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Old 07-14-2020, 04:29 PM
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Fullback66 Fullback66 is offline
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Default Problem with disk brake conversion

I am having a problem with my new brake conversion. I bought the kit back from "inline tube" in 2007 to convert my 1966 GTO drums to front disk brakes. I finally have had the opportunity to install them on my car. After installation. I was taking the car for a drive today and the front disks will not lock up. Slowed the car down, but would not lock up. I could lock up the rear brakes if I pressed hard enough on the brake pedal. I have a medium hard brake pedal. I know the brakes are put on correctly. We bled the brakes several times after a few drives with no help. My friend who builds hot rods and help me install the brakes thought that it might be the brake booster. Could the brake booster have gone bad after sitting so long? Is there an adjuster on the proportioning valve? Do you have any Ideas why the front disks will not engage properly? Thanks FB66

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Old 07-14-2020, 06:08 PM
JLMounce JLMounce is offline
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What all came with the kit? Specifically, was there a new booster, master cylinder and combination valve supplied?

The symptom you describe sounds like a combination valve issue. Disc brakes require more fluid volume than drum brakes do. If the combination valve is not replaced with a specific disc/drum style valve, it can cause exactly that issue.

While a booster/master cylinder could go bad from non-use over a 13 year period, I would look to an issue with the combination of parts that were or were not installed.

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Old 07-14-2020, 11:53 PM
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also check your brake lever. See if there is a second hole where the arm attaches to the push rod. You may not be getting enough throw on the lever.

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Old 07-15-2020, 12:13 AM
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In addition to what was said above, also check your power brake hose to the manifold... many times people use the wrong rubber hose and it collapses under vacuum and you will perhaps get the symptoms you are seeing. Just odd it is only the front brakes though.

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Old 07-15-2020, 01:03 PM
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It's not getting any vacuum. I think the booster is bad


Last edited by Fullback66; 07-15-2020 at 01:16 PM.
  #6  
Old 07-23-2020, 12:24 PM
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NeighborsComplaint NeighborsComplaint is offline
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Quote:
Originally Posted by Fullback66 View Post
It's not getting any vacuum. I think the booster is bad
Simple test is to shut the engine off and pull the check valve fitting out of the brake booster. You should get a "hiss" like you get when you disconnect an air tool for with a quick disconnect coupler.

Also, stat the car with your foot on the brake. When the engine starts, the pedal should drop slightly as vacuum pulls the booster diaphragm forward.

That's all I got. I did a a 4 wheel disk brake conversion 3 years ago and still haven't sorted out my issues. I used a kit similar to what Inline Tube sells but mine came from Pirate Jack. It's jacked, all right. See my "Sooooo tired of ... " thread. I've replaced every hydraulic component that came in the kit with no improvement.

My holy grail is at least black strips on the pavement when I slam on the brakes but it has eluded me thus far.

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