Tremec T5 (M49) Features & Benefits
OVERVIEW
The T5 is the five-speed manual workhorse found in the Pontiac Firebird. The unit has demonstrated remarkable longevity since its introduction in the early 1980s. Throughout the last two decades, a series of refinements have enabled this simple transmission to continue providing reliable performance in mid-torque applications.
NEW OR CHANGED FOR 2001 MODEL YEAR
# No changes are scheduled for 2001.
HISTORY
The T5 debuted in GM products with the 1982 model year redesign of the Pontiac Firebird, and it extended to the Chevrolet Camaro the following year. The T5 also saw duty in the S/T trucks throughout the 1980s and up until the 1996 model year.
DOUBLE-CONE SYNCHRONIZERS
The T5 uses double-cone synchronizers at the first and second gear positions. Double-cone synchronizers have friction material on both sides of the synchronizer rings. The extra friction material shares in the workload of accelerating and decelerating driven gears to the desired speed, thus providing a higher energy capacity for shifts. Along with the higher torque capacity comes greatly reduced shift effort given the overall size of the transmission. (The alternative solution for reduced shift effort would be to use larger diameter synchronizers, which would lead to an increase in the overall transmission size.)
CARBON FRICTION MATERIAL
Synchronizer rings on the T5 use a carbon friction lining material, which is more resilient and offers improved high-energy performance. This allows the gearbox to better withstand aggressive shifting and leads to a longer life under high torque load conditions.
POWDER STEEL FORMED BLOCKER RINGS
Blocker rings are an intermediary part between the synchronizer sleeve and the gear face. When the synchronizer sleeve slides over, it first pushes the blocker ring against the gear face, and the blocker acts as a cone clutch to help speed up or slow down the gear to the desired speed prior to the synchronizer sleeve sliding over further to engage the gear.
The T5 uses powder metal blocker rings instead of machined blocker rings. Whereas machined blocker rings are formed by machining away material until a desired shape is attained, powder metal parts are formed by pouring a fine metal powder into a die, which is then subjected to extreme heat and pressure to cause the powder to flow and fuse into a solid material. This process allows for more precise detail on each part and for more consistency between parts than does machining. The result is higher quality throughout the gearbox.
OVERDRIVE SYNCHRONIZER ON THE COUNTERSHAFT
The T5 employs an innovative arrangement of components to ease shifting in all forward gears. The fifth gear synchronizer (also called "overdrive," because the fifth gear ratio is less than 1:1) is located down on the countershaft instead of on the mainshaft with the other synchronizers. When a shift occurs, the synchronizer has to slow down or speed up the entire mass of the free-running transmission components (gears, countershaft, input shaft). Placing the fifth gear synchronizers on the countershaft reduces the reflected inertia of these parts.
Therefore, with each shift, the synchronizers have less work to do, resulting in easier shifting.
NEEDLE BEARINGS UNDER ALL SPEED GEARS
The use of needle bearings under all of the speed gears on the mainshaft results in reduced friction. Needle bearings are made up of a steel or plastic cage that holds many tiny cylindrical rollers or needles, which greatly reduce drag between the gear and the shaft. They also provide for much more efficient lubricant flow.
By comparison, some production car transmissions make do with a journal with an oil passage, and the gear slides on a thin film of oil. Under high-load or high-speed applications it may be difficult to maintain a proper oil film and problems may occur. The reduction in friction provided by the needle bearings results in reduced shift effort and increased high-speed performance.
