It is common for a convertible to shake and rattle a little when the top is taken off (especially the first few kilometers after the hard top is removed). The W107 does shake more as the R129, but even the R129 makes more rattling noises after you first take off the hardtop.
Even our SLK rattles and shakes a bit more during topless rides.

greetingz,

__________________
1990 300SL-24
1993 C250D with a minor 600+k kilometer
www.MBenzNL.com(the Netherlands)