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Offline Sandman North

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Bleeding the front Brake system
« on: 28 April, 2020, 10:05:20 PM »
I was doing maintenance on my bike changing the brake fluid at it's a 2012 with ABS and combined breaking.
Drained & changed the clutch, easy!
Drained & changed the rear brake, easy again!

Drained & changed the front brake,  :430:
Cant get any pressure.  I bled the front left bleeder first, then the top right next, using a bleeder vacuum.

Did it the Old fashion way too. held in the lever & cracked the bleeder then tighten before releasing the lever.

where is the air lock? What else can I do?

Or what did I do wrong.

Thanks

Offline AndyM

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Re: Bleeding the front Brake system
« Reply #1 on: 29 April, 2020, 07:50:27 AM »
Hi
Check this thread out as there is a specific sequence for bleeding the brakes.

https://www.cbf1000.com/index.php/topic,6077.0

Not a job I’ve ever done though  :084:

Offline Art

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Re: Bleeding the front Brake system
« Reply #2 on: 29 April, 2020, 10:37:14 AM »
Its more in the method then the sequence.

Brake fluid replacement Honda CBF 1000 ABS & CBS

DO NOT DRAIN OUT THE OLD FLUID – FLUSH IT THROUGH

Use the fresh fluid to flush the old fluid out. When bleeding the rear brake I displace the reservoir and stand it on a wad of rag to give easier access for topping up, for the front I just wrap the reservoir in plenty of rag to catch any spillage. My bleeding kit comprises of a 500 ml glass jar with an 8 mm hole in the lid for the bleed tube and a 3 mm hole as an air vent, 750 mm length of 6 mm ID clear plastic tube. Tools required No1 Phillips or No1 JIS cross point screwdriver, 8 mm combination spanner, 8 mm socket on short extension, tee bar or ratchet and 1 litre of DOT4 brake fluid.

The detail – Remove the brake reservoir cap, plate and diaphragm, put aside and keep clean. Siphon the old fluid from the reservoir leaving enough fluid in the bottom of the reservoir to prevent any air entering the system and top up with fresh fluid. Attach one end of the bleed tube to the bleed nipple, pass the other end through the glass jar lid to the bottom of the jar. With the brake applied open the bleed nipple and steadily pump the brake with the bleed nipple remaining open. There is no need to worry about air siphoning back into the caliper as long as there is a good fit between the plastic tube and bleed nipple, and you keep steadily pumping the brake, and you keep the end of the bleed tube in the bottom of the jar submerged under brake fluid. Keep steadily pumping the brake until fresh fluid appears in the bleed tube then hold the brake on and close the bleed nipple. I find it takes between 100 to 200 ml of brake fluid to flush each caliper, topping up the reservoir after every 15 to 20 pumps on the brake. After bleeding each caliper empty the old fluid from the glass jar leaving just enough brake fluid in the bottom to submerge the bleed tube.

The sequence I bleed the nipples is

Front brake reservoir - front right upper, front left upper
Rear brake reservoir - front right centre, rear lower, rear upper

The same method can be used to flush and bleed the clutch fluid.

While we’re on the subject of brake fluid if you are doing your own maintenance at home when inspecting the brake fluid at the Honda recommended 4,000 mile (6,000 Km) service intervals bleed a little fluid off at each bleed nipple to inspect the condition of the fluid at the business end, the caliper, don’t forget to top it up too. It is also

Offline Sandman North

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Re: Bleeding the front Brake system
« Reply #3 on: 29 April, 2020, 11:54:30 AM »
Bit of a problem!
This method will not work now as I did drain the system and have an airlock someplace.
I wished I had done it your way.
When you don't get what you want you get experience, I have experience now! LOL

My task today is to do a reverse flush with a 60cc irrigation syringe apparently if you change a break hose this is the way to get the air out.

Thanks for the reply

Offline Art

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Re: Bleeding the front Brake system
« Reply #4 on: 29 April, 2020, 12:47:48 PM »
I'm not sure you'll get any joy using a syringe to bleed the brakes, the syringe idea is to prime new brake lines with fluid making the bleed process easier because there is less air in the system.

I'd try flushing as above, my idea here, and its only an idea because I've never been where you are, is that by constantly pumping the brake the pressure in the system is maintained and the fluid together with any trapped air keeps moving in one direction towards the caliper and bleed nipple. This is pretty much how a vacuum pump brake bleeder works except the vacuum pump is sucking and the flushing method I describe here is pushing.

Try flushing as above and if you get no joy from that get your hands on a cheap as chips (£13.00 incl postage) vacuum pump off ebay, clickity clink link here, and bleed the system the same way the Honda workshop does. I found a short and to the point YouTube video to give you an insight into bleeding the brakes using a vacuum pump, the demonstration is done on a car but the principles and method is the same on a motorcycle, well worth the 4 minutes run time, enjoy

« Last Edit: 29 April, 2020, 12:54:16 PM by Art »

Offline Sandman North

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Re: Bleeding the front Brake system
« Reply #5 on: 29 April, 2020, 07:05:10 PM »
 :001:OK I think we are good now.
I did a reverse flush using an irrigation syringe and pumped 50cc in the brake bleeder (each side) and back up to the master cylinder.

My wife did not see any air coming out of the port hole in the master cylinder reservoir, but we have good resistance on the handle now.
I will bleed them again later.

Thanks everyone

Cheers Sandman