66 Control arm bolt finishes

[Dave K.]

[Gene M.]

Re: 66 Control arm bolt finishes

Dave, All the bolts (fine thread) are black phosphate as you stated. The hardware on the ends of the controll arm shafts was in place when the A-arm were painted less the ball joints. The likely hood of them not receiving any paint is remote. The bolts were tightened down after the car weight was lowered down to avoid twisting the bushing. Thus wrench impact marks are feasible. The studs on the frame securing the shims and pivot shafts are phosphate black again 7/16 fine thread till '66. The nuts were plain/grey phosphate or unfinished grade 8. The lower bolts are 7/16 fine threading into the twin nut (no finish) plate and are also black phosphate. You stated correctly the rear lower controll arm bolt as phosphate with plated nut. The washer on that bolt is a special serated type also black.

[Dave K.]

[Gene M.]

Re: 66 Control arm bolt finishes

In almost all cases the grade 5 hardware is not plated. The industry standards were to use phosphate or black oxide to provide a limited rust preventive. Short lived as it was. Other situations had oil or no finish at all. Electro plating was generally not used on high graded hardware because it can cause the piece to become brittle if not heated afterwards. If I was to guess hardware appearing plated in the chassis photos (graded hardware)was oiled or bare steel. When taking your car apart check the threads that are not exposed and many times the answer as to finish can be found.