Sticking Front Brake

Mark N.I. · Post by **Mark N.I.** » 22 Jun 2009 16:14

Hi all,
Havent been on much, been enjoying the bike.
However, took it down the road to-day, all of 10miles, when the front brake lever became very stiff into a roundabout, same into the next, and at the traffic lights I had 1 locked front wheel, no movement.
After about an hour I could move it again. I then adjusted the adjusted bolt, down the road and back, all of 3 miles and already getting stiff again.
Any ideas?
Im only on my R-plates and Im not a quick rider, so Im not flying up to corners and hitting the brakes hard.
Thanks

Mark

mantaray · Post by **mantaray** » 22 Jun 2009 17:12

15 years ago i had something like that on my 944 Porsche .
After driving 1 hour the cars started to brake.
Cleaned the brakesystem and changed the fluid----->>> problem solved

By our 82 sports the handle stuck after using the brake (but didnt block the wheel)--->> cleaned the master.

HTH
Raymond

ringer · Post by **ringer** » 23 Jun 2009 07:52

Brake fluid turns to sludge if not changed often enough. If your's has not been changed recently, or you are not sure if it has or not, then change the fluid now. It's a relatively cheap thing to do, and would need doing sometime anyway, so you have nothing to lose. Hopefully the problem will then go away. Of course, you will then have to go for an hour long test ride to check that out

MickeyMoto · Post by **MickeyMoto** » 23 Jun 2009 08:33

Hi,

The brake only has the pistons on one side and the caliper slides when the pad on the pistons side contacts the disc to pull the other pad to the disc. Check that the caliper has not seized on the pins. Copper grease is good (IMHO, but I'm sure some engineering degreed people would disagree). I had a Honda 400/4 that had a crap caliper that pivoted in the fork. After a few months in the winter it would seize and give the same symptoms you describe. The disc would be too hot to touch and to get moving I would have to kick the caliper to loosen it up. I hate sliding calipers.

Regards,

Mike.

3potjohn · Post by **3potjohn** » 23 Jun 2009 19:19

Worth looking at the brake caliper pistons for corrosion. When I have had this on non-Morinis mind you its been this.They can move out against the disc but not return gradually binding

Mark N.I. · Post by **Mark N.I.** » 26 Jun 2009 15:03

Thanks for the replies and help all.
Pistons seem good and free, pads are fairly new and again free.
The fluid was rather crp and wasnt much of it, mostly likely winner of the problem, had sucked in an air bubble.
So im bleeding them at present, however it is not going well, very slow.
Ive the caliper on the disc, wee tube on the bleed nipple running to a jar with fluid in it and the tube under the fluid, cover on the resivour but not screwed down and pumping like mad, opening nipple ever min but very little comes out.
Is this right, any cheats?
Thanks

Mark

Post by **morini_tom** » 27 Jun 2009 09:09

I've used a pressurised easy bleed system in the past when i've had trouble bleeding mine but normally the front brake on the dart bleeds nicely and doesn't need it. Does your dart have a braided front brake hose or a rubber one? if it's still got the rubber one then I'd recommend upgrading to a braided one, it might solve your problem and you may as well do it now while the brakes aren't working properly and need a good flush out anyway.

Failing that I had to replace the master cylinder seals and piston on my dart a few years back as the master cylinder just stopped pumping. Completely transformed the front brake and I couldn't believe how easy it was to bleed afterwards. The overhaul kit was very very difficult to track down, the usuals (Motomecca, Corsa Italiana and NLM) didn't have them listed. Eventually Roberto at IN MOTO managed to source me an overhaul kit from one of his many contacts in Italy. Unfortunaltely I can't find the bill so I can't give you a part number but Roberto should be able to help wih that.

There is a complete switchgear, caliper and master cylinder on ebay at the moment which would be worth a go at Â£30 buy it now. Useful spares if nothing else. Item number 290303645210 -Listed as Freccia 125 but it's the same as the dart. I've bought parts from this seller in the past and been very happy.

Hope that helps,
Tom

Post by **morini_tom** » 27 Jun 2009 09:14

Forgot to say, when I pump mine without the cap on I get a fountain of brake fluid from the return port which can get very messy so be careful when you finally do manage to get some pressure in the lines.

Jem · Post by **Jem** » 28 Jun 2009 19:04

I had problems with my Sport in the past. I had mounted the caliper so that it was behind the fork leg (which meant the brake hose went DOWN before it went up) and the brake light switch was in a T piece connector under the bottom yoke.

I replaced the master cylinder with one that had a built-in brake light switch and fitted a straight through brake hose from caliper to master cylinder. I still had problems bleeding the brake.

So, figuring that air rises in a liquid, I unbolted the caliper and rested it so that the hose rose above the horizontal, and turned the bars so that the hose was still rising when it connected to the master cylinder. Then I left it overnight.

In the morning - job done. Easing the bleed nipple just leaked a dribble of fluid.

Goodness know how you do this with cars!

Mark N.I. · Post by **Mark N.I.** » 28 Jun 2009 21:26

Thanks for the help.
I have toyed with the idea of changing the seals and the brake line, it is rubber and looks like new, but im out of work at the min and just trying to keep it ticking over.
Jem I have tried that too

On closer inspection it would seem that the free moving pistons have now got kinked in the caliper so fluid has been by-passing them and going out the nipple, off i go to war again
Cheers

Mark

Mark N.I. · Post by **Mark N.I.** » 30 Jun 2009 21:44

And yet again the morini throws a curve ball, freed up the pistons and as it turns out the window isnt sitting right in the resivour and so air is getting there

Mark