Author Topic: No more front brake  (Read 574 times)

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Offline Le ptit Quebec

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No more front brake
on: August 08, 2020, 07:50:44 PM
Hi all,

3 weeks ago, I changed the pads and bake fluid on the Versys. After we went for 5 days ride in the German forest, Over 1500km.

The bike sit in the garage since. Went I took it wout for a ride tonight, impossbile to build the pressus on the front pads. Brahe lever feels like there is not more oil!

But there is, and no visible leaks on the floor or after pumping several times. Any idea? Could it be the ABS valve that is stock open?

Offline Ben

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Re: No more front brake
Reply #1 on: August 08, 2020, 09:22:15 PM
Fortunate it did not happen while riding  :5:

If circuit is full and no air in it, so most probably an open valve... Try disconnect the battery and restart ?

Online Rockdoc

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Re: No more front brake
Reply #2 on: August 09, 2020, 07:54:18 AM
I once had major problems with a car's brakes. A garage replaced the master cylinder and, naturally, refilled the system. After four or five miles, with the family inside, I had no brakes on a dual-circuit system that was supposed to ensure that never happened. I complained and they had another go but with similar results. I fixed it by completely purging the brakes with new fluid. After a flaming row with the service manager, it became clear what they'd been doing to cause the trouble. They'd made a reservoir to sit on top of the master cylinder that could be pressurised with compressed air and they opened all the nipples and blasted the fluid in.

Except air dissolves readily in brake fluid at low pressures and British compressed air systems run at around 100psi. It must have been fizzing in the system like cola!

Keith
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Offline TYKE

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Re: No more front brake
Reply #3 on: August 09, 2020, 08:04:36 AM
 :762: 

And a possible reason why the O.P has this problem

OOI My racing TZ 250 had a Lockheed brake conversion fitted, I replaced the hoses with Braided items which was easy enough, but subsequent bleeding of the brakes was a nightmare  :125:   the only way I achieved it was by hanging/lifting the reservoir to the greatest height possible whilst it was still connected to the system and waiting until the bubbles within the new fluid gently rose upwards and out of the reservoir....it took a couple of days  :5:   

The point is, that as Keith states, fluid will absorb air bubbles under certain conditions
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Offline Vern

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Re: No more front brake
Reply #4 on: August 09, 2020, 09:50:27 AM
From your explanation you have travelled without problems for 1500km, and then you have a problem  :notsure:

As suggested air is in the system, which you may have introduced by accident as you replaced the old brake fluid.

Lets hope that is is as suggested that tiny air bubbles have formed into one bubble that is sitting somewhere in the system, and cannot be dislodged by simple bleeding. These bubbles of air tend to sit in the hose joints.

But, if you have no brake pressure then normal bleeding will make it impossible to shift that bubble.

To overcome this I recommend that you purchase, hire or borrow a vacuum bleeding attachment.
This is fitted to the brake bleed nipple, then pumped to create the vacuum. You carefully open the bleed nipple and brake fluid + air is pulled through.

Very effective, but be sure not to get to excited and draw out all the fluid.
Keep the reservoir topped-up, but pour the fresh brake fluid slowly into the reservoir otherwise you will have more air bubbles forming within the fluid.

Good luck Vern  :002:

Offline Le ptit Quebec

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Re: No more front brake
Reply #5 on: August 09, 2020, 12:37:24 PM
Hi guys,

Thanks for all the replies. At 7 this morning, the bike was on the center stand and the Allen key in my hand. I was able to build pressure, a bit more than yesterday with the 38C outside but yet, not enough.

Checks the fuses, OK
Check for leaks OK
Decided the take appart the MC... Both gaskets are still "kind of soft". Can't say if new ones would be softer. I'll get a replacement kit and try to fit before our trip to the Alpes this Wednesday.. Cleaned everyting with alcohol and put the MC back together.

When I bleeded to front brakes last time, the oil was already old and slightly colored. Since I dismantled the MC I had to purge the system again. Using a big syringe, a rubber hose and a clip, I slowly push the oil from the caliper top the MC. To me suprise, as soon as I opened the bleeder, bubbles rushed in the syringe  :whistle:. Found the problem...... (good guess Vern ;) ) Filled the MC, pressed the lever few times to evacuate the small bubbles for the MC piston and the brakes are back  :020:

Just when to buy a bottle of fresh Bosh brake fluid. I'll change it all front and rear.

Offline Ace50

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Re: No more front brake
Reply #6 on: August 09, 2020, 01:33:42 PM
Glad you got it fixed!  :152:

I'm feel I might even do this on my new 2019. The front brakes at rest, the lever is just soft.
I remember checking out the new Tiger 900 with Brembo's and wow. The lever was like, well it hardly moved and then it
was like up against a brick wall. Can't imagine what it was like on the road!

This thing, it's like a spring with almost no stop. (lever, not bike) I can see how that would help with the ABS as the pressure doesn't spike sharply
in a panic situation. Kinda reminds me of a device you could buy for the Master cylinder on the banjo bolt that did just that.
A small pressure chamber that would eliminate a spike in pressure when grabbing the brake too fast.
Seems Kawasaki built that right in!
These are Kawasaki brakes but look like high end sport bike brakes, they just don't work like them.

Offline markymark11

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Re: No more front brake
Reply #7 on: August 10, 2020, 08:29:41 AM
Silly question I know, but I haven't needed to do brake fluid for a while. I have always done the loosen nipple, squeeze lever, clamp nipple, release lever system with no special tools.

Do you have to bleed either side first as you would if there was a link pipe across the calipers, and do you have to have the ignition on / bike running so that the ABS pump is bled as well ?  :027:
you can't teach a pig to sing...it's a waste of time and it annoys the pig !

Offline Le ptit Quebec

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Re: No more front brake
Reply #8 on: August 10, 2020, 11:57:01 AM
You should always bleed the caliper further from the MC. On the bigV the split his in the middle, no issue.

The advantage of the bleeder tools or the syringe, is you can do everyting with one hand.

When plugged, you open the nipple and push the oil slowly, When the reservoir in full, close the nipple and empty the reservoir. Resume the same process until you get the fresh oil in the reservoir.

 



waggish