Mark Houlahan
Tech Editor, Mustang Monthly
June 1, 2004
Photos By: Courtesy Of TTC-Tremec
TTC-Tremec's new TKO five-speed overdrive models look similar to the company's previous models, but it's what's inside that'll get you excited. Bolt this bad boy to the back of your engine and be ready to bang gears with confidence.

Horse Sense: The TTC-Tremec engineers worked overtime to give owners of the TKO-500 and TKO-600 transmissions just what they were asking for. With six different part numbers, Ford owners don't have to figure out how to stuff a GM transmission into their Mustang anymore. The Ford models use Ford speed sensors, bolt patterns, and crossmember locations for a bolt-in swap.

So you've finally had it with that T5 in your Mustang. After three rebuilds and numerous other problems, your built-up 306 with a blower just wants to chew up the T5 and spit it out the back of your ride. So, do you spend the bucks on a decent rebuild, or should you put that money toward an aftermarket transmission?

It can be a difficult question to answer, but ultimately you have to make that decision. To be brutally honest, some people just don't know how to drive a manual transmission. Then there are shoddy rebuilds and the do-it-yourself types who only make things worse. On the flip side, there are plenty of people who either don't have enough power or they know how to be delicate with the T5 and have made their transmission last for many years. Again, it's going to be your decision as to if and when you upgrade to an aftermarket manual transmission.

The TKO-500, shown here, uses a 10-spline input shaft and a 3.27 First gear (see Geared for Action sidebar for full ratio listing). Whether you use the TKO-500 and its 10-spline input or the TKO-600 and its 26-spline input, there are numerous clutch choices for street and race use that will work with these two transmissions.

The good news is, when you're ready, the boys at TTC-Tremec have something for you that's going to make you grin from gear to gear! Introduced at the '03 SEMA and PRI trade shows, the new TTC-Tremec TKO-500 and TKO-600 transmissions can handle up to their namesakes in torque capacity. That's 500 or 600 lb-ft-depending on model, vehicle weight, clutch type, and so on-of tire-twisting ability to put behind that stout small-block that propels you down the quarter-mile or the highway.

About two years ago, TTC-Tremec began running focus groups with customers, distributors, and the two racing schools the company sponsors (Bondurant and Panoz). Armed with the results of that feedback, the guys at TTC put on their work clothes and got dirty. These new five-speed-overdrive transmissions were built from the ground up to fit race cars, street cars, vintage cars, and even street rods/kit cars, with multiple installation offerings, shifter locations, and gear ratios.

The TKO-600 model looks similar to the 500 but features revised gear ratios, increased torque capacity, and 0.82 and 0.64 Overdrive availability.

TTC-Tremec's new TKOs feature the famous 83mm-center-distance design of the previous TKO models, but just about everything else is upgraded or improved upon in some way. For example, the countershaft, which was a three-piece design with Woodruff keys, is now an all-new one-piece countershaft. This new countershaft and all the box's gears are made of stronger, 4615-high-alloy steel to take the abuse. The output shaft diameter was also increased to handle the monster torque levels and features a 31-spline output drive. The TKO-500 and TKO-600 also feature completely redesigned shift forks. The new TKO shift forks have a three-pad design (up from the previous two-pad) to virtually eliminate any fork deflection. They are made from steel forgings instead of the pre-vious aluminum design.

Besides engineering brute strength into these gearboxes, TTC-Tremec also wanted to reach as many customers as possible while keeping its product line manageable. The company was able to factor several different mounting points into the case casting to handle most any application. Then, to add the cherry on top of the sundae, TTC designed eight different shifter mounting points (ranging from 14 to 27 inches from the bellhousing) to fit virtually any application, tunnel opening, and driver position.

Considered an optional "GM shifter," this unit features an offset handle that can be positioned 2 inches either side of the main shift rail. While there's no normal application for this in most Fords, this optional shifter might just be the ticket to get the shift lever through the floor in a kit car or street rod, or for building a right-hand-drive vehicle. For race use where a modified floor opening is the norm, the offset shifter might also be an alternative for short-armed racers wanting the shifter closer to them.

But what of the shifter itself? Well, the TTC-Tremec people paid attention to the input from those focus groups, so both the TKO-500 and TKO-600 come with a high-quality billet shifter. The shifter base is billet aluminum for strength and features a variable-rate biasing system so the shifter can be tailored to the user's likeness for shift feel. Combined with a short-throw shaft design, multiple shift-arm mounting points, and a road-noise isolation design, this shifter will challenge the aftermarket to improve upon it. As with all TTC-Tremec transmissions, the shifter does not require shift stops since the transmission itself features shift stops internally.

Other new or upgraded features include both mechanical and electronic speedometer connections (using OE-type connectors for a plug-and-play installation in early and late Mustangs), neutral-safety switch and back-up light switch connections, and tapered roller bearings on all shafts.

The new Tremec TKO-500 and TKO-600 are available in six configurations-three Ford and three GM, to be specific. When ordering a Ford transmission, you'll get the standard short-throw shifter, Ford mounting points, and Ford speed sensor. The TKO-500 features a 10-spline input shaft whereas the TKO-600 features a 26-spline input shaft. Both transmissions come with the aforementioned 31-spline output shaft. TTC recommends GM Synchromesh or Dexron III fluid (3 quarts) for its Tremec transmissions.

Click here for TKO transmission congigurations