Preload/Suspension/Ride Height Questions

[Shimadorisanni]

Originally Posted by derass

Depends on how much thread distance you have between the lower mount and the spring perch. Those helpers are going to add a few inches to the total spring length. If its too long, you would have to actually raise the car to install the helpers. That wont help you achieve what you're trying to do.

You didn't mention what chassis your car is, but I know S14 have very long rear shock bodies, so there may be enough room for your idea to work.

Either of your options will preload the new spring combination, the assist spring more-so than the helper. The assist spring has stiffer rates and is intended to offer a progressive rate when installed on a coilover with an existing linear rate spring. The helper spring has a very low spring rate and is intended only to prevent the spring combination from becoming loose at full droop, with the weight of the car on them, they will be fully compressed.

Installing helper springs would not affect the overall spring rate. Assist springs, in a sense would soften the spring. This is because the progressive rate ideology behind their use. However, once they are fully compressed (cornering, taking a bump etc.) the spring combination will take on the rate of the original linear spring.

With that being said, I personally would choose to get the assist springs. They would preload the entire spring combination while giving the coilovers progressive rates, making them ride much more smoothly. I would probably get the 5kg/mm rate as I have 6kg/mm currently and find them to be a bit stiff.

Another option would be drop knuckles in the rear.

Sorry, i will take some pictures today of the tread distance as well as the measurement from top of spring to perch. The chassis is an s13, and soon I will be adding subframe risers which i hope will give me a little more leeway. So for an 8kg/mm rear spring I would want a 5kg/mm assist spring setup?