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I was asked to start this as a new thread.

Re: Has anyone tried one of these...

Guy's here is some good reading on whats going on with springs.The article was written by a good friend and fellow suspension guy Jeff Howe .I have had the great opportunity to work with Jeff the last couple years. Allthough this is a different product, the manner in which the spring acts will be the same.

It is time I shared with you guys one of the projects I’ve been working on. There has been some discussion on springs here lately and since I’m nearing the end of this project I thought you’d like to read about it. This is going to be long, and I’m sorry if it is too long but in order to cover all this I have to start from the very beginning. I have mentioned this company I’m dealing with here several times in the past and I’ve been working close with them on this thing since last July.

Over a year ago now, I learned of a product that was soon to be introduced by Hyperco that really caught my eye. But I entirely forgot about it until June of last year and finally got around to pursuing it in July. After a little fitting it was on my bike and being raced. I was the first guy in the entire world to put one on a dirt bike shock. Also the first to have them on a snowmobile. The product is one of the coolest things I’ve seen to be introduced in a long time. It is called a Load Centering Hydrualic Spring Perch. It is a shock product that helps to substantially reduce side load forces created by the spring deflection. This is an inherent spring issue few know of let alone consider. Admittedly, until Dec 2003 I didn’t consider it much myself because I didn’t know that these forces were as substantial as they are. I knew this phenomena existed because you could see massive spring rub(therefore spring bow) with some springs but didn’t know it was quite as disruptive as it is even when spring rub was non existent. Since I began working with it and discussing it with the 2 gentlemen most involved behind the product I have also learned a few things about shock springs you are going to find interesting. Maybe some will want to argue some of these points but I’ll tell you right now, you better have both barrels loaded if you do.

Ok, so we have this friction producing force referred to as side loads being placed on our shock through spring deflection. To explain that, you must first accept that a spring is a unstable column. In other words, as it deflects (compressed) it wants to bow. Since you have both ends of the spring constrained that bow in the spring is actually trying to bend your shock, thus causing more internal friction. What this amounts to is your shock being less efficient. I can tell you right now that most springs we currently use are more problematic then you think.

My first ride with the Hyperco perch installed was an eye opener. I could feel a difference right away. What I could feel was that my shock felt softer on compression and faster on rebound. It was enough difference that I had to go back in and make some changes to the shock adjustments. If you look at the picture of the perches you can see a gap between the base and top of it. Whats going on here is as the shock spring compresses and bows, it is sitting on top of this perch and the perch allows 4 degrees of tilt in an effort to reduce that spring bow, thus reducing side load forces on the shock. They claim 98% percent reduction of side load forces with a hydraulic perch mounted to both ends of the spring and 65% with it mounted to one end. I have only tested with one perch so far because it would require a custom made spring to fit them both on our dirt bike shocks. It doesn’t matter how you look at it though…65% is a LOT of reduction there. I think I would wet my pants at feeling what a 98 percent reduction would feel like! Fitting these perches wasn’t a drop on affair, there was some machining involved to do it, but I got it on there and it worked but it wasn’t without it’s issues either. Since the product was not designed for our specific shocks this is understandable so I’ve been working on getting them to fit for the last couple months. I sent 3 shocks off to ICP sometime in early October for them to look over and see what they thought. They were KYB, Showa and WP and I just got them back in early December. And I’m currently fitting a different perch and spring to my YZ shock for further testing. I will be doing a few emails with Kelly again shortly to discuss some things and will have some more info on the perches later. Right now it looks like biggest PITA is fitment to the Showa shock. That will actually require that a new bumper cup be designed to make it happen at a minimum and that means it is not a drop on product for that shock in it’s current state.

I wanted to share some things about shock springs with you too. I did some comparison testing involving the hydraulic perches and different springs the other day on my Intercomp spring tester. Before any of you go off raving you have heard they are worthless I’d like to state that mine has been very good so far and I trust it very much. I have known guys to say they have had problems and when I first got mine I set aside 3 springs that I use for comparisons to ensure it’s stayed accurate. Is it perfect? Probably not but it has helped me in numerous cases. When I got my first hydraulic perch I put it on the tester and put a spring on top of it and began deflecting it in an attempt to observe the perch in action. In less than 2” of deflection the entire 4 degree tilt range of the perch was used up. It worked! But that’s probably less then half travel of the rear wheel so the last half of the travel was like normal use then picking up any side loads produced by the spring after that point. Just recently I did this same experiment involving a new style KYB spring, a Showa spring, Renton Ti spring and a Hyperco spring. This time I was after a different answer but using the same procedure and I had 3 different perches as well. I have not logged any data as accurate yet and I am going to repeat this test again later and I’ll explain why. For now I want to tell you that this test is the basis of my comments on all shock springs not being equals. The KYB spring, Showa and Renton Ti spring all used up the 4 degree allowable tilt of the perch in under 2” of deflection. The KYB and Renton Ti were tested on the 2.25” diamter perch and the Showa and Hyperco were tested on the 2.5” diameter perch because of differences in coil ID. The Hyperco spring didn’t use the full tilt angle of the perch until over 3.5” of spring travel…nearly double that of the others. What does that say? It simply says the Hyperco is a more stable spring. That it is not producing the same side load forces as the others because it is bowing less. The Showa was the worst as I recall, the Renton Ti and KYB were pretty close to the same. Here is an interesting thing about them though. All of those springs are using wider coil spacing design with lighter wire diameter (seems to be the current trend now) except the Hyperco. Well, actually the Ti spring has a larger wire diameter then all of them but the coil spacing was wide. To be fair, these springs were not all the same rate either with the Hyperco being a 300lb (5.4kg), Renton Ti 5.4kg, KYB 4.6kg and Showa 4.7kg. That’s one reason I will repeat the test later. Another is the 2.25” perch has been used and the 2.5” has not. I personally believe there is a break-in time needed for these things to loosen them up. It still brings up some questions and opens paths for more testing yet as I’m going to include some other brands in the next round. Something you might like to know about springs and their characteristic bow in terms of design is that the smaller the coil id and longer the length the more prone the spring is to bow. It also seems to me that this current trend to wider coil spacing and smaller wire diameter may also create more side loads. Surely a spring with tighter spacing and larger wire is going to be more stable. I don’t know this for a fact, and I’m going to look into it more but just looking at one it sure seems like that would be true. Yamaha just recently started using this type of design in order to shed weight. They look nicer and they are lighter but for those few ounces is it worth putting more side loads on your shock? Not for me, I want a more efficient shock.

The bottom line is you are wondering what the cost is and if it’s worth it, right? A slip on model spring perch retails for $167. It is not cheap, but I think it is worth it. In fact, I think it is one of the best shock related products I’ve ever seen. I have 3 shocks that are going to be fitted with various setups of perches and springs to find the best options etc and I’m going to Texas this winter sometime with them for a few days and see what happens. You can expect to see some more test data comparisons a bit later involving more springs etc. Because the KYB fitment is easiest they will become available first and then we’ll address the fitment issues with the Showa and WP. The real interesting comparison will be between Hyperco spring and Renton Ti spring with the perch. I can tell you this for now though, when I had the Renton Ti and perch teamed on my shock last year it was incredible.

__________________

Russ

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Russ,

Have you got a link to a picture or website for these things?

:applause:

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Interesting and thanks for the post.

So if I understand this correctly, there are matters of binding and rotation, and matters of flexing and bowing.

Not of the same, of concern or resolution.

Correct?

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I have one here. I will have to take a pic of it and try to post it.

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That product is very cool, but there was one simple unresolved issue with long term tests. The design involves an inner and outer gap that allows the "tilt" to take place. The outer gap presented no problems as it was easy enought o fabricate a simple cover to keep the dirt out of it. The inner gap was not so easy to protect and still to this day I don't have a suitable solution for it simply because I didn't want to invest in making a properly designed cover for it. I didn't think anyone would be interested in the system, being you'd have to buy the Hypercoil spring from me AND the perch, plus this cover. We would be talking an expensive spring system here, although it would be more efficient then anything else on the market. They use these perches in road race, Nascar, etc with great success because the environment is cleaner. The perch is more expensive then a spring is, the gain is friction reduction which is always great, but they don't last long before they wear out and leak from the dirt wearing away at the inner sealing surface(in our environment). I personally do not want to invest in this system to solve it's simple problem because of the cost the entire system would retail for in the end. Furthermore, they do not currently fit a Showa shock without a complete redesign of the perchs body. I cannot see selling enough of these systems to justify sinking any money into it and it's why you have not seen it offered. However, from a technical veiwpoint these simple hydrualic perches remain, in my opinion, one of the coolest shock products I've ever seen and used.

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