On 25/01/2020 22:49, Roger Mills wrote:
On 25/01/2020 21:15, T i m wrote:


Thanks. They're the original clips - I didn't get new ones. [The Ebay
link was to show what the clips look like when not installed]


Old ones may have deformed a bit over time. I never understood why this
happened at ordinary temperatures until I asked a very good metallurgist
from an automotive background. Even tempered carbon steel has
microcracks within the structure and you can get plastic deformation at
these sites that relieves local stresses.

Riders of old british motorbikes will know how valve springs shorten
over time. Inlets as well as exhausts, although the exhausts shorten
more. Car suspension springs also shorten a bit.