Wednesday, January 12, 2022

Loose Leaf Spring-to-Differential Bolts

I have to admit that—by a fluke—I discovered that all of my Corvette's leaf spring-to-differential bolts were completely loose. Well, at least three of the four as one was missing, so I am pretty sure that one just fell off at some point.

The results of such a structural failure could've been disastrous, so I was very fortunate that I made the decision to get rid of the spare tire and also remove the spare tire carrier. This is how I spotted the missing bolt.

Years ago, I used a local shop when I lived in Central Florida and the mechanic made sure he used plenty of anti-seize on the threads where a thread-lock product should have been used.

This is why I tell Corvette owners that they have to inspect everything that's done to their vehicles whenever possible, or at least educate themselves so they can question the work being performed.

In my car's case, the exhaust pipes block two of the bolts, so in order for them to be removed, parts of the exhaust system would have to be lowered or maybe even redone so proper maintenance can be performed when necessary.


I also had to remove the metal shield so I could properly clean and tighten the bolts. And the only way to tighten two of them was by using a crescent wrench since there was no way to use a socket to do so.


As the picture above shows, one of the bolts had simply fallen off, and the remaining three were completely loose. In fact, I was able to turn them with my fingers. Scary stuff.


ACE Hardware had the correct size grade-8 bolts and washers, although in hindsight I should have bought 4-inch long bolts instead of 3½-inch. The same mechanic who installed the then-new hardware a few years ago broke one of the differential cover ears, and I chose to install a new reinforced unit instead, which has almost double the number of threads.

By the way, my 1976 Corvette uses 9/16-12 bolts and I like to use grade-8 hardware whenever possible. You can probably get by with grade-5 bolts, but using stronger hardware is the better choice.


I also decided to leave the metal shield off, for the time being anyway. My guess is that the cover is there as a heat shield, but that's only a guess.


And as you can see, I used plenty of blue thread locker although I will, at some point, replace at least two of the bolts with 4-inch long grade-8 hardware.

I also torqued the two bolts I was able to tighten with a socket to 70 ft. lb. each.



I really like the cleaner look and ease of access to this area without the spare tire carrier in place. Not to mention that I also avoid carrying over 60 pounds of dead weight around without any noticeable difference as far as driveability and/or performance.

Plus, I can also check the bolts easily at any time. Something I do almost every time I drive my Corvette nowadays.

And if you're wondering what in the world I will do if I ever get a flat tire?

Well, I now carry a small 12-volt compressor in the storage box over the factory jack and a tire plug kit. I plan to post an article covering that topic in the near future along with a video.

Thank you for following my 76vette Blog!


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