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Thread: Front Brake Reservior Cap Stuck

  1. #1
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    Front Brake Reservior Cap Stuck

    Hi,

    I am having problem uncapping the front brake reservior. Was hoping to bleed the system today, but the cap won't come off. All three screws were removed, tried wiggling it, and tried tapping it. But it won't budge. I don't believe that we are doing anything wrong. We (my son and I) have not had this problem with our other bikes (two Suzuki, one KTM and one BMW).

    Any advice would be greatly appreciated.

  2. #2
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    Three screws ? there is normally only two screws ! one on each end, you could try putting a thin wedge in the joint and gently tapping it, I suspect the rubber or plastic seal has fused in the joint. but I am still puzzled about the three screws unless it has four and you have missed one ?
    Last edited by oslin; 12-22-2018 at 08:02 AM.

  3. #3
    apriliaforum expert AndyT's Avatar
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    Three screws is correct (I had to go and check mine). It does sound like the rubber seal has fused to the reservoir. There will be a small air gap somewhere which you could try inserting a tiny screw driver or pick to lever off the lid. You will need to be very careful not to damage the rubber seal as it is very soft and any holes or nicks will allow moisture to get into the brake fluid. I think I would try using something like a small wooden dowel or similar as a drift and hit it with a mallet at a slightly upward angle to try to crack the seal. Just hammering on the edge of the lid isn't likely to break seal, but trying to lift it while tapping might free it.
    2009 Mana GT ABS; Andreani fork cartridges with uprated springs; Dorsoduro hand guards and heated grips; 30mm handlebar risers; Digital tachograph: Modified woodcraft folding brake pedal; R&G frame sliders

  4. #4
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    Thanks for confirming that Andy as you know I only sold it a few months ago but I do not remember three screws, but obviously there is, all my other bikes only have two :-) I have have found the rubber seal to have melted and distorted on some bikes in the past, I wondered at the time if somebody had used the wrong brake fluid which had attacked the rubber, I can not think of any other reason for that to happen in normal use ?
    Keith

  5. #5
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    Quote Originally Posted by AndyT View Post
    Three screws is correct (I had to go and check mine). It does sound like the rubber seal has fused to the reservoir. There will be a small air gap somewhere which you could try inserting a tiny screw driver or pick to lever off the lid. You will need to be very careful not to damage the rubber seal as it is very soft and any holes or nicks will allow moisture to get into the brake fluid. I think I would try using something like a small wooden dowel or similar as a drift and hit it with a mallet at a slightly upward angle to try to crack the seal. Just hammering on the edge of the lid isn't likely to break seal, but trying to lift it while tapping might free it.
    Thanks for advice. Used a small wood piece, placed on the cover's very slight over hang lip, tapped cover upward with mallet, repeat on the other side, and finally came off. Rubber seal ok. Not sure what was the problem but reservoir was filled well beyond max level.

    So front brake bleed. Still need to replace rear brake pump. Ordered one from AF1. Biggest concern is air in system given location of pump.

    Happy holidays

  6. #6
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    Quote Originally Posted by oslin View Post
    Thanks for confirming that Andy as you know I only sold it a few months ago but I do not remember three screws, but obviously there is, all my other bikes only have two :-) I have have found the rubber seal to have melted and distorted on some bikes in the past, I wondered at the time if somebody had used the wrong brake fluid which had attacked the rubber, I can not think of any other reason for that to happen in normal use ?
    Keith
    Thanks for comment. Fortunately seal intact. But did find some white material on inside surface either metal flacks or dryer chemicals.

  7. #7
    apriliaforum expert AndyT's Avatar
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    Quote Originally Posted by pmong View Post

    So front brake bleed. Still need to replace rear brake pump. Ordered one from AF1. Biggest concern is air in system given location of pump.

    Happy holidays
    I’m glad my tip worked out for you. The white material is probably corrosion, which means the brake fluid was definitely due for a change.
    If your bike is a standard 850NA then changing the rear master cylinder is straight forward and can be bled in the normal way. If the bike has ABS then I would bleed some of the old brake fluid out via the calliper before changing the master cylinder and then reverse bleed the system after fitting the new one. This means you push out the old dirty fluid that sits in the calliper to start with and don’t risk getting air in the ABS pump when bleeding the master cylinder end after the change.
    2009 Mana GT ABS; Andreani fork cartridges with uprated springs; Dorsoduro hand guards and heated grips; 30mm handlebar risers; Digital tachograph: Modified woodcraft folding brake pedal; R&G frame sliders

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    Quote Originally Posted by AndyT View Post
    Iím glad my tip worked out for you. The white material is probably corrosion, which means the brake fluid was definitely due for a change.
    If your bike is a standard 850NA then changing the rear master cylinder is straight forward and can be bled in the normal way. If the bike has ABS then I would bleed some of the old brake fluid out via the calliper before changing the master cylinder and then reverse bleed the system after fitting the new one. This means you push out the old dirty fluid that sits in the calliper to start with and donít risk getting air in the ABS pump when bleeding the master cylinder end after the change.
    Andy, thanks for the tip. I have ABS, so could be a little challenge. Below is the advice from AF1:

    try to get as much air out of the new master before bleeding the system. Install master, and fill with fluid, crack the top banjo bolt to bleed the pump. That way less air goes down the line.



    Then weíd use a vacuum bleeder to pull fresh fluid from the master thru the ABS pump, and out the caliper.



    Once done, you can find an empty parking lot and activate the ABS, and it may knock one last air bubble out for re-bleeding.



    What do you think?

    Also got this advice from a Ducati rider:

    Most bikes with ABS are designed to allow complete flushing of the brake fluid through the ABS actuator. This is the case with Hondaís ABS, as well as with several other Japanese makes. Motorcyclistís shop guy was, in a former life, an Aprilia and Moto Guzzi tech, and he says the Italian manufacturers donít bother purging the ABS module during a brake bleed. In other words, you bleed the system as though it didnít have ABS.

  9. #9
    apriliaforum expert AndyT's Avatar
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    In theory you should be able to bleed an ABS system in the normal way. If you were working on the calliper then this would work, no problem. However there is a very long run of pipe work from the rear brake master cylinder via the ABS pump (which is up just behind the steering head) and back to the rear calliper. The master cylinder is very small, hence the need for a vacuum bleed as there are several loops in the pipe where the air will accumulate and remain due to the tiny amount of fluid the master can push with each stroke.

    I accidentally got air in my ABS pump when servicing my front brakes and had to take the bike in to a dealer so they could run the pump to get the air out, so I’m now more careful about any bleed process that would involve pushing air through the pump. Hence my suggested procedure, above. You don’t want to push the old dirty brake fluid that accumulates in the calliper back through the system, so flush that out first and then after changing the master cylinder use a large syringe body and a short length of hose to reverse bleed the system. You should be able to see the air bubbles escaping via the little reservoir and can also suck excess fluid out of it with another syringe body. This completely avoids passing air through the ABS so you won’t end up trying to lock up the brakes to activate the system if you get air in it.
    2009 Mana GT ABS; Andreani fork cartridges with uprated springs; Dorsoduro hand guards and heated grips; 30mm handlebar risers; Digital tachograph: Modified woodcraft folding brake pedal; R&G frame sliders

  10. #10
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    Quote Originally Posted by AndyT View Post
    In theory you should be able to bleed an ABS system in the normal way. If you were working on the calliper then this would work, no problem. However there is a very long run of pipe work from the rear brake master cylinder via the ABS pump (which is up just behind the steering head) and back to the rear calliper. The master cylinder is very small, hence the need for a vacuum bleed as there are several loops in the pipe where the air will accumulate and remain due to the tiny amount of fluid the master can push with each stroke.

    I accidentally got air in my ABS pump when servicing my front brakes and had to take the bike in to a dealer so they could run the pump to get the air out, so Iím now more careful about any bleed process that would involve pushing air through the pump. Hence my suggested procedure, above. You donít want to push the old dirty brake fluid that accumulates in the calliper back through the system, so flush that out first and then after changing the master cylinder use a large syringe body and a short length of hose to reverse bleed the system. You should be able to see the air bubbles escaping via the little reservoir and can also suck excess fluid out of it with another syringe body. This completely avoids passing air through the ABS so you wonít end up trying to lock up the brakes to activate the system if you get air in it.
    Thanks Andy. Very helpful. I have flushed the system normally to get fresh fluid into the system, and will try to replace the pump this weekend because I received a couple of 100ml syringes yesterday. Hope it doesn't rain on Saturday or Sunday, but I guess we in Southern California need the water.

    Quick question about reverse flushing. Should I try to fill the new pump first after installing, or will just reverse flushing fill it up completely?

  11. #11
    apriliaforum expert AndyT's Avatar
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    When you change the master cylinder, add a little fluid to the reservoir afterwards. This will fill the pump and you might well see bubbles escaping as the fluid runs through. Reverse bleeding will push any remaining air out.
    2009 Mana GT ABS; Andreani fork cartridges with uprated springs; Dorsoduro hand guards and heated grips; 30mm handlebar risers; Digital tachograph: Modified woodcraft folding brake pedal; R&G frame sliders

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