Brake Air Bleeding that works for me

Discussion in 'Maintenance' started by Slick, Jul 6, 2013.

  1. Slick

    Slick Senior Member

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    Sam1985 has already gone into detail how to bleed the ABS side so wont repeat that. Great thread BTW and invaluable if you have a few hours handy and don't want to pay the extortionate amount dealers will ask for.

    Its here for your reference http://1000rr.co.uk/maintenance/10733.htm

    Just a quick disclaimer, these are the brakes you are maintaining , if you have any doubts don't touch or at least have someone around who does!!
    Brake fluid will ruin plastic and paints, before bleed try to cover body work, have kitchen rolls to mop up spills and water to flush the bad stuff away.


    Apologies if this repeats some other threads but this is my experience of getting rid of air from the braking system.

    The ABS lines are quite complex so the opportunity for air to be trapped is quite high. For me flushing and air bleeding should be treated as two separate processes. I will only go into the best method of getting rid of those pesky last remaining air bubbles in the main/normal hydraulic lines.

    The night before

    Park up and pump the front lever a few times till it's hard as you can get it then strap the lever tight. I've got a velcro strap but many use a zip tie.

    Now with something that wont damage bodywork ( something with a little weight and rubber, like a dildo I suppose) start tapping the callipers and follow the lines up to the master. Repeat on the other calliper. Don't forget to tap the MC itself and hose between the MC and reservoir. The purpose of this is to help the bubbles rise to the highest point, here we are trying to use gravity to our advantage. Also the theory is as the system is under pressure the bubbles will be compressed thus smaller again helping them rise through the lines.

    Do as many times as you like or until the wife/boyfriend questions you about their missing implement.

    Leave in this state overnight to give the bubbles a chance to rise.

    Bleeding Procedure

    In the morning you are likely to have pockets of air trapped at each of the bleed nipples.

    Release the lever slowly (dunno why but i read it somewhere)

    Start bleeding at the MC. Cover up bodywork to protect from the brake fluid. Remove the reservoir cap, attach a clear silicon tube to the nipple the other end into a large syringe to collect the waste.

    (I like this setup as it is a closed system ie air can not be fed back into the lines, you can use the syringe to clear or prime the tubes, also if necessary this can be used to reverse bleed (another thread will be needed to explain this) . Another thing is that it is light and can hang easily off the nipple without falling off.)

    (As an aside I dont get on with vacuum pumps as 1 they can waste loads of fluid, 2 they suck air from around the thread so you can not tell if there is still air coming from the lines or not.)

    Whilst applying pressure to the lever slowly loosen the MC nipple. In my head the first bleed is the most important as this will have the most air, and therefore the time you most likely to push air back into the system (that and allowing the reservoir to empty!!)

    Fluid and air will come out. Keeping the lever at the grip tighten the nipple then release the lever, repeat until zero air comes out the nipple. Remember not to let the fluid to go below the min mark.

    Repeat the process on the right calliper then the left, back to right then MC, each iteration tap the line again to allow air to rise.

    Repeat until you have zero air. As I said always keep an eye on the fluid levels.



    Ending Procedure

    I like to always end bleeding on the MC, but on the last bleed do the following. Fill the reservoir to the max and replace the diaphragm and cap. Complete the last bleed with the cap on. After the last bleed and reprime you should aim to have the level 5mm or so from the max. Effectively this will seal the system in a vacuum, not sure if this an advantage but I like the idea of it!


    Testing

    Once you've torque up and clean spills again put the lever under pressure and check for leaks. Then go for a test ride and check for correct operation.

    Just as a safety measure again keep the lever under pressure overnight and check in the morning for any leaks.

    Enjoy!!!!!!!!!!!

    If OK you are ready to go and enjoy
     
    #1 Slick, Jul 6, 2013
    Last edited: Jul 8, 2013
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  2. samd1985

    samd1985 Active Member

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    Brilliant advice Slick! It's good to hear some clear cut advice on how to bleed brakes.

    Coincidentally I've currently got my brake lever tied back to the grip and the rear pedal held down with rope overnight, just to see if it makes any difference. I checked it earlier after a couple of hours of them being pressurised and both had loosened off a bit. I noticed this happened last time, so by morning the lever was loosely back at the bar.

    Sam
     
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  3. Slick

    Slick Senior Member

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    Yes I didn't mention the lever after pressurising for a while will feel like there is no fluid in it.

    Once releasing very slowly I did not reprime but bleed immediately from the MC. My levers are now rock solid.

    On hard application, ie forcing the ABS to kick in you can really hear the tires squirming and screeching so you know you are at max braking before lock-up. If you apply front and rear in a emergency type braking manoeuvre you get a very controlled endo!

    I think there is a technician\s at the honda factory who are not bleeding the lines correctly. Folks without issue probably had other technicians.! Also I think many dealers are not doing the full bleed correctly or putting enough fluid through. (My estimate is a minimum of 250ml is needed for one bleed of the front lines)
    Also an air purge (ie pressurising the system and taping the lines as we are doing here) is in the most part necessary after the actual bleed.

    As you know the ABS is very sensitive to air and if it reaches critical parts of the system left untreated can cause the system to malfunction and even parts to fail.

    Jon
     
  4. samd1985

    samd1985 Active Member

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    Nice work managing to get a controlled endo! I'm surprised the system let you do it.

    I'll be getting up a tad early to quickly bleed from the M/C before I ride to work :)

    I notice the back fishtails around on hard braking after performing a fluid change - it doesn't do this after a while as the ABS begins to feel more 'intrusive', hence my decision to re-bleed recently (having covered 4k miles since the previous bleed).

    Sam
     
  5. Slick

    Slick Senior Member

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    I use the word 'controlled' very loosely, controlled in a manner that I didn't go over the bars!:). I find myself occasionally testing the ABS when it is clear on slip road etc. Coming down hard from motorway speeds the rears will lift momentarily and sort of skip as the system scrubs off speed quick time

    Weird I cannot get the rears lifting with use of the front brake only, as I said you need to use both.
     
  6. samd1985

    samd1985 Active Member

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    I love the feeling of hard braking personally!

    The brakes feel sweet after strapping them up last night! I got a small bubble out of the M/C this morning and the lever feels rock solid with hardly any movement required to get a decent bite at the front :) I tried a few hard stops and the ABS feels really good; very unobtrusive and my face felt like it was being inverted by the G forces encountered!

    DIY servicing is so much more enjoyable than parting with hard earned cash at a dealership, especially as that level of detail is unlikely to be followed. I'll be doing that again soon!

    Sam
     
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  7. Slick

    Slick Senior Member

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    Got this on my dash camera the other day, 35-0 in no time with zero drama, how ABS should work.
    Stopped so fast that I loads of space upto the line.


    BTW I already checked my rear was clear:)
     
  8. amnesia

    amnesia New Member

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    Slick;

    I'm confused.

    Are you guys actually doing a complete bleed of the entire ABS system, or just bleeding the "normal" (conventional) brake system.

    By full bleed I mean taking off the radiator to bleed the front "power modulator" in front of the headers as well as bleeding the "valve unit". In order to start air bleeding the front brakes you need to complete a sequence of rear pedal pushes followed by front brake lever pull. If you are only bleeding the "normal" system you are missing many of the parts and lines which are involved in braking when the ABS system is active (which is anytime you are riding above 6 kph). As well, "pressurising" the system (by applying the lever overnight) would not have any effect on the "ABS circuit" (power modulator and stroke simulator) since this circuit is not even connected when the ignition is turned off (or the speed is below 6 kph)

    Bleeding the "normal system" seems to be a piece of cake compared to bleeding the ABS system (which is what you really need to do to clear the air from the tricky ABS parts). While all the steps are quite involved, It's the access that's the real problem.
     
  9. Slick

    Slick Senior Member

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    This is meant to be complementary to the full ABS bleed to ensure the last bubbles of air are removed.

    In my case I did this procedure prior to the full ABS bleed, once happy I completed the bleed with this procedure again. My theory is you need to ensure the conventional lines are air free before you even attempt the ABS bleed, the last thing you want to do is push air further in the ABS vitals where the presence of air is going to cause serious issue.

    I've done this twice so far and have a solid lever at all times.

    This 'mini' bleed is now part of my monthly maintenance. Being doing this for the last few months in quite hot (for the UK anyway! my engine is constantly above 104C), in heavy stop/start filtering type traffic and had zero issues, touch wood it stays that way!:)
     

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