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Posts Tagged ‘suspension’

Rear Axle Bumpers

Thursday, February 11th, 2010

The placement of rear axle bumpers by GM on 1/2 tons proved to be an important feature. Owners can often load cargo over recommended weights, their shock absorbers may lose their resistance, and there is the existence of uneven road surfaces. All this can make axle bumpers very important.

During the hauling of freight, these bumpers occasionally stop metal to metal contact between the frame rails and the axle housing. GM placed them just above the rear axle.
See photos.

rear axle bumper

1947-1953 1/2 ton (above)

In 1954 GM increased the depth of the 1/2 ton pickup bed from 15″ to 18″. To do this they lowered the frame rail arch above the rear axle. This shortage of space caused the bumper to be placed at the side of the frame but still above the axle.

rear axle bumper

1954 1/2 ton (above)

Early Leaf Springs

Thursday, February 11th, 2010

Leaf spring width on 1/2 ton pickups remained at 1 3/4 inches until the introduction of the two inch width on the Task Force 1/2 tons in mid 1955. The early narrow springs worked well considering the engine horsepower and weight limitations of the 1/2 tons. The two inch springs became standard equipment on the rear of the 3/4 ton in 1946 but their fronts still remained the smaller size. This is because the increased weight carrying ability of the 3/4 ton is mostly felt in the rear. Only 1 ton and heavier were totally without the 1 3/4 inch springs.

With the abuse given pickups in the early days (poor roads, overloading, and almost no lubrication), the springs have held up well. Most mid 1955 and older 1/2 tons continue to operate with their tired original narrow springs.

In today’s world a new variable exists that puts even more demands on these small springs. It is the increased horsepower of later model engines. No problem if these trucks, converted to more powerful engines, are driven as if they still have their original six cylinder. However, problems arise with jack rabbit starts with or with a heavy freight load. Most of these Advance Design 1/2 ton’s with transplanted V-8’s have had their original closed drive shafts replaced with open systems. The replacement axle housings are clamped to the 1 3/4 inch rear springs. When heavy acceleration is forced on these modified trucks, the axle housings try to rotate due to the extra torque. Much of this movement is held in check by these narrow springs. They just weren’t designed for this. Breakage and permanent bending can occur.

Don’t push your 1 3/4 inch rear leaf springs beyond their limits. If you demand fast acceleration with your V-8 1/2 ton, convert to later model 2″ or 2 1/2″ springs. Check specialized suppliers, including Jim Carters Truck Parts (part # HP580), for add-on kits.

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Low Cost Front Suspension Upgrade

Thursday, February 11th, 2010

The straight axle ½ ton GM pickups (1959 and older) were built tough! They served their purpose as the best in work vehicles for over 30 years. Other than an occasional kingpin replacement, they were almost ‘bullet proof’.

In today’s world, the reasons for owning an older truck, has generally changed. Most have been retired from work responsibilities and have become ‘fun trucks’ driven with care on smooth streets. Hauling merchandise is far down the list of their use.

The resulting demand for a smoother ride and better braking is the reason for many suspension options available from supply houses. For those willing to compromise on originality for an easier ride, one of the most proven and less expensive upgrades is the front suspension of the AMC Pacer. The price is right and the results are excellent. This coil spring rack and pinion front suspension assembly gives passenger steering and ride qualities.

A specialized adapter plate (available from the catalog on this web site, HP127) allows for the connection to your ½ ton truck. Instructions explain parts to remove from the Pacer assembly before the plate is welded in place. The total assembly is then bolted to the truck front cross member. No cutting on your truck! You can even trim the Pacer coil springs to get a lowered level on the total vehicle.

The adapter plate is not expensive. The main project is locating a good Pacer front suspension. This AMC vehicle was produced between 1975 and about 1982. The later years even had disc brakes.

low cost 1

AMC Pacer (above)

low cost 2

1947-1953 Advance Design (above)

Lever Action Shock Absorbers

Thursday, February 11th, 2010

 

lever action shock

Early Rear Axle Bumper

Thursday, February 11th, 2010

Mechanical components on trucks were usually kept for many years by GM. Unless an improvement was needed, there was no need to change a proven design.

early axle 1

An excellent example of this is the rear ½ ton axle bumper. The design was used from 1929 through 1946 on Chevrolet and GMC ½ tons. A rubber bumper is held down on the rear axle housing by a metal cover with two ears. These ears are firmly secured by the two u-bolts that connect the leaf spring to the round axle housing. If the truck is overloaded or the shock absorbers are worn, the rubber bumper prevents metal to metal contact between the axle and frame rail.

Two of the attached photos show an original used retainer with bumper in place. The black bumper (now reproduced) is how the rubber part looks when new.

early axle 2

early axle 3

early axle 4

early axle 5