Saturday, July 11, 2020

How To Replace Rear C3 Corvette Shock Absorbers

A few days ago I noticed what appeared to be an abnormal amount of "float" or "bounce" as I drove my '76 Vette around town, which led me to believe the KYB shock absorbers that were installed about five years ago, were ready to give up the ghost.

So early on a Sunday morning, I took my car for a short test-drive down a stretch of Interstate 75.

As the speedometer needle approached 100 MPH, all hell broke loose and my Corvette started shaking so badly I felt it was going to come apart. I immediately let go of the gas pedal but the bouncy ride continued for what seemed like an eternity.

It really scared the bejesus out of me.

So yes, the shock absorbers were toast.

I checked online for shock absorbers made by Bilstein, which are top-of-the-line aftermarket replacement parts, but the $440 price tag motivated me to search for cheaper alternatives.

Of course, you sacrifice quality and durability when you allow your wallet to dictate what you purchase, but I have to keep an eye on my finances and settled for ACDelco shocks which brought the expense of buying new shock absorbers down to around $130 for the whole set.


OUT WITH THE OLD

Removing shock absorbers on a C3 Corvette truly is a do-it-yourself job, provided you have some basic tools and the means to securely lift the car in order to get the job done. My QuickJack portable lift makes this task so much easier.


With the car lifted, you can start by removing the rear wheels.

C3—and C2 rear shocks for that matter—are secured to the chassis via a bolt and nut in the upper mount and a nut for the lower mount hanger. They should also have lock washers which in this case, due to space constraints (I assume), are installed on the bolt side to keep it from moving.



Spraying a penetrant solution such as PB Blaster will help loosen parts that have been rusted or corroded by the elements and time. Also keep in mind that when it comes to accessing the top mount nut, space constraints will make this job challenging as the storage compartment tub is a bit too close for comfort.

The observant reader will notice that in the photo above, the bottom lock washer is missing a chunk.

For the record, the old KYB shock absorbers were installed by a professional licensed mechanic, which helps make my point that, oftentimes, a few "professionals" may do whatever it takes to get the job done quickly even though safety may be compromised.

I mean, a grade-8 lock washer retails for about 40 cents, so choosing to reuse 40-year-old hardware is not only foolish but it can be dangerous. You DO NOT want nuts and bolts falling off your car while you are driving it.


By the way, the top-mount bolts put up a good fight since they did not want to let go of the hanger bracket. My solution involved using a pair of locking pliers which gave me enough of a grip surface so I could yank them out.

The bottom hanger nuts are a lot easier to remove since there's a lot more room. All that was needed was a good couple of taps with a rubber dead-blow hammer.

I chose to start by unhooking the bottom shock mount from the hanger which allowed for some movement which helped remove the top mount bolt.

With the nuts and bolts out, I gave them a good cleaning and I also chased the threads (internal and external) to make installation easier.



I then smoothed the heads with a file since they got a bit chewed up by the locking pliers during the removal process.

Since the top shock mount bolts are specific to the Corvette, I did not find a proper replacement at the hardware store. As the picture above shows, the shoulder portion of the shank is meant to fit precisely within the brackets, and the bolt length is just right so you can thread the thin nut onto it.

I did purchase grade-8 flat and split lock washers since, again, there's no good reason to reuse 40-year-old hardware. I think I spent less than a buck fifty.


The photo above shows one of the top-mount bolts, which I cleaned and painted, the top and bottom shock mount nuts, and new grade-8 washers.


IN WITH THE NEW

Installing new rear shock absorbers on my 1976 Corvette is pretty much a reversal of what I described above. And based on the age and condition of your components, the steps may differ a bit.

For example, at one point during the removal of the right-side rear shock absorber, I used my floor jack to compress the shock as I tried to remove the top mount bolt. This did not work but I had to try different methods until I resorted to using locking pliers.

Having the correct Corvette Service and Overhaul Manual handy can also provide guidance as to what goes where, for example, and most importantly, the factory-recommended torque specifications.

The image below is a picture from the Factory Assembly Manual, another book that is a must-have for any serious Corvette owner, especially if you plan to work on your own vehicle. Highlights and torque settings in the illustration below are mine.




But before the new parts go on, this is the perfect opportunity to detail a few components, so I brushed on a couple of coats of Loctite Extend Rust Neutralizer on the calipers, sock absorber mount brackets, and a few other pieces.




The rust neutralizer dries in about an hour and it can be painted. However, I really like the black finish so that saves me time and extra work. And the whole point of applying this solution is to eliminate any surface rust or corrosion and also help prevent it. Looks of the finished product are secondary.

Installation of the new shocks can be a bit tricky and challenging. These cars were not built to close-tolerances and, therefore, oftentimes replacement parts don't fit 100% right, even though in this case I used ACDelco components which are OEM.

One area that appears to be poorly engineered is the top shock mounting bracket as the holes simply don't line up properly with the shock absorber in place. This requires forcing the bolt in place which in turn forces both the metal and rubber bushings into a weird angle, in my opinion. Unfortunately, I did not take a picture.

I installed the new rear shocks by pressing the bottom mount into the lower hanger. I did apply a thin coat of anti-seize to the bushing just in case. I did not use anti-seize or thread-locker for the threads though. Keeping nuts and bolts securely in place is a job for the lock washers.

With the shock absorber in place, I used my floor jack to raise the shock into the top mounting bracket, and I applied some anti-seize to both sides of the top mount since it's a tight fit. Actually, it is so tight, I had to file the top bushing a hair so it would fit properly.



I also had to use a large Philips screwdriver in order to align the bracket with the bushing which, again, does not line up correctly.


A rubber dead-blow hammer was required to help drive the top mount shock bolt into place. Fortunately, the bolt threads were okay.



The top bolt and bottom hanger nut were then torqued to factory specs. You may notice a bit of anti-seize squeezeout in the photo above. That's not a big deal as it did not affect the threads.



The two photos above show the new rear ACDelco shock absorbers installed!

If you want to do this job yourself, there are several how-to videos on YouTube, which should give you a better understanding as to what's involved.

Having a lift, whether a full-size, MaxJax or a QuickJack Portable Lift as in my case, is ideal. However, you can get the job done with a floor jack and jack stands.

I hope you find the information in this article helpful.

Thanks for following my 76 Vette Blog!



Product Links... (#sponsored)

1976 Corvette Service & Overhaul Manual
1976 Corvette Assembly Manual
Chevrolet Corvette 1968-1982 | Haynes Repair Manual
1976 Corvette Stingray Owner's Manual
Loctite Extend Rust Neutralizer

ACDelco 530-315 Gas-Charged Shock Absorber (Front)

ACDelco 530-4 Gas-Charged Shock Absorber (Rear)


1963-1982 Bilstein Front & Rear Shock Absorber Set

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