1979 Chevy Corvette - Part 5: Rebuilding the Front Suspension

We rebuild our '79 Corvette front suspension

Chris Petris Jan 28, 2005 0 Comment(s)

We can anticipate the upcoming road test causing a bit of excitement anddisappointment, knowing the engine is a worn-out, gutless slug. But thetight suspension and handling will make up for the lack of power, atleast for a little while. We also haven't had a manual transmission toplay with for a while. The beauty of this project is, after thesuspension and brakes are completed the car can be driven between theremaining phases. This keeps the adrenaline flowing and commitment tofinishing the project top priority.

Now we move on to front suspension overhaul. We'll remove all suspensioncomponents, upper and lower control arms, spindles, steering box,steering linkage, power-steering cylinder, power-steering control valve,and sway bar.

The upper control arms will be replaced with Vette Brakes & Productstubular pieces to increase positive caster, allowing better road feel.Positive caster occurs when the weight of the vehicle is placed on therear of the spindle. If you were to draw a vertical line starting at thelower ball joint to the upper ball joint, the upper ball joint would betoward the rear of the car.

Positive caster biases the front wheels to straight-line driving. Duringcornering, the vehicle's weight must be lifted slightly due to thepositive angle placed on the spindle. This makes steering effortslightly harder but pays off in tighter handling, especially at higherspeeds. The wheels inherently return to center after cornering.

Typically, a minimum of 4 degrees positive caster is required for goodhigh-speed road feel. If possible, 6 degrees positive is preferred foreven better feel at speed. At this point, you should understand casterand handling at high speed.

Negative caster causes a nervous feel--any rut or raised line can pitchyour car from side to side. A shopping cart is a good example ofnegative caster. As you push the cart, the front wheels flutter back andforth. This makes for quick, easy turns when loaded, but it doesn't gostraight.

Caster also controls front-end pull right or left. When aligning thefront end, caster can be offset with one side a little higher tocompensate for the crown of the road or steering-wheel pull. Castershould be kept within 0.50 degree (side to side) during alignment. Lowtire pressure and dragging brake pads can also cause a pull.

The '63-'82 Corvette chassis is susceptible to sagging, causingalignment concerns. When sag occurs, the chassis prevents correct casterand camber adjustments. A dead giveaway is the absence of shims in theupper-control-arm shafts at the alignment bolts. If the alignment shopcannot attain enough caster or camber adjustment, offsetupper-control-arm shafts with rubber bushings are available fromCorvette Central in kit form. Make sure the offset shaft is positionedtoward the outside of the car.

The steering box, often neglected, sits next to the exhaust manifold,cooking the lubricant, especially in big-block cars. The lack of goodlubrication causes drag and eventually bearing failure. The steeringcoupling (or rag joint) can appear to be tight when it's causing a lotof steering-wheel play. We will overhaul the steering box and replacethe coupling for tight steering and control.

While the front suspension is being serviced, the radiator and shroudwill be replaced. The radiator shroud interferes with theupper-control-arm removal process, so this is the time to multitask. Theradiator will be an aluminum replacement and the shroud goes away.

We do not want an engine-driven fan. They rob horsepower and work bestwhen they're needed least. It takes awhile for the A/C temperature torise with an electric fan, but engine-driven fans can't keep up withelectric fans. We're thinking about modifying a '90-'96 Corvettedual-cooling-fan assembly for use with the aluminum radiator. That's inthe next phase, though.

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Look at the number of shims in the upper-control-arm shafts to decide onthe need for offset shafts. The shims have yellow paint forclarification. This stack of shims indicates adequate alignmentadjustment is available. It's a good idea to tape the shims together andmark their location. This allows shim placement in the same area untilan alignment is performed.

If you find no shims, beware. Do a preliminary alignment to determine ifoffset shafts are necessary. The alignment shop may not tell you therewasn't enough adjustment available, and may not know offset shafts areavailable. They'll try to get it close, but your Corvette won't handlewell.

An area of concern is the frame where the spring pocket is located. Manytimes, the welds are broken or metal fatigue leads to cracking. Minoraccident damage leads to buckling and cracks. The entire front framesection should be cleaned well and inspected carefully.

The lower control arm is held at the rear of the frame with the largebolt. The weld from the factory is just adequate. We usually place abead of weld to reinforce the original weld. Many times, the weld isbroken or cracked.

This is the inside of the same lower-control-arm mount with the verticalbracket that attaches to the front crossmember. In some cases, thisbracket is cracked and, in extreme cases, broken off completely. Checkthe weld here also; if it's minimal, run a bead of weld.

This is the inside of the framerail with the steering box removed. Thethree bolt holes are where the through-bolts go into the frame, then thesteering box. Closely check this area of the frame inside and outsidefor cracking. The cracks start from the bolt holes and progress outward.In one case, 90 percent of the framerail was cracked around theperimeter. Usually, when you find one crack from accident damage, morewill follow.

As you can see, the upper-control-arm bushings are shot. The photo alsoshows how close the control arm is to the radiator shroud. It'simpossible to remove the control arm without removing the radiatorshroud.

Never say impossible! The rusty bolt head is the upper-control-armretaining bolt that goes through the frame. The bolt can be tapped outof the frame from the inside where it goes through the control-armshaft. Then the control arm can be removed. The downside is, the bolthas a serrated surface to prevent it from spinning in the frame wheninstalling shims during alignment. Repeated bolt removal makes the boltloose in the frame. Carefully feel the serrations in the frame and bolt,then line it up before tapping it in place, and it will stay tight.

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