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Bench bleeding
Posted by: Nelson ()
Date: February 02, 2018 09:08AM

Today I received my M/C conversion kit for my 63 monza convertible from clarks, on there instructions it states “DONT BENCH BLEED” From the posts I’ve been reading it says to always bench bleed. Your thoughts please
Thanks in Advance

Nelson Santos
Toronto Ontario Canada 🇨🇦

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Re: Bench bleeding
Posted by: rowin4 ()
Date: February 02, 2018 09:27AM

Thats a first. they must have stock in the brake fluid company. Bench bleeding always saved a lot of time pumping the pedal to get the air out of the lines. Wonder what the reason is for that statement?

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Re: Bench bleeding
Posted by: Nelson ()
Date: February 02, 2018 09:31AM

Lol. Ok Rowin. I’ll bench bleed
Thanks

Nelson Santos
Toronto Ontario Canada 🇨🇦

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Re: Bench bleeding
Posted by: Kyle_in_Mich ()
Date: February 02, 2018 09:32AM

I am under the assumption that they do not want persons to bench bleed because there is a great number who push the piston too far in and therefore cause damage to the master cylinder. Those same persons then blame the master cylinder for not working properly.

Rather than deal with those people, they just say don't bench bleed. Again, this is purely my assumption.

CORSA Member
Traverse City,MI
Daily driver- Bicycle
Fun driver/project- 65 Corsa 140/4 speed

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Re: Bench bleeding
Posted by: jjohnsonjo ()
Date: February 02, 2018 10:28AM

""I am under the assumption that they do not want persons to bench bleed because there is a great number who push the piston too far in and therefore cause damage to the master cylinder. Those same persons then blame the master cylinder for not working properly.

Rather than deal with those people, they just say don't bench bleed. Again, this is purely my assumption.""


X2 just take short strokes.

J.O.

65 Corsa Turbo Vert
79 Honda XL 500S
69 Honda CL 160 D
2010 BMW F 650 GS
2003 Bounder 36D
2013 KIA Optima SX turbo-AKA ZIPPY (wife,s car)
69 Newport Holiday Sailboat
Baja 150 dune buggy cart
Coleman HS 500 UTV
2016 KIA Sorento SXL Turbo

Bethlehem,Pa

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Re: Bench bleeding
Posted by: 66vairman ()
Date: February 02, 2018 10:33AM

The last MC I got had instructions warning against bottoming out the plunger while bleeding the MC.

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Re: Bench bleeding
Posted by: 63Darrin ()
Date: February 02, 2018 04:02PM

DO NOT BENCH BLEED!!!

You apply too much pressure and can blow the seal inside of the MC. I learned the hard way. My friend installed a MC on his 1960 after he bench bled the mc. We could never get the brakes to work correctly. He bought another mc thinking that one was defective. Bench bled again; no luck. He ordered one from Clarks and saw the same sticker on the box. We installed the mc then bleed the brakes, everything worked perfectly after that. Everyone always says they buy from Clarks because they know the part will fit correctly, so why question the sticker? It's there for a reason!

Hope this helps,

Darrin

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Re: Bench bleeding
Posted by: vairmech ()
Date: February 02, 2018 05:42PM

I have bench bled every master cyl. I have ever installed. You only need to push in 1/4-1/2". Just enough to make air bubbles come out of the weep hole inside.

As an FYI, in Kalamazoo, MI I did a tech session installing a dual master kit. I told everyone at the beginning that I was not going to crack a wheel cyl bleeder to bleed the brakes, needless to say I saw a few raised eyebrows! I test fitted lines, drilled the hole through the firewall, installed the coupler and plug then proceeded to bleed the lines at the fittings.

Without ever cracking a wheel cyl bleeder the master and lines were bled and all done in about 2 hrs. BTW, I had NEVER installed a Clark's kit before that!

Ken Hand
Handy Car Care
248 613 8586

Vairmech@aol.com

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Re: Bench bleeding
Posted by: jjohnsonjo ()
Date: February 02, 2018 05:48PM

I have been bench bleeding for more than 50 years, is the Chinese rubber so bad you can't bench bleed anymore.

J.O.

65 Corsa Turbo Vert
79 Honda XL 500S
69 Honda CL 160 D
2010 BMW F 650 GS
2003 Bounder 36D
2013 KIA Optima SX turbo-AKA ZIPPY (wife,s car)
69 Newport Holiday Sailboat
Baja 150 dune buggy cart
Coleman HS 500 UTV
2016 KIA Sorento SXL Turbo

Bethlehem,Pa

Image and video hosting by TinyPic

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Re: Bench bleeding
Posted by: Frank DuVal ()
Date: February 02, 2018 06:26PM

Same here. Bench bleed every master cylinder I install. Not only Corvairs, any vehicle.

There are two methods, the blow through and the plugs. Both work. Both just require easy pushing, no need to stroke to bottom.

Why suddenly we are having issues with this?confused smiley

Frank DuVal

Fredericksburg, VA

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Re: Bench bleeding
Posted by: rowin4 ()
Date: February 02, 2018 06:39PM

vairmech Wrote:
-------------------------------------------------------
> I have bench bled every master cyl. I have ever
> installed. You only need to push in 1/4-1/2". Just
> enough to make air bubbles come out of the weep
> hole inside.
>
> As an FYI, in Kalamazoo, MI I did a tech session
> installing a dual master kit. I told everyone at
> the beginning that I was not going to crack a
> wheel cyl bleeder to bleed the brakes, needless to
> say I saw a few raised eyebrows! I test fitted
> lines, drilled the hole through the firewall,
> installed the coupler and plug then proceeded to
> bleed the lines at the fittings.
>
> Without ever cracking a wheel cyl bleeder the
> master and lines were bled and all done in about 2
> hrs. BTW, I had NEVER installed a Clark's kit
> before that!






Opening the fittings will work if the wheel cylinders are full of fluid. if the wheel cylinder was replaced it would need to be bleed at the bleeder to remove the air. On older vehicles opening the bleeder will flush out the wheel cylinder.

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Re: Bench bleeding
Posted by: JimBrandberg ()
Date: February 03, 2018 04:26AM

I always bleed a lot of brake fluid out the wheel cylinders in order to change the fluid. I usually go around twice and use most of a quart bottle. Since I'm a DOT-3 guy it's cheap. Since the kids are gone I use a wood 2 x 2 between the steering wheel and pedal to hold it down while I close the bleeder.
I always bench bleed a new master cylinder these days, when I didn't do it previously I had too many times where it just won't get going for some reason which is frustrating.
I certainly can't dispute someone else's procedure if it works for them.
Jim Brandberg
Isanti, MN
CorvairRepair.com

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Re: Bench bleeding
Posted by: RKF ()
Date: February 03, 2018 04:45AM

vairmech Wrote:
-------------------------------------------------------
I did a tech session
> installing a dual master kit. I told everyone at
> the beginning that I was not going to crack a
> wheel cyl bleeder to bleed the brakes, needless to
> say I saw a few raised eyebrows! I test fitted
> lines, drilled the hole through the firewall,
> installed the coupler and plug then proceeded to
> bleed the lines at the fittings.
>

I must be missing something. What is the advantage of bleeding the lines through the fittings, rather than through the bleeder valves?

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Re: Bench bleeding
Posted by: vairmech ()
Date: February 03, 2018 05:33AM

RKF Wrote:
-------------------------------------------------------
> vairmech Wrote:
> --------------------------------------------------
> -----
> I did a tech session
> > installing a dual master kit. I told everyone
> at
> > the beginning that I was not going to crack a
> > wheel cyl bleeder to bleed the brakes, needless
> to
> > say I saw a few raised eyebrows! I test fitted
> > lines, drilled the hole through the firewall,
> > installed the coupler and plug then proceeded
> to
> > bleed the lines at the fittings.
> >
>
> I must be missing something. What is the
> advantage of bleeding the lines through the
> fittings, rather than through the bleeder valves?
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

When you have a working brake system and you break into it you only need to bleed as far as the fitting that you removed.

This is especially true when replacing the master cylinder or putting in a dual system.

It works really well when the brake line ends stay vertical, if the line is horizontal you probably will lose to much fluid to just bleed at the fitting. That being said I have replaced a rear steel line and just bled at the fitting.

When you have rusty wheel cylinders and the bleeders break what do you do? If you are short on cash or time, bleed at the fitting.

It works.

BTW, I do use the cylinder bleeders when needed, just not EVERY time.

Ken Hand
Handy Car Care
248 613 8586

Vairmech@aol.com

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Re: Bench bleeding
Posted by: dragvairclark ()
Date: February 03, 2018 06:27AM

What is the difference between moving the piston on the bench or moving it in the car? Besides, bleeding brakes gives your wife something to do while you get dirty.

Clark Hartzel, Fraser, MI
1965 Monza coupe

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Re: Bench bleeding
Posted by: irfgt ()
Date: February 03, 2018 07:04AM

I have been an ASE Master Technician since 1974 and never bench bleed a master cylinder and I have replaced hundreds of them.

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Re: Bench bleeding
Posted by: Frank DuVal ()
Date: February 03, 2018 09:21AM

I too have bench bled master cylinders, installed them on the car just bleeding at the master cylinder fittings and it works fine. No need to open any wheel cylinder/caliper bleeders.

Of course, this means the system does not get flushed, which we all know now is important. So I do not do it on systems with old fluid.

The real trick is to bleed at the MC fittings when working by yourself!grinning smiley

I used a hood prop tool to hold the pedal down, like a Lisle 45900.

So, Ifrgt, you never tried it? You work in the west where bleeder screws always come out?

Frank DuVal

Fredericksburg, VA

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Re: Bench bleeding
Posted by: irfgt ()
Date: February 03, 2018 12:55PM

Frank DuVal Wrote:
-------------------------------------------------------
> I too have bench bled master cylinders, installed
> them on the car just bleeding at the master
> cylinder fittings and it works fine. No need to
> open any wheel cylinder/caliper bleeders.
>
> Of course, this means the system does not get
> flushed, which we all know now is important. So I
> do not do it on systems with old fluid.
>
> The real trick is to bleed at the MC fittings when
> working by yourself!grinning smiley
>
> I used a hood prop tool to hold the pedal down,
> like a Lisle 45900.
>
> So, Ifrgt, you never tried it? You work in the
> west where bleeder screws always come out?

I can bleed the Master cylinder by myself by slightly loosening the fittings at the master cylinder and pumping the brakes until resistance is felt then tighten the fittings. I rarely ever flush brake systems since the bleeder is at the top of every component and it is almost impossible to exchange all the fluid.You could buy all new components as cheap as replacing the fluid. I work in S.C. and moisture in brake fluid is not a problem.

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Re: Bench bleeding
Posted by: Timothy Shortle ()
Date: February 03, 2018 05:46PM

I have been an ASE Master Automobile Technician since the early 80s (it used to be NIASE) and also have replaced many MCs. I have always bench bled before installing. My preferred method is to run "dummy" lines back into the reservoir and gently push the piston. Also I have learned to be patient and do this technique over and over again. I agree with Jim, fluid is cheap and should be periodically replaced. I use the fluid suggested for that particular car I am working on.

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Re: Bench bleeding
Posted by: Frank DuVal ()
Date: February 03, 2018 07:54PM

Quote
irfgt
I work in S.C. and moisture in brake fluid is not a problem

You have never seen white corrosion in a wheel cylinder? You have never had a stuck piston in a wheel cylinder?

I'm not trying to pick on you, I just can not say the same statement. I run into moisture problems with DOT 3 all the time. Hence why I switched to DOT 5 in non-ABS cars.

By bench bleeding, it is loosen fittings on new master cylinder slightly after installing it, press brake pedal once, set hood prop (explained above) tighten fittings, test for pressure holding, drive car.

Frank DuVal

Fredericksburg, VA

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