1968 Convertible top frame bolt size?

[Jon H.]

I need help finding and identifying the size of the convertible top frame bolts on my 68. I lost two durring restoration and can't find the correct ones. Thanks for your help
Jonathan

[Joe L.]

Re: 1968 Convertible top frame bolt size?

Jonathan-------

If you are referring to the bolts which retain the convertible top assembly to the pillar posts, those bolts are 3/8-24 X 1". There are 4 used----2 on each side. However, there is one thing that I don't understand. If you lost 2 of them, then I presume that means that you still have 2. If this presumption is correct, why not just use those 2 as the "model" for what you need to obtain for replacements?

[Jon H.]

Re: 1968 Convertible top frame bolt size?

I took them to all the harware stores and auto parts stores. They are not a 3/8-24 or a 3/8-16/ They are a fine thread bolt but neither of them fit. The threads are more fine. GM has discontinued these bolts. I am not sure exactly what they are.

[Joe L.]

Re: 1968 Convertible top frame bolt size?

Jonathan-----

As far as I know, most fastners used on Corvettes during the 50's, 60's, and well into the 70's were either national course (NC) or national fine (NF). There were a few things here-and-there that did use special threads. However, the bolts retaining the soft top frame to the pillar posts were not among those using a special thread. When you think about it, why would GM have used a special thread fastner for a common fastening application like this?

The bolts used were GM #3829942. The same bolt was used for all 1963 through 1975 Corvette convertibles. This bolt is a 3/8-24 X 1" indented hex head bolt. It is black phosphate finished with a captive flatwasher and it has a pilot point. I can't find any indication that it was ever available in SERVICE.

GM says that the above-described bolt was used. However, it's possible that GM could be wrong. So, I endured the exercise of going out, removing, and inspecting/measuring the bolts on my 1969. Guess what? 3/8-24 X 1".

If you require any other size bolt, then "bubba" has been in there previously or your bolts/weld nuts have suffered some other sort of damage. I feel very confident of that.