TECHNICAL
Shifting Evolution
TTC-Tremec’s new TR3650 5-speed combines the shift-ability of the production T45 with the durability of the legendary TR3550
By Donald Farr
When the Bullitt Mustang hit the streets in 2001, there's no arguing that the car had all the right elements for a specialty Mustang – more horsepower, muscular looks, and a lot of neat trim to differentiate it from the regular Mustang GTs. Less obvious, and just barely mentioned in Ford press release literature, is the fact that the Bullitt models were the first Mustangs equipped with TTC-Tremec’s new TR3650 5-speed transmission.
Designed to replace the T45, the TR3650 was the first production-based 5-speed to come out of the merger between Borg-Warner, manufacturer of the T45, and Tremec, a company best known in the Mustang world for its aftermarket Tremec 3350 (including the legendary TKO version) 5-speeds. "In general, the TR3650 represents an evolution of design from several sources," explained TTC’s Kevin Ryan. "With the T45’s T5-similar heritage from Borg-Warner and the Tremec TR3550’s track-proven durability, the design philosophies were combined in the TR3650 to provide extended durability with refined shift-ability and quiet operation." After the TR3650 5-speed’s production debut in the Bullitt Mustang at mid-year 2001, the new transmission also became the standard gearbox in all Mustang GTs and Cobras. It’s also a tremendous upgrade for owners of 1996 to early 2001 Mustangs, especially for the older cars that may be in need of a new transmission and, of course, for performance enthusiasts who require a stouter 5-speed for drag racing or spirited driving.
The TR3650 was designed as a drop-in replacement for the T45, requiring only minor modification to the back-up lamp switch pigtail in electronic speedometer 1999-to-present models because there is no gear-drive speedo in the TR3650.
The new TR3650 incorporates a number of design improvements, including its 360 lb/ft. torque capacity compared to the T45’s 325 lb./ft. This was accomplished primarily by the increase in the center distance from 81mm to 85mm. The TR3650 also provides an increase in synchronizer capacity, with a fully synchronized, constant-mesh , reverse gear train that produces a much more durable and smoother shifting operation over the double-disconnect T45 design, which produced in-consistent shift loads and block-outs. The TR3650s new multi-rail shift linkage, while retaining the track durability of the TR3550, has been refined to provide the enhanced shiftability delivered in the T45. Utilizing state-of-the-art materials, the overall TR3650 package provides increased durability and smoother shifting with lower effort operation.
Adopting TTC’s "Fill for Life" philosophy, the TR3650 uses premium synthetic ATF ( Mobil1 ) as the factory oil fill, as opposed to the Dexron III used in the T45. This change is an improvement that demonstrates TTC’s long-term durability focus for its products.
By taking the best of Borg-Warner’s T45 and the strength of the TR3550, TTC-Tremec has created a production 5-speed that offers both smooth shifting on the street and speed-shifting durability for the track. It’s a great upgrade, not only for 2002 4.6 Mustangs but also as a T45 replacement in earlier models. –MP
Not all '01 Mustangs got the new TR3650 tranny. The easy way to find out if a Mustang is fortified with 3650 goodness is to kneel down and look for the drain plug on the bottom of the tranny. The plug on a T45 is located on the side.
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