The Early Holden Garage

Common modifications / repairs

[Early Holden garage]

This is the Holden garage page where a few of the more common modifications performed to Aussie cars such as the Holden models produced between 1948 and 1968 are discussed.

Note that the following is supplied for information only! No responsibility will be accepted for anybody using or misusing the information supplied. It is not intended to be taken as complete, or even 100% accurate. Continuing to read the following information constitutes acceptance of the above. Always consult a qualified mechanic if you have any doubts about your ability to perform any modifications to your car. Most modifications to vehicles registered for road use require Engineers Certification for registration in most states of Australia. In some states, no modifications are allowed at all! Always check with your state vehicle registration authority, and your vehicle insurance company, before beginning any modifications to your car.

The following are issues which are discussed below. If you have something specific you would like to see here, forward details to me here. I'll try to update a bit more regularly!

So far, there are sections on Disc Brake conversions and Transmission options covered below.


Three sections are discussed on Disc Brakes. There are:

Front Wheel Disc Brakes
Disc Rotor selection
Rear Wheel Disc Brakes

Front Wheel Disc Brakes

The first item to be discussed is fitment of disk brakes to early Holdens. One of the most popular conversions for early (Pre 1967) Holdens is to add Disc Brakes to the front of the car. All Holdens produced prior to 1966 had four wheel drum brakes as standard equipment.

[Front Discs]
Click image for larger picture
There are two main ways to convert to Disc Brakes. The most common, and I believe best way, is to fit a complete front crossmember from the HR model Holden (1966-68)to your earlier model. Another advantage of this swap is that the HR model suspension unit makes use of ball joints, whereas earlier front ends employed king pins. Ball joints are by far superior in their ease of maintenance and replacement, and make for a much better handling package.

The fitment of an HR crossmember and suspension unit is fairly straightforward in most early Holdens.

You have the choice of modifying one yourself, or purchasing a pre-modified version from Rare Spares or the like.

The modifications necessary are typically a movement rearward of the engine mounts, and replacing the HR outrigger (the anti wind-up support located on the front of the crossmember)with an EH (or earlier) one. Then it's just case of bolting up the new crossmember using ther same four mounting points employed by the earlier front end.

By purchasing a pre-made crossmember, you will also receive engineers certification for the modifications performed. The price for a changeover crossmember is around AU$120, so if you are not handy with a welder, its cheap insurance!

Other items you will need are a disc brake master cylinder, and you may need to change the rear wheel cylinders to smaller diameter ones. Obviously, a vacuum booster should also be fitted, if one is not already in use.

[Front Discs]
Click image for larger picture

If using other than original HR discs, custom lines may also be required to connect the calipers to the vehicle's brake lines.

Note, however, that a change in the braking system of a car will require Engineers Certification for registration in most states of Australia.

Major modifications are necessary, however, to fit the crossmember to the first model Holdens the 48-215 (FX) and FJ. If you are looking at fitting one to either of these models, I would suggest that you consult an automotive engineer, or use a Rare Spares or similar crossmember which has already been modified, and comes with an engineers certification to cover the modifications.


Disc Rotor selection

One of the advantages or Holden using the same wheel bearings from early models to Commodore is that virtually any Holden disc will fit your HR front end.

Of course, the original HR two piece discs will work, but the offset of standard HR wheels is slightly different to that of the EH, meaning that you cannot run standard EH wheels on HR discs. This is of no concern if you are running aftermarket wheels, so long as their offset means that the wheel or tyre doesn't interfere with the caliper, steering arm or anything else.

Most HR discs and calipers discs by now are worn out, and replacements are fairly expensive. A cheaper alternative is to use LH or LX Torana discs and calipers, thus retaining your original stud pattern. These can often be sourced from a wreckers, or are fairly inexpensive to buy the rotors new. You will need to retain the HR stub axles, as Torana stub axles do not have the correct inclination, and will not allow you to set up the front end geometry correctly.

These width of these Torana discs cause the wheel to be moved about half an inch towards the guard of the car. This allows clearance for the use of original wheels, but may cause problems with deep dish wheels now rubbing the guards, or fouling them on corners.

HQ or later discs (up to WB) can also be used, allowing for a change to the later Holden / Chev stud pattern. You will need to use the HQ stub axles as well, to allow the calipers to mount up. This is a popular swap for people wanting to run imported wheels like Weld Wheels or Centrelines. It is also most popular with highly modified vehicles because it means that a change to the stud pattern on the diff is necessary. Often, a 9 inch Ford rear end will be converted to HQ pattern, or maybe a shortened Salisbury of Commodore diff installed.


Rear Wheel Disc Brakes

If you are really keen on having your early Holden stop like anew car, you can also convert the rear to Disc Brakes.

[Rear Discs]
Click image for larger picture
A reasonably straightforward swap is the use of a VB- VH Commodore disc brake assembly. The discs themselves need to be redrilled to the early Holden stud pattern, but there is plenty of metal on the disc to do this.

The disc backing plate will need a little trimming for clearance, and you will need a new handbrake cable to suit. A Commodore cable is used, but inserted into the standard early Holden cover.

A bit of tricky plumbing is required with the caliper brake lines if you have lowered your car. The lines pass between the rear of the wheel and the inside panel of your wheel arch. Your wheel offset will play an important part here. If you have wide wheels with an offset that brings them close to the inner guards, then this swap may not be for you.

Also, if you are using an LJ Torana diff to give you more wheel clearance, this swap is not possible.

[Front Discs]
Click image for larger picture

By using the standard diff, and LH Torana discs on the front, you are able to retain use of the original wheels, which was my aim. Nobody even knows the swap had been done unless you tell them.

If you have changed the front discs to HQ stud pattern to later, a better option may be to use a shortened VN Commodore disc rear end. This way, everything is factory and the rear stud pattern can be matched to the front very easily.

I must admit that I took the easy way out with this conversion. Rather than mess about with it myself, I had it done by Alex of the Brake Shop. I must thank Alex for his assistance with my car. Alex has been working on brakes for over 20 years and does many specialty one off systems for Hot Rods and similar. Give him a call for more info on the rear disc brake conversion. Alex also sells kits for you to do it yourself.

Alex is located in Werribee, one of Melbourne's western suburbs. Tell him where you saw his card!

[The Brake Shop]


After all these years, the original transmissions fitted to early Holdens are getting a little tired and outdated.

One of the major problems with the Hydramatic, the original automatic transmission offered in the EK, EJ and EH ranges is that parts are now extremely rare, and very expensive. A lot of these autos suffer from flaring between gears, and some, like mine, lose drive completely from time to time, and you have to let the car coast along until the transmission decides it wants to engage again, usually at about 20mph! Not a good situation in heavy freeway traffic.

The most popular, and easiest, replacement for the Hydramatic automatic transmission is to use a Trimatic from an HQ of LC-LJ Torana. They are practically a bolt-in swap. This is what has been done in my Prem.

Of course, you will still be running an auto if you choose this option. You may prefer to convert the whole thing to manual if you like, using an original 3 speed box. You will need a manual steering column, with the manual shift (obviously!). You would also have to modify or make up a mount for the gearbox crossmember. This way, no holes need to be cut in the floor.

The main differences between the manual and automatic vehicles in the EK to EH are:

The advantage you have with the auto floor is that the tunnel is much wider, and you can install virtually any gearbox you like, whereas the manual floor has much less room available. Most people, when wanting to install a 4 or 5 speed try to find a car with an auto - it's much easier, and lots less floor modification, often none at all! The registration authorities don't like people cutting up floors - with good reason. To install a 4 or 5 speed in a manual floor usually means cutting through one of the strengthening ribs.

If you want to go manual, and you don't like column shift manuals, you will have to cut a hole in the floor for a shifter. The options then would include an Aussie 4 speed, using a Holden 1 Tonner shifter to clear the bench seat, or one of many available Japanese 4 or 5 speeds, which have forward or variable shifter mountings.

Obviously, if you have An EJ or EH Premier, or have fitted bucket seats already, shifter position may not be a problem.

The advantage of the Aussie 3 or 4 speed is that you can stick to standard parts - eg flywheel, clutch and pressure plates etc. You may need a special slave cylinder, however, or convert to a cable clutch setup.

The advantage to a 5 speed are many - including the overdrive of course! You can buy a complete kit with all the necessary mounts, spacers, clutch etc. which is the best way to go. Often, an engineers certificate will be provided for the mount etc. You would still need one for the installation in your car if you RTA requires it. Try Dellow Automotive in NSW, or Rod Hadfield's Rod Shop in Victoria for information on complete kits. You could also try your local Rare Spares.

Hydramatic to Trimatic conversion - broad outline

If you decide to keep the automatic, here's a list of required changes when installing a Trimatic. Please note that this pertains specifically to the EH model, but I assume the EJ and EK would use a very similar process.

1. Column

Use the original column, but the shift pattern now changes. Instead of the wacky Hydramatic shift pattern, you will now have the standard Pk - R - N - D - 2 - 1 like all modern cars have. What this means is that there is no lockout between Reverse and Neutral, but unless you are manual shifting it's not a problem.
[Hydramatic 	shift pattern]
Hydramatic shift pattern

The other thing is that your quadrant shift indicator is now wrong. If you are used to it, it doesn't matter, but if anyone else drives the car - like your mechanic or similar - they may end up choosing the wrong direction! I guess the Police and RTA would also prefer that your gear selector is correct.

You can make up a new one - I've bought some thin plexiglass to cut to size - and add the letters with Letraset. Or I've been told you can use an HD /HR Powerglide one and just add an S for second. This would be a better option, but as I haven't found one to try yet, I don't know whether it is that easy. The hard part is the shape of the original - it's not just flat - and it has green coloured glass at one end at 90 degrees which gives it the same green glow as the dash lights.

2. Transmission Mount

You can use the original mount, but the center needs to be lowered slightly. This is usually done by cutting some metal out and rewelding. It's also a good idea to get a new rubber mount for the trans as the old ones are always squashed and usually cracking up.

3. Speedo

Of course, now you need a special speedo cable, using an EH head and an HQ gear in the trans. Rare spares or Rod Hadfield in Castlemaine should be able to make you one of these - or a good speedo shop if there's one near you.

4. Tailshaft

Use your original tailshaft, but you'll need a Trimatic/Aussie yoke with the broader splines. Replace those uni joints while you're at it!

5. Neutral Safety switch

You will need to find an donor car with a column auto and use the neutral safety switch which mounts to the column in the engine bay. An LH Torana switch works well. Also, the same car can supply the reversing light switch, which usually mounts on the column inside the car - down near the firewall - if you want to use reversing lights.

6. Floor

Generally, clearance should not be a problem with a Trimatic. Some floors may require some minor 'tapping' to clear selector rods or other parts or the transmission.

7. Shift linkages

This is where it can get tricky. The best option is to make up a one piece rod to use as the selector. The one rod means no jammed linkages etc. Otherwise, a combination of original and HQ parts can be used, but as I haven't been involved in this particular setup, you may have a bit of trial and error to see what works.

8. Kick down

You can use either the electric kickdown or mechanical kickdown transmissions. For the electric kickdown, you'll need to make a suitable bracket to hold the switch, and mount it to the pedal assembly. I have also seen a switch mounted to the floor which operates when the accelerator hits it.

Alternately, you could use the mechanical kickdown option by choosing a Trimatic with this. The original Hydramatic kickdown rods may be able to be modified to suit, but I haven't tried it. Or, you could just not use the kickdown at all.

I helped a guy who lives locally to me with his Trimatic conversion and he didn't even worry about the kickdown. The car still changes up and down where necessary, you just can't use the kick down for passing etc. Normal driving isn't affected.

There are lots of little things I haven't covered but check with your local mechanic or automotive engineer if you intend to complete this swap yourself.

For HD and HR models, the floors were all the same, so most any gearbox you like can be fitted. This includes the Trimatic as a replacement for the original Powerglide. Some people prefer the extra gear in the 3 speed Trimatic over the 2 speed Powerglide, and Trimatics are more readily available and much cheaper than the original Powerglide.

For models earlier than the EK, you are stuck mainly with manual transmissions, as the transmission hump in the floor will need serious modification to fit anything much larger than the original box. Many japanese 4 and 5 speeds are fairly compact, so this may be the best option. Fitting a 4 speed Aussie box usually requires to removal of a centre floor strengthening rib, as with the EJ/EH manuals. This can be done properly, and the floor strengthened again with metal plate, but Engineers Certification will be required for any welding you do to the floor. This also applies to cutting and reinforcing the shifter hole.

Always consult your Motor Registration Authority before making any modifications to your car. A call to a recognised Automotive Engineer may also save you lots of money and heartache later.

Other sites which may be of interest to you:

The Sixties Holden Archives
EH Holden Car Club Page
My Car page

or visit the Official EH Holden Car Club of Victoria Page.

Back to Mike's Home Page

Mike Long, MSLDesign, PO Box 4123, Croydon Hills, Victoria, 3136, Australia.
Copyright © 1997-2003, MSLDesign.
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