cygnusx1 Posted May 14, 2006 Share Posted May 14, 2006 Ha, I got your attention didn't I. Has anyone ever seen any springs that were adjustable rate? Not for height or damping, I mean truly adjustable RATE. ...oh and no airbags or compressors involved. I think I have a design for one. Let me know if you guys want more info and I'll present my idea. I really think I could patent it but I'm too damn lazy and I don't like dealing with lawyers. I am working on some 3D sketches to demonstrate the concept. Here it is: It's basically a threaded collar that matches spring pitch with the car jacked up. You unclamp the collar from the strut housing and spin the collar up or down the spring. Lock the collar in place and it effectively immobilizes all the coils that are inside the collar. It's the same effect as cutting off coils without actually cutting them off. It should work great with a coilover collar under the whole assembly to also adjust ride height. It has some drawbacks but I think they can all be addressed. SOFT................|STIFF.............|COLLAR ID............. Quote Link to comment Share on other sites More sharing options...
thehelix112 Posted May 14, 2006 Share Posted May 14, 2006 Sure. I'm interested. Dave Quote Link to comment Share on other sites More sharing options...
thehelix112 Posted May 14, 2006 Share Posted May 14, 2006 What makes you think thats changing the spring's rate? As far as I know the rate of a coil springs is determined by the number of coils per unitlength, the cross-sectional area of the metal tube, and the specific metallurgical characteristics involved. Dave Quote Link to comment Share on other sites More sharing options...
CruxGNZ Posted May 14, 2006 Share Posted May 14, 2006 The spring rate is determined by compressing the spring one inch and seeing how many pounds it takes to do that. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted May 14, 2006 Share Posted May 14, 2006 You're both right. By cutting a spring's length the spring gets stiffer. So what this gizmo does as far as I can tell is that it locks out part of the spring, essentially the same as cutting it. The problems I can see is that especially with coilovers there are coil bind issues with too short a spring, and it's already so easy to change a spring out, and when you cut a spring it doesn't dramatically change the rate. With that in mind I just wonder if there will be any need for this product. Quote Link to comment Share on other sites More sharing options...
tube80z Posted May 14, 2006 Share Posted May 14, 2006 Ha, I got your attention didn't I. Has anyone ever seen any springs that were adjustable rate? Not for height or damping, I mean truly adjustable RATE. A few years back there was system that Eibach was using on a F3 car that allowed for adjustment by stacking to coils and usiing a special cylinder that put preload on one of the coils. Because the springs were stacked this is how the rate could be varied and it allowed it to be varied over a range if needed through having one of the coils stack solid. It's basically a threaded collar that matches spring pitch with the car jacked up. You unclamp the collar from the strut housing and spin the collar up or down the spring. Lock the collar in place and it effectively immobilizes all the coils that are inside the collar. It's the same effect as cutting off coils without actually cutting them off. It should work great with a coilover collar under the whole assembly to also adjust ride height. It has some drawbacks but I think they can all be addressed. It's an intersting idea but I think it has some problems. From the drawing it looks like it is designed to screw up and down a spring. This will limit it to a certain rate as most springs have different pitches and diameter if wire. My second concern would be that this may cause the spring to put more side load on the shock since it isn't using the regular closed end. If you want to see what a coilspring does head over to hyperco and look at the video of their hydraulic spring seat in action. I think you may find it interesting to see how much the spring roates (it's basically a torsion bar). Cary Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted May 14, 2006 Author Share Posted May 14, 2006 I know it's not a perfect idea and all of those concerns crossed my mind. The biggest concern, as you mentioned, is not a technical challenge, it's the fact that springs are so cheap and easy to change. By locking out coils, the rate of the assembly does change. It will compress less overall for the same amount of load. There are rubber spacers at auto parts stores that you can stuff in between the spring coils if you want to try it out. It works. I doubt I'll ever make this thing. It was just an idea. In a perfect world, it would be nice to pull into the pits and be able to adjust spring rate wouldn't it? Of course it would be illegal in most classes anyhow. Has anyone seen the adjustments on the F1 cars? It's a shaft milled half way through so the cross section is like half-moon. It bends easily in one direction and stiff in the 90deg direction. They rotate it to whatever angle they want to get the right stiffness. I'll see if I can find a pic. Quote Link to comment Share on other sites More sharing options...
tube80z Posted May 14, 2006 Share Posted May 14, 2006 I'm not really sure what you're talking about on F1 cars. They all use torsion bars these days and you can't change the rate of those unless you change the bars. That said most can be pulled out in about 15 to 20 seconds and a new one installed. I'd be curious to see the pic if you can find it. Cary Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted May 15, 2006 Author Share Posted May 15, 2006 Here is a quote describing what I saw, albeit for swaybar adjustment...still looking for photos. " A convenient way of varying the swaybar stiffness is by use of a sliding attachment to the lever to change the lever arm length. This can be adjusted by the driver through a cable or other mechanical linkage, or more simply clamped and releasable at the lever. A more sophisticated approach is the use of thin, wide blades as levers. When the tin section is horizontal it operates as a spring member and decreases the swaybar stiffness. As the blade is rotated toward the vertical, it become stiffer as does the swaybar. Even more sophisticated push rod suspension dispense with the torsion bar entirely and just use a blade to serve the sway bar function." from http://www.aligncraft.com/performance/primer.html Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted May 15, 2006 Author Share Posted May 15, 2006 Aha! Sway Bar Blades http://www.hrpworld.com/index.cfm?form_prod_id=217,212,363_1436&action=product Here it is installed I dont see any major reasons this concept couldn't be used as an ajustable bend bar suspension as well. Quote Link to comment Share on other sites More sharing options...
johnc Posted May 15, 2006 Share Posted May 15, 2006 A spring rubber does the same thing for a lot less and would be quicker to install/remove. Quote Link to comment Share on other sites More sharing options...
RA64 Posted May 20, 2006 Share Posted May 20, 2006 What would it do to the springs frequency? Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted May 20, 2006 Author Share Posted May 20, 2006 I suppose it would increase it. Quote Link to comment Share on other sites More sharing options...
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