Front HR and other Disc Brake conversions
So you don’t think the General built EJ’s and EH’s with good enough brakes? Well there is someting you can do about it, and it needn’t cost you a mega amount of dough if you dont want it to.
Check these articles out for heaps more info too.
The first thing you will need to do is get hold of a HR front end. These later model ball joint front ends, not only offer better braking options, but also the advantages of ball joints, which are longer lasting, and easier to maintain. You options are to get either a disc front end complete, and run it totally stock HR or get a drum front end and get some disc stub axles for it. You will need to run HR rear brake wheel cylinders if running HR discs. A HQ proportioning valve is good for HQ or Commodore discs
Now, the stub axles and disc’s. Here are a few options; You can use the totally Stock HR setup, disc rotors and calipers. Rod Hadfield has conversion brackets to set disc’s and calipers on drum brake stub axles; You can get new lowered stub axles from Rod Hadfield, which take either LH Torana disc’s and callipers or HQ-HZ disc’s and callipers. You will need to make a small cutout in the lower wishbone to make clearance for full turning circle, you will need to try everything on to work out how much to groove out;
You can use LH Torana stub axles, disc’s and calipers, or HQ stub axles, disc’s and callipers if you want to use later wheel stud pattern. You can get blank HQ discs and have early Holden stud pattern put in them. What you actually need to do when fitting HQ discs is use the HQ stub axle. It is the only one that the calliper will fit onto to suit a HQ disc. Also HQ stud pattern and Commodore stud pattern is different. HQ is imperial and Commodore is metric. This means the stud outer edges are approx 1mm further from the centre of the hub, causing the full stud diameter to be about 2mm out.
A HQ steel wheel and a Commodore steel wheel seemingly fit each other, but are dangerous to swap. The alloy wheels with lug nuts will not fit each other at all. Also the threads are different. If you fit a commodore rear end at a later date, you will have to get your axles restudded to suit HQ It is worth noting that the LH disc rotors set your wheel base out about 10mm, and you can get Leyland P76 disc’s that set your wheelbase in about 10mm. You will need a conversion kit to fit these.
Whenever a car is converted to disc front end, you will need to fit a brake booster to suit. The VH40 unit is the most common. New they are about $350. You may be able to pick one up from a wrecker, and totally reco it for about $180. If you have access to the special double flaring tool required for brake lines, you will be able make them up yourself. Alternatively you can make up templates using a bit of wire, straighten it out, and get your local brake place to make up the lines to the length and put the ends on for you.
It is a good idea if you can, to convert your vehicle to a tandem brake master cylinder system. There are kits available from Rod Hadfield for this. It includes a spacer block so you can use the brake master with your clutch master next to it. You can buy this on its own, and buy the appropriate HQ style PBR brake master cylinder yourself. This also allows you to run the HQ proportioning valve and brake fail switch setup.
Remember above anything, you must consider all of the safety and legal requirements. If you have any doubts, contact your local registration branch.