Softer front springs for my XTA Coilovers

o2sys

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So I recently found out what springs rates come with my ST XTA Coilovers. This is directly from them:

Front Liner - 70N/mm or 400lbs/in
Rear Progressive - about 35N/mm or 200lbs/in.

So I asked if they offer a softer rate and they only offer a softer front and told me that either 286lbs/in or 343lbs/in compatible with the shocks valvving.

So in my quest for a better ride for a daily driver I was initially going to ditch the Coilovers and go with the traditional lowering spring and shock combo. Like H&R super sport w/ konis but now might consider swapping out my coil springs.

What do you think? 343lbs is barely any difference from the 400, so maybe try the 286lbs?
 

Lucky_13

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I used to have KW V3s on my car, and they used the 343 lb/in front spring, per KW. I wouldn't say it rode any better than my current JRi 400 lb/in, but those come with higher end monotubes and different damping. My guess is that the 286 lb spring will ride better until it doesn't - that is, it'll feel softer but bottom out/bumpstop engage more, so you'll get a soft-hard-soft-hard feeling. I think only rebound is adjustable on the XTA, so you can't tweak the bump curve to compensate.

That being said, I know the spring/koni combo is a popular one but I've had Konis with 4-5 different springs (BMR/P Spring/K Spring/Steeda Sport) and I felt they all rode like a dump truck. Wasn't until I swapped the Konis out of the equation that the feeling went away. I'm a NY city area native that moved out to Michigan, and had the car on both sets of (awful) roads, so your tolerance and mileage may vary. The car handled fairly well, though.

I had the Vorshlag StreetPro (P springs) setup prior to the V3s, and the bilsteins rode much better. I replaced them because the strut ear sway bar mount welds failed and sent me into the dirt at 80 mph; there was rust under the weld hidden by the paint. Probably would have stuck with them if not for that, to be honest. The rear dampers felt a tad low in the rebound department, but other than that they were solid.
 

Norm Peterson

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Is it the front or the rear that you really want softer? And are the rear springs actually mounted on the shocks or are they still on the OE perches (as Vorshlag and others generally do)?

If it's the rear and the springs are still in the OE locations, know that there isn't much room between the 200 lb/in springs that you have and the OE springs that range between 140-ish and 180 or so.


Norm
 

o2sys

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It's the front that I want to change to a softer rate. The rears are on OEM locations.
 

Mark Aubele

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IMO, if 400lb springs are too stiff for you, put the stock stuff back on. Even 400s aren't really adequate for these pigs on track with any kind of lowering. I was pounding bumpstops on 350s only lowered an inch on track. Started at 350, then 550, now at 800.
 
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o2sys

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But the shocks are shorten for the lowered height. This will still make them bottom out?
 

Mark Aubele

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Not necessarily, but these are heavy cars, and 400# springs really aren't that stiff. Depends on usage. Damper has a ton to do with ride as well.
 

Champale

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Part of the equation might be what wheels and tires are you running?
 

Champale

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I can honestly say I have never heard of those sizes on our cars!

What brand/model of tire and how heavy are your wheels? Obviously, what I am getting at is that some tires ride terribly and heavy wheels can make it worse.

For instance - I am running Michelin PSS 285/30/20 and 295/30/20 on light-ish wheels (~27lbs) with KW V3s and I don't find the ride objectionable at all. It would never be mistaken for a plush ride, but it doesn't crash or bobble over bumps or anything. Feels a lot like 911 Porsches I have driven.
 

o2sys

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Pirelli Pzero Nero A/S tires on Saleen 7 spoke wagon wheels 20x9 & 20x10. They are not lightweight wheels by any means just your typical cast wheels probably around 30lbs.
 

csamsh

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Agree with other Mark on this one. Your culprit is the damper not the spring.
 

o2sys

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Do you think stiffer front swaybars affect the ride quality as well?
 

Norm Peterson

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Under some conditions, like hitting a raised bump with one front wheel, yes.

But under others (like encountering a one-wheel pothole) the ride quality can be better (the involved wheel might not "fall" quite as far or as fast, and the bar ends up being slightly more helpful in assisting the far side of the hole pushing the wheel back up). One way to look at it.


Norm
 

o2sys

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Maybe I'll start with that, I have the front swaybar set to full stiff right now.
 

o2sys

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So KW dampers are crap quality?

Also that why I went with 40 series walls so it would be similar to 19s as far as sidewall aspect ratios go.
 
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csamsh

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That's like a...29" tall tire? Dayum.

They'll never be as comfortable as your bilsteins. Small twin tubes with small pistons. Not much you can do about it.
 

DevGittinJr

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Not crap, but twin-tube; which don't seem to ride as well as mono-tubes on anything with more rate than a typical lowering spring.

My front springs are 630# and ride no worse than an exotic, as mentioned above. It took quite a bit of work to make it comfy though. With higher spring rates, EVERY BIT of bind gets exaggerated. Suspension set-up (tuning) makes all the difference. Helm-joints in the rear (at the axles as opposed to chassis) seem to actually help ride quality, and some c/c plates (MM) have bump travel adjustment. Also, lowering the front spring rate from 400# is likely to reduce front grip.

It shouldn't affect ride quality, but those tire sizes seem awfully large, in diameter, as well. To run a 40 series I'd think you'd want to go with an 18" wheel and keep the outer diameter at or below stock. 265/35-20 is 27.3" tall (stock dia.). I run them on 9's, square, and they ride a bit softer than 255's on the same wheels. AS SOON AS I save enough for the 18's I want, the 20's are gone though.
 

o2sys

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I softened up the front swaybar and this has seemed to improve the ride quality drastically.
 

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