kind of reverse bleeding procedure into the routine. Do the normal bleeding of course, and when that doesn't work well enough, which it never seems to do, do a reverse bleeding thing and crack every other join I can.
I am sure there is easier ways to do it, and better ways to describe it, but I get a big syringe with some clear PVC tube on the end and fill the syringe with brake fluid and put the tube over the bleed nipple.
It really is a two person job for speed an ease but with something to hold the lever and a long pvc tube it can be done alone.
The proceedure goes,
Person 1. Pump brake lever and hold
Person 1 (or 2 if the join is lower). crack a join, for this example, the top banjo between the line and the master cylinder) and catch the leak with a well placed rag,
Person 1. tighten this join that was just cracked.
Person 2. crack the bleed nipple and start to apply a little pressure on the syringe as:
Person 1. release brake lever slowly to suck in fluid through the syringe and bleed nipple.
Person 2. Tighten bleed nipple.
repeat.
Then of course repeat and repeat at every bleed point possible- the junction of the line and the master cylinder and the caliper(s)- along with generous tapping of the brake line and other bits of the system in between. And now and again you can do the traditional bleeding from top down through the bleed nipple.
I find it works best with the person on the brake lever dishing out the commands- and it can flow really fast.
My mate and I got really good at this on his SR500 which was a pig to bleed, front and back.
With the normal tapping of the lines, and that clamping the lever overnight and waiting, I hate trying to get those last little spongy bubbles out of the system and I don't like that bleeding a brake system properly needs to be a multiple day job. Moving the fluid from the bottom up seems to help gravity do its job and the air bubbles actually start really moving (instead of trying to go up as the brake fluid keeps going down) and before long the bubbles will either find one of the multiple bleed points or the master cylinder.
It really does work well, and with two people, very quickly.
And it is great to hear you are up and healing and playing with bikes again Pete, we really missed you around the camp fire at the Alpine. I look forward to catching up at the next rally,
Due to struggling on all the old bikes I try to bleed brakes on, mine and my friend's, I've taken to including a kind of reverse bleeding procedure into the routine. Do the normal bleeding of course, and when that doesn't work well enough, which it never seems to do, do a reverse bleeding thing and crack every other join I can.
I am sure there is easier ways to do it, and better ways to describe it, but I get a big syringe with some clear PVC tube on the end and fill the syringe with brake fluid and put the tube over the bleed nipple.
It really is a two person job for speed an ease but with something to hold the lever and a long pvc tube it can be done alone.
The proceedure goes,
Person 1. Pump brake lever and hold
Person 1 (or 2 if the join is lower). crack a join, for this example, the top banjo between the line and the master cylinder) and catch the leak with a well placed rag,
Person 1. tighten this join that was just cracked.
Person 2. crack the bleed nipple and start to apply a little pressure on the syringe as:
Person 1. release brake lever slowly to suck in fluid through the syringe and bleed nipple.
Person 2. Tighten bleed nipple.
repeat.
Then of course repeat and repeat at every bleed point possible- the junction of the line and the master cylinder and the caliper(s)- along with generous tapping of the brake line and other bits of the system in between. And now and again you can do the traditional bleeding from top down through the bleed nipple.
I find it works best with the person on the brake lever dishing out the commands- and it can flow really fast.
My mate and I got really good at this on his SR500 which was a pig to bleed, front and back.
With the normal tapping of the lines, and that clamping the lever overnight and waiting, I hate trying to get those last little spongy bubbles out of the system and I don't like that bleeding a brake system properly needs to be a multiple day job. Moving the fluid from the bottom up seems to help gravity do its job and the air bubbles actually start really moving (instead of trying to go up as the brake fluid keeps going down) and before long the bubbles will either find one of the multiple bleed points or the master cylinder.
It really does work well, and with two people, very quickly.
And it is great to hear you are up and healing and playing with bikes again Pete, we really missed you around the camp fire at the Alpine. I look forward to catching up at the next rally,
1974 R90/6
1981 R80G/S
1981 R80G/S