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Five Speed Transmission in C3 Corvette (Ratio and online transmission final drive calculator)

When I first got the Corvette, I often wondered just what the heck I'd do with it. What do you do with a muscle car exactly? I thought about autocross or drag racing and all that other silly non-sense, but in the end it settled into just being a really fun vehicle to take on roadtrips. Unfortunately, as I began to take the Corvette on road trips I quickly discovered a major shortcoming of having 400+hp V8 with sidepipes and a 4 speed transmission... this puppy is LOUD on the highway! The engine spun 3,000 rpm @ 70mph in 4th gear with the original Muncie M21. The engine and road noise produce from this combination is enough to induce a headache, along with unnescessarily straining the engine over it's lifetime by keeping it spinning unnecessarily high RPM's for long distances. Oh and the fuel effeciency of spinning the engine up that much isn't exactly great either.

In researching the possibilities, I generated a fairly comprehensive document of the various transmisions, ratios, tire sizes (circumference) and other information to create the document below. This document has been useful in helping me determine which transmission would suit my car the best for the driving I want to do with it.

Google document of ratio calculation (includes possible MPG benefits).

Reviewing the document, it seemed pretty apparent that for myself and my needs, a TKO 600 was the way to go. Your mileage may vary however though (see what I did there?). Your wheel diameter, rear differential ratio, and intended usage will affect your choice. For me, I wanted a nice easy going low first gear for being able to putter around at low speeds in traffic with ease, and having the added bonus of easy rapid launches. I don't drive the car in traffic often, but when it does happen, it's nice not to be wrestling a stiff clutch and a lower ratio first gear.

The TKO 600 is now in the Corvette, and I will provide an ongoing review as time goes on. At the time of this writing I have about 100 miles on the transmission so it's too early to say. I will say the shift pattern is very narrow compared to other transmissions that I've experienced, and I now get why people complain about the 2-3 shift, it's easy to wind up in 5th gear. Beyond that though everything is as expected. First gear is lower, all other gears are similar enough and the gear spread is just right. Overdrive works great for nice and easy highway cruising, and the RPM is just about spot on in my calculator. The Corvette doesn't sound anywhere near as nice in 5th gear when getting on the gas, but that's not the purpose of a 5th gear... it's just there to cruise. 4th gear, and if necessary 3rd gear, is where the fun is at!