The 3-door/Rs500 was set up to give sharp response to turn-in etc - interesting little bit of info in the PC road test here -> Click

Read especially the first column of the 8th page for the Sierra front suspension details.

This is supposedly the changes from 3-door to Sapphire 2wd made by Ford.
Obviously the 4-dr shell was stiffer which has to be taken into account.
Spring rates went up from 106 to 118lb/in at the front and 263 to 286 lb/in at the back.
Damper rates were made softer in bump and stiffer in rebound.
ARB was increased to 16mm on back
Castor increased by over one degree
Camber made fractionally more negative
Kingpin inclination made slightly greater.
Front knuckles re-designed to lower the front roll centre from 144mm to 70mm

Work was also done to rid the tendency of the 3-door to "pitch" front to rear.

Much of the work above was done to create a less "nervous" car and for it to have better straight line stability

Hope that's interesting



Also I remember when they first brought the 3-door out it was supposed to be even sharper on the press release - some press journalists complained about the razor sharp turn in and nervous handling - Ford took the criticism on board and changed from rigid plastic joints in the front suspension to rubber and re-valved the power steering to make it slightly less responsive before it was put on general release apparently