Gearstar’s test mule is a 2000 Camaro SS that packs a 444ci C5R-based LS1 with AFR heads,
Muscle car guys can call it character if they please, but there’s nothing fashionable about single-digit gas mileage, subjecting your ears to a NVH beat down, or sweating like an Illinois governor. Late-models are all about knocking down 25 mpg on the way to the track, effortlessly clicking off 10-second passes while you’re there, then cruising back home in a quiet, climate-controlled cabin while the muscle car guys watch in disbelief.
Yeah, baby. The problem is that if your 4L60-equipped fourth-gen actually runs that fast, it won’t be long until the trans goes kaput. Not only is it ridiculously easy to eclipse the 500 hp mark with either an LT1 or LS1 Camaro, the fact that fourth-gens are already anywhere from 7- to 16-years-old—and usually have tons of miles on the clock—only compounds matters. Likewise, even the greatest of transmission builders have a tough time getting 4L60s to survive much past the mid-10-second mark. Perhaps the ideal solution is swapping in a heavy-duty 4L85E, and fortunately, Gearstar has it all figured out.
History has proven that the swap in question is an endeavor that’s very common, yet rarely executed. Instead, hard-core enthusiasts often opt for track-proven three-speeds such as the TH350 and TH400. Some simply adjust to the ignominy of life without overdrive, while others bolt on a Gear Vendors assembly to the tailshaft. Either option works just fine, but the 4L85E combines the best of both worlds. Essentially a TH400 with overdrive and more rugged internals, the GM 4L85E is the ultimate automatic.
When built right, they can handle over 1,000 hp reliably, and best of all, transplanting one into a fourth-gen is much easier than Internet mythology suggests. “People are very intimidated by the 4L85E. They think that swapping it into a fourth-gen requires a lot of fab work, but that’s just not true,” says Zack Farah of Gearstar. “The trans tunnel does not need to be massaged anywhere, and there’s very little cutting involved. It’s not the cheapest option out there, but it’s a long-term solution to a long-term problem, and it’s something you’ll only have to do once. Getting the electronics to work isn’t difficult at all, and you can even set it up with a full-manual valvebody which eliminates the need for a trans computer entirely.”
To see if the swap is as easy as promised, we watched as Gearstar’s technicians went to work on the company’s 2000 Camaro SS. Much sooner than anticipated, the crew was done. We now see a growing population of 4L85E-equipped fourth-gens in the near future, but don’t take our word for it. Read along and make the call for yourself.
Since the 4L85E was designed specifically for LS-series motors, it features a boss at the
The first step in swapping the ultimate overdrive into a fourth-gen is removing the stock
The 4L85E’s greater overall length requires moving the transmission mount location back ro