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I just had the first drive of the car and the brake pedal is hard as there seems to be no power assistance.Car is HT holden with HQ front discs VB commodore rear disc,HT v8 power booster and master cylinder.Original brake lines with no proportioning valve.Vacume line feeds from the manifold as normal.Brake pedal doesn,t move slightly when you start the car.what could be the problem?
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Is it a 4 wheel disc brake master cylinder? If not you'll have to modify the rear circuit to make it operate rear discs. |
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Disc/drum HQ mastercylinder brand new.Vaccumn line has vacumn,rear discs operate when pedal pressed.
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You need to modify the rear output of the master cylinder to operate discs. This involves removing the check valve from the master cylinder in the outlet of the master for the rear circuit. |
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If we all had the same (good) taste, who would buy all the Fords? |
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How do I get to the check valve.Remove circlip and disassemble piston or is it at the outlet where the brake line exits from the master cylinder or at the junction box under the guard?
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Rank: Veteran
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Outlet, you'll see it. I just screw a self tapper into it and rip it out with multigrips. I'd talk to a brake specialist first to understand what/why/how etc. |
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If we all had the same (good) taste, who would buy all the Fords? |
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Thanks for that HK1837 much appeciated.
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Rank: Member
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Have removed check valve from master cylinder and still have what appears to be no power assistance.Pedal pressure to stop whether engine running or not appears pretty much the same. Is there a rebuild kit for the ht booster and is it a diy project or a job for the professionals?
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In my opinion, it's a job for the pro's. Some brake places have a way of setting them up on a test bench and testing them without pulling them apart. Might be best to do this first.
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