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Hi Guys,
I have a 186 HK with drums all round. Want to change front to standard HK discs and leave the rear as drums. I want to give it a go by myself and wish to clarify a few things.
I understand I need a brake booster to ease heavy brakes, can I use my current master cylinder or do I need a new one?
I fit the booster hose where the vacuum modulator currently is on the inlet manifold? Where can I find a brass adapter to run both from the same outlet on the inlet manifold?
Someone stated I'll need a pressure limiting valve from the master cylinder to the rear brake line to avoid rear drum lock up. Is this correct? I can only find one for a HQ, do I just modify this?
Thanks for all the help.
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It's a fairly straightforward conversion, because you are using factory bits.
The front stub axle assemblies with disc rotor & caliper etc. are a direct bolt-in swap for the drum brake assemblies.
There is no proportioning valve used on HK, they limit rear brake lock-up by using smaller bore (9/16-inch) brake wheel cylinders. You will need these 2 smaller cylinders plus the different rear shoes to match.
The master cylinder is slightly different in that one of the 2 residual pressure valves is deleted in the disc brake version. There is only one of these fitted to the outlet to the rear brakes, the valve in the front brake line is deleted. In reality you are probably better off just buying a new brake m/cyl to suit the discs rather than muck around with an old unit that's probably due for replacement anyway, they are not expensive.
The booster is basically a bolt-on job, except for early HKs which only have one hole in the brake pedal, not 2. If yours is an early HK, with only the one hole, then the early relay lever style booster will fit straight on. If you get the later style booster (late HK, HT & HG), you will need the 2 hole pedal to match.
The vacuum fitting issue on the inlet manifold can be solved a few different ways, but the easiest method is to just get the correct T-piece from the same car as the booster.
Dr Terry |
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Just to add, you don't have to use HK stubs. Any HK-HJ will fit. HX-WB may too but there is a slight machining change from memory for the part alloy calipers - I don't know if this affects bolting up HK calipers or not. You have to swap side for side with HQ-WB stubs of course. It might be worth running HG rotors (same as HT GTS350), just use HG calipers as well with the spacer in them for the wider discs. I think you can buy both HK-HT rotors and HG rotors new still from RDA or DBA. |
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Thanks heaps for the info. I know I could pay someone to sort this out but then it wouldn't be worth it or mean the same as doing it yourself and learning new stuff along the way.
Dr.Terry, I am looking at just purchasing a new booster online so I will have to source the T-piece as a singular item. I searched Kilkenny brass adapters but can't find a T-piece. Any idea's on suppliers for these adapters.
HK1837, my main goal to to have a full original restored 186 HK. Will using HK-HJ stubs cause clearance issues with the rims. I've read HQ-WB stubs cause caliper clearance probs with the HK rim rubbing against it.
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The problem with ordering a 'new' booster online is that I doubt very much whether it would be the original type & also all the brackets & clevises etc. won't be attached.
I think you would be better off searching old Holden wreckers for the real item (with all the bits attached) & then getting the booster overhauled by a reputable specialist.
Don't believe everything you read. It's not the stub axle which causes the clearance dramas. It only becomes a problem when HQ-WB rotors are combined with original HK wheel rims, the tyre often rubs against the top ball joint. HT/HG rims don't have the same problem.
Dr Terry |
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quote:
Originally posted by Jeffro81
Thanks heaps for the info. I know I could pay someone to sort this out but then it wouldn't be worth it or mean the same as doing it yourself and learning new stuff along the way.
Dr.Terry, I am looking at just purchasing a new booster online so I will have to source the T-piece as a singular item. I searched Kilkenny brass adapters but can't find a T-piece. Any idea's on suppliers for these adapters.
HK1837, my main goal to to have a full original restored 186 HK. Will using HK-HJ stubs cause clearance issues with the rims. I've read HQ-WB stubs cause caliper clearance probs with the HK rim rubbing against it.
There is no difference between HK and HQ-HJ stubs. The rotors and calipers are different but the stubs are the same. All I was saying is don't go hanging out for HK stubs as HT-HJ will do the same job. Greg at Classicozwreck in Lake Macquarie will have a booster and other bits. Best bet is go there and get all you need. |
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Gee, you guys were quick. Thanks. I'm using HK calipers so I can keep HK rims. I was going to deal with Hopper Stoppers and Sunbury Brakes online but I will call the local wreckers too. Cheers once again.
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