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Old 07-14-2010, 05:17 PM   #1
HP Autowerks
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Join Date: Mar 2007
Location: Santa Barbara
Posts: 314
My Ride: E36 M3
How to Finally Get Performance Out of Your KW Coilovers

It's no secret that KW isn't much of a performance coilover. It is a mass produced product that sells due to such a low buy in price and an immense amount of marketing. Just look at the threads when someone asks what the best coilover system is, it is almost always KW and the reason being, "that's what I have on my car".

When you have never tried other systems it is easy to think that the KW system is great. BUT, take a ride a in a true linear rate car that has been set up properly with appropriate spring rates (or even the same spring rates) and you will see just how far off the best system you are. The reason for this being that KW uses progressive springs. This means that it takes an average over the springs compression. For example, say at 1 in of compression it is 200lbs, 2in compression = 250lbs and 3in compression= 300lbs. The spring rate would be 250lbs ((200+250+300)/3) This kind of springs set up is very unpredictable when it comes to handling and makes you car handle poorly because you don't have the quick reaction of the spring.

THE ONLY KW SYSTEM that is NOT progressive are the CLUBSPORTS.

Fortunately for those of you who already have KW coilover systems, you don't have to scrap you entire system to get a linear set up. We offer a KW conversion kit that allows you to use Swift linear coilover springs. We have offered this to the E9X community and they have been floored by how much they notice the difference and how they were for being suckered in on the KW product.

A fellow e46fanatics member explained it very well and this comparison is between two linear springs. KW springs would have been obliterated in this test.

Quote:
Originally Posted by ninjlao View Post
Now as for the testing I happen to have a spare volkland spring lying around because I had a friend that wanted me to test it out. I also have a set of lightly used Swift springs in almost the same dimensions. The Volkland spring that i have is a
2.5" ID 9" length 180lb/inch spring.
The swift on the other hand is
2.5" ID 9" length 4kg/mm spring which equals to 223lb/inch spring.

Now just a little background information on this little test that I did. The lower the spring rate the spring rate changes and spikes throughout its compression is much less affected than a heavy spring rate. The spring rate spikes are obviously much more noticeable but the percentage increased are about the same. The reason I tested out such low rates though is because these springs are the only springs comparable that I have lying around.



Now there is a lot more to a spring than the spring rate but that is by far the easiest to see the quality and accuracy of the spring itself. So that is exactly what I tested first.



There is nothing bad I can really say about this spring, it is really hard to tell the accuracy of the spring rate because it is not too hard to be off on a spring rate so low. But as a 180lb/inch spring it is pretty dead on its spring rate all the way through its compression.
1st inch- 181
2nd inch- 183
3rd inch- 186 (already starting to hike up)
4th inch-250 (it was nearing coilbind so its natural to increase this much so you can judge this spring at this amount of compression)


Now with the swift spring.

again this spring is also a low spring rate, it's a little stiffer than the Volkland but it is nowhere near high enough to accurately tell how precise this spring is. But this is the spring rate that was recorded throughout its stroke

1st inch- 220
2nd inch- 223
3rd inch- 222
4th inch- 224

Now I took a picture of every inch of compression, I tested it several times through the different strokes of the springs and the numbers for both really consistent throughout their compressions. The pictures and the recorded numbers I decided to post up are numbers starting with zero preload.
These pictures posted below is where the Swift started to outshine the Volkland. This is at 3 inch of compression.




You can clearly see that the swift spring has a much larger sweet spot than the Volkland spring. You can also see that the Swift spring is much closer to the desired spring rate.

But this is not the only advantage to the spring.
Right after being put on the spring checker I remeasured the springs to see if there were any difference in length.



The Volkland spring was brand spanking new. With just a few compressions on the spring checker it had already sagged 1/16 of an inch.

the used Swift on the other hand was dead on at its height.

This was just a few minutes of compression on the spring checker. Now you can imagine what the spring would do after a few months of use with the weight of the car and the vibrations exposed to the spring.

Well Volkland springs are known to sag after a few race events in the real time racing. This is why I decided to measure it before and after the checking of the rates. I already knew the results before going into the test.
Also to show the craftmanship of these springs

^This picture was also taken before the dyno testing. Now all springs do slant a slight amount. They usually are within whatever the manufacturer specs are. This spring though is almost like an S shape which is something I only thought came with Megan springs. This was kind of disappointing to me.
Quote:
Originally Posted by ninjlao View Post
Now I have tested time and time again, all sorts of different springs from all kinds of manufacturers. I am always pretty confident with the swift product. Now if I find a better product then I will back that, but so far to this day I have not found one.

Now Zerosum brought up a good point. What you claimed is the exact thing that splits the Swift springs apart from all the other spring manufacturer. Now lets say I were to get the most precise spring from Hiperco or Eibach and compared it with a Swift spring. On a spring dyno it will be very similar. The graph would probably look identical, but then if you were to physically use those springs and swap them out, to use back to back, It would be a night and day difference. You would immediately be able to tell which is Swift. The Swift will feel much more compliant, in fact its exactly what Zerosum said "the impacts are much better damped". I know it is hard to understand but I will explain.

It is not the spring rate that distinguishes the differences in the impact of uneven pavement. Spring rate has more to do with the reaction of the amount of force put onto the spring. In other words to put it in simple terms, it will affect body roll. I am not saying that initial impact of uneven pavement can be softened by softening spring rate, but that is not the correct way to make a car more compliant. The correct way is the shock absorber the main reason for this is because there is a form of mechanical lag with the spring. This is why some suspension companies do not even believe in adjusting spring rate (talk to the techs at KW).

Now for some reason the reaction rate or the time to respond from impact with the Swift spring is much much quicker than ANY other spring company. This is something that can not be seen on a spring dyno. But can be tested. In fact through the testing that I have done we have seen that even with the exact spring rates being used the tire temperatures with the Swift springs is always cooler. This is the reaction rate of the spring, or frequency of the spring is what some suspension scientists explained it to me as. (LOL)
But of course track testing is nowhere near accurate for testing because there are so many different variables that come into play with simply measuring tiretemps.

Anyways the reason why we came to the conclusion that the reaction speed is different is because we ended up taking the car to a shaker rig. Which is an extemely expensive process, which I obviously did not pay for but was there to help figure out why the Swift springs were so different.

Anyways what I am trying to say is that the Swift springs even with the same rates will durastically make a difference with the performance of the vehicle.
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