This is the article where we tell you that 10-bolt in the STI Killer finally broke and you get to write us letters saying, “we told you so!” And, that’s fine; bring on the mail. Seriously, I like getting mail…send it. Regarding the business at hand, if you recall, the Killer has been running a factory supplied 10-bolt since the beginning (we originally built it in the August 2010 issue) and it’s been stuffed with the best goodies we could find, and even narrowed for our new wheels, for the entirety of the project’s life. But, for all that was great about the little 7.625-inch rear, it eventually did what they all seem to do and managed to chip a couple of teeth off the ring and pinion. Unlike many a 10-bolt of the past, we managed to do this one on a particularly nasty downshift (no brakes into a hairpin at Sebring) and still got lucky enough to take the car to the CHP Nationals and make a couple of passes before the rear said goodbye for good. Physical carnage aside, we never really got to launch the car hard at the track, and we always knew it was just a matter of time before this happened, so there really was no love lost seeing the ol’ rusty 10-bolt head on out the door, even if we knew it meant hearing “I told you so” from every e-thug with an email account.
But where we’re headed now, we’re not ever going to have to worry about the rear end situation again, thanks to the highly regarded rear end specialists at Strange Engineering. After a quick call to J.C. Cascio at Strange, we were sold on the idea of an S60 for the Killer, even though it seemed a bit like overkill at the start. Up front, the weight seemed tremendous, with the cast iron S60 ringing in at over 200-pounds fully assembled. But, to be fair, that’s only 15-pounds more than a 9-inch, and just 25 more than a 12-bolt, and the advantages really do speak for themselves. First, lets look at the housing itself, which has been cast by Strange specifically for several applications, including the late model F-body. What you get is a bolt-on nodular iron housing with beefy torque arm mounting provisions that was designed “to be more rigid through the use of computer modeling for improved durability and quieter, long-lasting gears.” Inside the S60, Strange offers a variety of differential and ring and pinion options, although we chose to run with the company’s Strange Trac helical differential, 4.10:1 ring and pinion, and 35-spline axles. Unlike a traditional Posi unit, the Strange Trac features six massive pinion gears to control differential action, instead of clutch packs, which can wear out over time, and is positioned as an excellent unit for street/strip, road racing, autocross, and drift cars, which pretty much sums up the Killer in a nutshell. The 4.10:1 ring and pinion matches our old gear ratio, which we loved around Sebring, and the 35-spline axles are an obvious upgrade over the 28-spline units we had before.