Stuck on Rear ABS Bleed Procedure

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McRide

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Doing a Front and Rear Brake Bleed.... Done many times but, this time, I let the rear Reservoir go to zero and air got in. Maybe deep, and refilled. I have the rear speed bleeder cracked open and under about 25psi vacuum and I have the rear pedal tied down to full brake. Nothing is moving out. I did cycle the ABS and get the expected feedback on the Fronts but no feedback on the Rear, just ABS clicking. Anyone have a procedure to get Rear fluid moving again?
 
When the brake pedal (or lever) is in the "brakes on" position the master cylinder is sealed off from the portion of the system that should be under braking pressure. No brake fluid can flow from the master cylinder to the slave cylinders bleed screws while the brakes are "on" other than the small amount being pumped during the pedal stroke. To use a vacuum bleeder, the brake pedal should be in the "at rest" position.

If you are using speed bleeders you can leave the bleed screw cracked open, with a hose to a catch container, and pump the brake pedal to flush the system. But there is a lot of brake line from the master cylinder to the ABS pump and back to the wheel cylinders to pump any air out of the system.

Alternately, remove the speed bleeders and install the original bleeders. Then use a syringe or some other reverse bleeder to push brake fluid from the wheel cylinders back to the master cylinder.


dan

A man's got to know his limitations. -- Dirty Harry
 
Don't forget about the RH front linked circuit. If it were me, I'd start with a full rear reservoir and begin bleeding air from the front caliper. Once I had fluid there, I'd move to the rear and continue bleeding. With (potentially) empty lines, it will likely take a couple times going front to back to remove the air.

Good luck!

~G
 
Most helpful, thanks.... is the linked front-rear fed from the Handlebar Resvr or the Rear Resvr?
 
Most helpful, thanks.... is the linked front-rear fed from the Handlebar Resvr or the Rear Resvr?
Look up above the front fender from the bottom, tracing the brake hoses from the calipers back. You'll see two hoses that come together- that's the front brake lever actuated ones. The single hose is the rear brake pedal actuated one. Trace it back down to the caliper it connects to- that's the rear brake pedal one.
 
To clarify ...the lower of the two bleeder screws on the right caliper bled from the rear brake pedal and rear reservoir...
If this line isn't bled, you will never get pressure on the rear pedal.

Unlike many, I have never felt the need for either a vacuum bleed or Speed Bleeders on a motorcycle where I can easily access the bleeder screws and the brake pedal/lever - unlike with a car. Personally, I am a fan of the traditional bleeders with the "squeeze to pressurize-loosen bleeder-depress lever fully-tighten bleeder-release lever method". As Dan suggested, a reverse bleed should work if you can't get pressure any other way. Good luck - I'm sure you will be able to resolve it. Note: Using this method, do not do a quick squeeze or release or you will fountain brake fluid from the reservoir. Protect your paint with an abundance of rags - some people put a quarter in the reservoir to prevent fountaining...
 
To clarify ...the lower of the two bleeder screws on the right caliper bled from the rear brake pedal and rear reservoir...
If this line isn't bled, you will never get pressure on the rear pedal.

Unlike many, I have never felt the need for either a vacuum bleed or Speed Bleeders on a motorcycle where I can easily access the bleeder screws and the brake pedal/lever - unlike with a car. Personally, I am a fan of the traditional bleeders with the "squeeze to pressurize-loosen bleeder-depress lever fully-tighten bleeder-release lever method". As Dan suggested, a reverse bleed should work if you can't get pressure any other way. Good luck - I'm sure you will be able to resolve it. Note: Using this method, do not do a quick squeeze or release or you will fountain brake fluid from the reservoir. Protect your paint with an abundance of rags - some people put a quarter in the reservoir to prevent fountaining...
Thanks, yes, the SB are ...meh... They are new to me, seemed like a good shortcut but perhaps too finicky for me. I'll do the front link, then the rear and keep an eye on the REAR resvr. Duh.
 
So... I was going to change out the Speed Bleeders to factory, but no one has them. Sitting in Japan. I picked some generic 7mm/1.0 but have decided to stay with SB for now. Front wheel is done and I'm on the front right lower, linked to rear. It's cracked open 1/4 to 1/2 turn and on the MightyVac at 25psi. Question: Is this 'have patience' part? Under pressure for an hour and not showing any fluid. I've pumped the rear for quite a while to help it along, still nothing. Any ETA I should expect?
 
I'd revert to the old fashioned method for bleeding. For the stubborn RH front lower, try completely removing the speed bleeder and pump away on the rear lever. If you put a finger over the RH front hole do you feel any air and/or pressure?

~G
 
So... I was going to change out the Speed Bleeders to factory, but no one has them. Sitting in Japan. I picked some generic 7mm/1.0 but have decided to stay with SB for now. Front wheel is done and I'm on the front right lower, linked to rear. It's cracked open 1/4 to 1/2 turn and on the MightyVac at 25psi. Question: Is this 'have patience' part? Under pressure for an hour and not showing any fluid. I've pumped the rear for quite a while to help it along, still nothing. Any ETA I should expect?

If I recall correctly, the speed bleeders have a spring loaded reverse check valve ball in them. It's possible / probable that vacuum will not lift that check valve ball against the spring pressure to allow fluid flow. That same feature will also prevent reverse bleeding with a syringe or other reverse bleeder from the bottom up.

As mentioned previously, you will probably need to bleed the system the good old fashioned way by pumping the brake lever / pedal with a hose from the opened bleeder to a catch container. Watch out for brake fluid geysers from the master cylinder when first operating the lever / pedal.


dan

Things are never so bad they can’t be made worse. – Humphrey Bogart (as Charlie Allnut) from The African Queen.
 
Found OEM Bleeders on Partshark, here in a few days. Had the same thoughts on the SB Check Valve vs Vacuum Air Pressure, likely not going to move the ball bearing. I'll try again soon and post results, thanks every one, Cheers!
 
I've used SpeedBleeders and a Mighty-Vac on an AE model. I might suggest trying it again.

Make sure the brake is off (at-rest). Make sure the SpeedBleeder has been turned out between 1/2 and 1 turns (still needs to be loosened to operate and tightened to lock it). Make sure the cap is off and you have fresh fluid in the rear reservoir. Apply vacuum until you overcome the spring tension on the check ball inside the SpeedBleeder. Front right lower first, then rear.

Above, you said you have been at 25 psi, and mentioned pressure, I assume you meant vacuum and inches of Hg, which is what the Mighy-Vac uses on its gauge. Applying pressure will only lock the ball in the seat more tightly.

Don't be afraid to go over 25 in Hg of vacuum... I think I opened up the check-ball at 26 to 28 in Hg. You are correct in not having the patience to wait. If you haven't overcome the spring tension with vacuum it simply will not open. SpeedBleeders will not allow reverse-flow (pressure) bleeding.

If you hit 32 or 33 in Hg in vacuum and the SpeedBleeder hasn't opened, post back. It may be an issue with a bleeder valve, but I've never heard of one going bad.
 
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Found OEM Bleeders on Partshark, here in a few days. Had the same thoughts on the SB Check Valve vs Vacuum Air Pressure, likely not going to move the ball bearing. I'll try again soon and post results, thanks every one, Cheers!
I missed that you'd posted this. Great minds and all.
 
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