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Post by Kiwiscoot on Jul 27, 2009 5:43:12 GMT -5
Well I've read thru all the stuff in the Dawg pound on bleeding brakes and still no luck. First some history: I replaced the disk pads on both the front and the back. Well as it was I did the front brakes first and did I learn a lesson not to let things happen when I do the back break.  When I took the front brake caliper off the wheel, I removed the pads. Well....while I was taking the new pads out of the packaging, the caliper pistons/pots released and moved out all the way. This caused the master cylinder reservoir to be sucked dry (you right, that sucks  ) and air to enter the front brake master cylinder. Now I've pumped like a mad man on a sinking ship bilge pump, probably 500ml of new fluid. Front brake still as spongy as a trampoline. What does this all lead too.... Big question  has anybody had experience with pumping the brakes from the bottom with a pumping oil can?? Any "do and don't" -s?? I know about bleeding at the cylinder side where the hose exits the master cylinder, but that means taking off a ton of panels and I'm lazy!!  |
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Post by allworld on Jul 27, 2009 6:29:11 GMT -5
Hello Kiwiscoot:
There should be a little nipple on the caliper of the brakes, put a rubber tube/hose on it, use a wrench to open it slightly and put the the end of the hose in a bottle, so nothing leaks all over the place. Open up the plate to the brake reservoir and, remove the rubber membrane, get ready with the brake fluid, squeeze the brake ( slightly) and fill the reservoir, and keep doing this till all the air is out. ( that may take a while )
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Post by glassvial on Jul 27, 2009 8:48:24 GMT -5
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Post by unaggie on Jul 27, 2009 10:05:36 GMT -5
I used the reverse bleeding approach on a boat trailer that has a surge brake. Those use a sliding part of the trailer tongue to compress a dinky little piston each time you stop. Trouble is, there's 28 feet of brake line to replace fluid in and that piston moves a couple of mils with each pump. I'd still be pumping. The reverse thing worked great.
Now, back to your scoot. You're only dealing with a couple feet of brake hose and a few ounces of fluid. Get a clear piece of aquarium hose and a small clean container. The rhythm goes: turn the little bleeder valve enough to relieve line pressure and then squeeze the brake lever all the way down...and hold it down while you (or a helper) tightens the bleeder valve closed. Then release the brake lever. If the bleeder valve is still open when the brake handle is released, it will suck air into the brake line. Air compresses and that makes for a squishy brake. Repeat the bleeding rhythm again and again until you have replaced the fluid and no longer see air bubbles in the fluid when the brake lever is squeezed. If your catch container is really clean then you can recycle the fluid.
Now, someone said there is a type of scooter out there that has the bleeder valves below part of the brake caliper. This makes it impossible to get all the air out of it by just bleeding without removing the caliper. So long as the bleeder valve is at the top, bleeding will work.
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Post by boogernose on Jul 27, 2009 12:02:35 GMT -5
ok the best luck i had with motorcycle brakes is clean clear line stick it on the bleeder screw put the line into a jar with brake fluid in it open the bleeder screw,open the reservoir top off with brake fluid go in grab a cool drink and a snack let gravity do its thing. once the line that is in the jar is filled with brake fluid you can proceed to bleed the brakes. squeeze and release squeeze and release fill up reservoir and keep doing that till no more bubbles, the clear tube in the jar of brake fluid acts as an air lock while submerged so you will only suck in brake fluid not air dont the the reservoir get to low on fluid or you have to start over ,when no more bubbles come out tighten down the bleeder screw top off reservoir,put cover back on top and remove the clear tube from the bleeder screw at that point you should be golden
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Post by Kiwiscoot on Jul 27, 2009 16:47:05 GMT -5
Thanks dawgs, that is what I did when I mentioned pumping about 500ml of fluid thru.
My caliper has the bleed valve at the bottom. Not much air came out. Air must be trapped in the master cylinder. How to get that out?
I read that one can use a pump can to pump fluid up to the master cylinder, which expels the air at the top. Any experience with that?
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Post by Gary on Jul 27, 2009 17:58:58 GMT -5
Since you are down under, shouldn't the air go out the bottom?? Oh wait, no, I guess it doesn't work that way....
(sorry, somebody had to say it.)
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Post by Kiwiscoot on Jul 28, 2009 0:03:03 GMT -5
Gary - It's because you guys are under that it works for you. Air goes the the bottom of your scoot out the bleed nipple. Air always goes up in fluid, so there is a scientific proof that you live "down under". Even proven on a scoot, so there you go. Here in NZ the air goes up to the master cylinder. So no-one can argue that one.  LOL I think that is neat, at least that settles that in my mind. Oh but what about the 1000 other things that need to be settled in my mind!! |
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Post by mafunsalow on Jul 28, 2009 8:10:00 GMT -5
Next to the microwave oven speed bleeders have got to be the greatest invention in the world. Bleeder nipple with a check valve so you don't have to keep opening and closing. www.racerpartswholesale.com/category/Speed_BleedersAlso as you stated air always goes up in fluid, one of the least thought of things when bleeding is that air can get trapped at the highest point in the caliper too. Use a rubber mallet giving it slight taps |
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Post by Gary on Jul 28, 2009 8:36:47 GMT -5
Kiwi -
I stand corrected ....
Gary
PS: I would think you could bleed the line with the caliper off the bike (and the bleed screw pointed up). I'd put a piece of wood between the shoes so the pistons stay in.
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Post by Bought a Morph on Jul 28, 2009 12:37:32 GMT -5
Kiwi,
I just went through this with my helix. "open the bleeder, apply the brake, close the bleeder, release the brake," I must have done this for what felt like 1000 times, I finally gave up and called a motorcycle friend who works on bikes, he told me it could take hours to get the air out of the line and caliper and not to give up, just keep doing what I'm doing. So I continued for another half hour, always topping off the brake fluid, finally I felt the pressure build up and knew I was almost there.
If the fluid is emptying from the master cylinder as you indicated then your MC and line are working properly so all that's left to do is to continue with the process, you will eventually get all the air out.
BTW, I purchased that pump from harbor freight, it is JUNK!! SKIP IT. It worked the first few times a used and broke within a week.
I also just bought a buffer from harbor freight, it is also complete junk.
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Post by unaggie on Jul 28, 2009 16:34:21 GMT -5
If your bleeder valve is on the bottom of the caliper, you're either turning your scoot upside-down or removing that caliper to get the air out. Never tried the upside-down thing so I'd suggest caliper removal instead.
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Post by Kiwiscoot on Jul 28, 2009 17:41:07 GMT -5
Well I'll have to follow all your good guys advice. Seems like it is "back to the bilge pump sailor" and pump that brake. I think I am going to take the caliper off, wedge a piece of wood between pad and pump. Have to do something as I had almost no front brake this morning - not good!  Amazed at how much stopping comes from the front brake. |
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Post by Kiwiscoot on Jul 28, 2009 17:41:27 GMT -5
Well I'll have to follow all your good guys advice. Seems like it is "back to the bilge pump sailor" and pump that brake. I think I am going to take the caliper off, wedge a piece of wood between pad and pump. Have to do something as I had almost no front brake this morning - not good! Amazed at how much stopping comes from the front brake. |
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Post by Gary on Jul 28, 2009 18:33:35 GMT -5
Kiwi -
Is this on the SYM? I had something strange happen on my SYM Monday morning, after the scoot had sat over the weekend. I backed the scoot out of the garage and down the driveway (which has a slight slope to it) to turn around. The scoot began to build up a bit too much speed so I squeezed the brake handle to slow it down. Low and behold the brake handle went all the way to the bottom of its travel with no resistance (and no brakes)! Fortunately another quick squeeze on the handle and the brake caught. Otherwise I might have dropped the bike right there and then. It was a scary split second.
The brake has been fine since. it just seemed really strange that the brake would not work like that after a short period of non-use.
Gary
Gary
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Post by Kiwiscoot on Jul 29, 2009 6:15:03 GMT -5
Thanks, I somehow missed your post on using the syringe. I did look at a big syringe with the thought of connecting it to the bleed nipple and push fluid the other way to force the air out. Annoying.
Made a few hours job of a 5 minute disk pad exchange. That's what you call "live and learn".
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Post by Kiwiscoot on Jul 31, 2009 3:32:21 GMT -5
Kiwi - Is this on the SYM? I had something strange happen on my SYM Monday morning, after the scoot had sat over the weekend. I backed the scoot out of the garage and down the driveway (which has a slight slope to it) to turn around. The scoot began to build up a bit too much speed so I squeezed the brake handle to slow it down. Low and behold the brake handle went all the way to the bottom of its travel with no resistance (and no brakes)! Fortunately another quick squeeze on the handle and the brake caught. Otherwise I might have dropped the bike right there and then. It was a scary split second. The brake has been fine since. it just seemed really strange that the brake would not work like that after a short period of non-use. Gary Gary Yes it is on the SYM. Today I pumped the front brake for 3 hours and still no go! air came out, but it is still as bad as ever. I even took a big syringe and pushed fluid up into the master cylinder and a bubble did come out, but still no go. I must have pumped about 500ml to 750ml of fluid thro. I don;t understand! I think I'll give up and take to the shop.  It bugs me as it should just be so simple - how complicated can a brake be. I may have a go tomorrow at loosening the brake line at the bottom of the mater cylinder, but that sounds like a messy option. I'll keep the bucket with soapy water ready to wash any brake-fluid off immediately. Man talk of frustrating!! Your brake sound like it has air in as well. I would bleed them too. Scary if that were to happen in traffic. |
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Post by Kiwiscoot on Aug 1, 2009 5:43:02 GMT -5
Well today I pumped another 500ml thro! Still no go. Talk of frustrating! I have to give up |
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Post by stradarx150te on Aug 1, 2009 8:22:22 GMT -5
Hey i was doing the same thing yesterday. I went out bought a pump that broke. I think i pumped 64oz threw the lines. worked on it all day. Finally i took the calliper off and held it up and with the bleeder closed i just pumped the brakes untill the pistons were open all the way, then i opened the bleeder and got all the air out. Then i closed the bleeder and pushed the brake pads back it worked for me.
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Post by Gary on Aug 1, 2009 8:26:45 GMT -5
That is wierd Kiwi. Stradas method sounds like a good one.
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Post by Bought a Morph on Aug 1, 2009 10:10:29 GMT -5
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Post by Kiwiscoot on Aug 5, 2009 6:42:08 GMT -5
Thanks guys for all your help, advice and encouragement. I can state that as of tonight the "Black Bullet" has great brakes again. ;D ;D Turned out there was no air in the system, I did bleed everything out. The front brake has an "anti-chatter" plate in it and this caused the problem. The plate is of spring material and got dislodged in changing the disk pads. The pads have like "rabbit ears" on them where the holding pins go thro. Well one of these ears was caught between the housing and the anti-chatter plate, distorting the plate and causing the pad to skew out of alignment. That caused the spongy feeling. All good now. Decided tonight is the night to sort this problem. Went and got brake fluid at the 24hour petrol station. Got home and saw that it is DOT4 Synthetic Shell brake fluid. I know about synthetic oil, but synthetic brake fluid is something new for me. Well both brakes are now bled with beautiful blue synthetic brake fluid. ;D ;D Even the back brake feels better now.......phsycological I know, but it still feel good! ;D ;D Now ---Go Black Bullet Go!!  |
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Post by hualalai on Feb 10, 2010 1:11:45 GMT -5
MityVac is THE tool for bleeding hydraulic lines on scoots and motos. www.mityvac.com/ |
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Post by Kiwiscoot on Feb 11, 2010 3:13:34 GMT -5
Turned out to be an assembly problem on my part. Bleeding the brakes is really not such a big job on scoots. IMHO one don't need the MityVac, except if you do it for a living.
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Post by hualalai on Feb 12, 2010 21:21:33 GMT -5
If you have enough motos and scoots in the garage, a MityVac is mighty good.
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When I took the front brake caliper off the wheel, I removed the pads. Well....while I was taking the new pads out of the packaging, the caliper pistons/pots released and moved out all the way. This caused the master cylinder reservoir to be sucked dry (you right, that sucks 
) and air to enter the front brake master cylinder. Now I've pumped like a mad man on a sinking ship bilge pump, probably 500ml of new fluid. Front brake still as spongy as a trampoline. What does this all lead too....
LOL
Amazed at how much stopping comes from the front brake.
It bugs me as it should just be so simple - how complicated can a brake be. I may have a go tomorrow at loosening the brake line at the bottom of the mater cylinder, but that sounds like a messy option. I'll keep the bucket with soapy water ready to wash any brake-fluid off immediately. Man talk of frustrating!! 
