1969 Chevy Camaro Chassis & Handling - Thrasher Camaro Part III

Transforming a 1967-1969 Camaro Into a Corner-Carver

Mark Stielow Mar 1, 1999 0 Comment(s)

Step By Step

Initially, I carefully measured the '69 Camaro chassis to make sure it wasn't bent. Here I used a long carpenter's level to hang two plumb bobs off the centerline of the front wheels to check whether the front subframe was centered in relation to the body. This is important not only for handling, but to ensure that an oversize wheel and tire package will clear both wheel well openings.

As a precaution, I welded all the seams on the front subframe with an MIG welder. The frame was blasted clean to simplify any work on it, but I still needed a wire brush to clean the areas to be welded.

I like my Camaros tight, so I built these subframe connectors out of 2x3-inchx0.090-inch wall-thickness rectangular steel tubing. To tie the front subframe to the rear, I cut a hole in the front and rear of the passenger floor wells and passed the 2x3 tubing through as shown.

For competition the Thrasher will need a four-point rollbar, but I don't like to give up interior space, so I built a template out of 1/4-inch round bar stock. It took less than $4 in round stock to build this template. I then had a main hoop bent up to match.

I used a zip tie to hold the hoop in place while I fashioned 6x6-inch mounting plates (per NHRA rules), down tubes, and a removable seatbelt crossbar. Notice how the hoop mimics the vertical quarter window seal angle making the rollbar barely noticeable with the windows rolled up.

This is the Stielow Engineering and Development (SED) spindle I used for the Camaro. The SED spindle is higher in relation to the A-arms (which lowers the ride height) and improves bump steer and camber gain. The spindle assembly also has a built-in speed sensor to accommodate either anti-lock braking or traction control.

The Global West Del-A-Lum suspension bushings offer the best of both worlds--minimal deflection without squeaks or the wear problems of solid bushings. I have used these bushings on many of my cars.

Mullins Steering modified this GM 605 steering box to provide both variable assist and a quick ratio. This allows the steering to be slightly heavy when straight, yet makes slow-speed driving less of a chore with more assist. Mullins also supplied the rag joint to adapt the late-model box to the Camaro steering column.

Koni rebound-adjustable shock absorbers are used on all four corners. I've used Konis many times before and feel they are one of the finest street/performance shocks available. The knob is used to adjust the rebound damping.

The Baer brakes package is a complete bolt-on affair. I told Currie what type of brakes I wanted to run, and they built the rearend with the correct mounting pads, axles, and housing tubes. The housing was ordered in the stock width to simplify the wheel selection which will be BBS RK wheels--18x8.5-inch up front and 18x10-inch in the rear. I selected BF Goodrich Comp T/A tires with 245/40ZR18s up front and 295/40ZR18s in the rear. The SED spindles bolt directly to the 13-inch Baer rotors and dual piston calipers. Notice the wheel speed sensor in the center of the spindle (right).

Editor's Note: Doing the same thing multiple times, and using your experiences to develop a better way every time, is what engineering is all about. It is this type of development that has allowed Mark Stielow to raise the bar on '67-'69 Camaro performance with every Camaro he builds. He has developed and built enough bad-boy Camaros to field an entire race-day lineup. The '69 "Thrasher" Camaro he is currently building revolves around the chassis and suspension. Having driven his last car with these modifications, it's obvious he knows what to do and that these changes work to improve the handling dramatically on early Camaros. Enjoy.

I have always wanted to have a '67-'69 Camaro that resembled the early Trans Am car "look" but with '90s handling and ride quality. To achieve that, I have spent a lot of time modifying the chassis and suspension on these early Camaros. Some of what I do might be considered rocket science, but for the most part, the changes I make to a Camaro can be performed by anybody.

I know from the last two Camaros I built using many of these modifications that the Thrasher should blast down the road with minimal bumpsteer, snap into corners, stop solidly time after time, handle bumps in the road with no problem, and be more comfortable to drive--all with over-the-counter aftermarket products. I expect the Thrasher to be the best handling, most comfortable Camaro I have ever built. Future plans for the car include competing in the One Lap of America, the top speed Pony Express 100 in Nevada, cruising cross-country in the Power Tour and more, so this car not only needs to do it all, but must also survive.

With this kind of challenge, I have chosen race-proven aftermarket products. Some of these components you might not have seen before, like the hidden spring jacks for the front suspension. All of these parts have been around for a while and have proven themselves capable. I modified them to fit this application, but they have proven themselves in the past, and I feel they will work quite well in a street application.

The Package
The stock Camaro front suspension consists of two unequal length A-arms connected to the spindle by ball joints, with the weight of the car resting on a coil spring, and a shock absorber mating the lower A-arm to the frame. A sway bar ties both lower A-arms to the frame rails. The steering on the '67-'69 Camaros are referred to as a "rear-steer" design, which means the steering box and linkage are located behind the front axle centerline. The rear suspension consists of a solid axle riding on parallel leaf springs controlled by shock absorbers. The leaf spring rear suspension is extremely simple, as the springs both support the weight of the car and serve as locating links for the rear end. With a few minor modifications, this rear suspension works quite well for a street performance application.

The modifications performed to the front suspension revolve around a pair of aftermarket lowered spindles I have designed. I also drilled new mounting locations for the upper A-arms, modified the spring bucket to accept a Landrum hidden weight jack and spring, and installed a Mullins-modified steering box and rag joint. I finished the front half off with Global West Del-A-Lum control arm bushings and a pair of Koni adjustable shock absorbers.

I also made a few changes to the front subframe which affect how well the front suspension controls the motion of the wheels. For the subframe, I prefer to weld all the seams, mount it to the car with Global West solid interlocking bushings, and weld homebuilt subframe connectors under the floor to tie the frame sections together. This stiffens the car body/chassis combination considerably, which forces the suspension to absorb the bumps instead of flexing the chassis.

On the rear suspension, I installed Global West solid body bushings, used Eaton dearched springs, (to get the proper ride height), and Koni adjustable shocks. To reduce unsprung weight, I chose a Currie aluminum center housing 9-inch rear end. This entire housing is about 25 pounds lighter than a standard 9-inch, and with its 3.89 gears, Tru-Trac differential, and 31-spline axles it can withstand all the abuse our 450hp 406 can dish out.

As the final note, Baer 13-inch front and 12-inch rear rotors were installed with a Master Power master cylinder/booster/proportioning valve package to put the big whoa on the show. This brake package is essentially equal to the Corvette ZR1 brake system, so it is certainly capable of stopping from high speeds and repeated abuse without fading.

Doing the Job
I have performed all these suspension and brake modifications a few times now and can say none of it is really difficult, but it is time consuming. I would recommend measuring your car for squareness or taking your car to a professional chassis/alignment shop to be checked before starting on anything, as these early Camaros can easily be tweaked. I have built "crooked" cars that never handled very well because of it.

Once you know the car is square, follow the old carpenter's rule "Measure twice, Cut once" when performing these suspension and chassis modifications. If the chassis ends up out of square, the trickest parts in the world won't make the car perform up to expectations.

The most difficult part of all these modifications is drilling the new mounting locations for the upper A-arm in the frame mount. I use a template that I built. If you carefully follow the dimensions shown in the sidebar you should end up with everything in the right place.

Onward and Upward
Stay tuned next month as we continue to hammer the Thrasher together. It's shaping up to be a car with plenty of potential. I can't wait to drive it.

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