A nice inexpensive but worthwhile improvement. The OE rubber mounts are designed with voiding and have a degree of ‘comfort’ in mind, allowing the rubber to absorb any vibration from the gearbox. However the material makes them prone to softening and sometimes they can tear with age. Split or worn rubber will promote excessive gearbox and engine movement, resulting in imprecise gear shifting as well as impacting on the handling of the vehicle. The addition of a polyurethane gearbox mount insert, which sleeves into the factory rubber mount, will stiffen it and reduce movement. It aids premature failure of the factory rubber mount and helps to reduce movement in the mount and improve gear change.
The C4S with manual transmission has one gearbox mount at the front of the gearbox which can be fitted with Powerflex Part PFR57-530 and the best part is the poly insert is under £30. I have opted for the yellow insert (shore hardness 70) which is the suggested one for road use.
I will update with some fitting pictures at a future date in another post.