1956 - 1957 Corvette: Service News: Servicing Corvette Heavy Duty Brakes

Model Year: 1956 1957
Subject: Servicing Corvette Heavy Duty Brakes
Source: Chevrolet Service News
Number: Volume 29, Number 10, Page 1.
Date: October, 1957

A Heavy Duty Brake and Suspension option is used on many 1957 Corvettes equipped with the 270 H.P. (dual four barrel carburetor) or the 283 H.P. (fuel injection) engines. This regular production option includes heavy duty front and rear suspension components, special rear axle units and vented brakes with special lining material.

A Corvette with this equipment may be readily identified by examining the brakes. The drums are wider than standard and have external fins. In addition, the brake flange plates are equipped with air scoops.

Brakes

The heavy duty brakes utilize ceramic-metallic brake lining, finned drums, vented flanged plates, adjustable anchor pins, and air ducts for cooling.

The segmented brake linings are 2 1/2" wide on front wheels and 2" wide on rear wheels. Brake drums are 11" in diameter.

Serviceman must be especially careful to use only specified replacement parts when servicing these brakes. In most cases, standard passenger car service procedures apply with the exception of the minor and major brake adjustments.

Minor Brake Adjustment

The minor brake adjustment is made in the same manner as with conventional brakes with the exception that the adjusting screw must be backed off 27-32 notches to provide proper running clearance.

NOTE: Some 1956 Corvette models equipped with conventional flange plate and drum have ceramic-metallic facings of the same width as the original facings. These require an adjustment back-off of 35 notches.

CAUTION: The above adjustments will produce a slightly low pedal for normal driving, but must be maintained to give the proper clearance for heavy-duty operation.

Major Brake Adjustment

A major brake adjustment, performed on adjustable anchor pin, is necessary only when an unequal or severe braking condition is present.

The procedure is as follows:

Loosen anchor pin just enough so that pin can be shift3ed in anchor plate.
CAUTION: Do not loosen pin excessively, as the pin may then tilt instead of shift.
Turn brake adjusting screw to expand brake shoes until a heavy drag is felt on the drum.
Tap anchor pin and flange plate to allow shoes to center in drum. If the drag on the drum decreases, expand the shoes a few notches and repeat the tapping operation. When the drag remains constant, tighten the anchor pin nut to 60-80 ft. lbs.
Adjust brake shoes to a light drag and back off 27-32 notches.

Front Suspension

Front suspension changes include high-rate coil springs, large 1 3/8" shock absorbers with stiffer valving, a heavier, 13/16" dia. stabilizer bar and a fast steering adapter. The fast steering adapter changes the overall steering ratio from 21.1: to 16.3:1.

The above changes from standard production affect service only in the matter of part numbers of pieces to be replaced. The basic procedures, except for wheel alignment and simple replacement of the steering adapter, are similar to those of the 1954 Passenger Car. Reference should be made to the 1949-1954 Passenger Car Shop Manual.

Rear Suspension

Rear suspension changes include heavy 5 leaf rear springs and large 1 3/8" shock absorbers with stiffer valving. Positraction differentials are used in all rear axles. The axle housing incorporates special baffles and vent tube to control lubricant during fast cornering.

By using 1957 Passenger Car procedures, no special problems should be encountered in servicing the Corvette rear suspension.