Piston Slap: To Love, To Hate Aftermarket Rimz (Part II)

Sajeev writes:

In our last installment of this particular ‘slap, a reader had a question about aftermarket wheels. The solution was rather simple, the wheels discussed were not hub-centric. But I also mentioned a horrible “death wobble” problem with my aftermarket reproduction SVT Cobra wheels on my Fox Cougar, solution TBD. It was a big problem until…

I switched out the junky/unsafe lug nuts (bottom) that came with my aftermarket wheels for some OEM (top) units! Unsafe how? While the bevel that seats the lug nut into the wheel was identical, they were both a thin casting AND completely hollow. More to the point, that chrome end is actually a PLASTIC CAP giving the appearance of a solid casting!

NOTE: sadly, out of blind rage that I risked my life with horrible lug nuts, I threw away the actual problem units. These higher quality aftermarket lug nuts are for photography purposes: imagine a snap-in chrome center on this skinny+hollow design and you get the full picture.

And the only reason this happened? My Ranger (pictured here after running a RallyCross) received a healthy wheel upgrade, requiring chrome lug nuts to complete the look. After installing “good” aftermarket chrome lug nuts and these Alcoa forged alloys (shaving 40-50lbs of unsprung weight) the original FoMoCo lug nuts went on the Cougar’s 1993 Cobra wheels and presto…no more death wobble.

Last week I finally drove the Cougar on a notoriously “wobble inducing” stretch of Houston highway and sure enough, the problem is 99% gone. Hence the update you are now reading.

Moral of the story: check the basic components of any system, even if they are “new” and seem to be high quality. Because, odds are, it’s something simple causing the problem.