Rack and ruin
It might be thought that the rack in this phrase refers to the medieval torture device, as in the phrase rack one's brains. This rack is however a variant of the now defunct word wrack, more usually known to us now as wreck. The rather tautological use of the two similar words 'rack' and 'ruin' is for the sake of emphasis. In that respect the phrase follows the pattern of beck and call, chop and change, fair and square etc.
The term 'going to wreck' was the forerunner of 'rack and ruin' and was used as early as 1548, in a sermon by Ephraim Udall:
"The flocke goeth to wrecke and vtterly perisheth."
Henry Bull moved the phrase on to 'wrack and ruin' in his translation of Luther's Commentarie upon the fiftene psalmes, 1577:
"Whiles all things seeme to fall to wracke and ruine."
We finally get to the contemporary 'rack and ruin' in 1599, when the Oxford historian Thomas Fowler published The history of Corpus Christi College:
"In the mean season the College shall goe to rack and ruin."
Judging from the accompanying picture the college seems to have survived the following 400 years quite well, and Fowler need not have worried.