Hi mate,
Its fairly straight forward to swap the spings. You will need a set of spring compressors and know how to use them PROPERLY as an incorrectly compressed coil spring can be VERY dangerous!
A very quick guide....
Jack up and support the front of the car and remove wheel.
Remove the 2 bolts securing the strut to the hub (might want to soak them with penetrating fluid the night before)
Disconnect the brake pipe from its bracket on the strut.
Remove the bolt from the top of the strut (top of suspension turret in engine bay)((you may need to hold the center of the strut with an allen key whilst you use a ring spanner if you dont have access to a windy gun))
Remove shock and spring assembly from the car.
Use spring compressors (at LEAST 2 preferably of the type that lock to the spring so that they cant fly off) to compress the spring and take the tension off of the top mount.
Undo the top retaining nut and top mount, slide compressed spring off of shock.
Carefully uncompress old spring.
Fitting new spring is reverse of removal.
For the rears.......
Jack up and support the rear of the car. Raise the car both sides just enough to take the tension out of the suspension... not off the floor yet.
Remove the top mounting bolts for the shock absorbers (both sides)
Raise the car higher and now the rear beam will lower away from the car enough to remove both the rear springs.
If you dont have 2 trolley jacks etc you can do each side independently but will have to use the spring compressors again to compress the springs enough to come out.
I do STRESS though, that working with compressed coil springs CAN be very dangerous, so be very careful and make sure you are aware of what your doing!
A set of lowering springs can be had for anything from £50 to £150 but i would avoid the cheap and nasty ones.
The BEST way is adjustable coil overs. These include the shock and the spring. However a set of coilovers will be anywhere from £200 to £1000.
As for ride height, it all depends on how much you want to change and how practical you want it to be. Anything lower than around 40mm and you will need to change shocks. If your shocks are already old and tired, lowering any amount will probably finish them off anyway.
Best bet for deciding how much you want to lower is to look through the threads in the members motors section, and when you see one thats sitting how you want yours, hopfully the threads owner will have put in there how much they have lowered it etc.
Hope that helps,
Alan
