chef-j

freq

Good stuff!!!

Gernby

These results are very surprising! Thanks for putting all the effort into this!

Although, I now have some regret about my coilover spring rate selections...

lovegroova

This is fascinating and seems to be a fair diversion from what's been published here before, which is usually something like this:

------------Front Rear
MY00-01 218 291
MY02-03 240 230
MY04-07 256 207
MY08-UP 274 225

Whist the numbers aren't that far out, in all cases bar the MY00-01, the front is stiffer than the rear, whereas the research shows the opposite.

Now, this may be due tomy data being UK based and not having the the 2.2l engine on the MY04+ cars, but the 02-03 difference remains marked.

Any thoughts on this would be really helpful on what's an excellent article.

Gernby

I've been thinking about these results for a while. Do you think it could be that there was a difference in the way the springs were being rated? Could there be some compensation in the rating for them being "progressive rate", or something? Maybe a compensation for the suspension geometry that might give a different effective rate at the wheels? It seems that the geometry of the front suspension gives a higher effective rate at the wheel than the rear suspension does.

macr88

[QUOTE=gernby,Jan 20 2011, 09:01 AM] Maybe a compensation for the suspension geometry that might give a different effective rate at the wheels?

Gernby

So could it be that the "old numbers" were really just wheel rates?

twohoos

Hi all.

From my research and long history on the boards here, the idea that the '02-'03 rears got softer appears to be due solely to a single post from early '02 in which a member said he'd measured the rear spring's wire diameter at 11.6mm. (He also measured the front spring, but got the correct value.)

Subsequently, other members measured the rear spring wire diameter at 12.5mm (the same number that I found), but by then the initial estimate had already gained traction. When I wanted to know what the spring rates really are, I did some research, found some conflicting data, and eventually decided that it's so cheap to buy OE springs these days it'd be worth it just to measure them myself.

In that spirit, I hope everyone who sees this thread will not simply accept my results but will act as my "peer reviewers" and let me know if they have any thoughts or new data. (In particular, I've been contacted by a gent who was in the process of actually measuring some OE springs using a press and some chassis scales, but that was a while ago and I'm still waiting for his results.)

I've been selling off the springs I used for my measurements, but if anyone has the setup necessary to do some direct measurements, let me offer this up: I'll happily ship you whatever springs I have so we can compare results. We can even re-write the paper with you as co-author!

Edit: While we're at it, we should measure the bump-stop foam.

twohoos

I don't think they were wheel rates, but they are "as-mounted" rates, meaning they account for "inactive" coils. A coil can be inactive due to spring-end design ("closed" and/or "ground" wire), spring perch design, and/or suspension preload.

Again, I'm eager to get some direct measurements from someone who has the right resources.

macr88

I have a friend that should be able to do this. If he can't then I can have it done at PSI (performance shock Inc)