Topic: Idler Arm Washer Finish ~Natural? Phosphate & Oil? or Zinc?

[67gtasanjose]

Attached is a picture for reference, the two larger washers seen.  I want to say Phosphate and Oil, but wish to confirm.

Working on a 67 with power steering but likely the same finish for all classic Mustangs so I posted it here.

[67350#1242]

On NOS idler arms that I've seen, the washer on bracket end appears to be natural finish.  I believe that is also the case for the center link washer.

[67gtasanjose]

I've checked the assembly manual and have confirmed that washer 379297-S is intended for use at the center link end. This washer matches size anyways of the one I removed from the idler arm bushing to shaft location. I suppose I could assume assembly line versions also had the NATURAL FINISH on both washers.

AMK has no listing on this item per say. Perhaps I could measure the washer and see if a substitute in the correct finish is available with a different AMK listing or cross reference. I have located a hardware store washer (zinc plated) that matches the two washers removed in size and thicknes and I suppose I could simply remove the zinc and throw those in a tumbler.

Looking for what others are doing or have done for these washers.

[Bob Gaines]

I've checked the assembly manual and have confirmed that washer 379297-S is intended for use at the center link end. This washer matches size anyways of the one I removed from the idler arm bushing to shaft location. I suppose I could assume assembly line versions also had the NATURAL FINISH on both washers.

AMK has no listing on this item per say. Perhaps I could measure the washer and see if a substitute in the correct finish is available with a different AMK listing or cross reference. I have located a hardware store washer (zinc plated) that matches the two washers removed in size and thicknes and I suppose I could simply remove the zinc and throw those in a tumbler.

Looking for what others are doing or have done for these washers.

I have a couple of NOS ones and the washer appears to be a very light P/O or gun blued. I think ether process will give the desired look . I don't think the assemblyline ones were bare steel with no type of plating otherwise i would find them in a much more deplorable pitted state then I typically do.

[jwc66k]

The process that made large washers used a special lubricating oil (aka cutting oil?) in the stamping so residual oil would be present. That may have been the only rust preventative on them. For restoration, I bead blast, lightly phosphate (1 1/2 to 2 minutes at 190F +) and then oil. It's is a better alternative than nothing, or wire brushing. I've seen a "bluish tint" on cut edges from the tool being over used. The oil was also supposed to remove excessive heat. At least in theory.
Jim