Softer front springs for my XTA Coilovers

[Lucky_13]

Yep, Norm is always good for a calm,reasonable response. Your wheel and tire package is huge, so the dampers might be getting a bit overwhelmed. But with the relatively huge OEM bar sizes on our cars, people underestimate the real world effects of the bar on ride quality.

The Vorshlag guys have a point, though. KW isn't necessarily crap, but the jump from them to some of the higher end dampers can be significant. In my experience, the KW stuff I have driven on is still worlds better than Koni, etc which is to be expected from the price. But if you ever have the chance, take a ride in a car equipped with MCS, JRi, Penske, etc. You can feel the difference.

 

[Vorshlag-Fair]

Your wheel and tire package is huge, so the dampers might be getting a bit overwhelmed. But with the relatively huge OEM bar sizes on our cars, people underestimate the real world effects of the bar on ride quality.

Agreed. I've got a funny story about this... One of my good friends (a Vorshlag tester and former Roush Engineer) has a 2015 Mustang GT PP. We just sold him some bigger Eibach swaybars to go with his prototype Vorshlag S550 camber plates to work with the OEM springs...

As he was removing the STOCK front swaybar he realized it was BOUND UP IN THE STOCK MOUNTS. This adds a LOT of stiction and effectively spring rate, if the bar will not pivot smoothly in the mounts. We make sure that any swaybar we install on any car takes only "pinkie finger" force to rotate in the mounts, with the end links removed. Virtually every swaybar ever sold has mounts that do not fit the bar properly - always always too tight.

When he installed the Eibach swaybars the supplied mounts didn't fit either. He modified the body mounts to where the new swaybar rotates effortlessly and smoothly - lo and behold, the ride quality IMPROVED over stock.

There are a lot of factors that go into both OEM and aftermarket components... knowledge is power.

 

[Lucky_13]

As he was removing the STOCK front swaybar he realized it was BOUND UP IN THE STOCK MOUNTS. This adds a LOT of stiction and effectively spring rate, if the bar will not pivot smoothly in the mounts. We make sure that any swaybar we install on any car takes only "pinkie finger" force to rotate in the mounts, with the end links removed. Virtually every swaybar ever sold has mounts that do not fit the bar properly - always always too tight.

Yup, in the OEM world we call this a gripper bushing...spunkens up turn in a bit, but definitely adds parasitic rate, which increases wheel rate. When bar sizing is limited by other factors (supplier, etc.) it's a way to hit a certain target.

I chuckle sometimes when people replace the S197 bar with a "stiffer" bar, but that manufacturer hasn't tested the bar in its bushings. I'd wager some of the aftermarket bars that claim 10% on the softest hole or whatever are actually less stiff than the OEM bar when connected to its mounts - unless people crank down on those poly bushings, which as you mention happens quite frequently.

 

[CobraRed]

I also have ST XTA's.

I found the 400's up front to be completely mild. Not rough at all and not a track spring.

The rears (I called KW too, they wouldn't tell me the rear progressive rate, good to know) I replaced with 250# linear's and the ride quality overall I'd say improved. Those soft rears just made the rear end react with so much elevation change it was annoying and not super predictable.

It makes sense that going less on the front sway addressed your problems. Glad it worked out. With my set up, I have zero complaints about these coilovers.

I do use BMR's monster bar up front (partly because I think a 450-500lb spring would be ideal and like being able to adjust the bar to partly simulate some of this). It's only on hole 2/5 and is "finger loose" with endlinks off.

 

[o2sys]

My swaybars are not finger loose but not tight either. Yeah been driving for a while now and the swaybars were the main culprit especially going over uneven roads with lots of bumps and potholes.