Here's the blood. Notice the...
Here's the blood. Notice the small bits of differential housing lying about.
It started innocuously enough. Editor Heath needed a photo for the October cover. Preferring a brightly colored car and fancying an action shot, he thought D6C fit the bill just right. "Can you send me some burnout shots?" he asked.
"Absolutely," I responded.
Turned out, I couldn't.
It wasn't from lack of effort or a dearth of horsepower. No, I'm always up for making a smoke show, and D6C's got plenty of oats to liquefy the hides. In fact, it probably has too much power. And, as it turns out, the big Yokohamas provide too much traction as well. While the drag racers among you may scoff at the notion that anyone can really ever have too much of either, I assure you that when it comes to a certain Daytona Sunset C6, this proved to be the grim truth.
With a suitable location well hidden from the public, and the cameras ready to fire, I sat inside a happily burbling D6C awaiting the thumbs-up from my helpful, photographically inclined friends. With the go sign given, I quickly brought the revs past 2,500 as I released the clutch and-BAM!
Here are the guts. As you're...
Here are the guts. As you're no doubt aware, the ring gear and transmission output shaft are not usually visible under a healthy Corvette. Yep, I done broke it good.
Rather than the prodigious clouds of billowy white smoke everyone expected, the differential housing expressed its dissatisfaction with the whole process by promptly grenading itself. So what sounded like a shotgun being fired underneath the car behind my right elbow was immediately joined by a freewheeling engine bouncing off the rev limiter, a small cloud of blue-gray smoke that definitely wasn't coming from the tires, and the faintly noxious smell of gear oil on hot exhaust.
Now, understand that when I use the term "grenaded," I don't mean that I broke the ring gear or twisted an output shaft. No, D6C literally blew the rear third of the cast-aluminum differential housing clean off.
It turns out that D6C isn't the first '05 Corvette to suffer this fate. It seems this particular model year was cursed with a flimsy design that has proved even more fragile than the Fourth-gen F-body's infamous lead-crystal third member. General Motors was obviously aware of this problem in the Corvette from the get-go, as this housing design lasted just one model year. For 2006, the housing was completely redesigned and has proven substantially more robust.
Great, so just swap in the later-model diff and drive away, right? Well, not exactly. In typical GM fashion, the two cases are not directly interchangeable-or so you might think. The new diff has a revised bolt pattern for mounting to the transmission's intermediate housing. Due to rampant misinformation spread across the Internet, it was, for a time, believed this would prevent the updated differential from being installed in an '05 model.
Our friends at HiTech Motorsport...
Our friends at HiTech Motorsport agreed to replace the shattered differential with a stronger '06 piece further fortified by Zip Products. Once the car is in the air and rear wheels out of the way, the next step is to loosen all the exhaust clamps from the headers back.
Eventually one or two vendors figured out what needed to be done to mate the stronger '06-up unit with the '05 cars. However, at least one of these vendors chose to keep the info to himself and instead offer a radically overpriced kit, the implication being that he was producing a special part that allowed the transplant.
Fortunately for us, there are also vendors who take the high road. One of them is Zip Products. Already known for bulletproof differentials that powered World Challenge Corvette racer Reese Leighton through several seasons, Zip was completely forthcoming when it came to the straight scoop on upgrading the '05 diff.
It turns out that only the transmission intermediate housing needs to be swapped. This is easily accomplished with the trans in the car and can be completed in just 30 minutes. And guess what? The new intermediate housing is the same one found on all '06-up Corvettes. I guess the cat's outta the bag.
So, all in all, it looked as though D6C would be back and stronger than ever in no time. As is often the case, things weren't to be as simple as they seemed. While the car came apart easily enough, you're about to see what else I broke-and it's an even bigger helping of not good.
And no, I didn't even get the burnout photo.