need help picking which coilovers

[zdiddy22]

I'm got a question on how stiff of spring rate to get. I don't want to be to soft and sqat in the rear. And I don't want to be So stiff I fly on the track. I have a very high horsepower setup and I need a good spring rate idea. Thanks.

[makavelibranded]

How much hp do you have?, what kind of racing? daily driver?

Theres nothing that has too high of a spring rate for our cars imo especially if running slicks,.. also sway bars will play a roll in what spring rates to go with.

[gtimportfanatic]

wateveer setup u get u can always order custom sprins

[Lucid Moments]

wateveer setup u get u can always order custom sprins

Absolutely, and I would recommend doing exactly this. Ideally you will want a ratio of about 1:2 front:rear spring rates. The Ep has a much longer motion ratio on the rear suspension than the front so you need a stiffer spring back there to get something close to the same effective spring rates.

As an example I have the Buddy Club RSD. I got them with the stock spring rates that come with them which is 10k front and 16k rear. My car still has some significant mid corner under-steer. There are some other suspension things that effect that too of course. In my case I have some fairly stiff sway bars front and rear and I'm going to try to adjust my car with that because I already have the parts I need for that. We'll see what happens. If that doesn't work then I am going to increase my rear spring rate up to at least 18k and maybe as high as 20k.

Keep in mind that my car is a road course whore so you don't necessarily want the same spring rates I'm running but I hope this gives you at least some idea.

[zdiddy22]

Thanks, the motor is being built for 750hp. The car is going to be used for drag racing and is running 9" slicks.

[Lucid Moments]

Thanks, the motor is being built for 750hp. The car is going to be used for drag racing and is running 9" slicks.

Ah, then disregard anything I said in my previous post. Drag racing requires a very different setup from road racing.

As I understand it for drag racing you want a very, very stiff rear spring to help mitigate weight transfer, but that is about the limit of my knowledge.

[Zzyzx]

Eh, your suspension really doesn't care how much horse power you have, especially with drag racing.

Couple of tips,

Run stiff rear springs with out a rear anti-roll bar. It will help reduce squat a bit and the subsequent suspension geometry changes caused by it. By running no rear ant-roll bar you wont create a tail happy monster on your straight runs. You may want to run a stiffer front anti-roll bar as well.

Dampers are paramount here, and you want/need good ones. which means 99% of the prebuilt coilovers on the market should be stricken from your list of possibilities. Most of your launch traction comes directly from managing weight transfer (as far as your suspension is concerned). Remember you are fighting physics with a FWD car, and good dampers will help you maximize what traction you have in those first few seconds.

for alignment, you may want to run a hair bit of negative camber on the nose. Reason being, when the nose raises at launch the natural camber gain will flatten the tires out. (this is assuming you haven't dumped the car to the ground and completely borked the suspension geometry).

[donaldep3]

Eh, your suspension really doesn't care how much horse power you have, especially with drag racing.

Couple of tips,

Run stiff rear springs with out a rear anti-roll bar. It will help reduce squat a bit and the subsequent suspension geometry changes caused by it. By running no rear ant-roll bar you wont create a tail happy monster on your straight runs. You may want to run a stiffer front anti-roll bar as well.

Dampers are paramount here, and you want/need good ones. which means 99% of the prebuilt coilovers on the market should be stricken from your list of possibilities. Most of your launch traction comes directly from managing weight transfer (as far as your suspension is concerned). Remember you are fighting physics with a FWD car, and good dampers will help you maximize what traction you have in those first few seconds.

for alignment, you may want to run a hair bit of negative camber on the nose. Reason being, when the nose raises at launch the natural camber gain will flatten the tires out. (this is assuming you haven't dumped the car to the ground and completely borked the suspension geometry).

Woh~ I am always inpressed by your deep knowledge of Suspension and their physics behind them!!