Buying a Half-Cut

Buying a half-cut - the front half of the car containing all the good bits like the engine and gearbox - is an excellent way of getting together all that you need for an engine transplant, or simply as spares for the car you already have. But there are some distinct pitfalls as well.

The Positives

A half-cut exists because it’s much cheaper to cut off the part of the car with the engine than to transport the whole car. In fact, as the name suggests, a half-cut takes up around only half the space of a complete car. However, compared with buying a bare engine and gearbox, it’s much more bulky.

The advantages of buying a half-cut over an engine/gearbox combination are many.

Firstly, you get every mechanical component from the front half of the car. (In mid engine cars, a half-cut is the rear end.) So in addition to the engine and gearbox (and drive shafts in a FWD), you also get:

• The front suspension and brakes

• Complete steering system, including hydraulic or electric power assistance (and usually the steering wheel)

• The engine bay wiring loom and all the relays, igniter modules, etc

• The ECUs for the whole car (which can include power steering , central locking and immobiliser, as well and engine and transmission ECUs)

• The dashboard, including all the switchgear

• The radiator and other front-mount heat exchangers (intercooler, oil cooler, air con condenser)

• Often some external panels and the inner guard, radiator support panel, etc

• Often some exterior lights and other fittings

• The complete underbonnet assembly, already put together (not something to be undervalued!)

If you’re transplanting a new, more powerful engine into your car, a half cut will have the bigger front brakes to match. It will also have everything – the brackets, bolts, cross-member and all the rest that very few wreckers bother salvaging when supplying you with just an engine and gearbox.

The Negatives

So what are the downsides? Firstly, a half cut normally costs something like twice the price of a bare engine/gearbox. That ratio depends a lot on what car you’re buying the bits from, but it’s about right.

Secondly – and this is one not to underestimate – it’s a helluva lot harder to physically deal with a half-cut.

Despite the one shown here being the third that I have bought over the years, this half cut – from a Toyota Prius – was a real doozy. Basically, it was incredibly heavy, which made it near impossible to move around. Bought from interstate, I’d intended picking it up from the local freight depot with a 6x4 trailer, something I’d done in the past. (It’s a top-heavy load but still normally possible if taken very carefully and slowly.) But in this case it would have been dangerous. So that meant delivery by a crane truck – at extra cost, of course.

Then, when I’d expected to be able to put some heavy-duty castors under the pallet on which it arrived, it turned out that to move it around, an engine crane built on a very strong underpinnings was needed. It’s no big deal if you’re prepared, but don’t expect to man-handle a half-cut around like you can an engine.

Another negative is that it’s harder for both you and the wrecker to ascertain the state of the engine. Years ago I bought a Subaru Legacy turbo half-cut – only to find when I got home that the front cam pulleys on the engine had all been broken by a minor front-end impact. And of course, whether the engine crank had kept turning with stationary camshafts was also unknown... It went back to the wrecker – but it was all a hassle.

In this case, the car has obviously suffered a front three-quarters hit, damaging the radiator and the power converter heat exchanger. But I didn’t know that when I bought it sight unseen, and I doubt if the wrecker had spotted it either. It’s also a bit of a hit or miss affair (pun - ho ho) whether or not you get lots of good panels – or none. If you get a pristine set of panels, you can sell them off to defray the cost of the half cut.

Finally, you should know something about the car that you’re buying the half-cut from. In some cars there are very important bits which may be missing, simply because they come from the other end of the car. That might be the gearbox (some rear-wheel-drive, front-engine cars have the gearbox mounted at the back) or as in the case of this car, a high voltage battery that is normally mounted behind the rear seat. As can be seen here, in this case it was included.

Conclusion

When looking at doing a major engine transplant (or other major modifications that might result in broken mechanical items), we’d always recommend buying a half-cut. You just get so many important bits and pieces. But when making the decision to go that way, don’t overlook the negatives.

More of our most popular articles.

Drains and landscaping - and passing council inspection! DIY Tech Features - 9 September, 2008 Building a Home Workshop, Part 5 Why if you're interested in economy or power, you must know about water injection Technical Features - 15 April, 2008 The H2O Way, Part 1 One of the best electronic car modification tricks you ever saw DIY Tech Features - 15 October, 2013 Pots aren't just variable resistors Japan's first supercar Special Features - 8 February, 2008 Toyota 2000GT A new engine designed to extend the range of plug-in hybrid cars Special Features - 8 December, 2009 The Lotus Range Extender Engine The world's brightest flashing bike tail-lights? DIY Tech Features - 18 February, 2008 Building a High Performance LED Lighting System, Part 2 The future of cars - as seen from the 'Fifties! Special Features - 22 November, 2003 Revisited: The GM Concept Cars A brilliant do-it-yourself handheld spotlight or bike headlight DIY Tech Features - 11 February, 2008 Building a High Performance LED Lighting System, Part 1 What's happened to electronic advances in cars? Special Features - 19 May, 2009 Car Electronics Going Nowhere? When not enough current is being produced Technical Features - 14 July, 2009 Upgrading the Alternator