Quote:
Originally Posted by gkubed
See this section at the bottom (bold mine):
All that says is that Indy cars all use Eibach or Hypercos - and even then I'm sure those aren't remotely comparable to what we'd put under our cars. Swift may not even make springs of that variety. I want to be careful not to blanket-dismiss or praise a spring manufacturer based on a product I won't be using (Indy car springs). Either way, thanks for the input.
You're right - first posted in 2008, last edited in 2010. I suppose spring manufacturing has changed a significant amount since then.
Well, for now, my personal verdict is we don't really have any idea.
|
I would be very surprised if the Indy teams were ordering something not available out of Hyperco or Eibach's catalog that you or I couldn't order (maybe they make special orders with the springs not labeled or a spring that's right in the middle of two common rates, a 460# instead of a 450#, but nothing we couldn't get an equivalent of), but you're right, those aren't the typical ~60mm diameter 4"-8" springs that would go on a road car.
Not sure if you're being snarky about the spring manufacturing changing in the past 8 years, but I'd gamble it hasn't, at least not significantly. But company philosophies, engineering staff, manufacturing contracts, and quality control do change, sometimes on the order of months not years.
The thing I found most interesting is how proudly he (the NAM post you linked) touted the first 1" of travel, I know Eibach doesn't measure the first 20% or last 30% of travel when rating the spring, of course the spec doesn't line up when you don't actually measure the part the same way it was rated.
http://eibach.com/america/en/motorsp...sion-worksheet
Quote:
All Eibach motorsport springs are tested between 20% and 70% of the spring’s total travel.
This spring rate can be measured easily using the following steps:
|
It'd be easy to say 'well that's crap then! since the first X inches isn't consistent! "
But if you actually take into account what's going on where it matters, that's the car sitting on the ground and the suspension moving through it's stroke, that's the important part. When I was looking at Eibach's, the stroke was ~4", and 7kg/mm or ~400 lbs/in is a typical stiff spring used on an 86.
So, the rear end of an 86 weighs about 600 lbs, the front ~775, instantly as soon as you set the car down you've compressed that spring anywhere from 1"-2" depending on the details and you're into the precise area of the eibach. After that you start looking at how much suspension travel you want and need and that'll drive the spring choice, given that the bottom 30% of the Eibach's ~4" travel is 1.2" you're looking at the wheel being able to compress 0.8"-2.8", again depending on the details before the spring starts to get stiffer as you head towards coil bind.
One of the reasons why Swift gets a ton of love is they advertise a much greater stroke length than Eibach and Hyperco (you actually have to email Hyperco to get theirs, but their response time is fantastic), iirc they get another 1/2" or more of travel out of the same size and stiffness spring. Along with a few glowing vendor and forum poster reviews (that really don't provide much data, like the guy you linked provided 4 data points that he could have easily made up).
The two questions about Swift become, is the available travel real? Well, make sure you're looking at Swift's 'usable stroke', not the total actual travel, they definitely recommend you don't go into coil binding territory, which makes me wonder about what happens when you surpass usable stroke, is a pothole going to permanently deform the spring? I don't know, maybe it's entirely paranoia, but it's not an unreasonable hypothesis that they're designing closer to the limits of the materials available to them and that's how they get greater stroke length than Hyperco and Eibach.
The more important question, as you look at the price difference, (after all $10 is FOUR In n Out cheeseburgers, times 4 springs, that's food for a whole race weekend!) is do you NEED the travel? What's the point of 5" of stroke available in the spring when your suspension bottoms out at 3"? Of course it's easier to just take the spring that has more travel then you need, eliminate coil bind as a potential issue altogether... but $80 man! (I'm seeing Eibach's at ~$60/ea, HyperCo at ~$70/ea, Swift @ ~$80+/ea)
For some, the choice is easy, $80 is nothing, a 'lets have McDonalds for date night honey not the local 4 star Steakhouse' decision at worst. Some realize their car will never see the track, they'll never bother to measure their own suspension travel, perform their own calculations or even notice the car understeers on left handers and oversteers on rights and will happily save $350 using whatever bargain springs come with a kit, or saving $200 on the low end Megan lowering springs over the Swift or TRD/Eibach lowering springs.
At least we have options, good ones at that.