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Road Runner Chassis Restoration Part 1

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by Huw Evans  More from Author

Like-new looks for low bucks

In the context of muscle cars, it’s amazing what can happen over the course of a few decades. Back in the late 1960s, Chrysler went for broke, building some of the quickest and most outlandish machines ever to emerge from Detroit. Hemi Dodge Coronets, Dodge Chargers, and Plymouth GTXs carved out a name for themselves as an all out horsepower war was waged on America’s streets. But it’s cars like the Plymouth Road Runner that really struck a chord. The first-year 1968 model was that rare breed: a strictly business, no-frills two-door post coupe, with a big engine that went like hell in a straight line. Keeping things very much basic–like the taxicab interior with its rubber floor mats and steel wheels–also kept the entry price low at $2968. This was one of very few purpose-built muscle machines actually within the reach of aspiring young males back then.

The fact that Plymouth sold 44,598 of the blasted things in 1968 is testament to the car’s popularity when new. Fast forward 40 years, and whilst Hemi-engined Mopars currently get the lion’s share of attention, there’s a lot to be said for buying and owning a car such as a back to basics, 383-equipped 1968 Road Runner. This particular car is a survivor. It was never seriously modified, wrecked, or succumbed to the dreaded tin worm (despite being an original rust belt car). It’s probably best described as a nice, presentable driver. But the owner wants it to be better. As a result, the car has been subjected to a top-quality repaint, an engine rebuild, and interior freshening, making it look as good as new on the outside.

However, a top-quality car is only as good as its weakest link and one aspect many enthusiasts tend to overlook when buying classic muscle concerns the undercarriage. If you’ve gone to the effort of a bare metal re-spray, pulling apart the engine and doing the entire cabin and trunk, then you might as well do the same level of work underneath. And since the owner of this particular Road Runner had done just that, he felt to really finish the car off properly, it was time to detail the suspension, brakes, and underbelly. Besides doing it for your own satisfaction, a full chassis detail also enhances the value of your classic car, an important aspect should you ever decide to sell it down the road.

So, follow along as we embark on the first installment of a two-part journey with the restoration experts at Legendary Motorcar Company, transforming the underneath of this Road Runner from pretty to pristine. You’ll be surprised at what goes into it.

Here is what we started with. This SS1-code Yellow 1968 Road Runner is actually quite an interesting car. It’s one of 29,240 RM21-coded pillared coupes built for the model year. The hardtop body-style, coded RM23, was a late edition during the model year and a bit more expensive, partly explaining why production totals were almost half at 15,358 units.

Further emphasizing the complete bare bones aspect of this car are the presence of four-wheel drum brakes and a truly spartan cabin that doesn’t even feature an armrest. Given the lack of options, it was obviously purchased primarily for one thing–going fast in a straight line.

Although the engine bay has been fully detailed, along with body re-do and interior makeover, the car’s underneath is largely original, save for fresh underbody paint. However, the finish is glossy and not correct, which–combined with the rust coated exhaust system, springs, rear end, and control arms–lets down an otherwise very nice car. Time to change that.

Our first task was to bring the car into the shop and coat the body in plastic, to prevent any damage while we work on the underside. The last thing we need is to scratch or mar the paint and coachwork. With the wheels off our Road Runner, we can now begin the project.

We started at the back of the car first, removing the rear suspension and axle assembly. From this angle you can see that the rear end housing and the springs have been painted in the past–but not correctly. The springs should be steel instead of black.

Now it’s time to remove the car’s dual exhaust system. Even though it isn’t that bad, the surface rust on the mufflers and pipes is unsightly and to really bring the Road Runner up to par, we’ll be ordering a brand new, factory replacement system.

With the exhaust out of the way, our next task is to pull out the driveshaft and trans. Both of these items will be freshened and repainted in the correct colors, to look as good as, if not better than, when this car was brand new.

With the rear end, springs, and shocks out of the way, here you can see the factory fuel lines. These are also rusted and will be replaced with brand new items, courtesy of Classic Tube. It’s often the little things that really count in a top notch restoration, underbelly or otherwise.

One major obstacle before we can begin the task of cleaning and restoring is removing the front suspension assembly on each side. As per Chrysler’s standard practice of the day, the ’68 Road Runner uses Torsion-Aire suspension, whereby a pair of longitudinal torsion bars serve the function of springs, working in conjunction with the shocks, upper and lower arms, end links and sway bar to control lateral movement and isolate the body structure from road shock. The problem is that after 40 years, some of the parts can be rather tricky to remove…

As we found out, trying to pry the upper control arms from the spindles and the torsion bars, not only from their mounts, but also where they attach to the lower control arms, was tough. The driver’s side proved least problematic, but when we started tackling the passenger’s, the curse of the rust belt reared its ugly head.

With the top of the brake drum removed, we began working the spindle loose from the control arm. The backing plate for the brake drum needs to be loosened from the spindle, ready to pull it off when the time comes. Needless to say it required some penetrating lube and patience to loosen the bolts.

Now it was time to pry the top of the spindle away from the upper control arm. It took even more patience, a heat gun, and ultimately two wrenches to complete this task. When we did, we discovered that the bushings were shot. After further effort and some more penetrating lube, we also managed to separate the spindle from the lower control arm. From this picture, you can see that the spindle attaches to a bracket, which pivots on the lower control arm and attaches to the tie-rod end.

In order to remove the lower control arm, you need to first remove the end link that connects it to the front radiator support, and then remove the torsion bar spring.

This was where we had a major problem: the bushings inside the control arm which links the torsion bar were shot, and the mounts had seized. Normally, the torsion bar should rotate freely and independently of the lower arm, but in this case when we turned the arm, it turned the torsion bar and vice versa–not good. The mangled bushing had caused the mechanism to seize, reducing the resistance of the torsion bar and its ability to isolate road shocks.

Finally, after much deliberation and lots of penetrating lube, we carefully managed to pull the torsion bar out from the control arm and it’s housing on the underside of the car.

When we pulled off the lower arm on the passenger side, we could see the extent of the damage–the bushing inside had literally disintegrated and the mount on the K-member was covered in rust. No wonder it was so stiff!

Although we decided not to pull the engine out of the car, it was necessary to support it once the steering linkage was removed. A chain around the bell housing should fix that issue.

With all the required suspension bits off the car, we turned our attention to the rear end. Instead of just a repaint, we’ll take the time to pull it apart and inspect the axles, bearings, and differential assembly. Here we pull off the rear drums and backing plates, ready to remove the axles.

With the axles out its time for the restoration work to begin. Stay tuned for part two where we complete our underbelly restoration project, starting with cleaning, revamping, and detailing the suspension and driveline parts, before spraying the underside and putting it all back together.


Legendary Motor Car Company Ltd
8228 Fifth Line
Halton Hills
Ontario L7G 4S6

Classic Tube
80 Rotech Drive
Lancaster, NY 14086


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