280zx (s130) which lowering springs to go with Bilstein shocks

[bigbreak_2000]

On the 280zx 2+2 my goal is to firm the ride up and lower the vehicle about 1 - 1.5 in F&R. I can still get Bilsteins B46-0057 for the rear (max length 20.69 vs stock 21.15) and for the front I'm planning on using the Bilsteins P30-0264 for the '84 300zx N/A (max length 20.77 vs stock 21.3). According to Bilstein they should be fine for using with a 1 inch lowering spring. I need help on how to decide which spring would be most suitable to use on the 280zx, with the Bilsteins. I was thinking a F 175/ R 200 lbs/in should be fine for street driving. The car is not gutted. The wheel tire combination is 205/55-15 F and 225/50-15 R which is an overall almost full 1 in smaller tire diameter.

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• Tokico (progressive): 140lbs front / 165lbs rear and somewhere else I read they are in fact constant….175 F and 200 R
  
• Suspension Techniques: 125lbs / 182 lbs - maybe too soft
  
• Eibach (progressive): 68-148lbs / 85-306lbs - no longer available
  
• Ground Control Coilovers: 200lbs / 225lbs - maybe too stiff?
  

 

I don't want the car to be bouncy or too hard on the street. Making coilovers just seem overly complex for my need. I heard Hypercoils are very good quality springs, and an excellent choice for racing, but then what length, stiffness and coil diameter is recommended? I did a rough estimate on the Hypercoil application and the recommendation turned out 185 F and 220 R stiffness.

 

Here are the specs on the stock 280zx springs

Free length F 12.78 R 14.07

Spring constant lb/in F 126.6 R 140.6

Coil diameter F 5.91 R 3.94

wire diameter F 0.512 R 0.472

 

I am not educated in how to choose a suitable spring. I have an installer that will do all the fabrication and installation and alignment , but I obviously want the installation to be as easy as possible (using as much as possible of the stock suspension components).

[BluDestiny]

What kind of tire size are you running? If you have a lot of sidewall that will absorb more bumps.

 

Even of you don't though I'd suggest the tokico linear springs that MSA sells, you can call them to confirm the spring rates. They definitely firm the ride up and I don't think they would be hard enough to blow your bilsteins. I was running them with tokico hp shocks though, and I'm a young so it felt soft to me.

 

softness depends a lot on your sidewall and also the seat you have. A fiberglass bucket will transmit a lot more to your spine then the stock seat.

[bigbreak_2000]

The tires are brand new BFG G-Force Sports. The fronts are 205/55-15 and the rears are 225/50-15. The interior seats are all stock (very comfortable and top notch condition).

 

The question the Hypercoil engineer had for me, and unfortunately I don't have the vehicle with me to go check, is what's the design of the stock spring at both ends: closed & ground, closed & not ground ends, open & ground ends or open & un-ground ends? Can anyone tell me what this is on the stock 280zx? I did a quick google image search on the aftermarket springs for the ZX and it looks like all the ends are open and un-ground, Which may imply Hypercoils are not an option unless I convert to coilovers with proper spring perches.

 

For those using the Tokico springs, what is your experience, are they good quality springs? I'll call MSA to get the spring rate on them.

[BluDestiny]

Stock springs are open and ungrounded as they sit on a perch that cups the end if that makes sense. I'm assuming by grounded you mean it has a flat end to sit on. Hypercoil mostly sells coilovers springs so that makes sense.

 

Eibach can make a custom spring rate for you also if you just give them the dimensions and information.

 

I had no problems running my tokico springs, Never had a problem and for the year I had them I went cross country, towed a trailer, did a lot of hard canyon driving and definitely beat on it daily with the north hollywood streets.