C3 Spare Tire Lock Bolt and Bracket

[Sheldon S.]

I am looking for some info on the finish of the following items from a 71 car.
1- The spare tire lock bolt- know this is cad or zinc finish
2- The flat washer on it- not sure but assume cad or zinc
3- The rectangular nut- no idea
4- The bracket- i beleive is semi-gloss
5- the two attaching bolts and lock washers- no idea

Thanks for any info provided.
Sheldon Sands

[Terry M.]

Re: C3 Spare Tire Lock Bolt and Bracket

2 -- Natural, I think -- but see what others have to say.
3 -- I can't picture the rectangular nut in my mind.
5 -- bolts are black phosphate. Lock washers are likely natural, but could also be a dark color, like the alternator lock washer.

The rest I agree with your observations.
Does Patrick have pictures of the bolt and parts for his 1972 on his site?

[Bob D.]

Re: C3 Spare Tire Lock Bolt and Bracket

Sheldon

I am making an assumption that the rectangular nut you refer to is the nut that the long spare tire tub bolt screws into. If I have the correct nut then it is natural. My original one appears that way. Hope this helps.

Bob

[Steven G.]

Re: C3 Spare Tire Lock Bolt and Bracket

I have an early 70' and the bolts are undercoated as well as the wheel well tub, this may be different in comparison to other and later c-3's, I don't know. I unsucessfully attempted to test remove undercoating and its definately a harden factory tar base application, apparently no masking was used, the tub and bolts appear to have been undercoated the same time as the frame. Steve

[Mike E.]

Re: C3 Spare Tire Lock Bolt and Bracket

I have an early 70' and the bolts are undercoated as well as the wheel well tub, this may be different in comparison to other and later c-3's, I don't know. I unsucessfully attempted to test remove undercoating and its definately a harden factory tar base application, apparently no masking was used, the tub and bolts appear to have been undercoated the same time as the frame. Steve

How do you know it was a "factory" tar base application? I'm skeptical of that, since the frame was not undercoated. I suspect this was a dealer package, or even Ziebart or something like that. There is nothing that would lead us to believe that was standard factory procedure--I had a 70 in the 1000 range, and another 2500, and neither had any undercoating on the frame, tub, bolts, or lock. I also have a friend who has a late 69--38,000 range--nothing there, either.

[Peter L.]

Re: C3 Spare Tire Lock Bolt and Bracket

Sheldon - All original the lock bolt items you have listed plus the keeper pin at the end are zinc plated (most likely, but could be cadmium) with the exception of the bracket which is painted. Pete

[Joe L.]

Re: C3 Spare Tire Lock Bolt and Bracket

How do you know it was a "factory" tar base application? I'm skeptical of that, since the frame was not undercoated. I suspect this was a dealer package, or even Ziebart or something like that. There is nothing that would lead us to believe that was standard factory procedure--I had a 70 in the 1000 range, and another 2500, and neither had any undercoating on the frame, tub, bolts, or lock. I also have a friend who has a late 69--38,000 range--nothing there, either.

Mike and Steve-----


I agree. The only place that an undercoating was used on 68-72 C3's, if not all C3's, was on the rear portion of the wheel well area (all four). It was a relatively thin coating. No other use of undercoat from St. Louis that I'm aware of on these cars.

[Steven G.]

Re: C3 Spare Tire Lock Bolt and Bracket

Mike, I did not have the black coating analyzed by a chemist, when ever it was done, the spare tire tub was in place with bolts. I looked at the fram and it is not undercoated, however, the reverse runs on the spare tire carrier tub indicates this was done when frame was upside down, maybe using a hand mit. I am sure the dealer did not turn a new car upside down to do this and find it very hard to believe that this is the only 70' corvette that has heavy blacking with reverse runs on the spare tire tub carrier. Steve

[Joe L.]

Re: C3 Spare Tire Lock Bolt and Bracket

Mike, I did not have the black coating analyzed by a chemist, when ever it was done, the spare tire tub was in place with bolts. I looked at the fram and it is not undercoated, however, the reverse runs on the spare tire carrier tub indicates this was done when frame was upside down, maybe using a hand mit. I am sure the dealer did not turn a new car upside down to do this and find it very hard to believe that this is the only 70' corvette that has heavy blacking with reverse runs on the spare tire tub carrier. Steve

Steve----

It was not even done on 1970 Corvettes, let alone other years. I don't know how the undercoating got on your spare tire carrier, but if it was done at St. Louis, I'd say you got the only one ever done that way. If you were to have your car judged, I don't think you'd find any judge that would accept it as original.

The spare tire carriers consist of a fiberglass tub and steel reinforcing V-strap. The fiberglass tub is natural, un-painted fiberglass. The steel strap is painted semi-gloss black before attachment to the tub. The rivets attaching the strap to the tub are natural aluminum.

[Steven G.]

Re: C3 Spare Tire Lock Bolt and Bracket

Thanks for your info. Joe, It does appear to be sprayed with a black coating that could have been done by a dealer. The black undercoating with 1/4" thick runs, hard as a rock, made me think it was a factory mix. I'm glad I have a spare tub. Steve

[Terry M.]

Re: C3 Spare Tire Lock Bolt and Bracket

The spare tire tub was not on the chassis while the chassis was up-side down on the chassis build line. The spare tire tub was installed after the body was mated to the chassis. Even St. Louis did not turn the car over once the body was on the car.

If you have runs in the undercoating running up, it is probably because the tub was removed from the car and place upside down while the material was sprayed on it.

Like Joe and others have told you -- you have a very rare 1970 if that coating was applied at the factory. It would be interesting to see the car. We all might learn from it.

[Steven G.]

Re: C3 Spare Tire Lock Bolt and Bracket

After searching the archives, I noticed that Joe made mention that 70' frames may not be coated with paint or undercoating whatsoever and Terry mentioned methods of cleaning and preserving uncoated frames as well. I'll bet that many guys over the years did not know that and now those car frames have a fresh black coating. Thanks for all the information, Mike, Joe, and Terry, you guys have really helped in preserving my #9 coupe, removing unfactory paint or undercoating would have been quite a job. Steve

[Joe L.]

Re: C3 Spare Tire Lock Bolt and Bracket

After searching the archives, I noticed that Joe made mention that 70' frames may not be coated with paint or undercoating whatsoever and Terry mentioned methods of cleaning and preserving uncoated frames as well. I'll bet that many guys over the years did not know that and now those car frames have a fresh black coating. Thanks for all the information, Mike, Joe, and Terry, you guys have really helped in preserving my #9 coupe, removing unfactory paint or undercoating would have been quite a job. Steve

Steve-----

I don't think I ever said that 1970 frames were not not painted or coated, at all. I think the issue was whether the frames were coated with an ASPHALTIC COATING or painted with a semi-gloss black PAINT. Through at least 1969, the frames were coated with an asphaltic coating. This coating IS ABSOLUTELY NOT similar to "undercoating". In fact, it appears just like a paint. However, it's a coating that "dries" by simple evaporation of the solvent, leaving behind the black asphaltic material. It can be wiped off with common solvents.

Paint "dries" by POLYMERIZATION. It cannot be removed by wiping with most common solvents.

Some say that 1970 and later frames were painted rather than coated with the asphaltic coating. That may or may not be the case. I know that my original owner, late 1969 frame was coated with the asphaltic coating. I removed it with a rag soaked with petroleum solvent and "elbow grease". While it appears to be black on the frame, it's actually VERY DARK brown. The rag will show a very dark brown color and that confirms it's the asphaltic coating.

Paint will not be removed by petroleum solvent and, even if it could be so removed, the rag would show BLACK and not very dark brown.

In any event, whatever was used on the frames was applied by A.O. Smith at the frame plants in Milwaukee, WI and Granite City, IL. It was definitely NOT applied at St. Louis.

[Terry M.]

[Steven G.]

Re: C3 Spare Tire Lock Bolt and Bracket

Terry, you never said frames were uncoated, sorry I refering to an old reply you made about cleaning and preserving a factory painted frame. Joe, the type coating was that previous reply, I do apologize. I know there was a change over during this period from asphaltic coating to paint, after looking at the REAR frame, I have not found evidence of either coating or paint. I will take lots of pics.as I go and clean for now, and look for clues, does anyone know how early 70' frames were coated or painted, were they sprayed or dipped ??? Steve