N-5: Turbo Hydra-Matic Transmission

Last changed: 23 August 1998

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TURBO HYDRA-MATIC TRANSMISSIONS
FIREBIRD 400, GTO, CATALINA, EXECUTIVE, BONNEVILLE, GRAND PRIX

Turbo Hydra-Matic - Column Shift. Extra-cost option on Firebird 400, GTO, Catalina, Executive, Bonneville and Grand Prix. Designed to match the torque requirements of the powerful V-8 engines, this smooth performing transmission provides quick, responsive shifting throughout the driving range. A torque converter and planetary gear set produce three forward speeds and reverse. Three control connections govern the response of the transmission to driving conditions.

First Control is regulated by the driver when he manually moves the selector lever to the desired position.

Second Control is affected by a vacuum modulator. This vacuum modulator actually senses changes in torque input to the transmission by means of engine vacuum. The result is smooth, fully automatic upshifting or downshifting as required under normal driving conditions.

Third Control takes place when the driver presses the accelerator pedal to the floor at speeds below 70 m.p.h. This opens the throttle fully and activates an electric switch on the carburetor, which causes the transmission to downshift.

Transmission Quadrant. Transmission quadrant incorporates six positions. From left to right, these include P (Park) - normally the best position for starting the engine because the transmission is mechanically locked to prevent the car from moving. R (Reverse) - for backing the car. The selector lever must be lifted

toward the driver to engage this gear. N (Neutral) - disconnects engine from transmission and car can be started. A mechanical lock-out block in the shift linkage prevents accidental selection of reverse from neutral. D (Drive) - the recommended position for all normal forward driving. Depending on car speed, the transmission will upshift and downshift automatically with selector lever in this position. S (Super) - this corresponds to second gear and may be used to good advantage in congested areas and under stop-and-go conditions. L (Low) - this engages first gear only and is used primarily for climbing or descending steep grades or pulling heavy loads.

Note: The transmission can be shifted into Super or Low from Drive position at any speed by manually moving the selector lever. While in Super, the transmission may shift automatically to second gear as car speed increases. When in Low, however, the transmission will remain in first gear regardless of car speed.

Turbo Hydra-Matic - Floor Shift. Available at extra cost on Firebird 400, GTO and Grand Prix, and on Bonneville models equipped with optional bucket front seats. The floor console, standard in Grand Prix, is an extra-cost requirement in all other series when floor shift is specified.

Hurst-Cambell "Dual-Gate" Shift. Available for GTO only. This special feature enables the driver to shift the transmission automatically or manually, depending personal taste. (See pages N-1 and S-2 for transmission and console application, and page F-6 for complete details on the Hurst-Cambell "Dual-Gate" shift.)


TRANSMISSION GEAR RATIOS:
First Gear	...........................	2.48:1 X Converter Ratio
Second Gear	...........................	1.48:1 X Converter Ratio
Third Gear	...........................	1.00:1 X Converter Ratio
Reverse	...........................	2.08:1 X Converter Ratio

Note: Converter ratio in the Turbo Hydra-Matic is 2.05:1 for the standard engines and 2.30:1 for Firebird 400 and GTO (except 2-BBL engine).

N-5

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