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Topic: Master Cylinder

in Forum: C3 Engines, Driveline and Handling


Master Cylinder

Posted: 7/17/05 6:37am Message 1 of 9
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Grandville, MI - USA
Joined: 5/8/2004
Posts: 140
Vette(s): 1968 427/390 Coupe

I purchased a new master cylinder and installed it but I cannot get the brake fluid to pump out the side ports, what did I miss?

Any help would be greatly appreciated 




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Master Cylinder

Posted: 7/17/05 6:42am Message 2 of 9
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BINGHAMTON, NY - USA
Joined: 7/19/2003
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Did you bench bleed it ,B4 you installed it ?


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Master Cylinder

Posted: 7/17/05 6:51am Message 3 of 9
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Grandville, MI - USA
Joined: 5/8/2004
Posts: 140
Vette(s): 1968 427/390 Coupe
No, how do you bench bleed?


Master Cylinder

Posted: 7/17/05 7:32am Message 4 of 9
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You mount the master cylinder in a vise,fill it up with brake fluid,let it sit for a couple of minutes,put a small screw driver or rod whatever is the same size as the hole is ,in the back end of the M.C.where the push rod goes when it is mounted on the car.take out the plugs if there are any,for the brake lines.place a pan or a bunch of rags next to the holes to catch the brake fluid,and slowly pump the M.C. with the screw driver until it flows steady with no air and keep the M.C. full of fluid.Cap off the brake line holes,so the fluid doesn't leak out,and you are ready to install it in the car.you can try to do it with it installed in the car,but its a P.I.T.A.,unless you have a buddy to help you 


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Master Cylinder

Posted: 7/17/05 11:03am Message 5 of 9
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Grandville, MI - USA
Joined: 5/8/2004
Posts: 140
Vette(s): 1968 427/390 Coupe
I have done this in the car but nothing is coming out.


Master Cylinder

Posted: 7/17/05 5:19pm Message 6 of 9
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Duncanville, TX - USA
Joined: 11/8/2003
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Vette(s): #1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas
I ran across a similar problem a few years back, but in reverse. Here's what I mean.
I rebuilt a mast. cyl. from an '81, as an "emergency" spare for my '74. One day, I needed it, so I installed it, or at least I tried. It turns out, there was a difference in the length of the pushrod that pushes on the piston in the mast. cyl. I placed both of the masters side by side, and found that the original one from my '74 had a 'hollow' piston where the pushrod goes, and the original one from the '81 was pretty much flush at the rear of the cyl. Mine took a longer pushrod from the booster than the '81. Don't know if that's the case here, but it might be worth looking at it, if you still have your orig. cyl. If not, just compare the pushrod. If it doesn't stick out very far from the front of the booster (or firewall, if non-pb), and the mast. has a deep-well piston, that's the prob. Just an idea!
If you do have the correct mast. cyl., and you can't get it to pump any fluid out of the line @ the cyl., then it may just be a defective master. Adams' Apple38550.7237615741


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Master Cylinder

Posted: 7/17/05 6:51pm Message 7 of 9
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Damascus, MD - USA
Joined: 12/17/2003
Posts: 247
Vette(s): 1970 Conv. 350/350, Wht./Blk.,P/W P/B,P/S,TT, 4 Spd.

I just finished installing the original but rebuilt master cylinder in my 70. I found that by tapping on the front of the master cylinder with the cap off and enough fluid would cause air bubbles to start coming up through the small venturi in the master cylinder itself. I tapped until bubbles were no longer coming up through the fluid in the master cylinder from the one set of venturi. Work like a charm to get the air out of the master cylinder. I would try this before taking the MC back out.

Good Luck. I also put all new calipers on so I had bleed them via gravity and the old fashioned pump and hold method. Brake pedal is perfect so far.

Bill




Master Cylinder

Posted: 7/22/05 9:48pm Message 8 of 9
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CUYAHOGA FALLS, OH - USA
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Vette(s): 1975 C3 Red, T-Tops, Black Interior. All I need is time and money! Getting there!

You can also bleed the master on the car by taking off both lines.  Have someone pump the pedal GENTLY, and hold your fingers over the holes for the lines.  When the pedal is pressed down, open the holes, when the pedal is lifted, cover them.   When you start getting a strong fluid flow that pushes you finger off of the holes when the pedal is depressed, reconnect the lines.

One line is likely to bleed before the other, so connecting one then the other after a few more pumps on the pedal is okay.

With both lines connected, bleed the brakes AT the lines to the master by loosening and retightening the lines, like you would a  bleeder valve.   With both done, go to the wheels.  Sometimes you can get all the fluid out of hte system without going to the wheels, but it's a good idea to get clean fluid from the wheels anyway.  This helps prolong the life of the the brake system.

kstyer38555.9094097222


Master Cylinder

Posted: 7/23/05 5:47am Message 9 of 9
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Grandville, MI - USA
Joined: 5/8/2004
Posts: 140
Vette(s): 1968 427/390 Coupe

I got it , I had a little mental block when it came to bleeding the master cylinder but she is all set now.

Thanks everyone

 




in Forum: C3 Engines, Driveline and Handling


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