In New Zealand we have four Plus Sixes all made in the first 60 odd cars in the later part of 2019. All have experienced a loss of ride height. The lowest point is under the muffler where we have between 80 to 90 mm ground clearance on a flat surface in an unloaded state. In minimum clearance for all road vehicles in NZ is 100mm. All are going to be fitted, at owners expense, with SSL coil over damper units as soon as they arrive in NZ.
It would be interesting to know just how widespread this problem is - maybe the road surfaces in NZ are harder on suspensions than in the UK? Maybe the time to measure your Plus Six's clearance!
The Plus Four suspension appears to be different and fine. In fact SSL have said that they are happy with it and may not be able to improve on it.
Engineering hat on again.. If early Plus 6 cars are starting to show ride height reduction, then the issue is the spring. The SSL replacement modification ( I believe) changes both damper and spring in the coil over unit. and a modification to the front roll bar.
Dave Plus Six "Squeak" Roadster departed. 1936 BSA Empire Star Q8. 1935 BSA W7-35. 1938 BSA M20
