George
I had a new 4 seat in 2008 with this very same damper arrangement. There were mega issues with soft rear springs and part of the discussion with the dealer/MMC on the total lack of clearance between this rubber device and the damper body. I was assured by MMC and it was later confirmed by Peter Ballard that these in fact are not bump stops they are spring assisters and it was completely normal for the vehicle to run with them in contact on measurement the total rear axle movement in bump of about 20-25mm, crazy!
We were at the point of me rejecting the car as unroadworthy when the MMC finally agreed to the dealer sourcing a pair of rear springs from Mulfab (I collected and delivered them) and a pair of Spax rear dampers to be fitted.
The car was at the dealer for 4 months to sort this out as I refused to accept it, one set of rear springs supplied by MMC were so soft the car sat (when empty of fuel, no luggage or occupants) on full compression!
BR
Colin
