[phoenix]

Just thinking out loud here...

15 cm is about 6% of the wheelbase of the Escort.

I think I am right in saying that the engine and gearbox amount to about 33% of the cars total mass.

Overall, moving the engine back would seem to give about a 2% shift of mass relative to the wheelbaase. I am not sure what the weight distribution front/rear is, but guessing at 65/35, this would mean the c of g shifting rearwards about 3% of the wheelbase.

My thoughts are that this would not have a great impact on spring rates, though it may improve the handling a little (maybe a little less tendancy to understeer on turn-in).

Moving the tank forward would also have a relatively low impact on spring rates I would have thought.