low vs super low springs?

[zenetti 0]

I just talked to the importer and he does not disclose his spring rates to anybody.

Anyway I wasn't getting in to spring rate debates, the point of my original post was really concerning the inordinate amount of posts that have been surfacing on bimmersport recently that are factually baseless and almost bordering on libel.

Edited April 29, 2009 by zenetti

[CamB 48]

Yeah fair enough, and sorry for being so bolshy (sp?). We should still be able to give opinions, IMHO, but I am happy to admit that mine is fairly baseless in this instance. The Jamex springs will certainly lower the car.

I can't fathom why the importer won't give out spring rates. It's a bit like not disclosing the diameter of a wheel - its easy enough to measure and there is no competitive threat in divulging it.

[zenetti 0]

I can sort of understand why - it ensures that no one can copy the design, and I guess it gives him some sort of competitive advantage.

I have no problems with people expressing their opinions at all, in fact i think it should be encouraged. What I do have a problem with is the amount of hearsay that finds it's way onto and is written in this forum that is baseless and/or factually incorrect.

It's a bit like me calling you a foul name because someone said you were, even though I have never met you

[CamB 48]

That'd be ok though It might be true

I guess my point is that any competitor can find out his spring rates for a modest cost (ie, buy some springs and measure them). It's hardly a barrier.

[elliot7 0]

" the quoted rates do not look correct in particular they give front rate that is softer than a rear rate - the reverse is typically true as the front is subjected to more force. and there are no quoted units "

1) Check the design of the front suspension design/layout versus the rear suspension design/layout of an E36, and you may understand the need for a higher rate REAR spring.

2) Probably lb/in

3) Opinions expressed unqualified and in anonimity in a public domain should always be treated with a degree of scepticism.

[CamB 48]

I agree with #3. Especially anything I say.

Good discussion of spring rates, motion ratios and wheel rates are but a google away.

As it pertains to E30s

http://www.e30m3project.com/e30m3performan...te/eff_rate.htm

http://www.e30m3project.com/e30m3performan...e/eff_rate2.htm

[CamB 48]

I agree with that. But generally speaking some of the spring setups come up with fairly unusual setups.

The E30 ones (google "e30 spring rates" it if you want to see the table) have a MASSIVE difference in front / rear ratio (in wheel rates). Some are ridiculously hard at the rear.

[CamB 48]

It also depends on whether you use a rear sway bar, and how stiff.

I've never got around to changing the rear springs on my 2002 - they are only about 280lb when conventional wisdom suggests 350lb (for racing). Interestingly, it handles fine. Maybe it will handle better with stiffer springs - I'll get there eventually.

[kerrynzl 3]

Take note of the earlier comment stiffer springs suit higher speeds and smooth tracks

winding up the spring rate on My Alfa added time to my laps because I lost traction out of and through lower speed bumpy corners.

lots more comes into it as well but thats a disussion over a beer not a forum.

Ron, I'll take you up on that drink one day!!

stiffer springs suit higher speeds and bumpy tracks [ smooth tracks don't require much springing at all ]

stiff springs are used to increase the spring frequency but can also increase the roll stiffness , weight transfer is constant for the same G's even if the speed has increased [ eg: high speed corners vs hairpins ]

so you might need to back off the bar a bit [ unless you needed to increase the roll stiffness ]

Less body roll also needs less negative camber

[kerrynzl 3]

winding up the spring rate on My Alfa added time to my laps because I lost traction out of and through lower speed bumpy corners.

This problem is caused by too stiff rear springs [ It gets worse with an open diff, so most people fit an LSD to hide the problem ]

You need to soften the rear to transfer more traction to the rear [ squat ] or to fix mid-corner oversteer if this is a problem.

If the car then starts pushing [ understeer ] the "roll-couple" can be dialed back in with a 'rear anti-roll bar' which doesn't effect front to rear weight transfer [ or suspension frequency ]

Suspension frequency is cycles per second [ the faster you go, the more cycles per second ]

frequency is a ratio between stiffness and load [ via geometry etc ] A lighter car with the same spring stiffness has a higher spring frequency