C2_rear spring bolts

[Steve D.]

Reassembling a 63. Is it advisable to replace the spring bolts (connecting ends of spring to trailing arms)? From just a visual inspection, the bolts look good, but I didn't know if there was a fatigue issue. I don't have any idea how long the bolts were in the car.

Steve

[Duke W.]

Re: C2_rear spring bolts

Fatigue is not a concern, just corrosion. If the bolts appear to have lost signficant material due to corrosion,they should be replaced. If not, they are okay to use.

Duke

[Steve D.]

Thanks *NM*

[Joe L.]

Re: C2_rear spring bolts

Steve-----

I'm a fan of replacing these bolts whenever they are removed. The Chevrolet or Corvette factory service manuals specify that the spring link bolts, cushions, retainers, and nut should be replaced every time that they are removed. I think it's wise to do this.

A friend of mine who is also an original owner of his 69, had one of his spring bolts break unexpectedly in 1977 when his car was about 8 years old. His car was always garaged and "treated" to the sublime California weather, so corrosion was no factor, at all. Fortunately for him, the incident occured at low speed in a parking lot, but the car was instantly disabled and had to be towed. He cringes to this day at what would have happended if it had happened an hour later when he was on his way on the freeway to San Francisco for a party. The bolts aren't that expensive.

[Eugene B.]

Re: C2_rear spring bolts

Guys,
These comments raise a question in my mind. I just ordered a trailing arm kit from Paragon. With so many suppliers of Corvette parts and stiff competition, what are the chances that I/we are getting imported parts that look good but may not be equivalent (strengh wise) to the parts that we took off?

I was actually considering reusing my old bolts (originals) if the headstamps on the new bolts were not the same as mine. Am I sacrifacing safety to maintain originality?

Regards,
Gene

[Joe L.]

Re: C2_rear spring bolts

Gene------

Chances are that the Paragon kit is actually kit GM #14029851. This kit contains high quality GM parts, including the bolts. If it's otherwise, then, I suppose, it could be anything. However, these bolts are special bolts and not just "generic" sorts of things. I expect that the pieces that Paragon sells includes, at least, the GM bolts which are available seperately under GM #458982.

The new GM bolts won't have the same headmarking as the originals. If it were me, I'd use the new bolts. Are the old bolts unsafe? I don't think so, but I'd still use the new bolts. How do you know that the ones you have now are originals, anyway? Also, what finish do your existing bolts have-----zinc plated or black phosphate/oxide?

[Eugene B.]

Re: C2_rear spring bolts

Joe,
Thank you for your response. First, I didn't realize that I could buy a lot of what I need from GM. When I check most items with the dealer, they give me the old "I'm sorry, that is discontinued".

As far as my bolts being original, I have owned my '65 since 1970. It has 44,000 miles on it and everything that I have removed so far is original, including shock absorbers, etc.

I cannot say what the finish on the trailing arm bolts was. The finish is pretty much gone and they are lightly rusted. The headstamp is P with five raised tick marks facing outward.

Regards,
Gene

[Joe L.]

Re: C2_rear spring bolts

Gene-----

Based upon your description, I think that it's safe to say that your bolts were originally black phosphate. This is the finish that usually degrades to what you see today. That's also the original finish used for most of the spring link bolts used in PRODUCTION. The "P" headmarking is ONE of those originally used, too. Others were "C" and "SBC" and, I'm sure, still others. I think that "C" was the most common.

All of the original PRODUCTION and SERVICE bolts that I've seen have been the "5 radial lines". This is a very unusual bolt grade marking and indicates a GM 290-M grade bolt. I've often wondered if this grade bolt has some special properties that make it the most desirable for this application. Otherwise, I would think that GM would just have used SAE grade 8 (GM 300-M).

[Eugene B.]

Re: C2_rear spring bolts

Joe,
Thank you for your response. It is little details like this that cause me to want to use my original parts unless it's totally unavoidable. I even like the notion of using the original beveled washers and nuts. The car doesn't look bright and shiney new but it's as authentic as I can keep it.

Gene