racking / wracking are similar-sounding terms with different meanings (referred to as homophones). To better understand the differences, see below for definitions, pronunciation guides, and example sentences using each term. 👇
racking: (verb) stretch to the limits. (verb) put on a rack and pinion. (verb) fly in high wind. (verb) draw off from the lees. (verb) work on a rack. (verb) seize together, as of parallel ropes of a tackle in order to prevent running through the block. (verb) torture on the rack. (adjective) causing great physical or mental suffering.
wracking: NA
racking: r·AE·k·ih·ng
wracking: r·AE·k·ih·ng
(Examples are Wikipedia snippets under the CC ShareAlike 3.0 license. Definitions drawn from WordNet.)