Suspension Questions/Help: Spring Rates, Tein HEs, Grip and Drift

[mmtmatrix]

Hello everyone, I am just trying to figure some stuff out on Suspension (ultimately deciding on what I will buy). From what I have read (searched) here, people generally seem to say the high the spring rate the better the car will handle (this also makes the ride less comfortable), (S13/14 the front usually being 1-2 KGs higher than the rear), and this makes some sense. This allows the tires to put more pressure onto the ground, increasing lateral Gs... Am I correct in saying that? Is there more to it?

Then there are a few things I am curious about:

If this is correct then what I want to know is why did a Project Car like Sport Compact Car's S13, with JICs FLT-A2s (8 KG front, 6 KG rear) drop them down to 6 KG front and 5 KG rear, and then was able to achieve 1 G on the skid pad? They said it was too stiff (Vol. 15, No.10/Oct. '03)...

I am really interested in the Tein HEs, but I want to know if they are really "drift" specific Coilovers and why? I want a car that I can drift with, but ultimately (I think) I really just want to be able to go fast in a not straight line (Togue, roadracing/autox,). Would a setup with HEs (8kg F/6kg R) inhibit ultimate grip?

I hope this makes sense, and these questions have not been answered before/beaten to death.

Thanks so much, I have learned so much from the forums already (I have found it to be one of the best ones out there) wish I would have found it a while ago.

Thanks -- talk to you soon,
mmtmatrix

[240Dave]

Too stiff will allow a car to lose grip more quickly making it harder to drive. A car that can roll a bit seems to settle onto the tire and really grip hard...sorry I don't know enough technical stuff to explain it. A downside is that the more the car rolls the longer it takes to change direction.

[sykikchimp]

proper spring rate is dependent on the conditions that you require ultimate grip. If your driving on a fairly bumpy surface, like the boys at scc were doing on that skid pad, then softer springs will allow the tire to remain in contact with the pavement better. Instead of the stiff spring jolting the car upwards initially in response to a big bump and momentum carrying the tire with it off the ground, the softer springs will absord it, and allow the tire to roll over to imperfection and remain in contact with the pavement. Of course softer springs dilute transient response left and right, and will increase body roll. So, we improve body roll, and transient response with anti-roll bars. If they were on a smoother skid pad, they would have pulled higher lateral g's with the higer rates.

8K/6K isn't really that high. It is definately livable on everyday roads, if you don't mind a bit of back, and kidney pain after a few hours of driving. Lower rates in the 4-6K range are better for street use cars, as it will make the car more stable on crappy roads (scc's skid pad) If you track your car, you will thank yourself for having the higer rates like on the HE's or FLT-A2's, as race tracks are often very smooth.

I would think "Drift spec" is marketing hype...

cliffs note:

Soft springs = suspension compliance, and more grip on rough/ uneven pavement, more forgiving
Stiff springs = Fast transient response, less body roll, more precise tool when used on smooth pavement.

[SpeedMonkeyInc]

Additions to what sykikchimp has already said:
A softer spring rate will be better for you if you do mostly street driving and some mountain road stuff. Uneven pavement + stiff springs/high damper = unpredictable traction! Just like the guys at SCC and sykik say, the bumps will toss your car up and bring the tires contact patch with it. What that is like on the road is your car skipping along the road. Dangerous, and scary.
On the other hand, on a smooth surface, you will LOVE that suspension.
I live with the Tein HEs on the street everyday and do fine. Its not uncomfortable. I even drive up to my home town in Oakland from San Diego a couple times a year ( 8+ hours ) and the ride is fine.
On back roads, you have to know the surface conditions. There can not be any surprises.

[240Dave]

One more addition would be wet traction is reduced with a stiffer setup. I guess it makes the slight loss of traction over a bump a much bigger deal when its wet.
I enjoy a soft suspension for the street, driving to work every day is dangerous enough as it is, especially in the wet with bumps, construction, pot holes, etc...I honestly wouldn't want to go harder than what eibach has to offer with its line of springs.

Best way would be to drop 2k into a decent 2nd car and just track that.

But if you can't/won't do that, you'll have to make a comprimise somewhere between track performance and street compfort/safty.

[Parson]

Additional motivations for higher spring rates:

1) Allowing the car to be lowered further (CG and aero) while reducing the chances of bottoming either the suspension or the body work.

2) Reducing the affects of toe change (bump steer) and camber change through reducing the total suspension travel.

-- Joel

[mmtmatrix]

Thanks for all the help, I really appreciate it. I'm still learning and curious/confused about a few things.

I kinda understand suspension stuff, and looking at a set of Tein HE for me S13 coupe. I want a set up that is still somewhat streetable, but good quality that allows me to drift, but not so geared towards drift that it totally oversteers and I have not ability to road race (grip drive) and togue.

But, in talking to representatives at Tein, they say that not only are the HEs somewhat aggressive for street driving, but that they are meant for drifting, and the "spring rates and valving" are specifically R&D for drift driving. I am wondering if this is entirely true, and if I will have a hard time grip driving, and comfortably going fast on corners with the HEs?

Thanks for all the help,
mmtmatrix

[Dousan_PG]

COULD be true. thisis how tanabe's drift spec is engineered.
the FLTA2 and HE are very different valving wise. i have done both on my car. its really DRIVER PREFERENCE
(so dont ask me which is better drifting/grip wise--i have my own preference to my car setup)


ernie fixmer (rotora driver and usa d1 driver) posted this abuot the tanabe DD drift spec coilover on freshalloy.com

I wanted a set after talking to the R&D guys of Tanabe who were with Signal at the DD6. They said their suspension was expensive ($1800?) , but catered to drifters. Bai actually requested the setup they are using. I don't know much about suspension and all the settings, but Taka has explained a lot too me and the guys from Tanabe said pretty much the same thing. I like it pretty stiff on dampening and spring pressure in the front. I like to use a spring setting as stiff, but not over the dampers capacity and have the damper survive the spring strength for a long time. In the rear is the key to how I like to drift and future setup. I have no choice on what I am going to run, because that is left up to my sponsor (Rotora) on what he is able to get. Bai requested the he have dampeners thar a soft on the down stroke and stiff on the upstroke. The springs would have to be set relativly soft to allow for the shocks to compress, but still be able to reset. This setup allows the car to rock back and put more weight on the rear tires, which causes the car to increase traction and speed in the drift. Similar to drag racing, but the downstroke has to be slow and controled to make the car increase speed steadily and be stable. Benson describes it as "the car pushes while sideways" when driving the yellow S13.