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Having a little trouble with my HK's brakes. First off its running a VN V6, fresh rebuilt HQ calipers up front, HQ sedan diff out the back with new cyclinders and shoes. Big hktg V8 booster and standard disc brake master cylinder (i think) from hktg series.
I had a really hard pedal to start with, needed extreme pressure to get the beast to pull up. Internal vacumn leak in the booster. Replaced this with a working second hand one. Now my brake pedal touches the floor pan, really soft feel, but does pull the car up a lot better. Feels like its going to lock up - really sensative. Its as if the pedal is only starting to apply the brakes within its last inch of travel. I have bled the system 3 times and have no air, no leaks, and adjusted the rear shoes. Is there something I'm missing from my system, like a proportioning valve ?
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sounds like you have a drum brake master cylinder,had the same problem when i converted from drum to disc on a previous hk.proportioning valve is different.
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sounds like you have a drum brake master cylinder,had the same problem when i converted from drum to disc on a previous hk.proportioning valve is different.
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Hi Guys.
HK/T/G didn't have a proportioning valve of any sort. HQ-HZ did, are you running HQ-HZ rear cylinders & linings or are you running HK/T/G small cylinders (9/16") & linings.
Also there are 2 types of disc brake booster, 1
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Thanks Dr T for your quick reply. The push rod is in the lower hole already. Must mean I have the wrong master cylinder. Is there any way of identifying a drum brake master cylinder to a disc brake one. The part number on the one fitted is a P6613. I have
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The rear cylinders are large HQ ones and HQ shoes.
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Well according to the PBR website I have the correct master cylinder fitted.
P6612 - ACTUATION Brake Master Cylinder (****) - Suit: DRUM/DRUMBore Size 25.40 mm
P6613 - ACTUATION Brake Master Cylinder (****) - Suit: DISC/DRUMBore Size 25.40 mm
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I had the same problem with a UC years ago. Turned out the reaction pad that goes between the incoming pushrod and the master cylinder pushrod had fallen out (ie into the booster). Unsure if this can happen in a HK/T/G, but the symptoms were EXACTLY as yo
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Despite different part numbers HK-T-G master cylinders are similar whether for disc or drum. The only difference is a check valve in the front brake outlet found in drum brake master cylinders. This can be removed if you have the special tool or can be dr
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Could be also that either the front or rears are not working. Travel at about 15-20kph on a sandy surface and jam the brakes on, then check the skid marks see which ones come on first. Also feel the rear brake drums and front rotors to see if they are ge
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Hi GMGod.
I do beg to differ with you on this subject.
The part numbers mentioned are for HQ onwards, although some will fit HK/T/G.
On HQ onwards, the piston push rod depth is the same for either disc or drum. With earlier cars ie HK th
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Took the booster back off again, reaction disc is still in its place, has not fallen out. Dr. Terry I'm a little confused as to what master cyclinder I should be using, a HK T G disc brake front unit or should I be using a HQ unit. The part numbers I gave
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They made a Holden after the HK-T-G? I thought these were the product of legend and myth. I've never seen one in my garage (lol!)
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Hi Daniel.
Don't just follow PBR part numbers ,there are too many & they changed over the years.
The simplest way is to measure the depth of the push rod hole in the back of the master cyl & compare that to the rod portruding from the
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