Can someone please explain how the relationship between spring rates and shock selection works. I see that coil overs can run high spring rates over regular drop springs that tend to run progressive rates. If you ran an adjustable shock would the performance be similar between a coil over set-up vs drop spring (given you changed the shock adjustment for your set-up)?

thanks
Kelvin

 

Good TOPIC>>>
I want to learn more as well....

 

anyone???

 

By Drop Springs I assume you mean somthing like the Eibach Pro, Suspension Technologies, or Racing Beat kits. Those kits are designed to use the stock spring perches. The spring rates are fixed by the designers. You don't have any choice.

Coil overs on the other hand allow the use of a wide variety of spring rates and heights. Eibach alone offers hundreds of choices making it possibe to set your car up in almost any way you choose.

In most cases when you use a shorter spring to lower the car you reduce suspension travel at the same time. This then requires that you increase the spring rate to prevent the suspension from bottoming out all the time. If you are trying to build a performance car it is not beneficial to choose spring rates based on ride height. Spring rates should be selected to achieve a specific handling objective. Some coil overs are designed to offer adjustable ride height without the need to change suspension travel.

Rob

 

Rob500....
How do you like you ground-control coil overs???
I'm planning to put those on my 10th AE....
I would like first hand info about there setups....

 

Mr. 500 is refferring to the GC's when he mentions that Eibach has several options as far as spring rates are concerned. This however is only for their 2.5" ERS, Eibach Racing Spring, which is the spring that Ground Control mates up with their threaded sleeve and collar, make shift, coilover setup.

This system, for the financially conscious, is great. I have seen it setup with Illuminas, Konis, and AGX's. Bang for Buck, KYB AGX's. Best all around, track and street, Illuminas. I hear the Konis are too stiff, according to Mazdatrix, but I am going to use them anyways.

If you want to custom choose your spring rates, this must be disclosed at the time of purchase. Otherwise you will get what GC reccommends. I believe 375 and 250 is standard rec for them.

Let me know when interested, get you the forum deal. Not much markup on these items, so it is possible to get them cheaper by $10.00 somewhere else. But please be supportive of the forum and spend your money here.

Thanks, Rishie

 

I'm sorry it took me so long to reply. I was out of town for a week.

When I bought my GC Coilovers there were a few things I was worried about.

1. I had heard a couple of people say that the front ride height was actually higher after they installed the GC coilovers. The primary reason for this is the stock front spring perch limits the range of adjustability. The rear ones are not a prolem. Racing Beat offers a front lowering mount that helps. GC says that their camber plates also help. I modified my spring perches to get the adjustability I needed.

2. When the front suspension is fully extended (like when the car is on jack stands) the 7" spring that GC recommends loses contact with the lower mount. After driving around with them for about 9 months and a few autocrosses this hasn't been a problem and I wouldn't worry about it. If you like, GC offers a helper spring to take up this slack. But I don't think you need it.

I slightly modified my rear perches to give the threaded sleeve a flat place to sit.

I had to double nut and lock tight the rear upper mounting bracket bolts to keep the rear mounts from rattling.

But after all of that, I like the way the car handles and feels. Very solid and flat. No rattles or noise.

ARDT2 is correct when he says the GC's are a cost effective solution. But if you have the money, you may want to consider a threaded body coilover that offers ride height adjustment without loss of suspension travel. I put a bit of work into my setup to get it to work the way I like.

Rob

 

Standard GC FC spring rates are 300 front/200 rear.