Found a source for 5/8 wrench size C2 bumper nuts

[Larry M.]

I got into this based on an article in the last Restorer - author said the bumper nuts were 7/16-14 by 5/8 wrench SAE nuts except for the 4 black phosphate on the front. So I looked and all I had were 11/16 wrench except for the 8 that attach the rear brackets to the frame.


Now if you have original nuts this won't help but I looked a long time on line and could not find them as peice parts so I ordered complete hardware kits from Corvette Central (acutally packaged by Long Island Corvette). They had 11/16 flats so I sent them back. Paragon has an assembly sheet attached to their kit which lists 5/8 flats so I thought I was in luck. Called Paragon and they looked; theirs were 11/16 also. So 3 big vendors are out. But Ken, a tech at Paragon, rumaged around and found them in a bin, not perfect but nice enough. I offered him a small fortune and he agreed to sell me the loose nuts. So my problem is solved (and I really appreciate his help).

Then a couple of you responded to a post on exhaust attachment nuts and said they were stover. I went to the web researching what this was and bingo, I found a supplier who says he has 7/16-14 5/8 wrench nuts zinc for 15 cents each. I "think" this may help some folks. Here is the link.

https://www.belmetric.com/anz71614-grade-5-p-4224.html?zenid=c099097apl2mrk65op0icapb01&cPath=692_697_735_698

As an aside, the Paragon kit calls for 8 on the front and the CC/LIC kit calls for 6. I told CC their kit was wrong but I was wrong (or I can't find where the other two go on the front). And conparing the Paragon assembly sheet to the car I think it is six; they are showing a nut where a weld nut is already there. BTW, the back uses 18.

[John D.]

Re: Found a source for 5/8 wrench size C2 bumper nuts

HI Larry, Our own Gary Beaupre has a wonderful kit with the correct washers, nuts, and plating, etc. Quite affordable. John

[George J.]

Re: Found a source for 5/8 wrench size C2 bumper nuts

I'd like to store a set of those away. Maybe Gary can chime in with some more information.

George

[Gary B.]

Re: Found a source for 5/8 wrench size C2 bumper nuts

George,

There are a couple of challenges getting the C2 bumper mounting hardware right in terms of judging, especially at the national level. One issue is knowing what's correct for a given C2 year. The nuts changed over the C2 era, the lock washers changed dimensions and finish over the C2 era, and the bolts changed as well. Regarding the lock washers, there are still some debate about the finish in '63/64 vs later. But by far, the hardest items to find are correct bolts. To the best of my knowledge, no one makes a correct repro of the M head-mark bumper bolt. If you know what to look for the difference between a repro M and an original M is easy to detect. The other head-mark bumper bolt that is most common on '66 and '67 cars is the RSC bolt. Richard Fortier now produces an RSC bolt that in my opinion is as close as it gets to spot on. Part of his repro process, however, is done by hand, which makes the cost per bolt quite high. But if you want a quality RSC bolt, you'll get it. Some of the e-bay sellers occasionally have original C2 bumper bolts that sell in the range of $11 each, so the RSCs from Richard Fortier aren't that far out of line.

Having said all this, the generic 63-67 kits that most of the catalog companies sell will not cut the mustard if you wind up with a knowledgeable judge.

Gary

[George J.]

Re: Found a source for 5/8 wrench size C2 bumper nuts

Gary,
thank you for the education. I guess the question, now, is do you offer a kit, and is it offered through the Driveline, price, etc. You can PM me if this is beyond what we're allowed to discuss here. I would rather give the money to someone who has taken the time to research this and is an NCRS member.

Thanks,

George

[Gary B.]

Re: Found a source for 5/8 wrench size C2 bumper nuts

George,

You are correct that it's appropriate to talk offline. I sent you my contact info via a PM.

Gary

[Larry M.]

Re: Found a source for 5/8 wrench size C2 bumper nuts

I'm beginning to feel a little sensitive like I crossed a boundary I should not have. For the record, I didn't know about Gary, I talked to a long time knowledgeable NCRS guy who hadn't read the Restorer and I don't think knew about the size difference, three vendors sell the wrong thing, and I had a hard time finding them. I paid a lot for the ones I got (my car had replated bolts but hardware store flats, locks, and nuts), and I thought I'd be doing some guys a favor. I don't know if the link I posted even sells the correct size, but they say they do, and I don't know if they will look just right, but they have to look better than 11/16 flats. Let me know if I'm not supposed to post things like this.

[Gary B.]

Re: Found a source for 5/8 wrench size C2 bumper nuts

Larry,

What you posted is perfectly legitimate information for the DB, so there is no reason to feel awkward.

Gary

[George J.]

Re: Found a source for 5/8 wrench size C2 bumper nuts

Larry,
like Gary said, totally legitimate in my eyes. You've made me aware of the place to get a full kit that is probably as correct as it gets, today. Very valuable information to someone restoring a car. Keep it up!
George

[Tom D.]

Re: Found a source for 5/8 wrench size C2 bumper nuts

Thanks for a great article. I read it with interest.

[Larry M.]

Re: Found a source for 5/8 wrench size C2 bumper nuts

I did a search on something the other day and saw an old thread on bumper nuts from when Gary was doing his research. It covers the bases and says that the 5/8 flats zinc plate was changed to 11/16 Black (gray) Phosphate for 67 in documentation but may not have been effective on real cars until late 67, likely due to using up old inventory of 5/8 nuts. It was a very good thread.

[Gary B.]

Re: Found a source for 5/8 wrench size C2 bumper nuts

Larry,

I have an article in the last Restorer on the timing of the change from the 5/8" bumper nuts to the 11/16" nuts. The change occurred around Jan of '67, so it's not what I would call late; more like early-middle of the '67 model year.

Gary