Ok, I have a question. Me and a buddy were discussing this. We need to know which one rides better w/ the same spring rate. I am not really looking for which one handles better, just better ride. He claims it is one and I claim the other. We have a small wager on it and need someone to tell us who is right. The bad thing is that I did a google search and found evidence that shows that I am right, but he claims that he has done the same and found he is right.

If you guys could lead us in the right way and give as much evidence as possible it would be greatly appreciated.

Ben

 

Part of that depends on what you call "better", and part on what conditions you observe it under.

Linear springs will usually ride softer, but will bottom out easier. Progressive springs handle extra loads better. Linear ones are alot easier to set up for racing type applications.

 

By better, I mean a smother, more comfortable ride. We are assuming that the springs are rated at the same spring rate. On progressive springs is the rated spring rate the softer end or firmer end of the spring, or somewhere in the middle?

Ben

 

The rate is rated at rated load, which produces rated height. (what?) So I'd say it would be somewhere in the middle.

Generally a linear spring will ride softer; since it will allow more suspension travel for a given "bump". But, the shocks have to be set up accordingly. Otherwise you'll end up with too much damping on "bump", and not enough on "rebound".

 

Well if they both had the same rate I imagine they would ride the same. The reason the progressive rate springs are known to ride better than linear springs is because they dont have a static spring rate, it changes as load is applied. So during normal driving the rates are soft, take a turn and do some "spirited" driving (hahah) they stiffen up. So you cant really compare the two (progressive vs linear) because the linear springs have 1 rate while the progressive springs have multiple rates. If you'd like to know the rates for the Eibach springs, do a search on these forums.

 

The rate of a progressive rate spring does not change in response to driving technique. Rather, it is different at different applied loads. That includes the change in "load" that occurs as you drive down the road, with the car encountering the normal unevenness in the pavement. When the suspension gets compressed, the rate increases; when the suspension extends, the rate decreases. That happens whatever the reason for suspension travel is: whether it's more weight, or a bump in the road, or the forces applied differently to each side of the car in a turn.

Spring "rate" is given in pounds per inch, or similar units. In other words, it's the number of pounds it takes to compress the spring one inch. A linear spring has the same rate throughout its travel; but a progressive spring might have the same rate as the linear spring at its designed installed height, but as the height decreases, the rate increases (in other words, as load is applied, the part of the spring doing the work is stiffer). Which means that as more load is applied, whether by putting more people in the car or by going over a bump that forces the suspension to shorten, the spring reaches a part of its length where it's stiffer. When load is removed, either by taking stuff out of the vehicle or by the suspension extending beyond its normal location (such as going over a small dip in the road), the spring is softer.

The reason a linear spring usually gives a softer ride, is because the rate is usually chosen to be the same at normal installed height, for either type of spring. But the progressive spring deflects less (transfers more road bumps to the vehicle) than the linear one, in the one direction of suspension travel.

 

usualy the progressive springs at installed height are softer than linier springs, for the same application. that is the reason why they tend to ride better. RB is correct, if they are the same rate at installed height, then the linier are going to ride better because they are in essence softer.

example, stock rear springs are about 150lbs/in

Eibach pro-kit is progress, somewhere in the range of 109-177, so at installed height, the pro-kit is much sufter, but as the load incresses, and your start compress the spring, it will become stiffer than the stockers.

 

what rides softer is depends on the application.

take a low car like a camaro on a rough road...

lets say, with soft linear springs it bottoms out.. when it bottoms out, thats really rough....

but with the progressive springs, the rate becomes higher as the car goes thru its travel, and it absorbs the bumps just fine.

thats one case...



on the flip side, lets say you're going around a cloverleaf and while in the turn, you hit a slight bump.... the progessive springs on the outside are at a higher rate, and you feel the bump more then you would with the linear ones.





so really, you both are right..... the key is to just pick the correct spring for the app and the behavor you want.


personaly, id like to have some very stiff, short linear springs to fight weight transfer and lower the ride height.... but more for performance.. somthing you wernt intrested in.

 

I have both- linear on fronts, progressive on rears. Progressive ride much better.

 

FYI, I am not concerned w/ ride, but more performance on my car. This conversation came up when we were discussing the springs he got for his GTP. Also, I already understood most of what has been said in this thread, but you guys kind of helped me see it from more than one perspective.

Ben

 

I thought you were only concerned with ride, not performance? Anyway, RB you're confusing me man. I agree and understand that the rates change as load changes, but I've always been under the impression that this can be related to the driver input. Taking turns at different speeds will generate different ammounts of bodyroll which would generate different loads on the springs right? So wouldnt taking turns hard generate more load on the springs when compared to driving straight?

 

progressive springs dont care about the speed they are compressed at... you have to move down a specific amount to get a specific rate..

however if you whip a car one way and then the other direction, the momentum from the bodyroll can have a effect.