Hi,
I found this article in the September '08 issue of Australian Street
Rodding in the Technical Workshop section and found it very interesting so I thought I would share it.
It starts out with a letter from a reader stating "
I was hoping you could help me with a quick question. I thought I had read one of your articles and it had a reference to another article on shortening the front crossmember. Now I've searched everywhere and can't find it, so now I'm not sure if I was dreaming or if it does exist? If so, can you refer me to what volume number so I can order it. Also I have a 1948 Austin A40 tourer, if you have any suggestions on a particular front crossmember or ideas, that would be greatly appreciated. From memory, front track on Austin is 1221mm, LJ Torana I think is 1321mm but becoming very hard or very expensive to get my hands on. I would prefer to have Commodore stud pattern, but beggars can't be choosers. Keeping in mind I don't have a lot of money to throw at this project. I'm still not sure on motor as yet, tossing up a V8 or a Commodore V6. I would appreciate any help you could give." The response was this;
With regard to narrowing the front
crossmember, a keyword search of my computer files turned up that I had mentioned the possibility quite a few times, but had not done an in depth how-to article. I do recall writing of how I narrowed a HR Holden front
crossmember but it must have been in a
pre-computer issue, or not for
ASR. Note my use of "narrowing" because that is what we are doing when reducing the width and/or track of a component. The most practical
crossmembers to narrow are the L300 and
Torana units due to their relatively
straight across centre sections. Unfortunately I don't have any saved photos but can outline some points to look out for.
Obvious points to keep in mind when working out the amount to narrow the
crossmember is to know what wheel and tyre combination will be mounted and how much clearance to the mudguard lip is required, clearance to the side of the chassis rail when the wheel is turned full lock both ways and clearance between the shocker towers for the chassis rails to slip between. Also check to make sure steering universals and shafts don't end up too close to the chassis rail, or engine for that matter. If you plan notching the
crossmember to sit the chassis rails lower in it, make sure the the rails will still clear the rack boots once all is assembled, otherwise the chassis rail underside will have to be notched for clearance. In most cases this notching is an acceptable practise for front mounted steering, but should be avoided for rear mounted steering due to the chassis loading being higher behind the
crossmember. Less obvious is whether the rack and pinion unit is capable of being shortened by that amount, or indeed practical to shorten at all. With the
Torana IFS and stock rack there is a fair bit of latitude in shortening, but some racks, one piece alloy bodied and/or power racks for example, are more trouble than they are worth. Instead the word around is to search for a rack that has a centre to centre dimension from the pivots either end of the main rack close to what you need and shorten it to suit. Often 10 or so mm either way doesn't make much difference to chassis or guard clearance, but only you with tape measure in hand can be certain of the amount to cut. With limited funds to throw at the A40, the LC-
LJ front end, even though scarce, using the manual
Torana rack would be the simplest to narrow and mount. Narrowing the
Torana style rack has been done seemingly thousands of times and involves basic machining,
sleeving and welding operations that a local engineering shop should be able to handle for you. As for the actual
crossmember, once it is stripped and cleaned I would sketch it noting the dimensions between each lower pivot point, side to side, and likewise the upper points. Measure between the upper shock absorber mount hole centres too and any mounting holes because these will be handy when you are measuring twice, cutting once. These measurements will also be handy for checking once the
crossmember is tack welded together, then after welding. If not an experienced welder then seek out a mate who is, or pay for the service. Before slicing into the
crossmember make up a brace to bolt between the upper mounts and another between the lower pivot point (inner end of the lower suspension arm), but make each shorter by the amount you are narrowing so once the slice is cut out the braces hold it at the correct width.
Having a hefty slab of steel sheet or a sturdy steel plate topped workbench to clamp the
crossmember down to for welding will help too. If the
crossmember doesn't sit flat just weld temporary hold down tabs on it to position it flat. This is difficult without photos and everyone will have a different way of doing it, but whatever you do, don't just cut the
crossmember, trim off the amount to narrow and butt it up again without a jig. Even with a substantial jig, welding distortion is possible. My work around - not the only way - would be to carefully cut the section out so that the
crossmember butts together at the desired width with no gaps. I would then use substantial tack welds at each corner of the cross-section before letting it cool and then using an angle grinder to V along the
unwelded sections ready for final welding. MIG makes it easy to fill wide gaps but in doing so deposits more weld metal to shrink and cause distortion, hence no gaps to start with. Once the main sections are welded go to work with the grinder and grind down and V the original tack welds and finish weld. This takes time to do, but so does
re cutting the
crossmember to realign it. It should go without saying, but I will anyway, practice on scrap sheet metal of the same thickness to make sure you have the
V'ing and welding technique down pat.
Unless you are installing the
Torana/ L300
crossmember solid mounted to function as, or replace, an existing chassis
crossmember, butt welding with good penetration will suffice. Remember that there are two situations where life depends on good penetration and this is one of them. While in fabricating mode consider tack/
spot welding a doubler - second skin - under the
crossmember as reinforcement for the welded joint and stiffen the section that is likely to get deformed each time a floor jack is used to lift the front of the vehicle. The bottom surface of the
crossmember is more critical to the
crossmember's load carrying capacity than the upper or side sections, but if any doubt exists an alternative is to open up the bottom surface sufficient for access to weld strips inside, overlapping the upper and side joints. With the
crossmember opened up you may as weld in a piece of angle or
RHS positioned as a brace to take the floor jack load. Once done replace the cutout bottom surface with a thicker piece ( double the original
gauge ), grind the welds all around and no one would know you have narrowed it. If done to a
Torana IFS, the rack, once shortened the same amount, will bolt on and all geometry will still be as designed by
GMH for a
Torana. Just so I don't get a letter from a steering alignment expert, of course narrowing the
crossmember and therefore bringing the steering arm pivots a like amount closer together will alter the
Ackerman steering angle, as will mounting it under an A40 if the wheelbase differs, but seeing as these
Torana's didn't really have traditional
Ackerman geometry from the factory let's move on.
A40s are no stranger to these pages, although I don't recall writing about the tourer version before. Even front end swaps have been covered including some informative feedback from A40 owners.In
ASR 125 we discussed swapping in a corona IFS and ran a feedback letter from Paul Kelly outlining his experience in installing the LC-
LJ IFS under A40s. Then
in ASR161 Mathew
Boschen updated us on how the Corona RT40 IFS installation was travelling after a year on the road. These issues also touched on rear end and engine swaps amongst other things so if you don't have them place an order. Meantime let me put your mind at ease regarding the
crossmember narrowing. It is not practical for
an A40 installation because the Austin chassis rails only just fit down between the shocker towers of a stock width
Torana crossmember and even then a section of
Torana crossmember each side has to be cut away to let the chassis rails nestle down for a reasonable chassis ride height.
Paul's photo on page 14
ASR 125 gives a clue to how much needs to be cut out - and reinforced with similar gauge plate for strength. Even cut like this Paul says clearance is so tight that the
crossmember needs to be walked into place from the front to install it. From Mathew's letter
in ASR 161 it reads like the Corona
crossmember was an easier bolt in fit, clearing the shocker towers and chassis rails without any cutting needed. One item of note is that the Toyota steering box had to be adapted to the chassis rail, behind the
crossmember whereas the front mount
Torana rack and pinion didn't need any custom mounts.
As you noted the
Torana track is wider than the A40, but as reported it will work if close to standard width and offset 13"
Torana or 14"
HK Holden sized wheels are used. The Corona install likewise limits wheel width with Mathew using 14x5 steel rims. Brake upgrades with Commodore bolt pattern are available from Hoppers Stoppers so your desired wheel bolt pattern won't be a problem on the front, but this is scotched when you get to the rear, unless you are prepared to fund narrowing a Commodore rear end to suit, or widen the rear mudguards. Back in
ASR 161 I proffered " the LC-
LJ rear track at 1275mm is only 18 mm wider than the stock A40" so make sure the new wheels/tyres will clear the rear chassis rails (1023 overall width ) by first measuring between the inner edges of them. Modern wheels protrude inwards more than the A40's, eating up the clearance, so don't just assume the tyres will clear the chassis rails. Also that " if you need more clearance move up to the 97mm wider
LH or later,
Torana Rear end, but this time check to make sure the extra width doesn't push the tyres out past the rear guards". The LC_
LJ and
LH style rear ends will at least match the front bolt pattern, as will a Volvo 140/240 Four banger rear end. Mathew used a RA23
Celica rear end, but it was under a tray back A40 pickup, which has a more open mudguard design, so its width may not be suitable for a tourer. Of these options the Volvo diff would be my choice torque capacity wise for the V8 or Commodore V6 swap you are tossing around.
Note that the A40 owners mentioned chose four cylinder power plants that fit into the engine compartment and clear the front
crossmember easier. These days there are so many four cylinder options available at reasonable prices even power with economy is possible.
Be wary of the Commodore V6 protruding, hammerhead shark shaped, alloy sump which will interfere with the IFS front
crossmember and rear mounted steering, if that's what you fit. A better choice than the Commodore V6 for this swap would be the L36 code BOP 3800 Series 11 V6 used in the equivalent years Buick, Oldsmobile and Pontiac front wheel drive vehicles, as these engines use a stamped steel sump with a shape that better suits the engine bay of a rod, or early Holden for that matter. Local Commodore V6 Series 11 manifolds and transmissions bolt to the BOP V6 so there is no problem using it in a rear wheel drive configuration. If sump interference with steering or front
crossmember is still encountered, then at least being made of steel you don't have to become best mates with an aluminium welder to get it modified to fit. As for the Holden V8 option, of course it can be fitted, but you did mention a limited budget to play with. I would expect a more involved routing of steering shafts and universals as well as over the chassis headers would be needed, due to its bulk, all adding to the cost. On the plus side the V8 has a steel sump and a Volvo diff would probably survive if you are not a throttle warrior. V8 swaps and over the chassis headers have been done before, usually with flip forward fronts to gain clearance, but the reason I scoff at the idea is that you have a very rare car in the tourer version and being of a limited budget it would make sense to keep the body and frame as near to stock as possible, both to save money and to protect your investment. Yes I know the saying that anyone can restore a car , but it takes a real
rodder to cut one up, but doing so to a rare model narrows your pool of potential buyers by excluding restorers. Instead potential buyers are limited to just
rodders, and then it has to be one that shares our A40 Tourer interest. If you where playing with a more common and popular Ford tourer this wouldn't matter. Whatever you decide to do make sure you keep us informed, especially with photos.
Please note that this article was printed with photos and a copy of the magazine Australian Street Rodding 219 should be available to buy at
www.graffitipub.com.au
