bleeding brakes

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GEODAVKY
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Joined: Wed Nov 21, 2007 9:40 pm

bleeding brakes

Post by GEODAVKY »

A quick look at the rear wheels and I did not see the brake bleed screw. Where is it?
How does one "gravity bleed" brakes?
1967 330 GT 2+2 8767
George Davidson
DWR46
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Re: bleeding brakes

Post by DWR46 »

Bleed Screw: What model Ferrari is the car?

Gravity Bleeding: Open the reservoir cap, attach a clear plastic line to a bleed screw, route the line to a container ( I like to use white plastic "butter tubs" as you can easily see the fluid change color as the new fluid comes thru the system), open the bleed screw and let the force of gravity move the fluid from the high reservoir to the lower bleed screw. The flow rate can be anywhere from a steady flow to a slow drip depending upon the characteristics of the system. If you have no flow at all, then gravity bleeding may not work in your application. Do not forget to keep the reservoir full of fresh fluid so no air can get into the system during the bleeding process.
GEODAVKY
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Re: bleeding brakes

Post by GEODAVKY »

1967 330 GT 2+2 I've looked everywhere on the back brake drum for a bleed screw.
Thanks for the directions.
1967 330 GT 2+2 8767
George Davidson
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tyang
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Re: bleeding brakes

Post by tyang »

brake2.jpg
brake2.jpg (99.14 KiB) Viewed 13434 times
Your rear brakes should look something like this, and the arrow shows the bleeder.

On most of these cars, under the bleeder screws, there is a ball bearing that acts somewhat like a check valve. You can fish it out with a magnet. Sometimes with gravity bleeding, the bleeder screw has to be removed along with the ball bearing for adequate flow.

Tom
'63 330 America #5053
GEODAVKY
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Re: bleeding brakes

Post by GEODAVKY »

Thanks Tom. Guess I have take the wheel off to see it!
1967 330 GT 2+2 8767
George Davidson
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tyang
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Re: bleeding brakes

Post by tyang »

GEODAVKY wrote:Thanks Tom. Guess I have take the wheel off to see it!
Uh, Yeah...no shortcuts here!

Tom
'63 330 America #5053
John Vardanian
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Re: bleeding brakes

Post by John Vardanian »

When bleeding a new system (from dry), should the vacuum booster be bled first or last? Thanks.

john
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SLM
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Re: bleeding brakes

Post by SLM »

John,
I have loosely interpreted the manual to say-Servo,brakes,Servo.
Steve
62 250GTE S/N 3733
John Vardanian
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Re: bleeding brakes

Post by John Vardanian »

Thanks Steve.

On the equalizer brake cylinder, does anyone know how far the piston runs out when brakes are applied full on? Mine peeks out it's head no more than a quarter of an inch and the lines hold pressure even when the pedal is at rest; i.e., the front wheel cylinders do not fully release. I tend to think my EQ valve is not doing what it's supposed to do. I'd appreciate hearing about any similar experiences. Thank you.

john
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Re: bleeding brakes

Post by 250GT »

John, see article of " TY restauration tips "on the left side for explanation of this litle front wheel booster

those arec often stuck by longer lying around prof. overhauling and sleeving is almost allways necesserry.

Just did one of mine on a body off restauration but 508D Chassis 1958.

cost only Around 280 € at C&C brake specialist in Baarlo NL.

The air relieve opening must be clean can be found under the metalchassis bracket in the front( very small little hole) after numbering.


see below

C.
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250GT
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Re: bleeding brakes

Post by 250GT »

Sorry ,did reduce the pics too much I think.
hardly readable.
hope these are better.

best

C.
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BobA
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Re: bleeding brakes

Post by BobA »

John: I read recently that the rod pokes out 1/4" to 1/2" under normal operation. When I had my SWB, I tried to use silicon brake fluid and found that it was not compatible with the seals in the MC and calioers. The relief port to the reservoir was being blocked by a swollen o-ring and the pressure was held in the system. Single piston MC. I had to completely rebuild the calipers, MC and equalizer and use Castrol LMA to solve the problem. If you release the pressure between the MC and the equalizer, does the system retract? Bob
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Re: bleeding brakes

Post by 250GT »

John, you should consider non aggressive DOT 5 instead of DOT 4 in a new system.
DOT 5 is compatable with DOT 4
And Evans water free cooling fluid if you drive them.
Used it in all mine cars over the years without problems.
best

C.
John Vardanian
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Re: bleeding brakes

Post by John Vardanian »

Cornelis, thanks for the pictures and advice. I am using DOT-4 brake fluid.

Bob, yes the pressure is captured between the vac booster and the EQ valve, when I loosen the 12mm nut brakes retract.

I have a dumb question, it has nothing to with our problem at hand, but just curious as to how disk brakes work in general. In the drum brakes, when you let go of the brake pedal the springs pull the shoes back. What makes the calipers retract since there are no springs?

john
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Re: bleeding brakes

Post by 330GT »

John Vardanian wrote:I have a dumb question, it has nothing to with our problem at hand, but just curious as to how disk brakes work in general. In the drum brakes, when you let go of the brake pedal the springs pull the shoes back. What makes the calipers retract since there are no springs?

john
In the cylinder, there is a slot for a square O-ring. That is what seals the piston and cylinder. When the brake pedal is pushed, the piston forced out until brake pads contact the wheel disc. This deforms the O-ring into a parallelogram (if looking at the cross-section). When the pressure is released, the deformed O-ring pulls the piston back slightly so the O-ring is back to a normal square cross-section. If there is more than normal space between the pad and disc, such as when pads are changed or due to pad wear, the piston slides past the deformed O-ring. That is what makes the system self-adjusting for wear.
Regards, Kerry
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