Copy and paste extract from Wikipedia I remember being at devils elbow in the early 80's with my folks in a 1979 Renault 18ts
The A93 road, part of General Wade's military road from Perth to Fort George, runs north through the glen and on into Glen Beag, where it crosses the Cairnwell Pass, at 2200 feet above sea level the highest public road in the UK. The road climbing to the summit is now wide and straight but until the late 1960s included two notorious hair-pin bends with a 1 in 3 (33%) gradient known as the Devil's Elbow. One of the most spectacular roads in Scotland, this was a favourite subject for postcards. It was so steep that at the bottom buses unloaded passengers who had to walk to the top and until it was rebuilt the AA maintained a well in a layby for overheating engines. Locally the pass is still known simply as "the Elbow".