Some while back, I bought a 1997 Audi A8 Quattro with a bunch of problems for a little too much money, let's just not talk about how much. Not a lot, but still too much. I've worked through most of them problems, but then had an electrical issue that sent me back to looking for a front-end harness. Long story short, I wound up buying a parts car for $300 and then driving it home in limp mode over the Hopland Grade, like a boss. And since it's nicer than my car, I'm just going ahead and swapping the long-ago-warranty-replaced transmission which I've had fitted with the Transgo main pressure valve fix into the newer, nicer, lower-mileage car. And yesterday, I actually managed to extract the motor and trans from the 1997.
What's interesting about this is not that I'm doing it, but that I'm doing it on gravel. This is an unpleasant place to do the least of automotive jobs at the best of times, not least because of the high chance of having to spend inordinate amounts of time hunting dropped fasteners lost between stones under a car with dodgy lighting. And then there's the fact that nothing can roll around on it, not a jack nor a creeper nor a loaded dolly. In the summer months there's also a massive load of dust involved, but since I live in California and it's been raining pretty heavily for some time, it's quite soggy just now. I'm lying around on (second hand) yoga mats and long plastic tub lids, the latter of which slides surprisingly well on gravel if it's not too deep.
One way that people commonly solve the problem of needing to roll things on gravel is to use plywood. The package of engine+transmission is around nine hundred pounds, though, and at that weight a cherry picker tends to dig into the wood. It also gets contaminated with a variety of chemicals, and the upshot is that you buy a fairly expensive piece of plywood, and then you ruin it. If I'm going to spend money on lumber, I'd rather come up with something that is still useful at the end, and maybe even salable. I went with a wooden gantry.
Technically, I could make a metal gantry. I own a MIG welder, and I can kind of weld. But I trust my ability to bolt together a wooden structure more than I trust my welding, so I searched around the web for wooden gantry designs. What I finally came up with was a video on Youtube depicting a simple yet sturdy-looking design. Some time spent with a wooden beam design calculator and a related capacity of wood column calculator suggested that the design would be best-served with 2x10 gantry beams, and 4x4 columns. Single 4x4 braces keep the columns upright, and are tied to the column by being sandwiched by pieces of 2x6 (which is also used for the bottoms of the legs.) Dual 2x4 braces keep the gantry square, and 1" pipe supports a cheap-as-possible Chinese 1 ton chain hoist. This turned out to be plenty sturdy for this job, including pulling and swinging the motor this way and that in order to clear the vehicle. Pickup loops are cast into the heads, but in order to use them I had to remove the intake manifold, which sadly destroyed the gaskets.
Now I get to yank all my replacement front suspension pieces off of this car and replace them with the original worn-out pieces, which I saved in case I wanted to re-bush them with polyurethane. Then I will take whatever other bits I want (like the seats!) and push the car off to the side to be towed away at my convenience, when I'm sure I don't want anything else from it. Then I get to do it all over again with another car...