Installing Aldan Coil-Over Shocks on a ’66 Chevelle

One benefit of the Pro Touring movement is an appreciation for a performance suspension. Car guys now think both in terms of more power and how to improve suspension control with components like shocks, springs, anti-roll bars, and tubular control arms. While in the beginning stages of our ’66 SS396 Chevelle chassis restoration we decided to upgrade the suspension with an Aldan coil-over chock conversion.

Looking back at the original configuration of this Chevelle, the suspension now seems archaic. From the factory, this car came with a 360-horsepower 396 big-block, Muncie four-speed, tiny 9-1/2-inch drum brakes, weak springs and shocks, and a pitiful manual steering box. We’ve upgraded to ’68-’72 disc brakes, a quick ratio steering box and now it was time to think about shocks and springs.

Initially, we partially reassembled the front and rear suspension with Global West upper front and tubular lower rear control arms but didn’t torque everything in place. This allowed us to quickly disassemble the original package and install the Aldan coil-overs. We’ll run through the normal installation procedure to reveal how easy this conversion really is along with some additional information on front suspension alignment.

Reasoning For Rebound

To increase the overall suspension tunability, besides the ability to easily change ride height, these Aldan shocks are also adjustable. This means that via the small adjustment wheel on each shock absorber can modify the stiffness to adjust for handling or to massage the ride quality. For this application, the front shocks are single-adjustable for compression only, which means that the knob adjusts valving stiffness only when the rod moves into the shock, as when responding to a bump.

The rear shocks are also single-adjustable but in this case only in rebound (extension). Aldan also currently offers double-adjustable shocks for the rear and should have double-adjustables for the front by the time this story is published. As their name implies, double-adjustable shocks allow independent adjustment of both the compression and rebound valving.

Of course, one main advantage of coil-overs is that ride height can be easily and quickly altered. But keep in mind that a change of ride height either at the front or the rear will affect the front-end alignment. Ride height changes at the front will generally affect all three settings of camber, caster, and toe.

A change to rear ride height will mostly affect caster.  Lowering the rear will add negative caster. Positive caster is the rearward tilt of the top of the front spindle and generally improves high-speed stability. Stated another way, lowering the rear will decrease the amount of positive caster and can decrease high-speed stability.  It’s important to keep these changes in mind when altering ride height.

Camber, Caster, and Toe... Oh my!

The three main measurements when it comes to the alignment of your wheel and tire to the chassis are camber, caster, and toe. Each of these settings has benefits and drawbacks, discussion of which could take a whole article in itself. So here are the basic definitions of the terms:

Camber is the tilt of the wheel vertically, inward or outward from the center of the car. Positive camber puts the top of the tire out further than the bottom of the tire. Negative camber is when the top of the tire is more inboard than the bottom of the tire.

Caster is the vertical tilt of the axis around which the wheel rotates when turning left or right. Zero caster would mean the axis is perfectly vertical. Positive caster would lean the top of the axis rearward, while negative caster would put the top of the axis in front of the center of the wheel.

Toe angle is the direction of the leading edge of the wheel and tire in comparison to the opposite wheel and tire. Toe out (or negative toe) would mean that when the steering wheel is centered, both front wheels point outward. Toe in (or positive toe) is the opposite, with the front of the tires pointed inward.

We’ve also included a generic front suspension alignment recommendation for 1960s and ‘70s muscle cars that will both improve handling while not drastically affecting tire wear. Many ‘60s cars used very low positive caster and actually positive camber as stock alignment specs. We’re not sure why these specs were called out this way as the result is only to increase the car’s tendency to understeer quite badly.

This entire conversion can easily be done in your driveway with some simple hand tools and we were pleasantly surprised at how easy the process really was. So follow along as we show you how to upgrade a mid-’60s suspension to coil-over status with adjustable shocks.

The front coil-over kit is fairly simple. Note how the spring is wound with a large diameter on one end that fits inside the factory frame upper spring pocket and tapers down to fit the smaller diameter shock mount at the bottom.

The rear kit employs a few more components including new upper and lower brackets. The lower bracket distributes the load through to the lower control arm bracket instead of at the original shock mount. This also repositions the shock in a more vertical position, which is a positive step that improves inboard rear tire clearance on these cars.

Rear Installation

The first step is to measure the original ride height at all four corners. This offers a reference point from which to start in case you want to lower either the front or the rear. Keep in mind that even changing the rear ride height will affect front-end alignment.

We started with the rear by setting the frame on jack stands, placing a floor jack under the rear end, removing the tires and one rear shock, which was followed by the rear spring.

We installed the lower bracket first to the lower control arm with the new, longer grade-8 bolt supplied in the kit. The bracket’s proper orientation is with the coil-over mount facing inward.  We left all bolts loose until the entire rear suspension was converted.

The factory upper shock mount holes are 5/16-inch and need to be drilled to 3/8-inch for the new upper mount bolts. We set the upper shock mount with the bolts positioned facing upwards, as that allows the large horizontal bolt to be installed and also offer additional clearance to tighten the 3/8-inch bolts. Because the body was not in place, we discovered it was easier to install the lower shock mount through-bolt first and then place the entire upper bracket into the frame at the top.

Once the entire shock assembly was in place, we torqued the lower bracket bolts to 75 lb-ft and the 3/8-inch upper bolts to 20 lb-ft.

Both front and rear shocks were also fitted with Aldan’s optional thrust bearings that make turning the adjuster easier as the spring compresses.

Final ride-height adjustments will be made with Aldan’s special tool that comes with the kit.

The final result.

Here’s the completed coil-over conversion. We may trim the upper bolts slightly to ensure they do not come in contact with the body. One additional advantage to this system on early Chevelles is that the lower shock mount is moved inboard, creating much more clearance to the inboard tire sidewall compared to the original factory location.

Front Installation

We started the front conversion by removing the front shocks.

To allow easy access to the lower control arm, we removed the end link from each lower control arm and pushed the anti-roll bar up out of the way.

One quick way to release the lower ball joint from the spindle is to loosen the ball joint castle nut about four or five threads and then strike the spindle with a hammer. Spring pressure will pop the ball joint loose. Be sure to have a jack stand or floor jack under the lower control arm as a safety measure. You can remove the outer tie-rod but in our case this wasn’t necessary.

With the ball joint loose and castle nut removed, use a floor jack to slowly release the coil spring load on the lower control arm and then remove the spring. We were using shorter, heavy-duty springs, so they came out easily. Tall, stock springs can still retain high spring load when the lower control arm is as far down as it will go. This may require a spring compressor to remove the springs but more often just a long lever will remove the spring from the lower control arm.

Our performance front springs are substantially shorter and stiffer than stock front coils, making them easier to remove. You can see that our original springs are almost the same free height as the coil-over versions.

The Aldan lower shock mounts use 3/8-inch bolts, so the original lower control arm shock holes must be drilled out to fit them.

The lower nuts also need to be removed from the lower control arm. We used a cut-off wheel to cut the nuts into four pieces to make them easier to remove. The large Aldan shock crossbar will distribute the load out toward the original spring pockets.

We placed the spring on the lower coil spring mount with the Torrington bearings and hung the shock from the upper shock mount with the bushings in place.

When sliding the coil-over into place, make sure the coil spring is properly located in the upper spring pocket. There is a small recess for the tail end of the spring that must be positioned properly.

Raise the lower control arm up to meet the lower shock mount and install the two 3/8-inch bolts through both the shock mount and the lower control arm, with the bolts pointing down.

We next reassembled the front suspension with the lower ball joint and sway bar end link kit. Make sure to always install a cotter pin through the ball joint castle nut after tightening.

Aldan includes the tool that can be used to set the ride height. The adjusters on the coil-overs may have to be adjusted differently from one another in order to establish an equal ride height left to right.

With the lower shock bolts torqued in place, the system is ready for a test drive once the alignment is verified.

With the ride height set to your desired stance front to rear, you can check basic alignment if you have access to an alignment bubble gauge like this one. If not, camber can be measured with even something as simple as a smartphone equipped with a digital angle-finder app.

The advantage of adjustable shocks is that by simply turning the dial, you can adjust the ride quality. Keep in mind that the front shocks are compression adjustable while the rear shocks are adjustable only in rebound.

Spring Rates for Big-Block Conversion Kit
Front 550 lbs/in
Rear  160 lbs/in
Suggested Initial Alignment Settings
Camber ½ to ¾ Degree Negative
Caster 4 to 6 Degrees Positive
 Toe-In 1/16-inch Total (1/32-inch per side)
Parts List
Front and rear coil-over kit, single adjust 300103 Aldan
 Thrust bearing kit ALD-26 Aldan

Article Sources

About the author

Jeff Smith

Jeff Smith, a 35-year veteran of automotive journalism, comes to Power Automedia after serving as the senior technical editor at Car Craft magazine. An Iowa native, Smith served a variety of roles at Car Craft before moving to the senior editor role at Hot Rod and Chevy High Performance, and ultimately returning to Car Craft. An accomplished engine builder and technical expert, he will focus on the tech-heavy content that is the foundation of EngineLabs.
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