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I'd be very interested to hear what spring rates you land on. Next time I can take a look at my springs, I'll pay attention to what I've actually got on there.
And, ah yes, the 7" stroke is why I didn't do this in the rear.
I have a high main-only spring rate, but the combo is right around 250, and feels great on the street. Again, I'm reconstructing from my very leaky memory but I think one of the reasons my main spring is 750, is that the tender was rising rate to ~650, and I wanted to be sure the tender would bottom out, and leave me with just the higher rate main spring at full cornering.
Sorry, must be my dyslexia, I thought your user name said alpha.
T
I'm not sure how my username is tied to wanting to obtain this most excellent source of information that Trucho put a lot of time and effort into. You have your wires crossed, clearly.
I am a strong advocate for a progressive spring platform. The original cup car springs were progressive,(single spring but variable pitch and gauge) and Technodyne utilised a Eibach dual rate set up during the 90's. The latest GT3 Cup cars are also utilising a dual rate set up (Pic below). Interestingly the latest 944 race set up from Bilstein Motorsport Germany is also Eibach dual rate with packages aimed at both torsion and torsion delete cars. It is worth noting that Bilstein Motorsport recommend maintaining the torsion bar set up despite the weight penalty. This is there reply to a recent email enquiry. [Forgive grammar ]
OE Cup Cars drove it with the torsion bars . We have had a lot of requests from clients [[or torsion delete]. We advise them that the Car [wihtout torsion bars] is not stabil into corners and so on and they had all removed the torsion bars because of the weight. If you want to do that the car needs to be modified before on the rear suspension mounting points. Bilstein Motorsport recommend to drive it WITH the torsion bars in the rear.
Pics of the latest Bilstein Motorsport Struts and the 991 GT3 Cup car set up and lastly the oriignal 944 Cup car front spring.
I'd like a dual rate setup, but personally, I'd really prefer to find something like the cup car spring. The multi-part setup with sliding parts just looks wrong/forced (and as I read on hypercoil's web site, also detracts slightly from available spring travel which might be a problem in some setups).
Hypercoil has a nice writeup on the pros/cons/applications for using progressive rate springs. Our cars seem to be the ideal application, but someone has to do the math and experimentation to find the right combination for the ride height and spring travel on the car. Not as straightforward as installing a set of linear rate springs.
From https://www.hypercoils.com/tech-tips...nsion-springs/ For grand touring and high-performance driving, progressive rate springs offer great ride quality and superior handling due to the roll control offered by the springs. This is especially true if a reduced ride height is desired. The initial light rate provides a great ride, while the increased secondary rate assures a load carrying capability unavailable if lowering with a linear rate spring is attempted. Most high-performance driving involves a fixed vehicle package with only one or two passengers and very limited extra weight. This is the ideal situation for progressive rate springs.
06-22-2014, 08:48 AM
