Saturday, April 13, 2013

When Engineers Get Bored (or, another small part of why GM went bankrupt...)

2009 Pontiac G5 and 2006 Chevy Cobalt

On its own, engineering a vehicle is no easy task. Every component has to meet conflicting goals of being able to fulfill its purpose (whether it's an exterior part that simply has to look good and not weather fade in six months, or a suspension part that has to survive a decade or more of repetitive salt immersion and continual structural loading) while costing a minimum to produce, and increasingly, it has to do it while being as light as possible while remaining durable enough that it won't fail during its anticipated lifetime. I get this.

Typically, each and every part in an automobile, from the lowliest little clip, to major components like an engine block or body panel, has a part number, and those parts have to be cataloged, inventoried, warehoused, shipped, and carried by their respective dealerships. Imagine the costs involved just in that alone.

So redundancies would seem to be a costly, wasteful proposition, right?

Please note the two cars seen in the photo above. The foreground car is a 2006 Chevrolet Cobalt sedan. In the background is a 2009 Pontiac G5 coupe. Both of these cars are essentially identical, save for the body style (which just happens to vary in these two cars), and some minor trim and fascia parts. Both are built on the same version of GM's corporate platform known as Delta (first sold here as the Saturn ION), very probably in the same facility.

With so much commonality, you would expect that both of them would use identical parts, except where items specific to the two door/four door body and brand-specific differences came into play, right? That would just make sense.

Look a little closer. Notice anything?

One of these things is just like the other (but not)...

These two cars happen to feature an identical 16 inch wheel design (odd, as one is a Pontiac, and one a Chevrolet), fitted with the same 205/55/16 tires size, but they're actually not identical parts; count the wheel-nuts. They use two different bolt patterns. Which means that these cars will have, at the minimum, two different wheel hub/bearing assemblies - at each end, as front and rear are also different - and two different brake rotors (front) or drums (rear). Not to mention the wheels, which are not simply the same wheel with extra holes, as the back side of the casting is unique to each configuration.

Now, in fairness, this 2006 Cobalt has a marginally less powerful version of the same 2.2 litre four cylinder engine used in the 2009 G5 (which may actually have slightly larger rotors), but we're talking less than 10 hp and 5 lb-ft of torque, and in 2006, both four and five-bolt wheels were available in the Cobalt line using the same size brakes. (Later Cobalt SS/Sport and G5 GT models had yet again a different brake set-up, with even larger four-wheel discs.)

So it begs the questions: Who thought that it would be a good idea to engineer and produce two otherwise identical wheels with differing bolt patterns, and - this is the big one - why in hell would you spend the time and resources to create, produce, integrate into the production process, and stock two completely different sets of wheel-end components to meet the same engineering needs in a single vehicle line?

All non-supercharged IONs, even those with the Delta platform's "big" 2.4 litre engine, used four-bolt wheels, so I fail to see any engineering justification, other than perhaps to keep some engineers busy.

On its own, this pointless expenditure would be a drop in the bucket, but enough single drops together can break a dam, and there's little doubt in my mind that this and countless other questionable decisions contributed to GM's financial woes leading into the late 2000's recession and subsequent bailouts. While I'm just as certain that GM is far from being the only company to suffer from this kind of thing, these two cars illustrate the problem brilliantly.

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