I know how much everyone loves Jap "Coilovers"

[JohnL]

Stir,
Have you tested spring pairs for equality of rate? I have to say that I haven't, but I'd be surprised if there would ever be any significant rate difference between one spring and another if:
1) The wire OD were the same.
2) The number of coils were the same.
3) The coil diameter were the same.
4) Neither spring had a crack.
5) The free length were the same (though this wouldn't actually affect the real spring rate, only how much static weight that spring, relative to the other spring of the pair, carried when fitted to the car).

The reason for this is that nearly all steels (and all that are remotely likely to be found in a car spring) and regardless of the heat treatment of that steel, the modulus of elasticity is the same to within an utterly insignificant degree. So, for spring A to have a different rate to spring B, there would have to be some significant difference in physical dimension, not in some hidden metalurgical property of the springs...

Just speculating, but I suspect that spring companies tend to say things like "tested to ensure equal rate" (etc) because it sounds impressive in the marketing bumph. I'm not suggesting that they claim to test the springs but don't, I'll bet they do test them but for a slightly different reason(?).

I suspect what they may do is to compress each spring to X length to see if this causes the spring free length to shorten (or less likely for the spring to break), i.e. they are more likely to be testing the elastic limit of the spring (to ensure adequate heat treatment) than to be testing the actual spring rate (though while they're at it they may as well check rate just so they can say they do...).

If a spring (A) is too soft (heat treatment not rate), then it will have a low elastic limit and shorten if compressed beyond that elastic limit. If a spring (B) is too hard then it will also have a low elastic limit, but may break rather than permanently deform. A correctly 'hardened' spring (C) will have a higher elastic limit than either A or B, but A,B and C will all have the same stiffness (rate) up to their individual elastic limits. Incorrect 'hardness' could be a result of poor heat treatment, or faulty material.

So considering that all springs made to X dimensions will be within a cat's whisker in rate, testing the spring by compressing it may be more to do with quality control for spring longevity.

[RecceDG]

Hey guys, glad to see you enjoying the site. There is more info coming once I get settled in and get writing.

A couple of comments though:

1. I am NOT a Yank. I am Canadian, thank you very much - Commonwealth country, Queen Liz and all that.

2. I have nothing against the Japanese - my race car was a Mitsubishi, as is my daily driver. Great cars. But the Japanese aftermarket has yet to build a shock that crossed my dyno and passed my tests. And boys, my tests are *easy*. Accordingly, without a dyno plot to prove otherwise, I assume all Japanese aftermarket shocks are steaming piles of grade-A crap, because I have yet to see an example that demonstrates otherwise.

3. So let's say that you've dropped a bunch of coin on a set of Japanese aftermarket shocks, and you think they're the best thing since Vegemite. Based on my experience, I'm going to go with "crap" - and the amazing human ability for self-deception, especially when money has been spent and egos are on the line. There is a way to prove me wrong - dyno the shock. Until such time as you have verified the shock on a dyno, what you own is far more likely to be a telescopic turd than THE diamond in the rough.

Why so extreme? Because gents, I dynoed hundreds of shocks, and the only ones worth a damn were Bilstein, Koni, Ohlins, Penske, Sachs, and Dynamic Suspension. Everything else was an utter horror show.

If you are at all serious about suspension, you will not buy anything without a dyno sheet. If your shock guy cannot or will not do it, find another shock guy, because the one you have is ripping you off.

Springs: you'd think that a spring would be simple. Wire diameter, number of coils, free length... Bob's your uncle. It doesn't work out that way in practice. I have had a set of "purple" springs off a customer's expensive Japanese Industrial Company aftermarket coilovers differ by 14% on the spring tester. My pass mark is 3%.

Don't believe me? Buy or make a spring tester and see for yourself.

On average, springs aren't the horror show that shocks are... but you get what you pay for.

The lesson here is TEST EVERYTHING - take no marketing department's word for it; test it yourself.

DG

[SiReal]

wow, thanks for the above, i spent plenty of time reading your article, glad i bought koni's.

I had a 'green' set of street coils - the shocks felt terrible, coming from a koni/H+R setup. It also felt as if they weren't even working.

i must say, we're honoured to have the DB guy himself on here. Thanks very much

But i also must add most of us aren't serious shock enthusiasts as we only enjoy what we have to limited degrees.

[STiR]

We've tested spring pairs and they are not always the same... you'd expect them to be!

Stir,
Have you tested spring pairs for equality of rate? I have to say that I haven't, but I'd be surprised if there would ever be any significant rate difference between one spring and another if:
1) The wire OD were the same.
2) The number of coils were the same.
3) The coil diameter were the same.
4) Neither spring had a crack.
5) The free length were the same (though this wouldn't actually affect the real spring rate, only how much static weight that spring, relative to the other spring of the pair, carried when fitted to the car).

The reason for this is that nearly all steels (and all that are remotely likely to be found in a car spring) and regardless of the heat treatment of that steel, the modulus of elasticity is the same to within an utterly insignificant degree. So, for spring A to have a different rate to spring B, there would have to be some significant difference in physical dimension, not in some hidden metalurgical property of the springs...

Just speculating, but I suspect that spring companies tend to say things like "tested to ensure equal rate" (etc) because it sounds impressive in the marketing bumph. I'm not suggesting that they claim to test the springs but don't, I'll bet they do test them but for a slightly different reason(?).

I suspect what they may do is to compress each spring to X length to see if this causes the spring free length to shorten (or less likely for the spring to break), i.e. they are more likely to be testing the elastic limit of the spring (to ensure adequate heat treatment) than to be testing the actual spring rate (though while they're at it they may as well check rate just so they can say they do...).

If a spring (A) is too soft (heat treatment not rate), then it will have a low elastic limit and shorten if compressed beyond that elastic limit. If a spring (B) is too hard then it will also have a low elastic limit, but may break rather than permanently deform. A correctly 'hardened' spring (C) will have a higher elastic limit than either A or B, but A,B and C will all have the same stiffness (rate) up to their individual elastic limits. Incorrect 'hardness' could be a result of poor heat treatment, or faulty material.

So considering that all springs made to X dimensions will be within a cat's whisker in rate, testing the spring by compressing it may be more to do with quality control for spring longevity.

[eg5civic]

my JIC coilovers came with a dyno shock result sheet.. its in japanese but i'd be more than glad to post up if someone wants to translate... alse we have a shock dyno at work.... i shoul dof put them on t heir before they went on the car -_____-

maybe in a years time

[RecceDG]

Be sure that shock dyno plot is for YOUR shocks (as in, the very same shocks on the car were the ones tested) not a "representative" plot.

DG

[T-onedc2]

RecceDG: I like your info, nice work!
Oh btw, Dodge Stealth is the Mitsubishi GT0/3000GT in Dodge clothing right?
I went to the states in '94 and brought back a scale model of one, used to love 'em....lol

[aramiK]

You have to consider the fact that the person who originally wrote that article - was talking about a setup for a FULL race car.

Not, coil overs to handle better on the street.

Anyways, kind of turned me off now...

Anyone here running any of the brands he mentioned other then Koni?

[chargeR]

You have to consider the fact that the person who originally wrote that article - was talking about a setup for a FULL race car.

Not, coil overs to handle better on the street.

Anyways, kind of turned me off now...

Anyone here running any of the brands he mentioned other then Koni?

The guy who wrote that article posted two posts above you. Good dampers are just as important for street handling as they are for the track.

[fatboyz39]

ohlins ftw!

[aramiK]

The guy who wrote that article posted two posts above you. Good dampers are just as important for street handling as they are for the track.

I see ~ didn't really read past the first page of replies.

Thanks for pointing it out