So got the springs today and installed them right away.
New Swift spring is green also (they only fit Teins?), nice touch. 178mm instead of 150mm, 7kg instead of 6kg.
Also measured front damper stroke, it is approx 80mm. So 13mm went missing, a good look under the dust boot reveals an very small rubber bump stop, about a third in height of a regular coilover bumpstop...
so much the better considering how the HBS works (see above), but also even more important to get sufficient bump travel before you hit it. Which with the above spring (7kg gives 8mm more) and exactly 7mm preload, bump travel increases 15mm from approx 22mm on the shock (before hitting the above) to approx 37mm, quite a difference! As you can imagine with the increased rate also, the load needed to touch the final bump stop is a lot higher now.
As planned, I removed one collar and the springs sits on on the two remaining ones straight on the wheel carrier. Car is about -30mm in front from stock.
Went for a pretty serious drive doing most types of driving and roads, and now the Flex A are exactly as I hoped for. Front and rear feel much more balanced. Played with damping adjustments, only needed to turn the front 1 click firmer compared to the 6kg spring to get it to my liking (now 6/7 clicks front/rear from full firm). The bridge jump felt much calmer and undramatic at 50mph compared to the RCE yellow where one would bounce of the bumpstops and get launched a bit. I dared to increase speed to 56mph but then it started to bottom out just a bit, still less eventful than the RCE yellow. A clear improvement in (bump) performance driving.
Also the dreaded reference speed bump. Where before it would very noticeably bottom out at 16mph, now at the same speed it was uneventful. I increased speed to 21mph where it just started to bottom out. Like for like, I estimate the speed went up 6mph (15mph to 21mph), a big increase percentage wise. I didn't feel like going faster, it's the kind of speed that starts to feel unnaturally high for a lowered car. Also on back roads, I feel I can push on as much as I like without getting the distinct impression that front bump stroke is limiting the car, and front and rear seem to hit the HBS at the same time. And in other less bumpy circumstances, it still rides a lot better than the stock dampers. So more peformance, better ride, and yet it sits as low as I'd dare (-30/-25 fr/re from stock). All in all very pleased now with the (modded for my chosen rideheight) Flex A, a real upgrade!
