For Any doubt ask me i will be happy to answer it.
In a new part draw a circle with radius equal to that of the spring.
Under Curves select Helix and spiral.
Select Variable pitch. And select pitch and revolution under define by. You will get a table. Enter following values.
The meaning of these values is that at the beginning the pitch is 3 mm, which increases gradually with revolution to a pitch of 10 mm at the 5th revolution. For the next 5 revolution the pitch remains same. For the next 5 revolution the pitch gradually decreases to 3 mm. similar logic can be applied to the other define by types. You can define helix with different values for different purposes.
After clicking on green tick you will get the following variable pitch helix.
To create a spring on the suitable plane right or top (if angle of helix is 0, 90, 180 or 270 degree),draw the circle with radius equal to that of the spring cross-section.
Sweep it along the helix.
Your coil for suspension is ready. Render it. you can also insert dampers. to make it a complete suspension system