Brakes locking

Hi

I have recently changed my bars to the K100 ones. I was about to take it for my first test run and felt that it wasn't free wheeling as easy as expected- I was struggling to push it backwards out of the garage.

I have lifted the front end and noted that the front wheel was binding / rubbing on the brakes. I eased the pad of the discs and the wheel freely rotated. As soon as I squeezed the brake lever the wheel locked up and would not release when I released the lever.

I have tried bleeding a bit of fluid out of the callipers and I end up with the same result. My first thought is master cylinder, but I cannot see why it would have failed as I did not spilt/ brake into the system- I merely rerouted the hose and lever.


As I have changd the bars- is there a set angle that the master cylinder should be set at? (I not from the manual it just says align with mark on bars) I will probably remove the callipers and flush the fluid at the weekend, but any ideas or suggestions in advance of this would be greatly appreciated.

Karen- I originally posted in the wrong section before it got moved to here. Once I found it again, I have read a few of your posts and there are a few things I will try. I am pretty sure the pistons are fine- they were working perfectly ok before I started changing the handlebars, I suspect (and am hoping) that in the process of rerouting the master cylinder, that a bit of crud has got itself lodged in the opening. I will try this as a first course of action.

Steve

Karen said:

You need to check the MC first, there is a weep hole where fluid back fills in under a little metal plate, is it plugged?

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I second this.... most likely culprit.

In re-routing of the hoses, if you had the hose retaining clamp on the tripple tree off, might check and make sure clamp didn't pinch hose when it was re-attached.

Doing a bar change could've had the master cylinder in all manner of position (clutch too) providing a way for dirt (shouldn't be in there but possible) or air to move around the system and cause all kinds of havoc. I had this problem on my truck once, turned out to be a bad caliper.

In the end I went for new extended hoses and rebuilt the callipers with new seals. I checked the MC when I filled/ bled the system and there were bubbles coming through prior to bleeding (so not blocked)

Now for my latest problem- the brakes wont engage when I put the new seals in I pushed the pistons all the way in. I have bled the system- fluid is bleeding out with no bubbles but the pistons are not engaging and are still fully pushed in. Is there a chance that they could be held to the back of the calliper by suction? I am trying to think of a way of pulling the piston out a bit to get some fluid behind them, but as they are so far in I cannot think how to get them out.

Or should the MC push them out no matter how far they are in? Getting annoyed now, had a shoulder injury and with this brake issue means I haven't ridden it for over 2 months now.

sm0129 said:

Or should the MC push them out no matter how far they are in?

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You don't mention whether your bike has ABS.

I just finished rebuilding my calipers and pushed the pistons all the way back into the bores, and my brakes are working. But, I need to bleed them better, so I am installing some SB8125L speed bleeders.

You did put the pistons back correctly with the bottom of the pistons inserted first into the bore?

All sorted now! It took a hell of a lot of bleeding- I beleive I had an airlock in the MC. I cracked open the banjo, pressurised the MC and then bled them. Been out on it for the first time in 2 months and it feels great.

Thanks for your help and advice.