Pneumatic Brake Bleeder with Dual MC

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Ronald I. Maciejewski
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Pneumatic Brake Bleeder with Dual MC

#1 Post by Ronald I. Maciejewski » Tue Oct 12, 2021 3:25 pm

A smoking brake incident required a total rebuild of both fronts on my '58 A. Everything new except for turned in-spec drums and Zims dual MC. Now ready to bleed.

I was gifted, but never used, a HF pneumatic brake bleeder. Instructions are pretty straight forward.

Any reason not to use with dual MC?

Any concerns with 90 lbs compressor pressure?

Planned bleeding sequence; RR, LR, RF, LF. OK?

As always, any and all guidance is appreciated.

Thank you.
Ron

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Re: Pneumatic Brake Bleeder with Dual MC

#2 Post by Steve Douglas » Tue Oct 12, 2021 4:09 pm

I use one but only with 10psi, anything higher pressure makes the fluid shoot out of the bleeders in a spray. I have the manual pump up type, homemade but just like the Motive, make sure when done you suck a little bit of fluid out of the reservoir to leave an air space.

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Re: Pneumatic Brake Bleeder with Dual MC

#3 Post by Phil Planck » Tue Oct 12, 2021 4:11 pm

It helps to bench bleed the m/c before installing. If already It installed you can still bleed it in situ before starting with right rear.
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Re: Pneumatic Brake Bleeder with Dual MC

#4 Post by David Jones » Tue Oct 12, 2021 4:17 pm

One small correction here Phil. The right rear is not the furthest away from the MC if you are assuming that it is so. In a straight line it is but in reality the rear brake lane splits on the right side of the trans and then runs over to the left brake so that one is slightly longer than the route to the right side. I know I am nitpicking as it probably does not make one iota of difference in practical brake bleeding operation.
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Re: Pneumatic Brake Bleeder with Dual MC

#5 Post by Glen Getchell » Tue Oct 12, 2021 4:22 pm

You are going to be more specific as to what a HF brake bleeder is.

You have two types of pneumatic bleeders. The Pushers, and the suckers. I have both, and much prefer the pusher for a good bleed. The pushers attach to your reservoir and push fluid through. If you have a duel system with one reservoir, then you are good to go, but you should only used no more than 15lbs of pressure. If you have two reservoirs, then you will have to do the front and rear separately.

If you are using a sucker kind (I.E. vacuum) then you are still good to go with the duel system. But in my opinion 90lbs is insanely high. Maybe 40lbs or less. Personally I have not had very good luck with the vacuum style. Seems like you can pour gallons of fluid and always have bubbles. But they are good to get the system up and running so you can do an old fashion wife in the driver seat pumping bleed to finish the job off right. I can usually get a good bleed with the pusher.

Just remember to start at the wheel furthest from the MC and work towards it.

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Re: Pneumatic Brake Bleeder with Dual MC

#6 Post by Doug McDonnell » Tue Oct 12, 2021 4:42 pm

Like Steve I also use a pusher type and use 7-10 Lbs of pressure. It is important to remember that you are not trying to push fluid through. You are creating a pressure and want the air to come out. I think very minimal opening of the bleeder allows time for the air bubble to move and come out.
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Re: Pneumatic Brake Bleeder with Dual MC

#7 Post by gregg hake » Tue Oct 12, 2021 4:48 pm

I use the Motive Power Bleeder from Zims on my single circuit. It makes bleeding a JOY !!!

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Re: Pneumatic Brake Bleeder with Dual MC

#8 Post by David Jones » Tue Oct 12, 2021 5:01 pm

I'm cheap, I put a spare Schrader valve in a spare MC cap and pressurize it with my compressor set at 10 psig.
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Ronald I. Maciejewski
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Re: Pneumatic Brake Bleeder with Dual MC

#9 Post by Ronald I. Maciejewski » Tue Oct 12, 2021 6:05 pm

Hi,

Thanks to all.

To clear up a few things.

HF is Harbor Freight. The specific brand is Pittsburgh Central Pneumatic Brake Bleeder. It is the vacuum/suction style.

I'm assuming (hate that word) that the 90 psi at the compressor is somehow adjusted by the bleeder. Having said that I will start with a lower pressure of 40 lbs as recommended and work my way up if needed.

I have the dual system with one reservoir so I should be okay.

I've read David's comment before of RR vs LR being furthest from the MC and will modify my bleeding sequence accordingly; LR, RR, RF, LF.

Probably be a week or so before I get to it as my back is still recovering from multiple excursions under the car. Sorry now that I was talked out of a lift purchase a few years. back.

Thanks again to all.
Ron

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Re: Pneumatic Brake Bleeder with Dual MC

#10 Post by David Jones » Tue Oct 12, 2021 6:24 pm

Rin, the 90 psi of air at the compressor is required to be able to generate the vacumn suction needed by the eductor in the bleeder can. 40 psi will be unlikely to produce any useful suction.
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Ronald I. Maciejewski
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Re: Pneumatic Brake Bleeder with Dual MC

#11 Post by Ronald I. Maciejewski » Tue Oct 12, 2021 6:31 pm

David,

Thanks. That makes sense.

Ron
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Re: Pneumatic Brake Bleeder with Dual MC

#12 Post by Al Zim » Wed Oct 13, 2021 4:11 pm

I posted about brake bleeding using gravity rather than a pressure bleeder. With the dual master cylinder you must use a pressure bleeder. I apologize for being misleading.
Last edited by Al Zim on Fri Nov 19, 2021 2:39 pm, edited 1 time in total.
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Re: Pneumatic Brake Bleeder with Dual MC

#13 Post by Wes Bender » Wed Oct 13, 2021 5:58 pm

Ronald, that vacuum bleeder will be a bit harder to use because it will try to suck air in past the bleeder screw threads. It will work once you get the hang of it, but I found the pressure bleeder to be much better. In Al's method, they are using gravity as the sole force to bleed the brakes. That works too. I bleed mine once a year and keep removing fluid at each caliper until it comes out fresh. Check the reservoir and don't let it run out or you'll just be letting more air in.
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Ronald I. Maciejewski
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Re: Pneumatic Brake Bleeder with Dual MC

#14 Post by Ronald I. Maciejewski » Wed Oct 13, 2021 7:30 pm

Thanks AL and Wes. Like the Eveready Bunny the good advice just keeps on coming.

Thanks again. Love this Forum.

Ron
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Re: Pneumatic Brake Bleeder with Dual MC

#15 Post by DaveErickson » Wed Oct 13, 2021 8:18 pm

Another suggestion: get a piece of clear tubing that fits over the bleeder valve, so you can see the bubbles and avoid making a mess with the fluid coming out.

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