Even though the 1968 corvette frame is extremely strong, like most things, it has the tendency to weaken over time. For this reason, I am making a few minor modifications to make it as strong as possible without affecting the originality too much.
I first started with adding full welds. The factory originally assembled the frame with spot welds. Even though spot welds work fine, adding full welds will not hurt and is a cheap way to strengthen the frame if you are doing the work yourself. I only did it to the top of the frame but it can be done to the bottom as well.
I decided to add gussets to the frame. Yes, I know its definitely not stock, but I figured since this car will probably never go through a frame off restoration again, I want to make it as strong as possible while I have it all apart. And at 35˘ a pound for metal, this modification wasn’t all that costly. When designing the gussets, I decided to use 1/8” steel which should be strong enough. I took these pictures after priming to make them easier to see.
The right front gusset has been cut to leave clearance for the fuel pump. I probably could have made it slightly larger but the last thing I would want is to have to grind it after it has been painted. The reason I did not place a gusset on the back side of the passenger motor mount is because it would get in the way of the idler arm.
I also decided to strengthen the supports located toward the rear (before the kick-up), by adding an additional gusset on top. Then I drilled the holes so everything would align.
The last two gussets I installed are located before the front cross member. This may be a little on the overkill side but I also decided to box the front area in for more strength.
On the C3 corvettes and on some other generation vettes, many mechanics or previous owners have a tendency to lift the car from the front cross member. Even though this area looks strong, in reality it is hollow and does not have the strength to support the car’s weight. When lifted from here, it will cause the metal to dent inward. This was the case with my ’68 as seen in the picture below.
To repair this section, I simply cut out the dented area. Next, I welded two pieces of 1/8” thick steel to act as a support so this will not happen again. The area was then cleaned of rust and painted with glossy black Rustoleum.
To replace the cut out area, I installed four pieces of 1/8” steel. Once the plates are welded on, I grinded them to match the shape of the original piece and then drilled the holes in the same places as the original.
Now I can clean all the parts that have been removed and get them ready for painting.
You may have noticed I do not have the extra supports on the rear kick-up area like many C3 corvette frames. This factory modification was made during mid-year production for the 1968 vettes and later models. I have heard of some people adding them, but I didn’t want to mess with the frame to that extent. The pictures below show the supports on my ‘75 in comparison to the ‘68.