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ST XTA Coilover: User Review

ST XTA COILOVER: USER REVIEW | Image 1

Disclaimer: This Product Review and Installation Write has been supplied to RSW by Ryan Jacobs. Ryan is a long term customer and he has provided his feedback to help people decide if they feel they would benefit from what he has chosen to install on his own car.

The complete original article can be read here.

For a while now I have been compiling a list of proper suspension upgrades for an awesome daily driver which can also function as an occasional track car. I’m personally looking for the "awesome daily driver", striking a fine balance between a baby daycare shuttle during the week, spirited mountain warrior on the weekends and then an occasional HPDE track car. My goal was to increase stiffness in the right areas, correct or improve suspension geometry, improve traction, and realize better overall response from driver input while limiting NVH, rattles and feeling beat up from long drives. After rounding off power/braking/cosmetic upgrades, I left suspension upgrades for the end due to NVH concerns. Before upgrading any suspension aspect, I went as far as posting standalone threads devoted to these suspension upgrade options. For my own build I needed to layout all options and label them either "awesome daily driver" (low NVH, safe for the average driver) or "track car" (possibly higher NVH, stiffer, for experienced drivers).

ST XTA Close Up | Image 2

Entry Level - ST Coilover Kit:

The list goes on and on for available coilover kits. Being that it was the first time I had ever worked with a coilover kit, I spent close to a year monitoring feedback on Bilstein, HPA, KW and ST coilover kits. For the price (family man here), the ST coilover kit seemed to provide excellent quality and performance for less than the other options mentioned above. In the beginning, I couldn’t mentally handle a coilover kit with adjustable dampening and rebound at the same time. I would spend WAY too much time and concern over what the proper setup would be. Originally I wanted a "set it and forget it" coilover kit which would provide a balance between daily driving and aggressive driving while providing the ride height adjustability. I ran the original ST coilover kit with the firmer Audi TT-RS rubber strut mounts for 20,000 miles (90% highway / 10% town) and loved them. Here was my full HYDE16 review for the original ST coilover kit:

Next Level - ST XTA Coilover kit:

Before upgrading from the original ST XTA Coilover kit, I posted a standalone thread to gather some feedback on the design and addition of an adjustable aluminium uniball top mount for fine-tuning of the camber and caster: GolfMK6 - ST Suspensions XTA Coilovers. The original ST coilover kit is a perfect suspension upgrade for the DD but if you are looking for the next level of aggressive DD (added FWD traction, tighter turns, more feedback) the new adjustable ST XTA Coilover kit offers so many features over the standard ST coilover kit. The front receives linear springs (which provide the feel we loved with the Driver Gear springs) with helper springs while the rear gets beefier progressive springs. This new ST XTA Coilover kit seems to resemble the adjustability of the KW V2 coilover kit with external adjustable damping plus ST’s new aluminium adjustable uniball top mounts for camber or caster adjustability. At the time of this ST XTA Coilover kit installation I covered the majority of other suspension upgrades such as H&R Front 26mm & Rear 24mm Sway Bars, Racingline (formerly VWR) Subframe Mount, Stern Rear Subframe Brace, SuperPro Performance Control Arm Kit, TyrolSport Rear Hatch Brace, TyrolSport DeadSet Rigid Front & Rear Subframe Collar Kits, Unibrace UB, Vibra-Technics VAG455B Torque Link (Dogbone) Bushing, Whiteline Rear Trailing Arm Front Bushings, Whiteline Sway Bar End Links.

KW's ST XTA Coilover for VW GTI | Image 3

ST XTA Coilover kit Description:

For those who demand the absolute best performance comes the ST XTA coilover. The full driving behavior of your car can be adjusted using KW damper technology along with an adjustable aluminium uniball top mount for fine-tuning of the camber and caster!

Performance driving in mind ST XTA coilovers feature KW damping technology which allows the suspension to be made either stiffer or softer depending on the driving conditions. This damping adjustment is made on the upper end of the chromed piston rod allowing the setup to be changed almost instantly. If the rebound force is increased, the car will drive with even more track stability and further reduced bodyroll. If the rebound force is decreased, the car will feel more comfortable when on the move. For increased performance, the ST XTA features an aluminium adjustable top mount allowing the camber and caster to be adjusted depending on your driving needs or vehicle setup.

ST XTA Coilover kit Unboxing:

 

Between the heavyweight cardboard box, zip ties, foam socks, dense cardboard separators to secure parts from moving, ST is another company that shows respect to their customers by spending the extra money for proper packing. There’s no doubt that when unboxing this kit, that the parts are safely transported in their packaging. Right off the bat, the hardware is impressive. It could be the attractive, shiny new struts, springs and aluminium adjustable uniball top mounts but once you pick them up you immediately reassured of their build quality. The aluminium adjustable uniball top mounts are gorgeous and very beefy. As mentioned earlier, the front receives linear 400lb springs with helper springs while the rear gets beefier 285lb progressive springs. Also included are the ride height adjustment tool and damping adjuster key for damping adjustments.

ST XTA Coilover kit Installation:

 

For reference, here is the ST XTA Installation Document. Installation is very straight forward but I would definitely recommend installing on a lift if you have the suspension experience, proper tools, torque specs and new stretch bolts. Otherwise, I would recommend having a shop perform the installation for safety and reliability reasons (immediate and long term). During the installation, I would to check the torque specs of the aluminium adjustable uniball top mounts (4 camber screws @ 17 ft/lbs & 1 center strut piston nut @ 35 ft/lbs) before installation. I ran into a mild clicking issue where luckily KMD Tuning found that one of the aluminium adjustable uniball top mounts allowed the strut piston to move or click as the wheel was turned. KMD Tuning tightened the 1 center strut piston nut down to the recommended 35 ft/lbs torque spec and reinstalled the coilover.

ST XTA Installation Process | Image 4

ST XTA Coilover kit Damping & Camber Adjustments:

For reference, here is the ST XTA Adjustment Document. Like most coilover kits, the front and rear damping is adjustable at the top of the front and rear struts. The fronts can be adjusted through the small hole in the strut tower with a long allen key. ST includes a damping adjuster key but it’s not long enough to reach down inside the strut tower so I used a general metric allen key. I decided to have KMD Tuning trim the top of strut towers for easier access to the camber plate screws and to adjust damping with the included damping adjuster key. As for the rear, before installation I spent a lot of time researching what damping level to set the rear at to avoid rear squat and front lift during straight line acceleration. After my research, the rear damping was set at the midway point (50% soft / 50% hard) before the rear struts were installed. The front damping was set at 75% soft to avoid front end lift and to also see what the daily drive would be like with the 400lb front linear springs. Again, my goal was to set the car up for maximum front traction for straight line acceleration. With the right damping rates, my traction has improved vastly and front end lift/rear squat has decreased a ton but the car feels less stable at higher speeds (tends to float) which is to be expected. My next step is to test the front end damping setting at 50% stiff to see if the front end feels more stable at higher speeds and turns without decreasing traction (or introducing wheel again).

Now, do you need to trim your strut towers? Not, but if you want to use the included damping adjuster key and adjust camber without taking the strut assembly out and get a realignment each time, then yes. Will this weaken the strut tower area? No, after talking to some Volkswagen/Audi aftermarket companies, the area that was trimmed off is purely cosmetic.

VW MK6 Strut Tower Modificiation | Image 5

ST XTA Coilover Kit End Links:

ST provides 1" shorter solid end links but I already had Whiteline adjustable end links. When trying to re-use the Whiteline adjustable end links, it was evident that even at their shortest setting they were still too long to fit within the mounting point on the strut body and sway bar connection. There are a few companies that offer shorter adjustable end links (034 Motorsport offers end links that adjust shorter than 330mm) but I decided to trim the end link bodies down with a clean, straight cut on both ends. The locking nuts still sit flush when tightened against the end link body on both ends and haven’t loosened up. The reason I decided to keep and modify the Whiteline adjustable end links was to retain the adjustability in order to remove any front or rear sway bar preload after a final alignment and corner balancing.

ST XTA Endlinks Modification | Image 6

Corner Balancing & Alignment:

At this stage I wanted to maximize the car’s handling and traction with the ST XTA Coilover kit so I setup an appointment at Redline Speed Worx and worked with their tech John with 20+ years in Porsche racing experience. As expected, an alignment was definitely required with this level of suspension work and again, my goal was to set the car up for maximum front traction for straight line acceleration. With the TyrolSport DeadSet Front & Rear Subframe Collar Kit equalizing the added caster from the SuperPro Performance Control Arm Kit, the only alignment adjustment needed was toe and camber so I relied on John’s expertise for the recommended alignment settings. In preparation for corner balancing, I was able to dial in the starting ride height at 25.25" in the front and 25.50" in the rear. After making incremental changes to the front end ride height, John was able to attain a 60% front / 40% rear vehicle weight allocation with a ~50% left to right weight allocation and ~50% cross weight. After these incremental adjustments, the final front and rear ride heights remained even left to right with me in the driver’s seat. John then adjusted and reinstalled my Whiteline end links after the final alignment and corner balancing to remove any front or rear sway bar preload with me in the driver’s seat.

VW MK6 GTI Corner Balance at RSW | Image 7

Overall Results and Recommendations:

We all have the initial honeymoon phase after new performance parts are installed but for this review I spent nearly 4 months running the ST XTA Coilover kit, starting in the colder Winter months through the current warmer Spring months. I'm well out of the break-in and honeymoon phase as these have been on my car since the beginning of January. I made sure to run them at the tail end of Winter for the coldest weather to see how harsh they could really be in frigid temperatures. As mentioned earlier, the front receives linear 400lb springs with helper springs while the rear gets beefier 285lb progressive springs. Between the linear front springs, aluminium adjustable uniball top mounts and living in pothole ridden New Jersey, the ride comfort has been surprisingly nice on the highway, town and back roads. The proven twin-tube design is great for daily driving but is very reactive if you want to get aggressive. My biggest fear was that the loss of a thick, rubber strut mount would be an issue, but it is ABSOLUTELY not from a comfort perspective. The aluminium adjustable uniball top mounts do not add much, if any NVH, but rather provides more feedback from the road. I wanted the heaviest part of this review to cover my overall feedback so instead of going on and on about how great the ST XTA Coilover kit is (and they seriously are a great upgrade), I decided to present it in the same format as my original ST coilover kit review. Below is my quick fire categorical comparison to my original ST coilover kit.

Initial Settling: Unlike the original ST coilover kit, I don’t feel that there was any settling with the ST XTA kit. In preparation for corner balancing a few months after installation, I was able to dial in the starting ride height at 25.25" in the front and 25.50" in the rear.

Coilover Noises: I’ve read that some coilover owners hear binding noises or squeaks after installing coilovers. We all know the lower we go the more stress we put on the supporting OEM suspension components but this performance oriented ST XTA kit seems to like a mild drop and not be setup as low as possible. With the corner balancing and alignment, the end links were properly set equal on both sides so I do not have any noises coming from the supporting OEM suspension components. Aside from the one aluminium adjustable uniball top mount which needed the 1 center strut piston nut tightened to the recommended 35 ft/lbs torque spec, the only noise I hear is an occasional (and subtle) repetitive tapping or clicking noise during some turns. After ruling out axles, end links, aluminium adjustable uniball top mounts, subframe and other contributing factors, I have a theory that it may be the helper springs shifting. I plan to test something soon to see if that is where the noise is coming from. Again, this is a very minimal noise that won’t hear unless you are holding your breathe to listen for it. It is not a noise I can replicate at the same speed, on the same turns or when I want, it happens here and there and I rarely catch it unless I’m really listening for it.

NVH / Cabin Noise: Compared to the original ST coilover kit, I feel that NVH and cabin road noise may have increased 10%-15% which is still very minimal for a performance oriented suspension system with 18" wheels and Bridgestone RE-11 tires. From this added NVH, the feedback from the road is primarily conveyed through the steering wheel.

Bumpiness: As for bounciness, both kits felt bumpy during break-in but the original ST coilover kit still remained a tad bumpy at times while the new ST XTA kit bouncing at low speed cruising is barely noticeable.

On-ramps / Off-ramps: Compared to the original ST coilover kit, confidence in traction and body roll has increased even at the 75% soft damping setting up front. These coilovers provide more confidence through a turn and manage body roll when paired with properly sized sway bars. My next step is to test the front end damping setting at 50% stiff to see if the front end feels more stable at higher speeds and turns without decreasing traction (or introducing wheel again).

Braking: No more nose dives when stopping short, the front end feels more supported so you don’t feel like the car goes into a heavy rake situation before you resume acceleration.

Traction: With the damping settings, alignment specs, and corner balancing my goal was to set the car up for maximum front traction for straight line acceleration. With this setup, the car feels planted, firm, traction feels great and smooth. With the right damping rates, my traction has improved vastly and front end lift/rear squat has decreased a ton.

Wheel Hop: What’s wheel hop like again? GONE with the front damping set to 75% soft.

Steering Wheel Response: Thanks to the ST XTA aluminium adjustable uniball top mounts, steering wheel input and feedback from the road have been enhanced, making the front end feel more nimble, similar to when you switch to lighter wheels.

Dips in Highway (high speed): Similar to the original ST Coilover kit, I don’t feel like I’m going to bottom out as it has eliminated the bouncing or the hard compression when rolling over a dip in the road. The same highway dips I’m used to on my highway commute to work barely affect the car.

Dips in Road (low speed): At low speeds, dips in the road barely affect the car.

Potholes: I avoid them at all costs along my typical daily driving route so I have no feedback here.

Uneven Road Surface Levels / Joints: Even when rolling over the transition of uneven road surfaces (think when roads are prepped for repaving and the road dips), the car soaks up the change in road planes. I do not feel like my teeth are going to rattle out of my face or like I’m bruising my kidneys.

Railroad Tracks: At slow speeds it no longer feels like panels are falling off the inside of my car, smooth and quiet if I "crab walk" the car over the tracks.

Speed Bumps: I always take these at under 5mph and I used to even approach speed bumps on an angle with one wheel rolling over the speed bump at a time to reduce the front end pogo stick feeling of both wheels bouncing at the same time. The pogo stick feeling is not present and I can roll both front wheels over a speed bump at the same time without the car feeling like it’s on a pogo stick.

I’ve tested this ST XTA Coilover kit through pothole-infested daily driving and weekend bashings through the mountains. With 18" wheels, Bridgestone RE-11 tires and the other upgrades listed in my build thread (see link in signature below), the NVH and road harshness is at a minimum. With any financial investment towards suspension upgrades, we worry about deteriorating the ride quality of our vehicle. This performance oriented ST XTA Coilover kit makes the ride quality extremely enjoyable but also provides the next level of performance for spirited driving with damping and camber adjustability. I am genuinely satisfied with the damping adjustability, handling, comfort, low noise levels and improved feedback from the road. Overall, the ST XTA Coilover kit is a high quality, affordable suspension upgrade which provides great value and features for the price.

High level summary of Pros and Cons:

Pros:

  • KW/ST quality, reputation, customer service
  • front camber adjustability
  • twin-tube shock design for comfort with front and rear damping ability
  • low NVH increase in the form of road feedback through steering wheel
  • gain in traction depending on front damping settings
  • front receives linear 400lb springs with helper springs while the rear gets beefier 285lb progressive springs

Cons:

 

  • issue with the original top mount
  • slight occasional low volume clicking noise under turns now
  • adjuster key does not fit without modifying the struts
  • requires shorter adjustable end links if user decides not to use included fixed length ST end links
  • top damping adustment for rear struts
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