Is there a list of good vs bad springs for the EVO for use with stock shocks. This is the route I want to go. I would want a spring that lowers the car just about 1", not more and should be a tad stiffer to account for having less travel. It should not be too stiff where the stock shock valving no longer matches.

I understand that the stock EVO valving shock is very close to what you would get with sporty aftermarket shocks for most other makes. This makes me think that just swapping a spring is a nice cheap improvement over stock for track handling.

(Sorry folks, I can't afford coil overs)

So far, I got this:

Good:
- Swift
- GTWorx

Bad:
- S-Tech

My main question is why no one talks about H&R and Eibach springs on the EVO forums. I have had great results with these high quality and properly heighted and rated springs on other cars. I even ran H&R race springs in one of my cars and other than the lack of corner weighing ability....but for DE's.. who cares - you're not racing.

I am also considering throwing on a set of camber plates so I can up the negative camber up front on DE days. So, in summary, I'm thinking:
a) sporty springs with stock shocks + camber plates OR
b) rear swey bar

I think a) should give more more bang for the buck at the track over b). Sorry folks, can't afford both at this time.

Thanks for any input.
ANdy

 

Not a bad plan. Don't reinvent the wheel. Swift and GTWorx are the springs everyone uses, and there's probably a reason. If you decide to go the camber plate route, make sure you get yourself a set of toe plates to fix the toe whenever you change the camber.

If you're on street tires, I would start with springs and an adjustable rear bar. The camber plates can come later. R-compounds will require camber plates if you don't want to wear them out way too quickly, but I'm assuming if you're strapped for the cash for a sway bar you're probably not on slicks.

 

I'm at a bit at a loss why you would put higher spring rate in the back for a car that's front heavy (approx. 60/40 for Evo). It seems to doesnt' make sense from weight transfer during cornering point of view. With the softer spring in the front and car is 60/40.....it seems like the car is prone to dip to the front during cornering.

I have Ohlins R&T 10kg/mm front/8kg/mm back (factory setting) - seems to make more sense to me.

Anyway, people seemed to complain that Ohlins has a softer ride than the factory. I don't think that's a bad thing - much more comfortable.....all I can tell you is that my Ohlins can power through the corner and not lose any grips compare to factory KYB. I throttle hard to the point that I know that KYB would slight lose some grips (oh yeah....done that before).

People should care more about how well you can power/grip in the cornering - that's how you evaluate the shocks.....softer ride doesn't mean worse suspension.

Hypercoil also makes excellent springs.

 

The geometry is different front to back. As we all know the fronts are struts, but the back is multilink. The front motion ration is quite a bit higher. Notice that the factory springs are bigger in the back.

Every really good set up that I've seen has had equal or higher springrate in the rear, but still had lower wheelrates to account for the weight distribution.

d

 

It has to do with the system response and the resonant frequency of the suspension. Your suspension is essentially a mass-spring-damper system. The resonant frequency is related to the mass (sprung weight) and spring constant. You want the rear frequency higher than the front. In the case of the Evo, you get stiffer springs in the rear when you run the math. 2.2 Hz front and 2.5 Hz rear are around what you want to maximize performance. I think this works out to around 8k front and 12k rear assuming you're still near stock weight. Some of the autocrossers are running closer to 2.7/3.0 (12k front 16k rear). Most street cars are usually designed to be around 0.8-1.0 Hz.

 

But that doesn't get to the point.

You can't compare the springrates because the geometry is different. You have to compared the wheelrates, and those are lower as you would expect.

d

 

Interesting... never heard of those things. Who makes these? Got a link to the part?

Actually I'm going to be using R's. I'm not a novice driver, so my approach is to go what gives me the best bang for the buck! From past experience, the best mod anyone can do to a stock car is learn how to drive it at its limits and determine what you want to change to make it faster. Then go to R-compound & upgrade brake pads. I got these done. Next best return for the amount of $ you spend would be some tweaks to the suspension. Hence the delima of spring+camber plate vs. rear sway bar. Since my stock setup has slight understeer (but it is really not that bad compared to other cars) I'm leaning towards the spring & camber plates. I think the camber plates, lower center of gravity and slightly stiffer spring could add enough bite-in up front to make the car more neutral.

If I had say a VW or Audi, where the understeer is really bad in stock form, I'd be getting the rear bar no question as the first mod after the tires & pads.

The EVO's stock handling is quite impressive I think.

 

http://www.saferacer.com/longacre-to...?productid=486

They're not a part. They're an alignment tool. They're cheap and they're awesome if you want to start messing with your alignment on your own.

Yes you are correct on that point.

What I said is still valid about the basic reasons we choose the spring rates we do.

 

...duplicted accidentally.

 

K that makes sense. Thanks. But wouldn't you think the car's weight distribution would have to do with spring rate selection? (as in an aggregate effects of all 4 transfering the weight back and forth in corners/accel/braking). As a whole car dynamic system, I still see the front have higher spring rate makes sense......and then why would Ohlins have higher rate at the front?

So you select the springs and valve the shock accordingly?

donour - Bigger spring in the back? You mean higher rate? My stock rear springs are definitely smaller.

 

doh... I knew that. I must of been in a temporary state of caffeine deficiency...

 

To get the car to rotate.

 

Yes, weight distribution does have to do with spring rate selection. But you have to relate the spring rate to the wheel rate, which is the effective spring rate at the wheel. I'm not going to run through the whole calculation, but assume you end up wanting 900 lb/in front and 600 lb/in rear wheel rates. A MacStrut suspension has a motion ratio of 1, so you would put 900 lb/in springs on the front. If the multi-link in the rear has a motion ratio of 1/2 (the wheel moves twice as far as the shock mount point when you compress the suspension) for a 600 lb/in wheel rate you would need a 1200 lb/in spring.

 

Thanks for a useful answer once and again.

 

Yeah of course. I wasn't talking about the dimensions.

Isn't that what I said in the beginning?

cheers.

d