Trailing arm spring bolt cushion retainer cup

[Joe L.]

Re: Trailing arm spring bolt cushion retainer cup

Mike------


The inner retainers did change over the 63-82 period. The 63-E67 part was GM #3831588. This is the "short" retainer. Sometime in early 1967 this retainer changed to GM #3910701. This is the "tall" retainer. The 3831588 was discontinued from SERVICE in July, 1967 and replaced by the 3910701 for SERVICE of all 1963+ Corvette applications. The 3910701 remains available from GM to this very day.

All original examples of the 3831588 and 3910701 as well as all SERVICE examples I have seen were "bare-naked" steel. They rust almost immediately. That may be why reproductions are plated; most folks don't like rust. It's even possible that the GM pieces are plated now; I have not bought one in a long time. Want to get rid of the plating? Dip the parts in a weak acid solution (like vinegar). Leave them in for just a short period of time and keep repeating this until the plating is gone. Then, dip them in a sodium bicarbonate solution to neutralize any remaining acid and create an alkaline film. However, be prepared for them to rust in very short order, just like the originals.

I think you will find the crack you created during your installation to be present on most originals, too. In fact, there may be several such cracks.

[Gary B.]

Re: Trailing arm spring bolt cushion retainer cup

Mike,

As Joe stated, I've also observed splits on most original cups on C2 springs that I've examined. There usually are many more than 1 split per cup and the size of each split is smaller than the size on your cup, which makes sense since there is a certain amount of circumferential strain to be released and each split will release some of that strain.

Also, diluted muriatic acid will strip the plating on the repro cups very quickly, and as Joe said should be following by a baking soda bath to neutralize the acid.

The last set of cups I purchased from GM about 2 years ago where not plated. I used satin clear on my cups to keep them from rusting, and I re-applied some clear on the swaged surface after swaging since I figured the residual strain must have cracked the clear coat I put on the cup before swaging.

Gary