When Project g/28 started out, we were on a tight budget to hit our goals. Given this, the choice of a more wallet-friendly TH350 automatic transmission was the right way to go; it was built to handle all we could throw at it, even at the road course. About the only downside was that driving the car on the freeway with 3.73 gears was about as much fun as a root canal. We had been toying with the idea of installing a manual transmission,but we knew the task would be daunting since we would have to find linkage, a cross-member and all other minutia required to make the swap happen. Then in a chance encounter with Keisler Engineering, the company mentioned it had developed a complete swap kit for our '76 Camaro and we should give it a try. We no longer had to worry about chasing parts from a dozen companies, hoping they worked together, so the decision was made to pull the trigger and get the kit.
The Keisler kit is optimistically called the "Perfect Fit" kit, but we were a little hesitant to believe the marketing pitch. We have installed enough stuff to know that nothing fits perfectly, but if it were close, we would still be happy campers. After talking with Keisler, we decided to go with the Tremec TKO-600 transmission, which is rated to handle 600 ft-lbs of torque, since it had a gearing ratio that would work better with our setup. The .64 Fifth gear would make cruising the highways a breeze and the 2.87 First gear would work well with our 3.73 rearend gears. They also offer a TKO-500, which is rated to handle 500 ft-lbs of torque due to its more-aggressive First gear ratio of 3.27, for a couple hundred bucks less than the TKO-600. Also, its Fifth gear ratio of .68 is a tad less mileage friendly. Keisler offers these kits for a wide range of cars including GMs, Fords and Mopars. For some applications, they even have kits to swap in T56 six-speeds.
With the plan in motion, we took some measurements of g/28's driveshaft and answered a few questions about the engine currently in the car. (Our 383 was internally balanced, dictating a zero-balance flywheel). With gas prices over three bucks a gallon for the cheap stuff, we were anxious to get started. We also decided this was a great time to stiffen up the Camaro with a set of Global West subframe connectors and replace the worn-out 30-year-old bushings with some solid units.
Two weeks later, the parts showed up on our doorstep and we drove the Camaro over to Don Lee Auto in Cucamonga, California, where the owner, Tim Lee, is always happy to lend us a hand, and more importantly, one of his lifts. Check out the photos for the high points of the installation, which took just two days, not including time for the unrelated body bushing and subframe connector installation. This is clearly a job for the advanced mechanic, although the TKO kit has been installed time and again by the DIY guy in his driveway. We do recommend a lift, however.
Prior to the TKO install, gas mileage was firmly mired in the 11 to 12 mpg range. It's not so much that our mild 383 was a gas hog, but that the 3.73 gears and loose converter kept engine rpm in the stratosphere. Rolling along at a glacial 55 mph had the engine cranking 3,000 rpm. We can now cruise at 70 mph with the tach at a more reasonable 2,000 rpm. This huge difference is the result of the engine turning 36 percent fewer revs, and that's assuming the converter was locked to start with (it wasn't). Account for 5 to 10 percent more rpm from converter slippage with the old TH350, and the difference is even higher. We guess you could say we weren't surprised that we got a 33 percent improvement in fuel economy, from 12 mpg to 16 mpg-and that was with a heavy right foot.
But there is another dimension to an overdrive transmission. Pistons, rings, guides, valve seats, valvesprings, cylinder bores and bearings all have a finite life expectancy, so an overdrive transmission like the Keisler Perfect Fit TKO can literally add years to the life of an engine. Even without the added fuel economy, a typical hot street engine with a 50,000-mile life-cycle may last another 10K or 15K miles, and that's cash in the bank.
Lastly, the frenetic pitch inside the cockpit has been lowered from "deafening" to a dull roar. We can now hear a cellphone ring, although we're not sure that's a good thing. At least it's now possible to hold a conversation with a passenger without getting a sore throat.
And the performance? With a 2.87:1 First and 3.73 rear cogs, g/28 lays rubber like a champ. Then there's the simple fact that five gears are better than three, because it's easier to keep the engine in its power band when you want it. The mathematics of gear multiplication will have to suffice for now until we get it to the track for some real numbers (the outgoing TH350 had a First gear of 2.52 versus the TKO's 2.87, so you can imagine how much sharper the acceleration is). We're itching to try it out at the road course, but we've got a few more unrelated things to fix first. There is plenty to talk about on the up side, stuff like better fuel economy, longer powertrain durability, lower cabin noise and added performance. If you already have a manual trans in your ride, the cost of the Perfect Fit TKO kit is under $3,000, so it's an easy pill to swallow. If you are converting from an automatic tranny, there are a few more parts needed like a bellhousing, clutch, and pedals. This bumps the price up to $3,995 for mechanical linkage and $4,299 if you want to switch to hydraulics like we did. There simply is no down side to it, unless you don't know how to drive a stick. We'd have to say it's the best money you can spend on your car.