1970 Control Arm Finish

[Tom L.]

Following the finish description in the Technical Information Manual,I had my control arms blasted and powdercoated semi-gloss black. Today I was told, by a guy who I believe to be a very reliable source, that my control arm finish is incorrect. I was told that the arms were dip painted and that the ends of the arms, where the ball joints go, were left natural so the original rivets could be heated before crimping without blistering the paint. I was then shown pictures of originals that were done in that fashion. What is the correct finsh supposed to be? Thank you.

[Chuck S.]

Re: 1970 Control Arm Finish

I have seen NOS service part control arms painted that way, but production 70 Corvette control arms were not painted that way to my knowledge.

Control arms on 70 Corvettes were apparently painted, and in some cases where the shafts are natural, the ball joints, shafts and bushings were then installed afterward. In other cases, the shafts will be black like the control arms meaning the bushings and shafts were apparently installed before the arms were painted. In either case, the ball joints will be unpainted natural steel, meaning that they were installed after paint.

The 70-72 TIM&JG makes no mention of any paint configuration other than full coverage being used. If you are trying to make your car appear as original as possible, or if you plan to have it judged, the TIM&JG (judging guide) will be an invaluable reference. Judges may have a problem with the powder coating, gloss level, or other details concerning the bushings and shafts, but not with full coverage.

[Patrick H.]

Re: 1970 Control Arm Finish

Agreed.

The only control arms I've ever seen with no paint on the ball joint ends are service replacements or late 70s-and-after originals.

Your 1970s should be all black as Chuck describes.

Patrick

[Joe L.]

Re: 1970 Control Arm Finish

Patrick, Chuck, and Tom------

I agree; the unpainted outer end of the control arms didn't happen in PRODUCTION before the late 70's, including SERVICE arms manufactured from that time onward.

One other point about what Tom was told: I don't think that the ball joint rivets were ever heated in order to install them. That may be what folks in the field have tried to use to set the rivets, but I don't think this was ever used in PRODUCTION. In PRODUCTION I believe that the rivets were set with hydraulic pressure alone in a special machine designed for that purpose. In PRODUCTION, the ball joints were installed at St. Louis and the shafts installed at the a-arm manufacturing plant. In SERVICE, the ball joints were installed at the a-arm manufacturing source and the shafts installed later by the installer of the arms.

[Donald T.]

Re: 1970 Control Arm Finish

For what it's worth, here's a pic of an NOS upper control arm I recently acquired. You can clearly see the paint line from where it was dipped. Also, the ball joint is installed but not the shaft, just as Joe described.

[Sal C.]

Re: 1970 Control Arm Finish

That is a case where the ball joint was already installed in the arm prior to the dip paint process. Possibly a change in production technique later on as I have had many service replacement arms that were finished like assembly line units.

[Chuck S.]

Re: 1970 Control Arm Finish

..."In PRODUCTION, the ball joints were installed at St. Louis and the shafts installed at the a-arm manufacturing plant. In SERVICE, the ball joints were installed at the a-arm manufacturing source and the shafts installed later by the installer of the arms."

Where the ball joints were installed is not something I had considered, but that is indeed correct...Part numbers for the upper and lower ball joints and rivets are itemized in the 70 AIM, UPC 3, Sheet A3. This fact means the ball joints were riveted onto the control arm assemblies, complete with bushings and shafts, at St. Louis.

[Tom L.]

Thank you *NM*