Lgbzone

I wouldn't have thought you had to totally rebuild them at this stage, i'd be looking at draining them, cleaning them and then adding the new oil. although it wouldn't hurt if you did rebuild them.

I wouldn't change both the spring and oil at the same time, ideally; change the springs and them preload them until the correct amount of force is needed to compress the suspension, this depends on car weight, speed and how rough the track is. then look at how fast the suspension returns after being compressed, if it's too fast; the car will bounce on the rough, traction and stability will be compromised, so add thicker oil to slow it down. if it's too slow/damp; then the suspension compresses on a bump, but won't return quick enough for the next one, so on the rough you're hitting bumps with the suspension already compressed, again the car will start to bounce and traction and stability will be lost, obviously you won't be able to get the power down either. when you get it right; the chassis will travel flat, horizontally as the wheels are going up and down tracking the ground, here the car is most stable with the best traction.