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1970 LT1 - frame restoration

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  • Chuck S.
    Expired
    • April 1, 1992
    • 4668

    #31
    A Corvette Restored to NCRS Quality...

    Has to LOOK like a brand new factory Corvette EVERYWHERE; NOWHERE IS EXEMPT. Outside, inside, underneath...anything that is visible has to LOOK like it did originally. Powdercoating and/or galvanizing changes makes the part "thicker", puts a radii on sharp edges that never had them, smoothes metal surface texture, and obfuscates the detail of weld beads and splatter.

    If something non-original to the car is hidden inside the engine, behind the wheel covers, or any component normally installed on the car, you get a pass...it's not judged. But if it's inside the engine, and it changes the SOUND, such that it doesn't sound like it did when it was new, you will be penalized at some judging level.

    Removing rust...If you are doing a frame off restoration, the best way to remove rust is to remove it completely down to "white metal" with a media blast cabinet, or in the case of a frame or other large components, contracted sand blasting. Chemical cleaning can be thorough, but it's efficiency is accompanied by other headaches: it has to be neutralized before refinishing, and this is usually done with a water-based solution that causes the clean metal to begin rusting anew with gusto. Storing cleaning chemicals in your work area is also fraught with peril...the vapors off a leaking container will rust the everlivin' **** out of any steel within a few feet radius; experience talkin' here.

    Patrick hasn't removed his rust because he's not restoring the car, he's keeping it original...when he's having it judged, he applies a temporary "moisterizing make-up" to the aged area; it doesn't last, but it looks better for a short time.

    Comment

    • Chuck S.
      Expired
      • April 1, 1992
      • 4668

      #32
      A Few Exceptions...

      "If something non-original to the car is hidden inside the engine, behind the wheel covers, or any component normally installed on the car, you get a pass...it's not judged."

      The only normally installed components I can remember that are removed for judging are the carburetor air cleaner, and the ignition shielding distributor cover.

      You will also be requested to lower your spare tire carrier to permit judging of the spare tire, and to generally assist the judges in opening the vehicle doors, operating the wiper door to expose the wipers, and any other access to areas of the car required for judging. This is done to assure the owner that it remains his car, and so judges take no risk of any possibility of damage, misuse, or abuse during judging.

      Comment

      • Stephen L.
        Very Frequent User
        • August 29, 2007
        • 205

        #33
        Re: A Few Exceptions...

        thx chuck

        Comment

        • Stephen L.
          Very Frequent User
          • August 29, 2007
          • 205

          #34
          70 LT1 - Frame Off - Rust

          Chuck wrote:

          "Removing rust...If you are doing a frame off restoration, the best way to remove rust is to remove it completely down to "white metal" with a media blast cabinet, or in the case of a frame or other large components, contracted sand blasting. Chemical cleaning can be thorough, but it's efficiency is accompanied by other headaches: it has to be neutralized before refinishing, and this is usually done with a water-based solution that causes the clean metal to begin rusting anew with gusto. Storing cleaning chemicals in your work area is also fraught with peril...the vapors off a leaking container will rust the everlivin' **** out of any steel within a few feet radius; experience talkin' here"

          Chuck, All, if media blasting is the preferred method...how is one able to save (or even find) the original marks, numbers, hashes, etc. that the factory used when assembeling the car or manufacturing the part

          - as an example, if I just sent the frame out to be blasted, i would not have found the stenciled part number, which is barely, barely visible under rust - rust because the last person who discovered not only did not paint over it, they put no protective coating over it

          - an alternative I can think of is to use something like ridrust and degreaser to get to bare metal where it is rusted (it supposedly does not lift paint, unless rust got between the original paint and metal) and grease to see the paint - this would seem to be ok for where bare metal shows up with markings (like the stenciling) - but I won't be able to see under any parts of the frame that might be painted - so again, how do I remove paint, without risking removing an original marking from underneath...???? Thanks, stephen

          Comment

          • Stephen L.
            Very Frequent User
            • August 29, 2007
            • 205

            #35
            Re: 70 LT1 - Frame Off - Rust

            Bump...:):)

            Comment

            • Dick W.
              Former NCRS Director Region IV
              • June 30, 1985
              • 10483

              #36
              Re: 70 LT1 - Frame Off - Rust

              Stephen, you document the markings before you remove the coating. Almost anything strong enough to remove years of caked grease and road grime will also remove the coating. There should only be shim marks and a frame # and date stencil on the frame, which will be easy to duplicate. Once you have removed the body from the frame, the Bowtie/Survivor qualifications have gone out the window for that section. So just restore it to the best of your ability
              Dick Whittington

              Comment

              • Stephen L.
                Very Frequent User
                • August 29, 2007
                • 205

                #37
                Re: 70 LT1 - Frame Off - Rust

                Dick - many thanks - a few follow on questions:

                - i have found the stencil...so that is good...it is beneath rust, but i can make it out - in terms of duplicating it, do folks just use pictures and notes - or is there a way to make marks (scratches??) in the frame as to where they go such that after blasting you would know?

                - re the shim marks, is this the "masking tape" that is sometimes referred to? - or is this something else? - if the latter, is it engraved (stamped) into the steel or something just painted on?

                - ditto for the frame number

                And just to be clear, other than these three things, there is nothing else on a frame - no little paint blobs, numbers written on or the like?

                many thanks Dick - Stephen

                Comment

                • Dick W.
                  Former NCRS Director Region IV
                  • June 30, 1985
                  • 10483

                  #38
                  Re: 70 LT1 - Frame Off - Rust

                  Stephen, make a note of the frame stencil, Quanta will make you one with the numbers that you have, or if you are so inclined, you can do it yourself.
                  There may be some crayon marks near the body mounts indicating the # of shims used. Always count the shims when you remove the body, it makes life a whole lot easier when remounting the body. Most of the time it will take a little shimming to get it correct, but having a good starting point helps
                  Dick Whittington

                  Comment

                  • Chuck S.
                    Expired
                    • April 1, 1992
                    • 4668

                    #39
                    Re: 70 LT1 - Frame Off - Rust

                    The masking tape holds the shim package in position on the frame's body mount locations until body drop; it has nothing to do with how many shims are used. The shim marks on the frame will be at each body mount location, and on a 70, will consist of arabic numerals in lumber crayon (green on mine). If there are no shims at a location, only the aluminum "biscuit", then the frame may be marked "0" or have no mark at that location.

                    The shims and the aluminum "biscuit" were placed on the frame mount, and a strip of tape placed over the shim package to hold it in position. This tape looks like ordinary masking tape, but may have been a special product. My car had 2" tape on one side of the frame, and two pieces of 1" wide tape on each mount on the other side.

                    The tape is not visible on any mounts except the Number 4 mounts that are exposed at the rear of the rear wheelwell. Sometimes, on an original car, the tape will still be visible at that location. I suppose it could also be visible at the Number 1 mounts as well, but I have never seen it there.

                    Comment

                    • Stephen L.
                      Very Frequent User
                      • August 29, 2007
                      • 205

                      #40
                      Re: 70 LT1 - Frame Off - Rust

                      many thanks dick and chuck!

                      Comment

                      • Stephen L.
                        Very Frequent User
                        • August 29, 2007
                        • 205

                        #41
                        Re: 70 LT1 - Frame Off - Rust

                        p.s. i discovered yesterday that a product called "evapo-rust" is sold at Harbor Freight Tools - so will try that on the rusted area where the stencil is and report back - thanks again! stephen

                        Comment

                        • Chuck S.
                          Expired
                          • April 1, 1992
                          • 4668

                          #42
                          Are You Saying...

                          You can't read the stencil and you're using this product to make it more visible? Better be careful, if you can't clean the area well enough to be readable with paint thinner, then this product will probably only remove the rust under the last remanants of the stencil paint, making it less readable. Better mark some clear plastic wrap to record the exact location of the stencil before you apply the rust remover...just mark some permanent reference points on the plastic wrap as well as the stencil extent.

                          The important information from the stencil is the date, which is in MM.DD.YY format, and the frame part number suffix, written as -XX. The part number for all 70 manual transmission cars is 3974600. Since yours is a very early car, the suffix is probably -80 from Corvette Chassis Restoration Guide by Joeseph A Tripoli, Jr.

                          The frame part number portion of your stencil is therefore likely going to be 3974600-80. The complete stencil is probably going to be something like the following (Remember, it will be upside down on the frame rail):

                          3974600-80
                          1.14.70

                          Comment

                          • Stephen L.
                            Very Frequent User
                            • August 29, 2007
                            • 205

                            #43
                            Re: Are You Saying...

                            thanks chuck - i have readable pictures - unfortunately they are at work - so i will double check on Monday

                            as for rust...have done a search (tried "black residue" all words; "rust removal black" all terms...? and nothing came up - because I tried that evapo-rust stuff (similar to rid rust (rust rid?)) - not on the frame, but on another item - it worked really well - question: there are black patches here and there where the rust had been - not sure what it is exactly, but what are your thoughts on how to clean it off - clearly the rust buster won't do it - degreaser? - polish of some kind? - thanks!! stephen

                            Comment

                            • Chuck S.
                              Expired
                              • April 1, 1992
                              • 4668

                              #44
                              Re: Are You Saying...

                              Being unfamiliar with the prodcut, I can't say for sure, but I expect the black patches are some form of hard ferrous oxide that is not removed by the product.

                              I have cleaned parts with acid, but I'm not a big fan...there are too many associated negatives which I have already discussed. In some cases, I have deeply regretted having ever seen the stuff. If you're going to use an acid product, then use something strong enough to eat it ALL off. Otherwise, bead blasting is the way to go...JMHO.

                              Comment

                              • Stephen L.
                                Very Frequent User
                                • August 29, 2007
                                • 205

                                #45
                                Re: Are You Saying...

                                chuck - thx as always - i believe you were right on the money - the product is supposed to bond with anything ferrous - so it basically breaks rust down and attaracts away the ferrous part (called "chelation") - the attraction is not strong enough to break the bond that contains the iron in steel - and for this reason, it does not eat away metal - supposedly, for the same reason, it does not affect paint, plastic, etc. - anyway, i left the part in the ziploc soaking in this stuff for another day or 2 and the black residue is gone as well - now i need to wait for the books you recommended and that i bought to come, so i can determine what this part is to and how to finish it, to then tuck away for the eventual rebuild - so...my initial experience with the product "Evapo-Rust" has been very favorable - they list their distributors on their website - 5 gallons is $100 at Harbor Freight or O'Reilly's - the dist offered it at 80 - they did not ask me for a trade license or anything like that - by the way, i have no affiliation with the product and pass this on for what it is worth - ymmv - thanks! stephen

                                Comment

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