Go to the Hardware aisle area for the nuts, bolts, machine screws, etc. Several sections of drawers down the aisle will be the drawer for spacers. I'd get the chrome ones and spray 'em with Flex Seal. They come out with a dull black hard-as-hell finish. If they don't have the 1 1/8" length, get the 1" and rack will only be off in the back 1/8". Happy hunting. Here's a link.................

https://www.lowes.com/search?searchT...log=4294934474

Found these at Home Depot site. They have 5/16 x 1/2" and 5/16 x 1" spacers as shown in the link. Your bolts just might fit through those holes in the spacers.

http://www.homedepot.com/s/chrome%2520spacers?NCNI-5

http://www.homedepot.com/p/Everbilt-...-204604743-_-N

http://www.homedepot.com/p/Everbilt-...-204604745-_-N