SECTION 3 - CREATING THE SUBFRAME

Note: Engineers Certificate - Sorry should have put this up earlier. Towards the end of this chapter (Section 5, I think) I talk about Engineers and certification. Well I should be talking about it here. Or even before you get the halfcut but there wouldn't be a lot to talk about if you don't have an engine. Anyway, once you have the engine talk to an engineer and preferably one that is recognised by your local RTA. They will be able to tell you a few things. One, that's it's possible to get it registered! Two, what's required as far as how you go about creating the subframe and the rest (like the fact that should you do an engine swap it is most likely that you will require a dual circuit braking system, i.e.. separate brake lines front and back. Three, they can probably help you out as far as getting hard to find parts, such as custom driveshafts. I will be talking very soon (actually 5pm today 7 Sept 2004) to an engineer about this project so, I'll let you know how it goes.

PS. In all descriptions on the subframe it is assumed that you are looking from the front of the subframe as it would sit in the car...

Engineers Certificate - The outcome!

Spoke to the Engineer on Friday. This is the process for getting the Engineer's signoff (Only applicable to the ACT, but I hear QLD and a few other states are just as bad if not worse)

Basically as the engineer described to me, this is the process I have to follow:

1. Get an initial inspection done (like the one I did on Sept 10). The engineer then goes away and writes a report about what you are attempting to do. They will pretty much say yay or nay on the spot. Luckily he said yay to my attempt.
2. Once the you have the car close to complete the Engineer will come and do another inspection. And if there are things that need doing then they will tell you and you will have to sort it out.
3. The car is then road tested. I didn't realise it was this involved but essentially I get to go out to the dragstrip and give it a flogging (that will be interesting). Basically they will be testing things such as acceleration, emergency braking (for things like extreme and premature brake lockup) and handling. I explained to the engineer that as far as weight transference is concerned the Starlet engine weighs almost exactly the same from the sources I have found (Starlet 118Kg inc gearbox, Mini 154Kg inc gearbox). This I think would be the greatest concern because obviously a vastly heavier engine would lead to radical changes in suspension load and handling but that doesn't look like it will be a problem. The only possible issue is that the Starlet engine may sit a tad further forward than the Mini engine but I don't think this will be a big problem. There will also be testing done on such things as going through cones etc. Basically if you pass then it is onto the next stage. They are essentially looking to see that the design you have made is up to the task. In some ways dropping a Japanese engine in a Mini is actually more radical than allot of other conversions because you are taking two cars that are miles apart in engineering terms and putting them together. Now you could argue that dropping 454ci Chevy engine in a 1934 Ford is radical but essentially a 34 Ford has a full subframe and loads of space even for a 454. A mini is decently smaller than even a Starlet and differences between the Starlet and a Mini are huge and probably greater than just about any other combination. Plus allot has to do with the way the engines are mounted. Like old Holdens the Mini engine is supported from underneath by two engine mounts. In Starlets the engine has three mounts on three different levels within the engine bay and the engine is supported from the top (suspended).
4. At this stage the Engineer will provide a report outlining essentially that the car does all the basics to an acceptable level e.g.. braking, turning etc.
5. Then you go to the Motor Vehicle Inspector, and unfortunately you can't go to your mate down at your local garage who an authorised inspector (at least I don't think so, the engineer explicitly stated that I have to go to the Motor Registry). I have subsequenly confirmed that it has to be the government boys. They will decide whether it is roadworthy. If they pass it you, then they will issue you with a roadworthy certificate! Easy NOT! And hey presto $600 later, you have a registered car.

Still at least I got past stage one. And I think I should get past stages 2,3 & 4 it is the last stage that could bring this all undone. The engineer indicated that he found the Motor Registry guys to be fair, unfortunately myself and members of the ACT Mini Club have a slightly different appreciation of the situation but I am keeping an open mind!

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Step 1 (OPTIONAL)

Place the engine into the vacant Mini engine bay

Before removing the subframe from the car lower the new engine into the Mini engine bay this give you a good idea of how things fit together inside the Mini engine bay. Before lowering remove the Mini radiator.

You may also like to do some measurements here as to how low in the engine bay the new engine has to go. The Starlet engine without the intercooler is approximately 62 cm from base of sump to topside of fuel rail. I have yet to measure the Mini Engine properly but it is most likely to be as tall if not a shade taller (due to the gearbox in the sump.

Famous Brad has kept the intercooler in the original position and still been able to fit the engine. I am not sure about the Suzuki GTI Engine as obviously I don't have one to measure (pretty similar I would say, though I am pretty sure that they are slightly shorter lengthwise, a smaller gearbox I think). How high it sits is vitally important as obviously you want to be able to close the bonnet but equally you want have the engine as high up off the ground as possible to aid ground clearance. With the intercooler removed this does not become an issue if the driveshaft/diff orientation is correct.

BUT THE SINGLE GREATEST DETERMINATE OF WHERE THE ENGINE SITS IS THE LOCATION OF THE DRIVESHAFTS/DIFFERENTIAL.

You essentially wants these to be horizontal and as close to a straight line from wheel to wheel as possible. Now the thing is (and this only occurred to me after reading Brad's website and also doing some measurements for the diagram adjacent Photo 6) that the Starlet GT has no layshaft, now for the uninitiated, the layshaft is basically and equalising shaft that comes out of the diff to a point equal with offset of the diff on the other side of the engine. See diagram. This layshaft is supported at the end and the driveshaft is then attached to it instead of directly into the diff. This solves the problem of unequal length driveshafts (which creates possible torque steer).

Now the solution the Starlet adopted and it is pretty much par for the course on quite a number of modern japanese engines, and that is differently weighted driveshafts. When you get your engine look at the driveshafts there will be possibly 3 things you will notice. 1. One is thicker than the other 2. One is longer than the other. And 3. The longer one has a balancing collar on it. These are all designed to balance the amount of power that is transmitted through each driveshaft thus suppressing torque steer. I could explain how it does this but we don't have room.

Now a few things I have surmised from doing some measurements of the subframe. The distance between the centre of the driveshaft and the side of the gearbox on the Starlet engine is going to cause a few problems. Obviously I won't know for sure until I have the engine hoisted above the subframe but basically the gearbox seems to hit the tower before the driveshaft can go directly through the driveshaft aperture(See photo 6). Now the almost vertical line in the centre of the image is one side of the box section where the lower and upper suspension arms attach. I really don't want to have to mess with this area if possible. I will report back..

I had a look at brad's site and he seems to have got it in there ok so maybe I am worrying about nothing. We will see. I am still thinking about which way to create the new subframe. I want to put fairly thick spars on either side of the engine bay leading to the front but with the engine very far to the left this will be tricky. there are a couple of ideas I have floating in my head such as spars leading from the bulkhead rather than the suspension towers. Like all things there is always a solution it's just a case of how much you effort you want to go to, to solve it. And as one engineer said to me "Anything is possible it's just a case of how much money you want to spend!".

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Step 2

Create the jig and place the subframe on it.

This is the best way to ensure that when you cut the subframe up nothing moves and will ensure that when you go to place the subframe back in the car it fits! You need to support the subframe in all the places where it would normally bolt onto the chassis of the car. The picture refers. Make this pretty sturdy as you will need it to support not only the subframe but also the engine while you make measurements and finalise welding jobs. The last thing you want with your jig is for it to fall apart while you are working on the subframe. You could try and weld the whole thing up without a jig but I guarantee you it will cause problems. And the engineer seem to take me a whole lot more seriously when I told him I was going to make a jig, when you want precision (and this has to be pretty precise) it is the only way to go. It will also ensure that the frame doesn't warp when you chop the two main spars out of it. Also buy yourself a metre ruler ($12.50 at Supa Cheap Auto). It makes measuring the subframe etc much more accurate than a tape measure)

Now you can elect just to cut it up and weld it back together but I recommend a jig (and so did my engineer) approach if you want to make absolutely sure that everything will go back together and that where you place things like engine mounts are perfect. Your choice...Do you think I feel a jig is the way to go????

Click on picture 3 for a larger view with dimensions and general layout. Now one other thing you may want to think about. This all depends on what type of welding setup you are going to use as some are more finicky than others. I am going the MIG approach as I am pretty new to welding and MIG is reasonably easy (Editor's Note: MIG is not that easy, no welding is it is just a case of practice makes perfect!) to learn compared to some other styles. Well with MIG things like paint, rust, dirt etc make for very poor welds if at all. So I will have to clean the frame thoroughly and possibly remove allot of the paintwork so that I can get a good current working when I go to weld. The closer you have the earth clamp to the weld site the better. Plus I intend to give it a really decent coat of paint when it is finished so this is probably something I will have to do anyway...

Step 1 - Create the front and rear frames. They are basically H frames with the width of each determined by where you are going to mount them front and back. So in other words a "H" frame which is the width between the holes where the subframe attaches at the front of the engine bay. Approximately 26 inches apart. For the rear it is a little trickier as you are aiming to have the uprights match with the centre hole in the cone towers, approximately 30 inches apart. I made each upright exactly 1 metre high. The cross members should be approximate 30 centimetres above the ground rather than central as you need room for the engine to drop through. This will become clear soon enough (refer Photo 4 for view of rear H frame).

Step 2 - Using pieces of wood clamp the two H frame together so that it forms a kind of table (photo 4). Make sure they two crossmembers are equally distanced from front to back. I spaced them approximately 26 inches apart. Enough space that the subframe can bolt to the front and leave a gap between the cone towers and rear frame uprights of approximately an 3cms (photo 5 - see how the upright is not flush against the cone tower)

Step 3 - Drop subframe into jig. Making sure that you have clamped the pieces of wood to the H frames and all is sturdy. Then raise the subframe up so that the cone towers are level with the top of the rear frame uprights. Take two small sections of tube and place them so that they meet up with the centres of the centre holes of the cone towers and then back to the uprights, so that they form an inverted L shape. These are going to support the cone towers so make sure they are correct!

Step 4 - Weld the cone tower arms and then weld a piece going from the front crossmember to the rear one. Don't unclamp the pieces of wood until this has been welded. Also try and make sure that this is in the centre between the two and at 90 degrees to each cross member this will help ensure the whole thing is square.

Step 5 -Weld in upright supports for all four posts going from the cross member to the upright as in photo 6.

Step 6 - Weld in supports for the arms holding the cone tower support arms. This is very important as the arms could easily bend under the weight once both the subframe and engine are supported.

Step 7 - Create metal plates to go inside the cone towers. These are placed inside the cone tower and rest against the ring where the rubber cone sits. A bolt is then passed through the top of the frame arm down through the hole in the cone tower and then through the plate and then a nut tightens the whole thing up. See photo 9 for a better idea. You are welcome to come up with another solution there are plenty I am sure.

Step 8 - Attach the front of the subframe to the front frame uprights. As per photo 7. This can be tricky as you have to make sure you drill holes that are level from one upright to the other and go through the holes in the subframe. Use a pen to mark the holes from the frame and then drill! Also make sure the subframe is level when marking the holes. To know it is level use the engine mount holes as a guide. These should be horizontal, as I found out on inspecting my Mini engine bay that the uprights actually sit at a little bit of angle! Also don't tighten the bolts up too much as the front of the frame is slightly angled and if you straighten it by tightening to much you could buckle the front of the frame!

Step 9 - The rear of the subframe needs to be supported. I did this by running two lengths of pipe approximately 11 inches apart from the front crossmember across the back crossmember to a point equal with the back of the tips of the two rear mounting arms. (see photos 10 - 13)

Step 10 - Create uprights and a crossmember to create bolting points for the rear of the subframe. (see photos 10 - 13)

Step 11 - Weld a base frame around all the feet of the uprights to lock the whole thing together. This will give the jig good strength and ensure nothing moves. You can do this in several ways. Just weld between the feet or create a full rectangular frame (See photo 1 to get an idea of what I mean by rectangular frame) that encompasses all the feet. I am still tossing up about which way to go?

Note:, all measurements are in inches. Why, well simply I found that everything came to a perfect measurement in inches rather than centimetre. For example from the holes in the top of the cone towers to the front spare is almost exactly 16 inches and the width of the towers from centre hole to centre hole is almost exactly 30 inches. This makes sense when you think that the people who designed it were English!!

Below is the subframe almost completed to the bolt in stage. You can see below the supports I have welded in place to support the back of the subframe. At the moment I have only tack welded them in place and will complete seam welds at a later date. As you might have seen I have deviated somewhat from my original design so I will put a schematic up of the final result.

Also you may want to use a small spirit level to also ensure all the uprights are vertical.

Here is the pictures of the completed jig with subframe in place. Now I am ready to start cutting and welding the spars for the new engine. About bloody time too...

Step 3

Lower the COMPLETE engine into the subframe.

Using a hoist lower the complete engine onto the subframe and jig. By complete I mean with alternator, covers, crank pulley, water pump and oil filter and if you have them leave the headers and turbo on as well. Why I hear you ask, well simply because this will give you a better idea of what you have to take out. Rather than guess how far things stick out.

This is more a consideration at the front of the subframe than the back, for the most part as there is little clutter at the back apart from the diff and the fuel rail but there is a hollow space between these which should allow for the bulkhead. Where as at the front there is the oil filter, turbo and exhaust manifold, alternator, and coming from the front the radiator and if you choose the front mount intercooler, that as well (see photos 6 & 7). So as you can see it gets a little congested at the front. This should make for some interesting solution ideas.

You must get the engine as horizontal and vertical as possible. Then slowly lower onto the subframe. Obviously, with the spars still in place you cannot move the engine down into the subframe. This is more a case of getting an idea of how it will sit. Now that you have access all round you can start to get an idea of where you have to remove metal and add it. The most obvious places are the front bar and the left and right hand spars of the frame (with frame facing you).

My solution to the front bar is similar to many other people's. And that is to follow the front apron. i.e. move the section of bar corresponding to the gap at the front of the apron forward and then join this up in parallel with the remainder of the front spar. Basically you moving this portion forward while leaving the sections where they bolt to the front in place, as indicated in the image below. If you are wondering why the connecting bars come in at an angle this is because the supports for the front mounts are angled as well.

This is important as this also the place where your tie rods that go to bottom suspension arms mount and these need to be secure. I am also going to augment the tie rod mounts as part of this process (in extreme situation they have been known to rip out!).

Below is a step by step description with pictures of what I removed and replaced. And in the next few steps is a diagram showing distances and where to put what.

This is rough approximation of how the engine sits in the Mini. Based on overall measurements of the Starlet engine and the Mini engine bay (guide only). More exacting details will be forthcoming when I get that far...

Step 4

Mark areas for removal and make measurements

Using something that leaves a visible mark and can write on rough surfaces and is permanent. Don't worry in all likelihood you are going to respray the frame once you have done all welding anyway. My pick is one of those gold paint pens, works well, highly visible. Opposite is a picture of the frame all scribbled on. While it looks rough it is mainly just a guide. It just saves you cutting and then checking and then cutting etc etc. To use the old carpenters saying "Measure twice and cut once!"

Now it is time to get the angle grinder out!

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A rough approximation of what you have to remove.

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What you should be left with...

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Step 5

Remove excess metal from the frame

Essentially there isn't a great deal of science to this one. Basically assuming you have created a jig for the subframe (and even if you haven't) you want to remove both left and right spars from the cone tower forward (See photos 1 & 2). This should leave you with the front spar and the rear section of the subframe with a gaping hole left to right. Lower the engine back into the subframe.

Make sure that engine is perfectly vertical but also perfectly horizontal. To determine just how low you should go mark the mid point of the driveshaft apertures (see last photo if you are not sure what I mean). You are trying to line of the centre of the diff outputs with the centre of the aperture for the driveshafts on either side of the cone towers (see photo 3).

One thing to consider with the front spar is that if you remove the side spars and most of the front spar is that you will end up with the two mounting points and the tie rod flanges floating around. Therefore you have to create some kind of support for them. As you will send in the next step (see image 2 in the next step) I devised some rods of mild steel which I tack welded to the tie rod flanges to keep the whole section in place.

Once this is all accomplished, and don't stop until you are sure that these are all correct (a great deal of tears could follow otherwise!), start marking things up. This is another reason to use a jig as you have something to mark off against. I am going to use string and a little brickie's string level to aid accuracy. I am also going to make a simulation (out of wood) of the bulk head where the subframe attaches so that I have a rough idea where the fuel rail of the EFI unit will go. I bet by now you think I am pretty anal about this and yeah I probably am...

As you move the engine to the back you most likely find that the diff housing will impinge on the rear webbing of the subframe (but only slightly). Now to get you back in the game requires the use of the trusty angle grinder (again!). But be judicious with this as you don't want to sever the webbing completely, at least not yet. What you can do is think about welding in frame supports between the two cone towers right now and you can sever the webbing as much as you like to make room for the diff. This is how I will proceed.

Now using pieces of wood or anything else you have, create the spars for the new frame concentrating on meeting up with the engine mounts. Now the left and the front mounts are the most important and easiest to get at and also create mounts for. But the rear one will be more difficult to measure up and create a mount for.

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Step 6

Cut the frame rails

Opposite is a series of images showing what has been removed from the frame step by step. Now you wil notice in Image 2 that there is the tie rod mount with a rod of metal coming from it. This is because I realised that without support once I cut the all the connecting members away the tie rod mount would just flap aroudn which would make it difficult to ensure that is was located back to the exact spot in relation to the subframe when I went to weld it back into place.

So I just make up some rod that connected across the face of the flange and then down the side of the jig.

Also you will notice I left a bit of metal on the cone towers. This will probably have to be removed completely so that the whole side of the tower is flat. Went through about 6 cutting discs chopping it all out! In Image 6 you will see the finish product after cutting.

In the next step on Conversion Page 3 Step 2 you will hopefully see the engine sitting in the frame. Once it is in then you can start thinking about where the spars for the frame have to go and what they have to avoid like the oil filter on the left hand side and the engine mount on the right. The right engine mount could be tricky but not impossible. I have several ideas floating around in my head on how to tackle that one.

If you look in the bottom right hand corner of Image 1 you can see the 35mm tube steel that I bought to make the subframe. Welding tube steel as most welders will tell you is quite a bit trickier than square section, but it is also much stronger than square sections of tube and looks funkier (in my humble opinion). Let's see if I am up for the challenge.