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Thread: HZ Rear Disc Brake Conversion

  1. #1
    Leadfoot rallyvan's Avatar
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    HZ Rear Disc Brake Conversion

    I just completed a round Australia trip in my van and found myself having to adjust the rear drums every 5000km. I have heard that VB to VS Commodore rear disc set up will work. Does anyone have the Commodore rear disc on their van/ute? What was involved in getting them to work?

  2. #2
    It's a rockin' Sandaro's Avatar
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    Why did you have to adjust so often? We're the tightening up or wearing out? It doesn't sound normal either way

  3. #3
    Leadfoot rallyvan's Avatar
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    The adjuster failed on one of the drums which is the main contributor. I have always found that drum brakes on that vintage of Holden need frequent adjustment to maintain good pedal feel. Over having to adjust them hence the question about Commodore rear discs.

  4. #4
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    They should adjust themselves when you hit the brakes in reverse.
    You can make Statesman discs work but you will have trouble getting the handbrake to work on any disc brake conversion.
    I haven’t adjusted the rear drums on my WB since 2000 and over 100000km.

  5. #5
    Sandman Driver maxsandman's Avatar
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    Would be a lot of work to put the com brakes on a Salisbury diff.
    The commodore rear disc rotor wont fit on to the holden axle, the axle would need to be machined both the "snout" where the wheel centres on axle is bigger on the holden, & also the radius of the axle, for the rotor to slip over.
    Then the diff housing/ends of axle tube, would need modifying for the bracket that mounts the com backing plate and caliper.

    That's before any clearance issues, but I think there's enough various commodore models to get some clearance. On different com models, the handbrake cable is mounted at top or bottom of the backing plate, so I think that would be worked out.

    I would reccomend: 1/..
    VB, VC, VH & early VK 5 litre Salisbury diff conversion. I have seen these in HQ-Zs, is narrower for wider tyres, & looks stock from diff plate point of view. I sold one to a guy put in a HR ute with a blown 6, & worked OK

    2/...
    VN onwards B/W diff. Common to find & stronger than Salisbury. Anything out of a ute is LSD + Calais is LSD.

    3/...
    9 inch

    Late VK & VL (V8) B/W is a better diff, but getting hard to find.

    End of essay, cheers
    Max

    SORRY, my train of thought wondered off from brakes to diffs... I will blame old age & alcohol!
    Last edited by maxsandman; 12-09-2019 at 11:14 AM.

  6. #6
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    Just use WB Statesman parts. It’s the simplest way. You will need to change the brake master cylinder to suit rear discs as well.
    If you start with a Statesman diff you only need to weld on the leaf spring mounts to fit it but I seem to remember you have to fiddle around a bit for clearance between the springs and the callipers. It will be far simpler than using a Commodore diff I would imagine.
    Last edited by wbute; 12-09-2019 at 03:58 PM.

  7. #7
    Sandman Driver maxsandman's Avatar
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    Thumbs up

    Quote Originally Posted by wbute View Post
    Just use WB Statesman parts. It’s the simplest way.
    Yes, I agree, except all these are old & need rebuilding. I was looking for the bracket that mounts the caliper a couple of years ago, as they were worn from caliper not sliding square. Could not find any that were better than what I had.

    Anyway, the question was about commodore rear discs fitting holdens, & that's what I was trying to answer:

  8. #8
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    Yeah I guess. Not sure how you get around the wrong stud pattern. Unfortunately even the Commodore diffs are all old too now though.

  9. #9
    I think I saw you at the BP in Katherine & then caught up again in Mataranka, was gonna give you a call on the uhf but the road trains were gossiping & I was turning off down the Roper hwy, the old girl looked great on the road, reminding me of my good old days in a van in the top end. Between seeing yours on the road and WB's recent efforts I'm almost inspired to think about mine again
    AB60E436-CFD4-4295-8A71-84C2E9AAE8BB.jpeg

  10. #10
    Leadfoot rallyvan's Avatar
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    It was me at the BP in Katherine. The photo is of sandman77hx's van. He was also the other support van on the trip with us. Great experience.

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