All 3-speed and 3-speed with overdrive transmissions have a bell crank idler added to the second and third gear linkage to reduce linkage reaction to engine torque roll.

CORVETTE

The optional 4-speed transmission features a manually controlled reverse lock-out which eliminates any possibility of accidental reverse engagement during ratio selections.

TRUCK

The 4-speed truck transmission now has a lip type clutch gear oil seal to prevent oil leakage into engine clutch. The clutch gear, bearing retainer and seal assembly, bearing retainer gaskets, bearing retainer ring and synchronizer cone and transmission case are changed to permit this seal installation.

An important addition to the line is a Clark, model 267V, five speed synchromesh transmission. This unit is available with the 2-barrel 348 cubic inch engine on the 70 and 80 series models. The closely stepped shifting pattern achieves high performance in highway truck or tractor operations. Constant mesh helical gear, synchronized in the top four speeds, provide smooth, quiet shifting. First and reverse gears are the straight spur type.

Gear ratios in the Clark transmission are as follows:

Automatic Transmissions

PASSENGER CAR

Balance markings are used on 1959 engines and automatic transmissions to provide closer indexing of these components and improve engine-transmission balance conditions.

All the flywheels used with automatic transmissions will have a "white" paint mark on the outer rim, on the transmission side, to indicate "heavy" side of engine.

All automatic transmissions will have a stripe painted across the ends of both converter cover and housing, to denote the "light" side of the transmission.

These paint markings are to be aligned as closely as possible during assembly of transmission to engine.

The V-8 and L-6 flywheel assemblies to be used with the Powerglide transmission also have been changed to provide six transmission attaching holes instead of three. The three holes have been added to permit more accurate indexing of the converter to flywheel. The actual attachment, however, will remain the three bolt type as in the past.

TURBOGLIDE

Converter Section

To provide greater durability, the second turbine has a five-spoke design hub, replacing the previous 3-spoke design.

Second turbine shaft durability is improved by the use of new support bearings. The new bearings are located in each end of the stationary stator support shaft, and it is their function to maintain concentricity of the two shafts as well as support the loads on the second turbine shaft.

The improved front bearings permit an increase in turbine shaft minimum section, since it also functionally replaces the iron ring defining one end of the stator oil pressure exhaust passage. The new bearing added at the rear of the stator support shaft is grooved to permit stator oil flow past that point.

Reverse Clutch

The reverse clutch, a cone type design in 1958, is now a multiple disc type (Fig. 12). The larger mass and frictional area of the disc clutch permits it to dissipate heat much more readily, contributing greatly to longer clutch life particularly under conditions requiring rocking of the car from Drive to Reverse.

The new reverse clutch has six active faces and utilizes a diaphragm spring as a return spring and as a polar lever to multiply the "apply effort" of its piston. The driven plates are faced with a non metallic compound, the pressure plate is of sintered iron, and the reaction plates are made of steel.

Fig. 12 - Turboglide Reverse Clutch

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