Hi There,
The bellows, arm and linkage on the 40v FL S8 is identical as the my 4.2 D3 A8
Since it was two nuts to remove them whole and that reduced the chance of the ball linkage getting sloppy and gave me a chance to check what the flap was like it seemed the right way to go. The flap has a little resistance moving from one state to another, but was free with it. Seemed a positive movement rather than tottally loose (potentially broken) so i took that as a reasonable sign. I did put some lube in and worked it, same with cleaning up the old belows and the arms. Watching the engine now it's fitted and it moves corectly!
And as for the drive. WOW. I wasn't expecting much but it's really freed up the engine. I'd felt that despite on paper the 4.2 D3 being a touch better than the D2 FL S8 it was rather lackluster. It had power but it delivered it in a wafting ease, rather than any slam. A gentle grace despite a heavy foot.
That's changed it's much more pick a speed and you're there that I loved of my old beast. Back to accidentally breaking the speed limit on an overtake!
Looking at the quattrow world post, it was the bottom flap and due to the spring, it would have always been in the mid band mode which tallies with what i've noticed. A slightly odd way to design it since the majority of the time you are going to be lower than 3360rpm, so i'd have expected Stage one to be the default sprung setting!
Lee