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Old 04-29-2013, 10:19 AM   #1
RobboJ OP
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twin ATE front brake bleed problem

Been trying to bleed my front brake but have very little feeling (if any) at the lever and brake not really working at all.

Twin ATE calipers with a splitter under the tank, handlebar m/c (not sure on diameter piston), brand new stainless hoses.

Have tried to bleed it through normally - open nipple, squeez lever, close nipple, release lever, repeat until no bubbles in the tube from the nipple - I usually go a bit longer just in case.

I've only been doing one calliper at a time, do I need to do both at once?

I left the lever pulled 1/2 way in and tied overnight to see if that helps, hopefully get round to checking it in the next few days.

Bike is finally booked in for MOT on Saturday so keen to fix it as soon as possible.
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Old 04-29-2013, 10:32 AM   #2
usgser
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Quote:
Originally Posted by RobboJ View Post
Been trying to bleed my front brake
Have tried to bleed it through normally - open nipple, squeez lever, close nipple, release lever, repeat until no bubbles in the tube from the nipple
Leave the nipple closed, pump up brake lever to pressure up the caliper, hold lever, then crack nipple open, close nipple, top off fluid, repeat
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Old 04-29-2013, 10:48 AM   #3
Stan_R80/7
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I found that gravity bleeding often works better than the pump-hold method. With gravity bleeding: a tube is run from the bleed nipple to a container to catch the fluid, the brake MC cover is loosened to allow air, and the brake fluid drips from the bleed nipple after opening - taking the air along and out of the brake system. Changing the position of the front wheel to move the air in the caliper helps. The technique is done for each caliper separately. The brake MC cannot be allowed to empty during the gravity bleed or air gets back into the system.

If the system is truly being stubborn, pressurizing the MC to ~ 10 psi will force brake fluid through the system - again taking the air along and out. The MC is pressurized using a plate clamped or screwed to the MC with an air pump (Schrader) valve. This second technique is especially useful for ABS systems.

Good luck!
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Old 04-29-2013, 03:50 PM   #4
chasbmw
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If you have just fitted new lines then bleeding can be a bit of a bear.

When you have most of the Air out, then tie the lever back and leave overnight, normally the brake gremlins come ou and finish the job for you.
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Old 04-29-2013, 08:05 PM   #5
Kai Ju
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Originally Posted by chasbmw View Post
If you have just fitted new lines then bleeding can be a bit of a bear.

When you have most of the Air out, then tie the lever back and leave overnight, normally the brake gremlins come ou and finish the job for you.
+1 on tying the lever to the bar.
One more trick though if you're still having problems.
Take the wheel off, remove the fixed pad and use a C-clamp to push the piston into the caliper. This will force everything that is in the caliper and the brake line into the master cylinder and it's reservoir, including trapped air.
The amount of fluid that's in the lines is far smaller than what's in the caliper so the air gets purged into the master cylinder reservoir.
Let the air bubbles rise to the top, reinstall the fixed pad and wheel and pump the brakes .
Should be good to go.
When I did my double disc conversion, using the stock single disc 14mm master cylinder, it took me a while to realize that I'll never get the rock hard feel that I'm used to on current brake components. Especially when you consider the cable actuation to the master cylinder. So I kept trying to bleed air out that wasn't there...
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Old 04-30-2013, 07:08 PM   #6
craydds
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bench bleed

+ 1 on all the suggestions above. Here is one more and it works; it's called bench bleeding, and yes, it is a bit of a chore:
1. Remove both calipers from the fork sliders, hoses attached, brake pads in place. Place a wedge/spacer between the pads at each caliper to prevent the piston from extruding.
2. Elevate the calipers above the MC (if possible, you have a handlebar MC, right?). At best, elevate them above the under-tank splitter.
3. Now proceed to bleed in all possible methods (I know all the tricks) and yes, it still takes time, effort, and a lot of wasted brake fluid (it's cheap).
4. You should end up with a firm brake lever (wedge between pads).
5. Install calipers to fork sliders. Now, you have to re-align the calipers (inner brake pad) to the discs, a minor chore, and several of the inmates above, including myself, can help you make this quick and easy.
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Old 04-30-2013, 07:12 PM   #7
craydds
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bench bleed p.s.

I have a crazy homemade brake hose set-up that can ONLY be bled by BENCH BLEEDING. Do a search for my pics and weep with me.
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Old 04-30-2013, 07:37 PM   #8
DaveBall
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OK, Brake Bleeding 101

I have posted this before, more relating to rear disk brakes, but it works the exact same on front brakes.

I see that everyone wants to bleed the brakes using the most time consuming and difficult methods.

1. Leave everything mounted as it should be.
2. Go to local pharmacy / drug store and purchase 2 large syringes that hold at least 30cc of fluid. and purchase some clear surgical tubing from them as well, about 2 feet is more than enough.
3. Use 1 syringe to suck all the fluid out of the master cylinder and dispose of it in a disposable container.
4. Using the 2nd syringe attach about 12 inches of tubing and suck up some new brake fluid.
5. Attach the tubing and the 2nd syringe to the bleeder on the caliper, and crack the bleeder.
6. Slowly inject the fluid in thru the bleeder while having someone hold the brake pedal slightly depressed, or hold the brake handle part way in. I just put a 1 quart paint can on a brake pedal or use a zip tie on the handlebar.
7. Close the bleeder and refill the syringe.
8. Repeat steps 5 and 6, watching the master cylinder for bubbles and remove excess fluid as required.

I have done the above procedure on a lot of friends bikes with "useless non working rear disk brakes" and every one of them has ended up with an excellent rear brake. This procedure is simple and once you do it, you will be very surprised how easy it is to get a good solid pedal, and a brake that will actually stop the bike.

I also use this same procedure on front brakes if I have had to remove any lines, or I just can't get the spongy feeling out of them using the normal methods. This is especially useful when you have replaced any lines.

Now class, please take notes on the above as it will be on the test.
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Old 05-01-2013, 05:42 AM   #9
craydds
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Originally Posted by DaveBall View Post
Now class, please take notes on the above as it will be on the test.
Notes taken. I will give this method a try on my brakes next time.
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Old 05-01-2013, 07:47 AM   #10
RobboJ OP
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Thanks, will try this week
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Old 05-01-2013, 07:53 AM   #11
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When getting air out I bleed from the bottom up like Dave does... except I tend to do it with a much smaller syringe and a much much slower and much more painful method... the basic premise is the same though and it works well.
I'm going to bust out the big syringe next time.
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Old 05-01-2013, 08:47 AM   #12
DaveBall
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Once you have done the bottom up bleed a few times, you will be surprised how easy and quick it is. I totally change my brake fluids this way every winter, as part of my regular maintenance schedule.

The pump, pump, bleed, repeat process is way to time consuming and never seems to get all the air out. Air naturally wants to rise, so why not force it up thru the system and out thru the master cylinder.


The test will be in a few weeks, right when that idiot that we all know is out to get us, makes that left turn in front of you. Keep your eyes wide open and constantly scanning and with your newly setup brakes, you will be able to stop in time. I fully expect every one of you to survive this riding season.
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Old 05-01-2013, 05:39 PM   #13
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Originally Posted by DaveBall View Post
Air naturally wants to rise, so why not force it up thru the system and out thru the master cylinder.
DaveBall, I have a MightyVac, with which one is supposed to be able to fill the container with brake fluid and pump it into the brake lines (or suck fluid out of the lines which fills the container) - either way it is supposed to be a bleeding device. Sounds like it might work like your now famous DaveBall Super Bleeding Method. Any experience with the MightVac?
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Old 05-01-2013, 05:58 PM   #14
damurph
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I also use the syringe method from the bottom. However the last time I did this was on my R65 with single ATE caliper. I had to replace the pressure activated brake light switch and I had to tip the bike onto the throttle side to get the last bit of air out of it. I never had to deal with it on any other machine because the rest were lever activated electrical limit switches.
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Old 05-01-2013, 06:39 PM   #15
DaveBall
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craydds,
I have used a MightyVac a number of years ago on cars. This was back when cars tended to have pretty standard Master Cylinders, so, ok, many years ago. They were very common back then. Nowadays, every car seems to have a different design to the master cylinder, and on some, you can't even find the damn thing. With all the crap they put under the hood these days.

Never used a MightyVac on a bike. I have used the reverse bleeding on bikes since I first learned about it back around 1971. I was having one hell of a time trying to get the air out of a disc brake setup I had grafted onto a Yamaha R5B 350cc 2 stroker. Little rocket in it's day with real crappy brakes. A friends father came over and suggested the reverse bleeding process. Had great brakes in less than 15 minutes. Have used the same process ever since. Even used it on a few cars that I had to work on.

damurph,
I have the exact same setup as your R65 on my wife's R45. I used the reverse bleed on it when I replaced the brake lines a few years ago. Not one single problem. But, the bike had been sitting for a long time and I was replacing almost the whole brake system. Was able to rebuild the ATE caliper, but had to replace everything else. Now has a newer R65 master cylinder and all new braided lines and a new distribution block with a new pressure activated switch. It was all in really bad shape. Works better than new now.
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