This front spring compressor is for all Early Post-War cars including RR Silver Dawns, Silver Wraiths, Bentley Mark VI's and R-Types.  This compressor incorporates the later modifications detailed by The Company.  Included are the Compressor RH368 and the Compression Stud RH672. 
All of the lower linkages, pins and standoff studs are made from heat-treated Chromoly.    The threaded nut on top is made from high-strength 544 phosphor bearing bronze and it rides a roller thrust bearing for smooth operation.  There are two different risers that can sit on top of the hook portion.  One is fixed and straight, the other sits on a radiused washer and the riser has a matching radius so the whole screw assembly is allowed to pivot independent of the light green hook while it is attached to the frame of the car.
Once the compressed spring is captured by the compressor, the compression stud can be inserted and installed and the compressor can be removed.
The compression stud is made from Grade 8 threaded rod with fully machined Chromoly nuts.  One nut is pinned to the threaded shaft to avoid any surprises.  Thick Grade 8 washers are included with the compression stud but might not be able to be used on all cars.
The spring does not have to be removed for all repairs but if it does, the compressed spring is placed into decompression pot STD416 and secured with the handle nuts.  The compression stud can then be removed and the spring can be relaxed by undoing the handle nuts.  The handle nuts ride on roller thrust bearings.  The new spring is compressed the same way.  STD416 is available separately.
Instructions and the factory bulletins will be provided.