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Junior Charter Member
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Discussion Starter · #1 ·
I have the whole brake system installed, but didn't bench bleed the MC. Can I do the whole system in the car or does the MC have to come out?

Thanks

Dennis
 

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FFCobra Craftsman
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1,273 Posts
Dennis, You will need to bench bleed the master cylinder. You can do it in the car but it makes a mess. Easier to take it off and put it in a vice.
 

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Junior Charter Member
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Discussion Starter · #3 ·
Thanks Dave.

How do you bench bleed the MC?
Never done that.

Thanks!

DEnnis
 

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Charter Member
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2,649 Posts
Dennis, I bled my MC installed. I made up two semi circular tubes with spare fittings to go into the outlet ports on the MC which then feed back into the MC cavity. I then filled the MC with fluid and made sure the ends of the tubes were below the fluid level so I knew when all the air was out of the power piston cavity. Then just pump the pedal slowly until no air comes out either of the tubes. Remove the tubes one bye one and reinstall your brake lines.
Bob MAc
FFR3981
 

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Moderator
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Ditto what Bob Mac said. In addition, take a small hammer or a drift and lightly tap the bottom of the MC . This helps to release trapped air and will give you a good firm bleed.
Frank
 

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I bled mine in the car. It took about 12 minutes to remove all the air. I used Russel DOT5 brake fluid.
 

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Premium Member
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The trick is to make slow and deliberate strokes in and out. Particularly on the release stroke you need to be slow so that the air will escape the pressure chamber in the MC through the reservoir...

Seems kinda wierd giving advice to someone that calls himself Mr. Goodwrench! :D

Maybe you should change your handle to Miter-Saw!
 

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Sr FFR builder
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I just posted a similar question this morning and I solved my problem. I used a vacuum bleeder to get the juices flowing and then bled the rest using the speed bleeders and pumping the brake pedal. The pedal is very firm now. I have NEVER bench bled a MC before and don't know why everyone says it needs to be done. :rolleyes:
 

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FFR Craftsman
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5,834 Posts
I get it now. This is akin to priming the engine. Just a safety issue. If you bench bleed, you're at least getting the bubbles out of the MC. This removes the compliance from that assembly. Once done, the rest should be gravy. Never really thought about this. I can see a situation where you bleed like hell and still get a spongy feel even though you see no bubbles from the bleeder screws. The bubbles in the MC never had a chance to escape. Am I thinking this out right?

Of course you may get lucky like Dan, which is perfectly fine too. That would be preferrable.
 

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Discussion Starter · #10 ·
BIGFOOT

Actually I was thinking more like "HACKSAW"...
I have hacked a few things up.
I knew someday I'd take some heat for that name.
And why exactly do they call you big foot?

And thanks to everyone on the bleeding lesson.
Gotta luv this forum!
Dennis :D :D
 

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Premium Member
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18,090 Posts
Originally posted by Mr Goodwrench:
BIGFOOT

Actually I was thinking more like "HACKSAW"...
I have hacked a few things up.
I knew someday I'd take some heat for that name.
And why exactly do they call you big foot?

And thanks to everyone on the bleeding lesson.
Gotta luv this forum!
Dennis :D :D
Long story but the Reader's Digest version is;

At 6'4" & 335# I was nicknamed Lurch at the company I worked for. When I left that company, I was sporting a scraggly beard and my new co-workers nicknamed me Sasquatch. That was too difficult to pronounce for my boss who had a speech impediment (later became a good friend) so he just changed it to Big-Foot.

Now a number of years have passed - I have lost a ton of weight (I am now 200# and 6'3") but the nickname is still there..
 

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3,487 Posts
Bleed my donor brakes this weekend and did the mc bleed first then the rear all was going fine using the mityvac. Then I went to the right front and nothing. I think the gutted brass distribution block was interfering with the miteyvac on the right front. So I went with the alternative, brake down open valve close value release technique front right front left then went around again with brake down open valve close value release technique.
Rob Baker
 

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554 Posts
jack up rear of car to make mc level. It helps in getting all the air out of the mc.
 

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Over Engineerer
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When you first install your brake system everything is full of air - MC, lines, prop valve, calipers and wheel cylinders (for drums). If the air gets pushed out of the MC in a bench vise, why won't it get pushed out & through the lines if it's in the car? Bench bleeding is essential when you're replacing an MC in an existing brake system, but I don't understand all the fuss about it on a new system.
 

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Junior Charter Member
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371 Posts
Discussion Starter · #15 ·
Since this is a totaly new system why couldn't I take a long piece of clear plastic tube and go from the right rear bleeder all the way back to the MC and just keep pumping. Fred S got me thinking.

Thanks
Dennis
 

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Premium Member
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18,090 Posts
Originally posted by Mike Holt:
you shrunk an inch?
Actually I shrunk a bunch of inches... :D

Yes - Gravity does weird things and my family has had that malady for many generations.

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Whetting the system (getting fluid in all the nooks and crannies) is not always easy. The recommended routing of the brake lines from FFR (regardless of it being "Cobra Correct") UP_down_UP the "X" causes even more trouble with air that gets trapped in the tops of the X on either side..

Like I said before - make sure you pump that master cylinder slowly and allow the air to escape from the master, back up through the port in the reservoir.
 
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