1942 - 1947 Chevrolet Shop Manual



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	RIDE CONTROL Shock absorber resistance and action may be altered from standard by changing the relief valve or valves as requirements demand. Ride can be softened by substituting a valve having a larger orifice and weaker spring, or more control may be obtained by using a valve having a smaller orifice and heavier spring. Variations in either direction can also be made by changing either the orifice size or the tension of the spring as the occasion demands. When a larger orifice is used it may be necessary to use a heavier spring so as not to sacrifice the maximum control required for extreme conditions. Likewise there are times when a somewhat smaller orifice with a lighter spring may give better control for certain kinds of service where the maximum control can be reduced slightly. The orifice size, within certain limits, controls the resistance for small movements and the spring tension determines the maximum resistance such as would be required over very rough or wavy roads or high speeds. No set rules can be given on valving for any type of ride as too many conditions enter into this problem. The desired ride must be worked out by experimenting with various valve combinations and observing the results of the changes. The valves as originally installed in production, are designed to give the best results under average conditions, and will be found entirely satisfactory except under the most extreme conditions. SHOCK ABSORBER MAINTENANCE Valves of proper spring strength and orifice size are selected for the particular car or truck after exhaustive tests to give the best possible ride under practically every riding condition. There should be no necessity for making valve changes unless some extraordinary road or load conditions are encountered. In such cases valves for heavier or lighter resistance are available. Only genuine G.M. Shock Insulating Fluid should be used in Chevrolet shock absorbers. Genuine G.M. Shock Insulating Fluid is a mineral oil base with characteristics developed specifically for the proper operation of the Chevrolet shock absorbers. It is non-corrosive and has only a slight viscosity change through a wide range of temperatures. The use of other fluids such as ordinary automobile oil or other makes of shock absorber fluid often causes a gum residue and results in poor lubricating qualities. This results in sticking pistons, clogged valves, and the ultimate failure of shock absorbers. Shock absorbers should be checked every 10,000 miles to be certain that they contain sufficient fluid, and should be completely overhauled every 50,000 miles.	SERVICING SHOCK ABSORBERS Because of special equipment needed for complete disassembly and assembly of shock absorbers, the body, arm, packing glands, camshaft and cam are serviced as a unit. Other service operations may be performed as follows: To Check for Amount of fluid 1. Lubricate car springs and shackles. 2. Check air pressure in tires to see that pressures do not exceed recommended amount. NOTE—In order to obtain a smooth ride, shackles must operate freely and tires must not be over-inflated. 3. Disconnect shock absorber link from axle and pull arm down. NOTE—If the arm conies down easily, part way, then comes to a stop and moves down slowly the rest of the way, there is not enough fluid in the shock absorber. A quick check as to whether or not the shock absorber requires fluid may be made by performing Operations 1 and 2 above, then bouncing each corner of the car up and down in turn. If the shock absorber is in need of service, the car will continue to bounce up and down after the weight exerted to bounce car is released. If this method does not indicate need for service, a more positive check can be made by proceeding with Operation 3 above, WORN OR BROKEN LINKS OR BUSHINGS These parts can be checked for excessive wear by moving absorber arm up and down slightly to determine tightness of bushings or wear in link pins or link pin holes. Also check link or bushing wear by twisting link with pliers or by prying link connection with screw driver or small pinch bar. Outward appearance of bushing or linkage will usually disclose excessive wear. FLUID LEAKAGE Fluid leakage can easily be determined by excessive fluid on outside of shock absorber. The leaking unit should be removed from car for repair or replacement. Where there is excessive leakage, refilling alone will be only a temporary correction because the internal pressure will soon empty the shock absorber again. Leaks at the end caps, valve plugs, or filler plug can usually be eliminated by installing new gaskets. Packing washers on shock absorbers which have been operating with oil below the proper level are