suspension springs discussion linear vs. progressive
 

I have heard differing opinions with regard to springs/suspension - best spring manufacturer, amount of lowering, the spring rate, best shocks, and very little on the pros and cons of linear vs progressive springs.
Id like to open up a discussion on all aspects of suspension with regards to springs and where pertinent affects of various shocks with these types of springs as well as application - daily driver, drag racer, etc.
thanks,
chuck

well if you dont know the difference linear springs are the same spring rate no matter how much you compress them. progressive the spring rate acually increases as you compress the spring rate. you prolly know this but just incase im puttin it out there. hopefully someone smart will come and shed some real knowledge... free bump

I purchased my M2 coilovers w gab r 8way adjustable and eibach linear springs. I forget the spring rates but I can tell you that the linears tend to bounce a little. Keep in mind the gab tend to be stiff and I daily drive. My shocks are set at 4. I would really like to throw a maching set of progressives on and see the difference.

Most people dislike progressive rate springs for sports cars because they aren't as "predictable" as linear springs. Since the rate isn't linear, it's hard to predict how the car will behave. But, for normal driving they are better on the butt. :)

Given that, I'm not sure there are any progressive rate springs for the FD currently. It was once thought that H&R and Eibach were progressive rate. Eibach directly said theirs were not. There have been other mentions of H&R's not being progessive either.

One of the points that Ive heard is that the progressives are not as predictable, for example in hard cornering. What I am looking for is a spring that is comfortable in everyday driving but when pushed hard provide a firm and predictable stiffness. I believe this is where the shock comes in with its expansion and compression ratios in controlling how the spring reacts under pressure and release. So what combinations are working for everybody and in what kind of use? Anyone have any input as to the "unpredictable" nature of a progressive spring?
chuck

Interesting, because the Eibach web site states the following for their PROKIT:

High Performance Handling
Lower Center of Gravity–Lowers vehicle 1.0"-1.5"
Progressive Spring Design
Excellent Ride Quality
Million Mile Warranty
Part of the Eibach Pro-System

Dont the progressive springs look different in the way the coils are arranged and the gauge of the wire changes? The linear coils are evenly spaced and the gauge of the wire is consistent.

chuck

That's just a generic message for their springs:

https://www.rx7club.com/suspension-wheels-tires-brakes-20/eibach-springs-linear-progressive-289625/

As for the look of the spring coils, I have no idea.

unless you are a pretty gifted driver driving 10/10ths, I don't think it will matter much on the street.

great link mahjik.

Try softening the shocks. Try 2F/1R, 3F/1R, or 3F/2R. The GAB super-R shocks have a lot of damping, and overdamping can really make for a jarring ride.

-Max

Everything you ever wanted to know about springs and their measurement here:

http://www.stockcarproducts.com/spgtech.htm

I did some testing on the stock springs here:

https://www.rx7club.com/race-car-tech-103/spring-rate-tester-498429/

There are several links in the Suspension and Handling sticky as well:

The Physics of Racing by Brian Beckman Explanation of vehicle and tire dynamics

Shocks and handling by Grassroots Motorsports An article about how shocks and their behavior effect your car's handling.

Smithees Race Tech Some great tech articles about weight transfer, shocks, springs and suspension geometry.

Shock (Damper) Tuning Explained Some theory behind shock adjustments (keep in mind some of this is geared towards oval racing).

Chassis and Suspension Tech Articles! A wealth of knowledge is featured in this UBB forum! Features many chassis topics from Mark Ortiz along with Brian Beckman's Physics of Racing series of articles. When you get serious, this is the place to read up.

1st, most springs listed as "progressive rate" are just dual rate.... soft-stiff. These will look like 1/2 the coils are spaced closer than the others. Concept is normal ride has all active coils used, hard braking or cornering collapses the more closely spaced coils and now the spring rate doubles. Problem is light end/side of car is still on soft rate, and actually jacks up that part of the car a bit.

Of the dual rate springs, the best concept is having just ~1/3 of the coils closely spaced (mazdaspeed coilovers). This makes the the transition from soft to stiff less abrupt.

Dual rate springs include old PFS comfort-sports, and H&R. Intrax may sell them too. These are fine for combined track and street use. Some general catalogs show what look line dual rate, but are really single rate as the close coils just collapse under static load and act as spacers.

True progressive rate springs for an FD would have the pitch between coils change continuously from end to end. I haven't seen any.

Damon,
Thanks for the links. There is a wealth of info which covers just about every aspect. Good stuff!

It seems that the Eibach pro kit springs are a predominant and popular choice for the FD and the feedback is mostly positive about this setup. Have there been any alignment issues with these springs? Any favorites for shocks used with these springs and what kind of settings are being used on those shocks?

chuck

Not a help in the Rx7 application, but came across a true progressive spring last week off an old Surtees F1 car.

The spring varied in both winding spacing and wire diameter from end to end and was manufactured in titanium. Shudder to think what it would cost to produce though!!