last night, my '90 IROC convertible lost a center cap on the highway. this isn't the first time--the car was missing that center cap when we bought it--so i simply tried to screw in an old center cap that i had lying around the garage. for whatever reason, the cap won't 'hook' and insists on falling out of the wheel. looking at the 82-92 Parts CD i have, there is what is listed as a cap hub for some of the IROC wheels (it shows up in all diagrams, but is only listed on one of the pages).

could this part be missing? if not, what else could be causing the problem? getting a new center cap will be easy (especially with the Englishtown, Carlisle and Hershey swap meets coming up), but i'd hate to buy a new one and *hope* it stays in.

oh, and the car has factory 16 inch wheels and they're in excellent condition.

 

Your wheels may be different since the car's a 90, but my 85 IROC has an insert which actually pops into the wheel itself. The cap, the portion with the IROC-Z script, is essentially glued to the insert.

JamesC